Anatomy – Exam 1

Introduction to Anatomy ○ Objectives

Describe anatomical position. Why is it significant?

Identify the planes of reference used to locate the structure of the body

Define and be able to properly use descriptive and directional anatomical terms

○ Anatomical Position – standing erect, palms forward

○ Supine – reclining, face up

○ Prone – reclining, face down

○ Body Regions

Axial region – contains thorax and abdomen

Appendicular regions

Upper limb

Arm – shoulder to elbow

Forearm – elbow to wrist

Wrist, hand, fingers

Lower Limb

Thigh – hip to knee

Leg – knee to ankle

Ankle, foot, toes

○ Anatomical Planes

Saggital – divides into right and left halves

Midsaggital – right at midline

Coronal (frontal) – divides into anterior and posterior

Transverse (horizontal) – divides top and bottom

○ Terms of Position

Ventral (anterior) – front of body

Dorsal (posterior) – back of body

Superior (cranial) – toward the head

Inferior (caudal) – toward the feet

Midline

Medial – toward the midline

Lateral – away from the midline

Core

Internal – toward the core

External – away from the core

Surface

Superficial – toward the surface

Intermediate – between the surface

Deep – away from the surface

Attachment

Proximal – close to the point of attachment

Distal – away from the point of attachment

○ Terms of Movement

Angle

Flexion – decrease the angle between two bones

Extension – increase the angle between two

bones

Midline

Abduction – moving away from midline

Adduction – moving toward the midline

Rotation – movement around a long axis

Circumduction – circular movement where the structure forms a cone

Palms

Latin Singular vs Plural

Singular Plural Example -a

-ax

-en

-ex

-is

-is

-ix

-ma

-on

-um

-us

-us

-us

-x

-y

-yx

-ae

-aces

-ina

-ices

-es

-ides

-ices

-mata

-a

-a

-era

-i

-ora

-ges

-ies

-ices

Axilla, axillae

Thorax, thoraces

Lumen, lumina

Cortex, cortices

Diagnosis, diagnoses

Epididymis, epididymides

Appendix, appendices

Carcinoma, carcinomata

Ganglion, ganglia

Spetum, septa

Vicus, viscera

Villus, villi

Corpus, corpora

Phalanx, phalanges

Ovary, ovaries

Calyx, calices

Because radius and ulna rotate over each other

Supination – turning palms up

Pronation – turning palms down

Foot

Dorsiflexion – bring foot up

Plantar flexion – push foot down

Sole of Foot

Inversion – turn sole of foot medially

Eversion – turn sole of foot laterally

○ Select Surface Landmarks in Anatomical Position

Cephalic – head

Cervical – neck

Cheek – buccal

Mental – chin

Inguinal – groin

Olecranal – back of elbow

Popliteal – hollow behind the knee

Sural – calf of leg

Femoral - thigh

Calcaneal – heel of foot

Acromial – shoulder

Axillary – arm pit

Brachial – arm

Cubital – hollow of elbow

Antebrachial – forearm

Pollex – thumb

Coxal – hip joint

Tarsal – ankle

Hallux – great toe

Organization of the Nervous System ○ Objectives

Describe the basic anatomical organization of the nervous system

Diagram a typical neuron and list its parts. Identify distinguishing characteristics of motor and sensory neurons

Describe the gross anatomical features of the spinal cord

Describe the location, organization and structure of the spinal meninges

Diagram a cross section through the spinal cord. Be able to label all of the parts as described in class

Describe the components of a typical spinal nerve and explain the normal branching pattern

Explain the numbering of spinal nerve pairs

Give the definition of a spinal cord segment. Explain the difference between the spinal cord segment and the vertebral level

Define the term dermatome and state its clinical significance Give the anatomical basis for administering a successful lumbar puncture

○ Two ways to organize

Functional Organization

Somatic components – somatic afferents (receive sensory information) and somatic efferents (send

muscle information)

Visceral (autonomic) components – visceral afferents and efferents that innervate smooth muscle,

cardiac muscle and glands

Anatomical Organization – more common

Central Nervous System – brain and spinal cord

Peripheral Nervous System

○ Cranial Nerves – mostly directly attached to brain

12 pair; Innervate head and neck

○ Spinal Nerves – 31 pair, attached to spinal cord; innervate everything else

○ Types of Neurons

Multipolar – many processes; motor neurons

Pseudounipolar - primary sensory neurons

Peripheral process - „dendrite‟

Central process – „axon‟

○ Definitions

Nucleus – collection of neuronal cell bodies within the CNS (collected because they do the same thing)

Ganglion – collection of neuronal cell bodies outside the CNS

Tract – nerve processes (axons) bundled together in CNS

Nerve – nerve processes bundled together in in PNS

Gray matter – unmyelinated

○ Spinal Cord

Connects brain to body; responsible for spinal reflexes; continuous with brain

Afferent (sensory) – receives from body

Efferent (motor) – sends away from CNS

Size and shape

In general it tapers as it gets down to coccyx since less information is transmitted as you go down

Cervical Enlargement – between C4-T1, due to upper limb connections

Lumbar Enlargement – between L3-S3, due to lower limb connections

Conus Medullaris – tapered inferior end of spinal cord

Cauda equina - „horse tail‟ – a continuation of dorsal & ventral rootlets for spinal nerves below vL2

(where spinal cord stops)

Protection

Vertebral Column – spinal cord housed in vertebral foramen

Meninges – three connective tissue coverings that surround the brain and spinal cord

○ Dura mater – (tough mother) outermost layer, dense CT

Continues into sacrum to vS2 (it is longer than spinal cord) and is anchored to coccyx

○ Arachnoid mater – thin transparent membrane with thin weblike extensions that connect to pia

mater

Normally contacts dura mater

Ends at S2 with the dura mater

○ Pia mater – (delicate mother), very thin layer of CT which can‟t be taken off spinal cord

Follows every contour of CNS

Filum Terminale – inferior extension of the pia mater from the conus medularis

○ Attached inferiorly to inferior part of dura at vS2

○ Inferior anchor for spinal cord

Denticulate Ligaments – lateral extensions of pia mater

○ Act as lateral anchors (and connect to dura mater?)

Spaces Between Meninges

○ Epidural Space – between dura and bone

○ Subdural Space – between arachnoid and dura mater

only a potential space, nothing is there normally

○ Subarachnoid Space – between arachnoid and pia

Contains CSF

Internal Structure of Spinal Cord

Gray and white matter

Dorsal horn – contains axons involved with sensory reception

Ventral horn – contains nuclei of multipolar motor neurons

Lateral horn – contains autonomic neurons

○ only in T1-L2 & S2-S4

Spinal Nerves

Formation of Spinal Nerves

○ Dorsal Root – sensory, between dorsal horn and dorsal root ganglion

○ Dorsal Root Ganglion – where nuclei of pseudounipolar sensory neurons are housed

○ Ventral Root – contains axons of motor neurons

○ Spinal Nerve – DRG and ventral root unite and form spinal nerve

Are mixed nerves because they have afferent and efferent neurons

○ Intervertebral foramen – where spinal nerve comes out

Only visible when two vertebra are stacked on top of each other

Branches of Spinal Nerve

○ Each branch of the spinal nerve is still a mixed nerve

○ Dorsal primary ramus – innervates skin and muscles of back

○ Ventral primary ramus – innervates all other skin and muscles (trunk, limbs, etc.)

Is much bigger because it innervates more things

Number of Spinal Nerves

○ 31 pairs

○ Numbering – all spinal nerves (except the cervical ones) exit below the vertebra they are named

after (ex. T1 exits below T1)

Exception – C1 spinal nerve exits above vC1, C2 spinal nerve exits below vC1

○ C8 exits below vC7

○ Cervical – 8

○ Thoracic – 12

○ Lumbar – 5

○ Sacral – 5

○ Coccygeal – 1

Spinal cord level vs Vertebral level

○ Spinal Cord Segment – portion of spinal cord that contributed to the formation of the spinal

nerve

○ Vertebral Level – anatomical landmark that is associated with a specific vertebrae

Ex. Spinal cord ends at vertebral level L2

○ Why? At birth spinal cord and vertebral column end at same place, but vertebra grows

Dermatome – area of skin supplied by a single spinal nerve

Lumbar Puncture – done in area of cauda equina so that spinal cord is not affected

This allows for CSF to be sampled from the dural sac

Back ○ Objectives Vertebral Column

Define the normal and basic pathological spinal (postural) curvatures

Identify the features of typical vertebra

Distinguish the characteristics of vertebrae from different regions of the vertebral column

Describe the joints and ligaments of the vertebral column. Understand how these contribute to movements of the

vertebral column

Describe the craniovertebral joints (atlanto-occipital; ligaments between atlas, axis and occiput)

Understand how spinal nerves emerge from the vertebral column.

Describe the relationship between the number of spinal cord segments/spinal nerves and vertebral level

Describe how the length of the spinal cord changes during development relative to the length of the vertebral canal

Explain the blood supply of the spinal cord and vertebral column and identify the sources Muscles of the Back

Define the muscle groups associated with the back. Contrast their actions and innervation

Identify the attachments and compare the functions of the superficial (extrinsic) back muscles; trapezius, latissimus

dorsi; levator scapulae and rhomboids (these will also be considered with the upper extremity)

Identify the attachments and compare the functions of the basic attachments of intrinsic back muscles

○ Movements of the Back

Extension, flexion, lateral flexion, rotation

○ Vertebral Column

31-33 Vertebrae

7 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral (fused), 2-4 Coccygeal (fused)

Sacral Hiatus – opening in the inferior portion of the sacrum that you can feel

Closed by a membrane

Contains – filum terminale (which passes through to coccyx) and fat

Important for caudal anesthetic

Curvatures of the Vertebral Column

Types

○ Kyphosis – anteriorly concave curvature of the vertebral column

Occurs normally in thoracic and sacral regions

Abnormal exaggeration occurs in the thoracic region

○ Lordosis – anteriorly convex curvature of vertebral column

Occurs normally in cervical and lumbar regions

Abnormal exaggeration usually occurs in lumbar region

○ Scoliosis – abnormal lateral curvature of the spine

Development of Curvature

○ Primary curvature – anything that is kyphotic (thoracic, sacral)

Early in development all curvature is kyphotic

○ Secondary curvature – anything that is lordotic (cervical, lumbar)

This curvature is associated with weight bearing

First to develop is lumbar (right around birth)

Typical Vertebra

Vertebral Body –

Pedicle – attaches directly to vertebral body

Lamina – connects pedicle to spinous process

Vertebral Arch = lamina + pedicle

Vertebral foramen = lamina + pedicle + vertebral body

Spinous process

Transverse process

Superior and Inferior articular processes

Zygapophyseal joint – superior articular process + inferior articular process from above

○ One on each side of the spinous process

Superior vertebral notch + inferior vertebral notch = intervertebral foramen

○ Spinal nerve passes through intervertebral foramen (so does DRG)

Distinguishing Characteristics of Vertebrae

Cervical (8) ○ Transverse foramen – hole in transverse process where vertebral artery passes through

○ Transverse process has posterior tubercle and anterior tubercle

○ Spinous process is bifid

○ Vertebral body is more square

Thoracic (12) ○ Has facets for the ribs (flat connecting points)

Each rib has three contact points, one on the transverse process, one on the superior facet of

vertebral body, one on inferior facet of vertebral body on the vertebra above

Ribs are only in the thorax

○ Spinous process is angled inferiorly

○ Vertebral body is heart-shaped

Lumbar (5) ○ No transverse foramen or rib facets

○ Spinous process is short and sturdy

○ Vertebral body is large and kidney-shaped

Special Vertebral Bones

Both have transverse foramen just like other cervical vertebrae

Atlas (C1) – “holds world on shoulders” – the skull rests on it

○ Lacks vertebral body – has anterior and posterior arches instead

○ Superior articular facet touches skull

Axis (C2) –

○ Dens (odontoid process) – used to be the vertebral body of C1, but now it is fused to C2

Vertebral Ligaments

Anterior Longitudinal – on anterior side of vertebral body

Posterior Longitudinal – on posterior side of vertebral body, inside vertebral canal

Supraspinous ligament – on dorsal side, connects spinous processes

○ From cervical region on up this ligament is called the nucal ligament

Here it becomes triangle shaped? And fills up a greater area

Interspinous ligament – in between spinous processes (lots of CT)

Ligamentum Flavum – covers vertebral arch

○ Connects adjacent laminae

○ Flavum = yellow

Intervertebral Discs

Numbering – eg L4-5 disc is between L4 and L5

There is no disc between C1 & C2

Anulus Fibrosis – outermost part of disc

○ Contains fibrocartilage rings that are thinner posteriorly (where rupture occurs)

○ Vascularized

Nucleus Pulposus – inner part of disc

○ Contains mucoid – made of reticular & collagen fibers

Avascular

70%-90% water

Water content decreases with age and is associated with decrease in height, decrease in

compresibility and increased probability of rupture

Disc Herniation

○ Nucleus pulposus protrudes through annulus fibrosis

○ Occurs most frequently in cervical and lumbar regions

○ Most frequent site = in posterolateral direction (often to either side of the posterior longitudinal

ligament)

This will compress the spinal nerve

○ Affects lower spinal nerve root

Ex. L4-5 disc herniation affects L5 nerve root

Atlanto-Occipital Joint

Anterior Atlanto-occipital membrane - ?

Posterior Atlanto-occipital membrane – connects posterior skull to posterior portion of C1

○ Covers spinal cord

Internal Ligaments (plate 22)

○ Tectorial Membrane – continuation of posterior longitudinal ligament starting at C2

○ Cruciform ligament – where the bands cross it holds posterior of dens in place, composed of

three bands

Superior longitudinal band – connects to skull?

Transverse band – connects laterally to C1

Inferior longitudinal band – connects to vertebral body of C2

○ Alar Ligaments – laterally connect dens to skull (two of them)

○ Apical ligament of dens – connect anterior of dens to skull

○ Back Muscles

Origin – more medial, less movement

Insertion – more lateral, more movement

Overview of Musculature

Extrinsic Back Muscles (quick overview)

○ Control Upper Limb Trapezius – connects shoulder to neck Latissimus dorsi – connects lower back to side?

Rhomboid mm (major and minor) – connects shoulder blade to spine

Levator Scapulae –

○ Accessory respiratory mm

Serratus posterior inferior muscle – lower ribs to lower back

Serratus posterior superior muscle ○ Innervation

Ventral rami of spinal nerves

Accessory n (CN XI) for Trapezius

Intrinsic Back Muscles

○ True back muscles, maintain posture, move vertebral column and head

○ Superficial Layer

Looks like one bundle, but splenius cervicis is inferior

Spine to head

○ Intermediate Layer

Erector spinae mm

○ Deep Layer

Transversospinal (starts on TP ends in spine?)

○ All extend spine or head

○ All rotate to opposite side

○ All are TP to SP

○ Innervation

○ Dorsal rami of spinal nerves

Intrinsic Back Muscles

Origin Insertion Action

Superficial Layer

Splenius Capitis – more

medial than cervicis

SP (T3-C3) -superior

nuchal line -mastoid

process

-Bilateral – extends head

-Unilateral – laterally flexes and rotates head to same side

Splenius Cervicis SP (T3-6) TP (C1-3) -Bilateral – extends head

-Unilateral – laterally flexes and rotates cervical spine to same

side

Intermediate Layer - Erector spinae

Spinalis -

most medial

Capitis

Cervicis

Thoracis

SP SP Bilateral – extends spine & head

Unilateral – lateral flexion

Longissimus

Capitis TP & AP mastoid

process

rotates head to same side

Bilateral – extends spine & head

Unilateral – lateral flexion (only

acts against gravity) Cervicis TP & AP TP

Thoracis -Sacrum

-iliac crest (common tendon)

-SP and TP

-Ribs

-TP

Iliocostalis -

most lateral

Cervicis ribs TP Bilateral – extends spine Unilateral – lateral flexion Thoracis ribs ribs

Lumborum -Sacrum

-iliac crest (common tendon) -TF

-ribs

-deep TF

Deep Layer - Transversospinal

Semispinalis - highest TP SP Bilateral – extends spine & head Unilateral – lateral flexion,

rotates to opposite side

Multifidis – mostly in

lumbar

TP SP Note - origin and insertion 2-4

vertebrae apart

Rotatores TP SP Note - Origin is 1 vert below

insertion

○ Note – SP = spinous process, TP = transverse process, AP = articular process, TF =

thoracolumbar fascia

○ Note – thoracolumbar fascia is the covering of deep back muscles

Innervation

○ Dorsal Rami innervate

Intrinsic back muscles

Middle skin of back

○ Sensory Innervation

Dorsal rami – innervates middle of back

Ventral rami – innervates lateral parts of back

○ Ex. Supraclavicular nerves (from cervical plexus)

○ Ex. Lateral branches of intercostal nerves

Vasculature (Plates 171 & 172)

○ Arteries

Neck

○ Vertebral Artery – supplies vertebral column in the neck

○ Ascending cervical artery -

○ Deep cervical artery -

Posterior intercostals artery - in thorax

Lumbar arteries – in abdomen (a small branch goes into the canal)

Lateral sacral arteries – in pelvis

○ Feeder Arteries

Two Paths

○ Thoracic aorta → posterior intercostals artery → spinal branch →

radicular artery → ant and post segements to dorsal and ventral roots

segmental medullary artery → ant and post segements to dorsal and ventral roots →

spinal arteries From there both the radicular and segmental medullary arteries split into posterior and anterior segments and supplies dorsal

(including DRG) and ventral roots

The segmental medullary then goes on to supply the spinal cord (via spinal arteries), the radicular artery does not

Extra notes

○ Spinal branch – at posterior aspect of vertebral body and vertebral arch

○ Segmental medullary artery varies in level of origin and number

Average 8 anterior and 12 posterior

Great anterior segmental medullary artery – supplies 2/3rds of spinal cord

Mainly in thoracolumbar region

○ Spinal arteries – 2 posterior and 1 anterior

○ Veins (plate 173)

Drainage of spinal cord

○ anterior and posterior spinal veins (inside pia mater, right between halves of spinal cord)

→ radicular and segmental medullary veins (they look the same) → internal venous

plexus (inside vertebral canal in extradural fat) → external venous plexus (surrounds

vertebral column

Extra notes

○ Veins inside the spinal cord (and head and neck) are valveless, but radicular and medullary

veins do have valves

○ Clinical point – due to the low venous pressure (since no valves?) venous stasis can cause

dangerous change in pressure within the spinal cord

Clinical signs include gait disturbances, spastic paralysis and sensory deficits

Development of Extraembryonic Membranes and Bilaminar Embryo ○ Objectives Define and describe: hypoblast, epiblast, primitive streak, primitive node, notochordal process, prochordal plate, cloacal

plate, notochord, ectoderm, mesoderm, endoderm

Describe the formation of the bilaminar embryonic disc from the inner cell mass

Describe the formation of the extraembryonic mesoderm

Describe the formation of the primary and secondary yolk sacs

Describe the formation of the body (connecting) stalk

List three functions of the secondary yolk sac

Define and describe: lacuna, intervillous space, deciduas basalis, deciduas capsularis, deciduas parietalis, amnion, chorion

Describe the formation of the amnion and the chorion List the functions of the placenta

Describe the morphological changes that occur during the development of placental villi

Describe the components of the placental membrane or “barrier”

Describe the formation of the amniotic fluid

List several functions of the amniotic fluid

Define amniocentesis and list several indications for the procedure

Integument ○ Objectives List and describe the morphology and function of the layers in the skin

List and describe the morphology and arrangement of the layers and components in the epidermis, dermis and hypodermis

List and describe the morphological and functional changes in epidermal cells as they move from the basal lamina to be sloughed off at the surface of the stratum corneum

List and describe the morphology and function of all cells in the epidermis

Describe the morphology of the epidermis/dermal junction and its functional significance

Define and describe the cleavage linds of Langer and their clinical significance

Describe the arrangement of the blood supply to the skin and relate it to temperature regulation

List and describe the functions of the skin

Integrate the morphology of the skin to its functions

List and describe the arrangement and location of skin appendages (hair, glands, nails)

List and describe the arrangement of the parts and layers of the hair and hair follicle

Relate the layers of the epidermis to those of the hair follicle and nails

Define and describe terminal, vellus hair and lanugo hair; give their distribution over the body List the parts and describe the growth cycle of hair

Describe the process by which a hair shaft increases in length

Integrate the morphology of hair and its function

List and describe the morphology, function and secretion of the 3 types of glands (sebaceous, sudoriferous and ceruminous)

List the distribution of different types of glands across the body

List and describe the morphology and function of the parts of nails

List and describe the morphology, function and location of the sensory receptors of the skin (free epidermal nerve endings,

Merkel endings, Pacinian corpuscle, and Meissner‟s corpuscle)

○ Integument Overview

Consists of Two Components

Appendages of Skin – derived from the epidermis and associated with the skin

○ Hair, glands (sweat, sebaceous, ceruminous), nails

Skin (Integument)

○ Covers entire surface of body

○ Variable thickness across body, thicker on dorsal surface, thickest between shoulders on back

○ Continuous with mucosal linings of the body orifices

○ Mucocutaneous junction – (ie. lips) reddish due to blood in capillaries and lack of keratin in

cells

Basic Structure of Skin

Epidermis Dermis Hypodermis

Stratified squamous

keratinized epithelium

Derived from ectoderm

Avascular

Sits on basement membrane

Has 5 layers

Stratum Basale

Stratum Spinosum

Stratum Granulosum

Stratum Lucidum

Stratum Corneum

Dense irregular connective tissue

Derived from mesenchyme

Vascular – supplies nutrients to

epidermis

Has 2 Layers

Papillary Layer – superficial

layer immediately underneath

epidermis

Characterized by dermal

papillae Reticular Layer – deepest

and thickest layer, contains

skin appendages

is not part of the skin

Areolar connective tissue

(loose CT with fat in it)

Other names -

subcutaneous/superficial

fascia and panniculus

adiposus (when in

abdomen)

Dimples – where dermis is tightly attached to underlying deep fascia or bone

Functions of the Skin

Mechanical Protection – trauma, bacteria, UV

Maintenance of Body Fluids – prevents dessication (waterproof), prevents absorption

○ Excretion – sweat glands secrete water, ions, urea, ammonia (just like kidney)

Maintenance of Body Temperature – sweat cools body, blood vessels bring warm blood to

surface to radiate heat, adipose tissue insulates

Synthesis of Vitamin D ○ In Skin: Vit D precursor + UV → another precursor (cholecalciferol)

○ In Liver: cholecalciferol → 25 hydroxy cholecalciferol

○ In Kidney: 25 hydroxy cholecalciferol → vitamin D

○ Function – Vit D stimulates Ca and PO absorption in gut

Immunity – contains wandering cells of immune system

Reception of Sensory Stimuli ○ Communication – embarrassed, nervous, cyanosis, jaundice, age, nerve damage

Repair – repairs and forms scars

Morphology of Skin

Epidermis

○ Layers of Epidermis

"Ball State Girls Love Cock"

Stratum Basale (Germanitivum)

○ Deepest layer

○ Diagnostic Characteristic – single layer of cells sit upon basement membrane

○ Shape - Cuboidal to columnar

○ Mitosis occurs here (constantly resupplies epidermis with new cells)

Stratum Spinosum ○ Diagnostic Characteristic – spiny appearance, the „spines‟ are where desmosomes attach

and hold adjacent cells toether into one unified sheet

○ Several layers

○ Shape - irregularly shaped cells

○ Artifact – gaps between cells form due to shrinkage during tissue processing

Stratum Granulosum ○ Diagnostic Characteristic – contains numerous, darker staining keratohyalin granules

(which are involved in keratinization)

○ Narrow layer, 3-5 cells thick

○ Shape – flattened with nuclei disappearing (as you get more superficial)

Stratum Lucidum

○ Diagnostic Characteristic – cells and nuclei are not visible at light level

At EM level, the cells are indistinguishable from stratum corneum (thus can be

considered part of stratum corneum)

○ 2-3 cells thick

Stratum Corneum

○ Diagnostic Characteristic – no nuclei visible

○ Numerous layers of dead cells

○ Cells filled with keratin

○ Stratum disjunctivum – part of stratum corneum where superficial cells slough off

○ Types of Epidermis

Thick (Glabrous) Skin – lacks hair and sebaceous glands

○ Refers to thickness of epidermis only, not thickness of entire skin with dermis

○ Epidermis more than 1mm thick

○ Found only on palms and soles

Thin (hairy/non-glabrous) Skin – characterized by presence of hair & sebaceous glands

○ Another Diagnostic Characteristic – reduced thickness of stratum corneum, granulosum &

spinosum (basically the three outermost)

○ Stratum lucidum is absent

○ Found everywhere else

○ Epidermal Cell Types

Keratinocyte – produces keratin, main cell of epidermis

○ Derived from ectoderm

Melanocyte – pigmented cell

○ Found only in stratum basale

○ Derived from neural crest cells

Langerhans cell – mobile immune system cells scattered in stratum spinosum

○ Appearance - Stellate shape with many branches, clear cytoplasm

○ Present antigens to helper T cells

Merkel cell – cutaneous mechanoreceptors responsible for light touch

○ In stratum basale

○ Appearance – small clear cell

○ Do not contain catecholamiens (why is this important?), innervated by single axon

○ Keratinocytes in More Detail

Create the protective, waterproof barrier

Cytomorphosis – differentiation and maturation (takes 26-30 days)

○ Keratinocytes do this, they start in the stratum basale and move to stratum corneum

As keratin builds up the cells start to die, this is the degeneration phase

Keratin – fibrous proteins that make up intermediate filaments

○ Amount of keratin in the cell increases as it migrates toward surface

Keratinization in Each Layer

○ Fibronectin in basement layer regulates rate of keratinization

○ Epidermal growth factor – stimulates proliferation of keratinocytes

○ The cytology of cells in different layers reflects maturation and keratinization

○ Stratum Basale

Main function is mitosis (mitotic structures present)

Tonofilaments - Small bundles of keratin (start to appear here)

Desmosomes – attatch cells to other cells

Hemidesmosomes – attach cells to extracellular matrix

○ Stratum Spinosum

More keratin is produced to make more tonofilaments

Tonofibrils – tonofilaments eventually form these

Lamellar granules – membrane bound granules rich in glycolipids.

Appear as light and dark bands.

Extruded as cells approach top (to make waterproof barrier)

○ Stratum Granulosum

Keratohyalin granules – irregularly-shaped, dense staining inclusions in cytoplasm

Eventually extruded

Tonofilaments continue to increase in cytoplasm

Filaggrin – a protein that cross-links tonofilaments

Involucrin – attachment to cell membrane, crosslinking done by transglutaminase.

Creates water impermeable cell membrane that helps cause cell death

Lamellar Granules increase in the intercellular space

Because they are glycolipids, they form a waterproof barrier between cells

Move from synthesis phase → degenerative phase

Cell nuclei begin to disappear

○ Creating the waterproof barrier

Impermeability due to buildup of keratin in cells

Thickening of cell membrane due to involucrin

Presence of glycolipids between keratinocytes

○ Stratum Lucidum - Keratinocytes are dead, lack nuclei, lots of waterproofing

○ Stratum Corneum – the cells in this layer are called squames

There are no keratohyalin granules or lamellar granules remaining

Epidermal Proliferation Unit (EPU) - The original keratinocyte and all its progeny?

○ Original stem cell produces 10ish basal cells which migrate laterally?

As more proliferation occurs the unit of cells moves upward as a group?

○ Melanocytes in more Detail

Artifact - Actually looks clear at LM level because it doesn‟t have desmosomes and shrinks

Highly branched

Normal Skin – about 1000 melanocytes/mm

Pigmented Skin (areolae, genital, etc.) – about 2000 melanocytes/mm

Different Races – have same number of melanocytes just have different # of melanin granules

Skin Color Caused By

○ Melanin – only pigment produced by skin

○ Carotene – yellow exogenous plant pigment deposited in stratum corneum and adipose

○ Oxyhemaglobin – red protein in blood

Melanin Epidermal Unit – melanocyte and associated keratinocytes (keratinocytes that have

melanin made by that melanocyte)

○ Located in the stratum basale and spinosum

Production of Melanin

○ Tyrosinase – converts tyrosine → melanin in melanocyte vesicles

○ Premelanosomes – small vesicles containing a little bit of melanin. Arise from Golgi

○ Melanosomes – more developed with more melanin

○ Melanin Granules – mature melanosomes

Migrate out to ends of branches??

The end of the process is pinched off into the cytoplasm of the keratinocytes??

cytocrine secretion??

○ Melanosome Complex – forms after keratinocyte and melanin granules fuse with

lysosomes. These form a cap over the nucleus

Slowly degenerate

Dark skinned races: 1. Produce more melanin, 2. have longer lasting melanosome

complexes, 3. have granules in all layers

Function of Melanin

○ Protects nucleus from UV rays

○ UVA – 320 nm (short)

Causes wrinkling, sagging of skin, skin cancer

does not burn the skin (tanning salons use it)

○ UVB – 370 nm (long, this gets in farther)

Causes sunburn – induces inflammation of blood vessels in dermis

Most sunscreens only block this

Melanin Related Clinical Applications

○ Tanning – darkening of melanin with exposure to sunlight and increased tyrosinase

activity over several days of continued exposure

○ Albino – lack of tyrosinase but same number of melanocytes

○ Vitiligo – depigmentation genetic disorder in skin and hair characterized by scattered

patches of white skin and white hair

Melanocytes are destroyed

Michael Jackson

○ Freckle – patch of skin with slightly higher concentration of melanin granules

○ Nevus (mole) – benign localized overgrowth of melanocytes arising during early life

○ Malignant melanoma – very malignant

○ Diseases of the Epidermis

Psoriasis – chronic condition characterized by patches of red-brown area with whitish scales

○ Due to excessive proliferation of keratinocytes

○ Takes 1 week, instead of 4 for keratinocytes to reach top, they aren‟t mature when at top

Waterproof barrier not formed because cells not fully keratinized, lamellar granules not

secreted

○ Cause unknown

Eczema – characterized by edema, exudation, crusting & severe itching

○ Dermis also affected (edema and infiltration of immune cells)

○ Cause thought to be immunological

Phemphigus – autoimmune disease against desmosome proteins in epidermis resulting in

severe blistering and loss of fluids

○ Makes it easier for infectious agents to enter

○ Potentially fatal

Basal Cell Carcinoma – cancer of the keratinocytes in the stratum basale

○ Most common of all skin cancers, but does not readily metastasize

Squamous Cell Carcinoma –

○ Second most common skin cancer, readily metastasizes

Not a disease – DMSO – a penetrating agent used for arthritis (unofficially) that can bring

foreign substances into the body

Dermis

○ Papillary Layer – composed of modified areolar CT

Immediately below epidermis, and is the thinner of the 2 dermal layers

Epidermal-Dermal Junction – interdigitation of dermal papillae and epidermal pegs or

ridges to prevent side shearing forces from separating the two layers

○ Dermal papillae – fingerlike projections of CT of dermis into epidermis

Thin vs. Thick Skin

○ Thin Skin – dermal papillae present but are simply rounded bumps or mounds of CT

○ Thick Skin – has more pronounced ridges (makes fingerprints and improves grip)

interpapillary peg of epidermis divides primary dermal ridge into 2 secondary

ridges

the primary dermal ridges correspond to the epidermal ridges?

○ Reticular Layer – composed of dense irregular CT and is rich in collagen and elastic fibers

Bundles of collagen fibers interwoven and oriented in all directions to resist shearing

Thickest layer in dermis

Cleavage lines of Langer – predominant direction of the bundles of collagen in a region of

the body

○ Important for surgery – if parallel incision then little scar, if across then big scar

○ Stretch Marks – tear of the dermis but epidermis remains, due to skin being too tight

Gap is repaired by scar tissue

Blood Supply for Skin

○ Blood supply derived from arteries in the hypodermis (subcutaneous fascia)

○ 3 Layers

Subcutaneous Plexus – located in the hypodermis

○ The deepest layer; all the blood supply originates here

Cutaneous Plexus – located in the dermal-hypodermis junction

Subpapillary Plexus – located just below the papillary layer

○ Capillary loops run up into the dermal papillae

○ Vasculature and Temperature Regulation

A-V Shunts – control blood flow and are located between cutaneous and subpapillary plexi

○ Found in Apical Skin, not Non-Apical Skin???

Apical Skin – found in finger and toe tips, nail beds, nose and lips

Normal Temp – AV shunts partially closed to allow warm blood to flow near surface

High Temp – AV shunts completely closed and vessels dilate passively to increase skin blood

Cold Temp – AV shunts completely closed and precapillary sphincter closes to prevent blood

from going to surface

Norepinephrine – causes vasoconstriction, released by sympathetic nervous system

Acetylcholine – usually causes vasodilation

○ Clinical Applications

Decubitus Ulcers (bedsores) – compromised circulation in area of skin usually due to

compression of vessels

Contusion (bruise) – leakage of blood out of capillaries

Erythema – redness of skin due to enlarged capillaries

Capillary hemangioma (birth mark) – benign vascular tumor of dermal capillaries

Appendages of Skin

Hair

○ Hard keratinous epithelial fiber composed of keratinocytes

○ Hair Follicle – where the hair is anchored, tubular invagination of the epidermis which extends

down through the dermis to the hypodermis

Enters skin obliquely

Surroundings

○ Dermal Sheath – CT surrounding follicle

○ External Root Sheath – extension of the stratum basale and spinosum, completely

surrounds

○ Internal Rooth Sheath – derived from outside region of matrix

Goes only half way up, cells slough off before sebaceous gland

Contains soft keratin

Subdivisions

○ Hair Shaft – the actual hair above the surface

Cuticle of Hair – outer single layer of hard keratin

Cortex – inner bulk of hair, hard keratin

Medulla – center area made of soft keratin

○ Root of Hair – from center of follicle down to bulb

○ Bulb – nutrient supply to hair follicle, enlargement at deep end

Contains dermal papillae composed of CT

Zones

○ Matrix/germativum Zone – where proliferation of keratinocytes occurs, equivalent of

stratum basale in epidermis

From here keratinocytes move upward and differentiate via keratinization

○ Keratogenous Zone – where cells become fully keratinized

Hard Keratin – has more disulfide bonds than soft keratin

○ Hair Color

Melanocytes in matrix produce pigment which is transferred to the keratinocytes

Pheomelanin – yellow, develops from tryptophan

Eumelanin – brown & black, develops from tyrosine

Gray Hair – melanocytes lack tyrosinase (which is responsible for producing melanin)

White Hair – pigment lacking + air pockets that reflect light

○ Associated Structures

Errector Pili Muscles – smooth muscle which connects basement membrane of dermal

papillae to dermal sheath

Sebaceous Gland – oil gland in acute angle of hair shaft near top

○ Hair Cycle

Hair does not grow continuously, it grows in cyclic stages

All hairs are in different phases of the cycle

Anagen Phase (growth phase) – due to proliferation of matrix

○ Different length of growth phase in different areas of body

Catagen Phase (transitional phase) – growth stops, but hair remains in follicle (short time)

Telogen Phase (resting phase) – hair shaft falls out and bulb involutes

Glands

○ Sebaceous – secrete sebum, oily substance

Associated with hair follicles

Morphology – simple or branched alveolar

○ Secretory unit – single alveolus (IS THIS REDUNDANT??)

Duct – single duct opening into hair follicle

Mode – holicrine (entire cell degenerates and is secreted)

Clinical Connection – when infected by bacteria they cause acne

○ Sex hormones at puberty increase secretion

○ Sudiferous Glands – sweat glands

Eccrine Sweat Glands – secrete serous and mucus substance, most common sweat gland

○ Separate from hair follicle

○ Morphology - simple coiled tubular glands

○ Duct – open at top of friction ridges (when they are present)

○ Mode – merocrine (secreted through exocytosis)

○ Function – temp regulation, excrtetion of ions (like a kidney)

○ Types of Cells

Clear Cells – serous

Dark Cells – mucous

Myoepithelial cells – help expel secretions

○ Hyperhidrosis – excessive sweating

Apocrine Sweat Glands – secrete serous substance

○ Duct opens into hair follicle

○ Morphology - simple coiled tubular glands

○ Mode - merocrine, not apocrine

○ Don‟t function until puberty

○ Located in axilla, pubic region, etc.

○ Modified Glands Meibomian (tarsal) Glands – secrete oily substance

○ Modified sebaceous glands on inner surface of eyelids

Ceruminous Glands – secrete wax (cerumen)

○ Modified apocrine sweat glands in external auditory canal

Mammary Glands – modified apocrine glands

Nails

○ Nail Plate – main body of nail containing keratinocytes with hard keratin

Replaces stratum corneum

Lateral Nail Groove – lateral edge of nail plate

Nail Root – proximal portion where nail plate starts

○ Nail Matrix – portion near nail root where keratinocytes proliferate to form nail

Lunula – whitish crescent that is distal-most part of nail matrix

○ Nail Bed – portion of epidermis where nail plate lies

Continuous with strata basale & spinosum

○ Eponychium – flap of skin that grows over the root of the nail

○ Hyponychium – excess stratum corneum under free edge of nail

Sensory Receptors

It is difficult to match functional classification with morphological classification because they mix

Functional Classification

○ Mechanoreceptor – touch, pressure, stretch

○ Thermoreceptor ○ Nociceptor – pain, itch, etc.

Morphological Classification

Free Nerve Ending Lack Schwann cells and myelin

at terminal end

Thermoreceptors &

nociceptors

Free nerve ending

Merkel Cell Ending Between keratinocytes in

stratum basale

Light touch

mechanoreceptor

Unmyelinated nerve

terminating on Merkel cell

Meissner’s Corpuscle Located in dermal papillae of

papillary layer

Light touch

mechanoreceptor

Encapsulated

Pacinian Corpuscle Large onion-like structure in

lower dermis and hypodermis

Pressure and vibration

mechanoreceptor

Encapsulated

Ruffini Corpuscle Elongated in lower dermis and

hypodermis

Tension

mechanoreceptor

Encapsulated

Krause End Bulb Located in conjunctiva, oral

cavity, tongue

Unknown Delicate capsule (axon

branches within capsule)

Development of Trilaminal Embryo ○ Objectives

Define and describe: hypoblast, epiblast, primitive streak, primitive node, notocordal process, prochrodal plate, cloacal

plate, notocord, ectoderm, mesoderm, and endoderm.

Describe the formation of the bilaminar embryonic disk from the inner cell mass.

Describe the formation of the notocord.

Descirbe the formation of the intraembryonic mesoderm.

List the derivatives of each of the three basic germ layers.

Describe a somite and its derivatives.

Briefly describe the intraembryonic coelom and its formation.

Briefly describe the folding processes that occur in the embryo and the consequences of these processes.

Briefly describe the changes in appearance of the embryo and the fetus during development.

Folding of the Embryo, Basic Body Form, Coelom Formation ○ Objectives

Describe the results of the lateral and longitudinal folding processes that occur in the embryo

Define: coelom, mesentery, septum transversum Describe/define the adult structures derived from the primitive intraembryonic coelom

Describe/define the origin of the cells lining the intraembryonic coelom and its definitive derivatives

Describe the configuration of the intraembryonic coelom following the development of the head fold

Describe/define the pleuropericardial membranes and the pleuroperitoneal membranes

Describe the relative position of the (thoracoabdominal) diaphragm during early development

List the four major tissue sources contributing to the definitive diaphragm. Correlate each with the related area of the

definitive diaphragm

Describe the probable developmental errors that produce: congenital posterolateral diaphragmatic hernia, congenital hiatal

hernia, congenital retrosternal hernia

Integumentary System – Embryology & Wound Healing ○ Objectives

List the embryological origin of the epidermis, dermis and skin appendages

Relate the types of wound healing and burns to the morphology and function of the skin

Define and describe the periderm and vernix caseosa. Be able to describe their origin, formation and function

Describe the origin and usual destination of melanocytes. Describe what occurs if migration and proliferation fail. Be able to describe what determines skin color

Describe the process of hemangioma formation

Describe the formation of sweat glands, sebaceous glands and mammary glands. Relate the causes of polythelia and

polymastia

Describe the formation of the hair follicle and hair shaft

Describe the formation of a fingernail/toenail

○ Embryology

Just Know Chronology, not specific weeks

Epidermis and Dermis

Epidermis - derived from ectoderm

Dermis - derived from mesoderm

Development of Layers

○ 3 Weeks – single layer of ectodermal cells resting on layer of mesenchyme

○ 4-5 Weeks – surface ectoderm forms two layered structure

Periderm – superficial layer of squamous epithelium

○ Cells undergo keritinization and are sloughed off

○ Secretes amniotic fluid

Basal Germanitive Layer – layer of basal cells that make periderm

○ 11 Weeks - Intermediate Layer forms and makes up bulk of skin

○ 21 Weeks – periderm stops sloughing off and forms normal stratum corneum

This is influenced by many factors (epidermal growth factor, etc.)

Vernix caseosa (greasey layer) – forms now to cover fetus and protect it from amniotic fluid

○ Turns baby into greased pig

○ Contains sloughed periderm cells and sebum

Clinical Application – hyperkeratinization

○ Lamellar Icthyosis – scale-like appearance of skin, usually lacks hair and sweat glands

○ Harlequin Icthyosis – extreme hyperkeratinization, „alligator skin‟, deep fissures, fetus dies

Fingerprints – form at 10 weeks, completed by 17 weeks

Other Cells

○ 1st, Langerhans Cells – arise from bone marrow and enter epidermis

○ 2nd

, Neural Crest Cells – arise from neuroectoderm and enter dermis

Once in dermis → melanoblasts → once in basal layer then melanocytes

○ 3rd

, Merkel Cells – appear in stratum basale

Hair

Hair follicle is formed by both epidermis and dermis

Stages (hair germ → hair bud → hair bulb)

○ Stage 1 – hair germ forms (slight invagination of epidermis into dermis)

○ Stage 2 – elongation of the bud into hair bud

○ Stage 3 – characterized as club-shaped and is called hair bulb (looks like full follicle)

Types of Hair

○ Lanugo Hair – first hair to form

Very fine and covers entire fetus by 5 months. Falls out before birth

○ Vellus Hair – found on fetus at birth. Very downy, (65% of adult female hair)

○ Terminal Hair – coarse hair of scalp, pubic & eyebrows (95% of male body hair)

Hirsutism – excessive hairiness in women & children due to vellus hair turning into terminal hair

by increased androgen

Hypertrichosis – excessive hairiness due to excessive hair follicles or persistence of them

Glands

Apocrine and sebaceous glands form with hair follicle

Eccrine sweat glands are not associated with hair follicles

○ Epidermal bud elongates to dermis → cells form coil → central cells degenerate to form lumen

→ outer cells differentiate into secretory cells

○ All eccrine sweat glands are formed prior to birth

Nails (about 10 weeks)

Nail starts on palmar surface of digit, but migrates to dorsal surface quickly

Primary nail field forms nail bed → nail field drives wedge of cells into dermis → wedge forms

nail matrix which produces nail plate → eventually nail folds show

Periderm/epidermis covering of nail eventually degenerates by birth

Nail plate only reaches end of finger tip by 32 weeks

○ If nail plate isn‟t at end of the finger then it is an indicator of prematurity

○ Wound Healing

Epidermal Wound Healing Process

Note - Only epidermis is affected

Clot Formation – blood clot is formed by leakage of blood from capillaries in underlying dermis

○ Platelets and fibronectin in clot provide matrix for macrophages and keratinocytes

○ Platelets release a bunch of growth factors to start wound closure

Activation/Proliferation - chemotactic factors recruit neutrophils and monocytes

○ These enter via extravasation, which requires p-selectin

○ Neutrophils cause keratinocytes and fibroblasts to proliferate

○ A bunch of growth factors are released

Migration – keratinocytes migrate along bottom of wound towards its center via diapedesis

○ Migration occurs beneath or through clot

○ Requires metalloproteinases to break hemidesmosomes of basal lamina (like a basement

membrane)

○ Plasmin is also used

Maturation – keratinocytes meet in the center of the wound and stop proliferating via contact

inhibition ○ Now normal keratinization takes over to resurface the epidermis

○ Basal lamina synthesis occurs. Scab eventually sloughed off

Deep Wound Healing Process

Note - Dermis is also affected

Inflammation Phase – blood clot forms and vasodilation of capillaries (due to histamine) cause

extravasation of neutrophils and macrophages

Proliferative Phase – fibroblasts and keratinocytes proliferate due to growth factors

○ These cells begin to secrete matrix to form granulation tissue

Migratory Phase – keratinocytes and fibroblasts migrate through blood clot to form granulation

tissue

○ Blood vessels grow into granulation tissue

○ Fibroblasts at edge are transformed into myofibroblasts which produce actin and myosin in cells

to cause contraction of the wound

Maturation Phase – granulation tissue slowly turned into dense irregular CT

Note - Scars are lighter because melanocytes don‟t migrate into them

Burns

1st Degree Burns – only epidermis is affected

○ Causes redness and mild pain (like a sunburn)

2nd

Degree Burns – epidermis and upper part of dermis affected

○ Causes blisters, pain and edema (touching stove)

3rd

Degree Burns – full thickness of skin is affected

○ Causes charred skin, no pain in center of burn, just around edges where pain receptors intact

○ Systemic effects are greater threat to life than the local effects

Dehydration, bacterial infection, renal shut down (due to ↓ removal of urea), shock (blood

circulation is reduced due to loss of fluid, reduced urine production due to low blood volume)

Shoulder ○ Objectives

Define the skeletal and ligamentous elements of the shoulder girdle. What is the shoulder girdle?

Define the muscles acting on the shoulder: extrinsic, intrinsic, pectoral, serratus anterior, arm muscles

Know their origins, insertions, innervations and primary actions Identify the shoulder muscles that comprise the “rotator cuff” and discuss their function

Identify the boundaries and contents of the quadrangular and triangular spaces

○ Shoulder Movements

Scapular Movements - Very flexible, but this causes lack of stability

Abduction (protraction) and Adduction (retraction)

Elevation and depression

Upward/downward rotation – reference point is glenoid cavity (if it rotates, then it is rotation)

Glenohumeral movements – joint between arm and scapula

Flexion/extension – tends to deviate to middle with flexion (not completely perpendicular to body)

Abduction/adduction – only to 90

Medial/lateral rotation

Circumduction

○ Skeleton

Scapula (has superior, medial and lateral border, superior and inferior angle) superior angle is closer to

medial border than superior border

Acromion – highest point of scapula, comes out posteriorly

Spine of Scapula – on posterior surface, continuous with acromion

Coracoid process – comes out anteriorly

Suprascapular notch –

○ Superior transverse scapular ligament – goes across the suprascapular notch to form

supracapular foramen ○ Suprascapular artery – goes over the ligament

○ Suprascapular nerve – goes below the ligament

“Army goes over the bridge, Navy goes under the bridge”

Supraspinous and Infraspinous Fossa – cavities above and below spine of scapula

Subscapular fossa – on anterior of scapula

Greater scapular notch – things go through here (under one end of spine of scapula)

Glenoid cavity – where arm attaches

○ Supra- and infraglenoid tubercles – above and below glenoid cavity

Humerus

Head of humerus – where it contacts glenoid cavity

○ Much bigger than the glenoid cavity (gives more flexibility, but less stability)

Anatomical neck – just surrounding head of humerus

Surgical neck – many fractures occur here

Posterior View – can see greater tuberosity

Anterior View

○ Lesser tuberosity – more medial

○ Bicipital groove (interubercular sulcus) – biceps brachii goes through this

○ Greater tuberosity – more lateral

○ Deltoid tuberosity – midway down bone, in line with bicipital groove. Where deltoid attaches

○ Synovial Joint

Fibrous capsule – outermost part

Synovial membrane - contains synovial fluid which surrounds joint and bathes hyaline cartilage on

bone

Synovial Fluid – produced by synoviocytes, contains hyaluronic acid

Cushions, lubricates and nourishes via diffusion which requires movement

○ Shoulder Joint

Sternoclavicular Joint – true to name (connects sternum to clavicle)

only bony attachment of upper limb to axial skeleton

Sternoclavicular ligament (anterior and posterior) – true to name

Interclavicular ligament – true to name

Costoclavicular ligament – attaches to rib

Acromioclavicular Joint (AC Joint) – true to name

Acromioclavicular ligament - if torn → shoulder separation

Coracoclavicular ligament – attaches coracoid to the last quarter of the clavicle

Coracoacromial Arch – prevents superior displacement of humerus

○ Coracoid process

○ Coracoacromial ligament – just forms roof so humerus doesn‟t displace (connections on same

bone)

○ Acromion

Glenohumeral Joint - true to name

Shoulder dislocation – disruption of this joint

Fibrous Joint Capsule

○ Glenohumeral ligaments – strengthen anterior part of capsule

Contains thickenings called superior, middle, and inferior

○ Coracohumeral ligament – strengthens superior part of capsule

Transverse humeral ligament – strengthens superior part of capsule

○ Holds tendon of biceps in bicipital groove

Glenoid labrum – fibrocartilage ring around circumference of glenoid cavity, deepening it

Bursae – a synovial sac which facilitates movement of a structure over bone

○ Subacromial & subdeltoid bursa – looks like shoulder pads over just the shoulder

Does not communicate with glenohumeral joint cavity

○ Subtendinous bursa of subscapularis – over glenohumeral ligaments and does communicate

with glenohumeral joint cavity

○ Muscles

Extrinsic Muscles

Extrinsic Muscles

Origin Insertion Action Nerve

Axial skeleton → scapula

Pectoralis

minor

ribs (3-5) coracoid process -stabilize scapula -protraction

-pull tip of shoulder downward

medial and lateral pectoral nerve

Serratus

anterior –

curves around

ribs to inner part

of scapula

ribs (upper 8) medial border of

scapula

-holds scapula against thorax,

protraction (abduction) -rotates scapula to direct glenoid

cavity upwards

-essential for raising arm above

head

long thoracic nerve

Trapezius -ligamentum

nuchae

-SP of vertebrae

-spine and acromion

of scapula

-lateral portion of clavicle (wraps around

front)

-elevate and depress scapula

-retraction (adduction) of scapula

-rotate glenoid process of scapula↑

-accessory nerve

(motor)

-C3-4 (proprioception)

Levator

scapulae

C1-C4 -superior angle of

scapula

-medial border of

scapula

-elevate scapula

-rotate glenoid cavity↓

-If insertion point is fixed then it can laterally flex neck

dorsal scapular nerve

Rhomboid

major &

minor

SPs of thoracic

vertebra

medial border of

scapula

-retracts (adducts) scapula dorsal scapular nerve

Axial Skeleton → humerus

Pectoralis

major

-clavicular head

-sternocostal

head

lateral lip of

bicipedal groove

-adductor of arm

-medial rotation of arm

medial and lateral

pectoral nerve

Latissimus

dorsi

-T7 to sacrum -iliac crest

Intertubercular sulcus

-Adducts arm -medial rotator of arm

-extends arm

thoracodorsal nerve

Axial Skeleton → clavicle

Subclavius rib 1 clavicle -depression of clavicle -anchoring of clavicle

nerve to subclavius

Other Serratus posterior

superior

SP (C7-T3) Ribs 2-5 Expands ribs Ventral rami

Serratus posterior

inferior

SP (T11-L2) Ribs (last 4) Expands ribs Ventral rami

Note – "Lady between two Majors"

○ The latissimus dorsi has its insertion point in bicipital groove (intertubercular sulcus) which is

between two insertions of 'major' muscles on the medial and lateral edge of bicipital groove

Note - „medial‟ and „lateral‟ pectoral nerve based on origin of nerve, not what they innervate

Intrinsic Muscles

Origin – all scapula

Insertion – all humerus

Action – all act on humerus and help stabilize joint

Intrinsic Muscles

Origin Insertion Action Nerve

Rotator Cuff – group of muscles and tendons that stabilize glenohumeral joint by attaching the scapula to the humerus

Teres Minor Scapula – lateral border greater tuberosity lateral rotation Axillary

Infraspinatis Scapula – infraspinous fossa greater tuberosity lateral rotation Suprascapular

Supraspinatus –

goes through scapular notch

Scapula – supraspinous

fossa

greater tuberosity abduction (initiates) Suprascapular

Subscapularis Scapula – subscapular fossa lesser tuberosity medial rotation Subscapular

Other Intrinsic Muscles of Shoulder

Deltoid Scapula (front and back)

- lateral 1/3 of

clavicle - acromion

- spine of scapula

deltoid tuberosity -Abduction

-extends

-flexes -medial & lateral

rotation

Axillary

Teres Major Scapula – lateral border medial edge of

bicipital groove

-medial rotation

-(a little adduction)

Lower subscapular

○ Scapular Rotation with Humeral Abduction

0-30 Degrees - Abduction at glenohumeral joint only via supraspinatus

30-120 Degrees – abduction at glenohumeral joint via supraspinatus & deltoid

scapular rotation via trapezius & serratus anterior

>120 Degrees – scapular rotation only

(humerus has hit acromion and can‟t move anymore

Axilla and Brachial Plexus ○ Objectives

Axilla

Define the skeletal and muscular boundaries of the axilla

Identify the contents of the axilla. From what structure is the axillary sheath derived? What structures are included in

the axillary sheath

Brachial Plexus and Axillary Vasculature

Define the typical branching pattern of the brachial plexus. What landmarks can be used to find each level of the

plexus: roots (ventral rami) → trunks → divisions → cords → terminal nerves

○ What are the supraclavicular branches and what do they innervate? What are the infraclavicular branches and what

do they innervate?

○ What are the terminal nerves of the brachial plexus? Which groups of muscles do they innervate

Autonomics of the Upper Extremity

At which spinal levels do preganglionic sympathetic fibers destined for the upper extremity arise?

Do parasympathetic fibers innervate vasculature of the upper extremity?

Blood Supply of the Upper Extremity

Which branches of the subclavian artery supply structures of the shoulder?

Where does the subclavian artery change its name to the axillary artery?

Which branches of the axillary artery supply structures of the shoulder and upper arm?

Understand the concept of collateral circulation and its application to this region

Lymphatics of the Upper Extremity

Understand the basic lymphatic drainage of the upper extremity. How does lymph from the right upper extremity reach

the right brachiocephalic vein?

How does lymph from the left upper extremity reach the left brachiocephalic vein

○ Borders of the Axilla

Apex – rib 1, upper edge of scapula &

clavicle

Base – skin (subcutaneous tissue and deep

fascia)

Anterior Wall – pec major and minor,

subclavius muscles & clavipectoral fascia

Posterior Wall – scapula, subscapularis,

latissimus, teres major, long head of tricep

Medial Wall – ribs 1-4, intercostal and

serratus anterior muscles

Lateral Wall – humerus

○ Contents of Axilla

Axillary Artery – continuation of subclavian

Axillary Vein – thinner walled than axillary artery

Axillary lymphatics and nodes – most common site of breast metastasis. In axillary fat

Axillary Sheath – extension of prevertebral fascia

Contains – brachial plexus, axillary artery, axillary vein

Brachial Plexus – C5-T1 nerves (ventral rami)

○ Brachial Plexus

“Randy Travis Drinks Cold Beer”

Made of ventral rami of spinal nerves

Note – Posterior cord is posterior to axillary artery

Note – Radial nerve goes medial, axillary nerve goes lateral

Outline

Roots – in posterior cervical triangle, contains 5

Trunks – at/above clavicle, contains 3

Divisions – posterior to clavicle, lots of crosses

Cords – around axillary artery, back to 3

Terminal Branches – 5 named mixed nerves

Terminal Branches

Vertebral Motor Sensory

Axillary C5-6 shoulder Over deltoid

Musculocutaneous C5-7 arm flexors Anterolateral forearm

Median C5-T1 mainly forearm, but a little hand Palmar surface lateral 3.5 digits

Ulnar C8-T1 mainly hand, but a little forearm Palmar surface medial 1.5 digits

Radial C5-T1 extensors of arm and forearm (and

a few others)

Posterior forearm & dorsolateral

hand

○ Note – motor innervation for radial nerve “BEST – brachioradialis, extensors, supinator, triceps”

○ Note – musculocutaneous pierces coracobrachialis (a good place to orient yourself)

○ Note – the more caudal the spinal nerve that innervates a terminal branch the more likely it is to

innervate a distal structure When testing for damage of the brachial plexus, you can test sensory areas or muscles. When testing muscles

remember that as you move distally on the arm you test lower aspects of the brachial plexus

Other Nerves

Don‟t worry about specific spinal nerves, just know groupings

Supraclavicular Nerves Infraclavicular Nerves

1. Dorsal scapular – C5 5. Lateral pectoral – C5-7

2. Suprascapular – C5-6 6. Medial pectoral – C8-T1

3. Subclavian – C5-6 7. Medial cutaneous nerve of arm – C8-T1

4. Long Thoracic – C5-7 8. Medial cutaneous nerve of forearm – C8-T1

9. Upper subscapular – C5

10. Thoracodorsal – C6-8

11. Lower subscapular – C6

Note – medial pectoral pierces pec minor and innervates pec major

Note – medial cutaneous nerve of the arm joins the intercostalbrachial nerve (a branch of T2)

Areas of Dermatome to test specific spinal cord levels of the Brachial

Plexus

C5 – upper lateral arm

C6 – pad of thumb

C7 – pad of index finger

C8 – pad of little finger

T1 – medial elbow

○ Axillary Artery

Subclavian artery → lateral border of rib 1 → axillary artery → ends at

lower border of teres major → brachial artery

Parts of Axillary Artery

Parts Branches Structures Supplied Notes

1 - Proximal to

pec minor Superior thoracic a.

-Pectoral mm

-Thoracic wall mm -Serratus anterior m

2 - Posterior

to pec minor

Thoracoacromial a.

-Clavicular branch

-Acromial branch

-Deltoid branch -Pectoral branch

This supplies branches

"Cadavers Are Dead People"

Lateral thoracic a.

-Serratus anterior m.

-Pectoralis minor

-Mammary glands

Not always there

“L-L” Lateral goes with

Long thoracic nerve

3 - Distal to

pec minor

Subscapular a.

Subscapularis m Largest branch of axillary artery Circumflex scapular a.

- posterior scapula

- teres minor - infraspinatus

Thoracodorsal a.

- latissimus dorsi

Anterior humerial

circumflex a

-Deltoid -triceps brachii mm

Smaller

Posterior humerial

circumflex a

-Deltoid

-triceps brachii mm

Larger

Note – "Screw The Lawyer, Save A Patient"

Note – the two humerial circumflex arteries go around humerus and eventually join

○ Spaces and Intervals

Contents Boundaries

Triangular Space -Circumflex scapular a (deep to it)

-Teres major -Teres minor

-Long head of tricep

Quadrangular

Space

-Axillary nerve -Posterior circumflex

-humeral a.

(these go through)

-Teres major -Teres minor

-Long head of tricep

-Lateral head of tricep

Triangular

Interval

-Profunda brachii a. -Radial n.

(deep to it)

-Teres major -Long head of tricep

-Lateral head of tricep

○ Scapular Arterial Anastomoses

End to end joining of blood vessels which provides redundancy

Basically, two blood vessels venture down, one branches off and connects head on with the other

Suprascapular ↔ circumflex scapular artery

Posterior circumflex artery ↔ anterior circumflex artery?

Dorsal scapular artery ↔ posterior intercostals arteries

○ Venous Drainage

Superficial Veins

Both originate on the dorsum of the hand

Basilic vein – continues as axillary, becomes a deep vein (so it is both a deep and superficial vein)

○ On medial side of arm

Cephalic vein – on lateral side of arm, joins axillary after going through the clavipectoral triangle

○ Clavipectoral triangle – made by deltoid, pectoral and clavicle

Deep Vein?

Paired and on either side of accompanying arteries (vein, artery, vein)

○ Lymphatic Drainage

Are not within the axillary sheath

Lateral & Anterior & Posterior → Central → Apical → Subclavian lymph trunk → venous system

Note - apical lymph node drains all other nodes and the mammary glands

Cellular Controls in Development ○ Objectives

Briefly explain why the conceptus is not immunologically rejected by the mother during and following the process of

implantation

Define/describe homeotic genes (homeobox genes). What is their role in development? How are they regulated?

Define the term critical (sensitive) period of development. List several examples of critical periods and the results of

alterations in the regional microenvironment within the embryo/fetus during them

Describe the principle of cranio-caudal and proximo-distal growth sequences

Define induction and give two examples of induction during embryonic development

Describe the following processes that are important in development: tissue aggregation, cell death, differentiation, growth and regeneration

Define teratology

Give and example of a defect caused by each of the following classes of teratogen:

Environmental: infectious agents, radiation or chemical, hormonal

Chromosomal or genetic: autosomal abnormalities, sex chromosome abnormalities

Arm and Forearm ○ Objectives

Veins of the Upper Extremity

What are they and where are they?

Arteries of Upper Extremity

What is the course and branching pattern of the brachial artery?

Which arteries contribute to collateral (and recurrent) circulation of the elbow?

What happens to the brachial artery as it passes into the forearm?

Compartments of the Arm

Which muscles are found in the flexor (anterior) compartment?

What are their attachments and what are their primary actions?

What nerve innervates the muscles of the flexor compartment?

Which muscles are found in the extensor (posterior) compartment?

What are their attachments and what are their primary actions?

What nerve innervates the muscles of the extensor compartment?

Compartments of the Forearm

What are the boundaries and contents of the cubital fossa?

Which muscles make up the Flexor-Pronator group?

What are their attachments and what are their primary actions?

What nerves innervate these muscles?

Which muscles make up the Extensor-Supinator group?

What are their attachments and what are their primary actions?

What nerves innervate these muscles?

○ Movements of the Arm and Forearm

Glenohumeral Movements

Flexion – extension

Abduction – adduction

Medial rotation – lateral rotation

Circumduction

Elbow and Forearm

Flexion – Extension

Pronation – supination

○ Arm/Elbow

Skeleton

Foramen for nutrient artery – hole for a blood vessel into bone

Radial Groove – where radial nerve travels along the bone

Distal Humerus

○ Lateral suprachondylar ridge –

○ Radial fossa – for radial head, on anterior side

○ Coranoid fossa – for coranoid process of ulna, on anterior side

○ Capitulum – a round protrusion, on anterior side

○ Trochlea – a „valley‟ on the distal end

○ Lateral epichondyle –

○ Medial epichondyle – ulnar nerve passes behind it

○ Olecranon fossa – on posterior side, accepts olecronon of ulna

Forearm

○ Ulna – the stable bone

Olecranon process – what you feel at the elbow

Trochlear notch – on the other side of the olecranon process (huh?)

Coranoid process – outside of the other end of the notch (huh?)

Radial notch – accepts radius

Ulnar tuberosity – accepts brachialis insertion

Styloid process – on distal end of ulna

○ Interosseous membrane – connects radius and ulna and has openings at top and bottom

○ Radius – the rotator

Head of radius –

Neck of radius –

Radial tuberosity – accepts biceps tendon

Styloid process – on distal end, the ulna also has one

Elbow Joint

Fibrous Capsule – all the CT holding the joint together

○ Radial Collateral Ligament – thickening on lateral/radial side

○ Ulnar Collateral Ligament – thickening on medial/ulnar side

Anular ligament of radius – wraps around radius like a „ring‟ to hold it in place while letting it

rotate

Muscles around Humerus

Muscles around Humerus

Origin Insertion Action Nerve

Anterior (Flexor) Compartment

Biceps brachii

Long Head -

Supraglenoid tubercle

-biceps tendon to radial

tuberosity

-bicipital aponeurosis (which blends with deep fascia)

Elbow - Flexor

Elbow - Supinator

Musculocutaneous Short Head –

coracoids process

Brachialis Humerus – body Ulna – ulnar tuberosity Elbow - Flexor (Pure)

Coracobrachialis Coracoid Humerus – medial body -Arm – flexor

-Arm – adductor

Posterior (Extensor) Compartment

Triceps brachii

Long Head

infraglenoid tubercle

Lateral Head humerus – shaft

Medial Head (same as

lateral head?)

Ulna – olecronon Elbow - extensor

Radial

Aconeus Humerus – lateral

epichondyle

Ulna – proximal Elbow – extensor

Stabilizer

○ Note – humerus is mainly in anterior compartment

○ Note – Long head of biceps brachii is based on the length of the tendon

○ Note – brachialis is covered by bicep

Cross Section

○ Lateral intermuscular

septum – separates

anterior (flexor) from

posterior (extensor)

compartment

○ Brachial Fascia – a “deep

fascia” which surrounds

both compartments

maintains integrity of

the muscles; allows

them to function as one;

helps venous return

Arteries

At inferior part of teres major

the axillary artery becomes

the brachial artery

The profunda brachii artery branches off the brachial artery and then becomes the radial

collateral

The brachial artery branches just after passing under the bicipital aponeurosis into the radial

artery and the ulnar artery

Redundancy

○ The proximal end of the elbow joint is supplied by three collaterals

○ The distal end is supplied by three recurrent arteries

○ All of these connect at the elbow to form anastamoses

Veins

Paired brachial veins – deep to the bicep

Medial cubital vein – the cephalic and basilic vein merge to form this

○ A good place for drawing blood

Nerves

Musculocutaneous – is motor in the proximal portion, but sensory in the distal portion (the

forearm)

○ Penetrates the coracobrachialis

○ When in the forearm it is only sensory and is called the cutaneous portion of the

musculocutaneous nerve

Median – no major branches in arm

Ulnar – no major branches in arm, travels behind the medial epichondyle

Note – medial and ulnar travel with the brachial artery in the arm

Radial – is motor in the posterior arm compartment and sensory in lateral and posterior arm?

See cross section

○ Note – paired brachial veins, radial nerve barely sits in the radial groove, “deep artery and veins

of arm” = profunda brachii

○ Forearm

Note – basically, when a muscle passes over a joint it will play a part in moving it

Compartments

Lateral intermuscular septum – between radius and deep fascia

Interosseous membrane – between radius and ulna

Medial intermuscular septum - between ulna and deep fascia

Flexor-Pronator

Note – superficial muscles have origin on medial epichondyle or

humerus OR proximal-anterior radius/ulna

Flexor-Pronator

Origin Insertion Action Nerve

Superficial Muscles – have origin on medial epichondyl

Pronator teres

Hu

mer

us

– m

edia

l

epic

ho

nd

yle

Ulna – head

Radius - middle Pronator Flexor - elbow

Med

ian

Flexor carpi

ulnaris

2nd

metacarpal Flexor – wrist

Palmaris longus Palmar aponeurosis (deep fascia in palm)

Flexor – wrist

Flexor digitorum

superficialis –

beneath the other

superficial muscles

Radius -

body

Middle phalanges Flexor – digits (and

wrist)

Flexor carpi

ulnaris

Wrist – pisiform

bone

Flexor – wrist Ulnar

Deep Muscles – have origin on radius and ulna on anterior side

Flexor digitorum

profundus

-Ulna

(-Radius)

Distal phalanges Flexor – digits (and

wrist) Ulnar side = ulnar

Radial side = median

Flexor pollicis

longus

-Radius

(-Ulna)

Distal phalanx of

thumb

Flexor – thumb

M ed ia n

Pronator

quadratus

Ulna – distal Radius – distal Pronator

○ Note – „carpi‟ = wrist

○ Note – 'quadtratus' looks like a quadrangle

Extensor-Supinator

Extensor-Supinator

Origin Insertion Action Nerve

Superficial Muscles

Brachio-radialis suprachondylar ridge Radius – styloid process Flexor – elbow

Rad

ial

Extensor carpi

radialis longus

suprachondylar ridge II metacarpal Extensor – wrist Radial deviation (abduction) -

wrist

Extensor carpi

radialis brevis

late

ral

epic

ho

nd

yle

III metacarpal Extensor – wrist

Radial deviation (abduction) - wrist

Extensor

digitorum

Distal phalnx of fingers Extensor – fingers and wrist

Extensor carpi

ulnaris

V metacarpal Extensor – wrist

Ulnar deviation (adduction) –

wrist

Extensor digiti

minimi

V distal phalanx Extensor – pinky

Deep Muscles Supinator -Lateral epichondyle

-Ulna

Radius – proximal Supinate

Rad

ial

Extensor Indicis -Ulna -Interosseus membrane

II distal phalanx (index finger)

Extensor – index finger

Snuff Box

Abductor pollicis

longus

-Radius

-Interosseus membrane

I metacarpal Extensor – base of thumb

Rad

ial

Extensor pollicis

brevis

-Radius -Interosseus membrane

I base of proximal phalanx

Extensor – middle of thumb

Extensor pollicis

longus

Ulna I distal phalanx Extensor – end of thumb

Note – Superficial muscles have origin on lateral epichondyle OR proximal-anterior radius/ulna

Note – „pollex‟ = thumb

Note – the „brevis‟ vs. „longus‟ refers to the tendon

○ Cubital Fossa

Space at elbow that contains biceps tendon, brachial artery (and its

radial and ulnar branches), brachial vein, parts of median and radial

nerves

Boundaries

Superior – intercondylar line (imaginary)

Lateral – brachioradialis muscle

Medial – pronator teres muscle

Floor – brachialis & supinator muscles

Roof – deep fascia including bicipital aponeurosis & skin

○ Note that the median cubital vein is also here (the place for

drawing blood)

○ Arteries (skipped hand arteries)

Brachial artery branches in cubital fossa →

Radial artery – basically goes to hand

Ulnar artery – branches just past elbow into:

○ Common interosseous – can be very short; branches into:

Anterior Interosseous – supplies deep flexors of forearm

Posterior Interosseous – supplies extensors of forearm

Note – he made a big point of this

○ Nerves (skipped hand nerves)

Median

Ulnar

Radial

Deep Branch – muscular, goes through supinator (goes through posterior interosseous???)

Superficial Branch – cutaneous

Development of the Muscular System ○ Objectives

Define and describe the location of three types of muscle tissue: skeletal, cardiac and smooth

List and describe the differences between the developmental origins for the skeletal muscle of the body: trunk muscles,

pharyngeal arch muscles, ocular muscles, tongue muscles and muscles of the limbs

Define and/or describe: epaxial musculature, hypaxial musculature

Describe the process of muscle cell maturation

List the major regulatory factors that influence muscle cell maturation

List/describe the origin of cardiac and smooth muscle

○ Initial formation of the muscular system is independent from skeletal system, but later maturation is

closely tied

○ Phases of Development

Commitment to myogenic lineage

Activation of a myogenic program

Proliferation of myogenic precursors

Specification of specific myogenic cells

Fusion of mononucleated precursors to form multinucleated fibers

Organization of contractile proteins of the sarcomere

○ Formation from Mesoderm

Muscle system develops mainly from mesoderm

Exception – muscles of iris and ciliary body

Mesoderm condenses into 3 layers

Paraxial – around axis

○ Head

○ Somite

Sclerotome – cartilage, ribs and vertebrae of axial skeleton

Myotome – axial muscle tissue

Dermatome - dermis

Intermediate → kidney & gonads

Lateral

○ Somatic (dorsal layer) → CT & vascular smooth muscle

○ Splanchnic (ventral layer) → smooth muscle of GI and cardiac muscle

Somitogenesis

Somitomeres – unsegmented mesoderm that develop into somites which are segmented

○ Differentiation is helped by somitomere expression of adhesion proteins causing compaction

○ Initiated by tyrosine kinase receptors called Eph which receive Ephrin signal molecules from

surrounding tissue

○ After about 20 somitomeres form, then the 8th one begins to differentiate into a somite

This development starts rostrally and ends caudally (rostral → caudal)

The first 7 somitomeres do not develop into somites

○ These first 7 → muscles of face, jaw and throat

Axial Specification of Somites

Sclerotome somites (skeletal) that are experimentally moved to a different region will make the

structure they are programmed to make in that new region.

○ Myotome somites don‟t do this, they are more influenced by the signals in the tissue which they

migrate to

Somites are programmed where to go before being fully formed

○ Cells within a somite are only told to differentiate into a specific muscle after the somite is fully

formed

Somite Differentiation

Cells within a somite will need to differentiate into sclerotome, myotome and dermatome

The ventral region of somite wall forms the sclerotome

The dorsal wall forms the dermomyotome, this differentiates into:

○ Dermatome – forms dermis of back

○ Myotome – forms below dermatome in two stage process

1st – MyoD and Myf5 cause some cells in dermomyotome to commit to myogenic lineage

2nd

– myogenic precursors move away from dermomyotome to form their own layer

○ the myotomic cells then split into an epaxial region and a hypaxial region

Epaxial Myotome – found dorsomedially

○ Forms extensor muscles of neck & deep muscles of the back (ex. Erector spinae,

transversospinosus)

○ Innervated by dorsal ramus of spinal nerves

Hypaxial Myotome – found ventrolaterally

○ Forms muscles of lateral and ventral body wall, limbs, tongue

Flex trunk and rotate vertebral column

○ Innervated by ventral ramus of spinal nerves

○ Extends aroundish the developing embryo

Pharyngeal Myotome – from the 1st 7 somitomeres which didn‟t develop into somites

○ Forms muscles of mastication, facial expression, pharynx and larynx

Myogenesis

MyoD & Myf5 continue to influence myotome

○ Induce specification to myogenic fate (this is already accomplished)

○ Promote fusion of myogenic cells to form muscle fibers

○ Direct the organization of contractile proteins within the maturing muscle fibers

Somites in different rostro-caudal levels form appropriate muscle groups

Limb Muscles

Limb buds form from mesenchyme overlain by ectodermal tissue

Limb muscles form from the lateral portions of limb level somites, specifically the hypaxial area

○ These differentiate into myoblasts and then myotubules

Upper limb buds form around day 24 from C5-T1 somites

Lower limb buds form around day 28 from L2-S3 somites

Within a limb bud the myoblasts form two masses

○ Dorsal Limb Bud Mass – forms all limb extensor muscles (upper limb suppinators, all lower

limb abductors)

Innervated by dorsal branch of ventral rami

○ Ventral Limb Bud Mass – forms all limb flexor muscles (upper limb pronators, lower limb

adductors)

Innervated by ventral branch of ventral rami?

Limb bud masses eventually split to form specific muscles

○ Which muscle they become is not an intrinsic property of the myoblast, instead they get their

cues from the surrounding CT

○ Muscle fiber type (fast, slow, red, white) is specified by intrinsic properties of myoblasts

Craniofacial Muscles

Pharyngeal Arches – 4 archlike masses of neuroectodermal cells which help create the face,

mouth, nasal cavities, larynx and pharynx and differentiate into head and deep neck muscles

○ Form during the 4th and 5

th weeks of gestation

○ Form from unsegmented somitomeres

○ Aggregate into pre-muscle masses

○ CT elements lay down tracks so that these somitomeres can migrate to the proper place to form

the pharyngeal arches (this is a long way)

○ Innervated by cranial nerves once they make the pharyngeal arch, these nerves stay with the

myoblasts as they move to their final destination

Pharyngeal Arch Cranial Nerve Muscles

1st V Mastication

2nd

VII Facial Expression

3rd

IX Stylopharyngeus

4th

X-XI Larynx, pharynx

Muscle Cell Fusion

Myoblasts → Skeletal Muscle Fibers

○ 1. Fusion of myoblasts to form multinucleated myotubules

Two classes of progenitor cells form

○ Founder Cells – primary cells which seed a distinct muscle

○ Fusion-Competent Cells – secondary cells which aggregate around the founder cell and

fuse with them to form myotubules

Fusion requires – cell-cell recognition and attraction, adhesion, alignment, fusion

○ 2. Expression of contractile proteins and arrangement of sarcomeres

Here the fiber type is established

○ CT sheath plays a part in expression of proteins for different fiber types? (contradiction??)

Muscle Cell Regeneration

Satellite Cells – mononuclear mygenic precursors that can divide at a slow rate to sustain self

renewal and growth of muscle tissue

○ Replicate themselves due to Pax7

○ Differentiate into proper muscle cells via MyoD and Myf5

Regeneration is rare, but can happen after mechanical tearing or muscular disease

○ Smooth Muscle

Derived primarily from splanchnic mesoderm

GI – splanchnic mesoderm surrounding primordial gut

Vessels – somatic mesoderm

Iris & Ciliary Body – ectoderm

Mammary & sweat glands – myoepithelial cells derived from somatic endoderm

Note – splanchnic and somatic mesoderm from lateral plate mesoderm

○ Cardiac Muscle

Develops from splanchnic mesoderm surrounding the developing heart tube

Do not undergo fusion, instead they develop cell-to-cell connections (gap jnx, intercalcated discs)

Hand ○ Objectives

Skeleton of Hand and Wrist

What are the bones of the hand and wrist? Be able to identify them in bone specimens as well as on X-rays

What is the carpal tunnel and what are its contents? What nerve is affected in carpal tunnel syndrome?

What is the Canal of Guyon and what are its contents?

Blood Supply of the Hand

Where is the radial artery at the wrist and how does it enter the hand?

Where is the ulnar artery at the wrist and how does it enter the hand?

How do the radial and ulnar arteries contribute to the collateral circulation of the hand?

Cutaneous Innervation of the Hand

What spinal levels innervate the thumb?

What spinal levels innervate the little finger?

Which portion of the hand would you test for median nerve innervation?

Which portion of the hand would you test for ulnar nerve innervation?

Which portion of the hand would you test for radial nerve innervation?

Muscles of the Hand

What are the extrinsic muscles of the hand and what are their primary actions?

What are the intrinsic muscles of the hand and what are their primary actions?

What are the snuff box muscles and what are their primary actions?

What intrinsic hand muscles are innervated by the median, ulnar, and radial nerves?

Clinical Conditions

What nerve is damaged in “crutch palsy”?

What are the typical effects of an upper brachial plexus paralysis?

What are the typical effects ini the hand of a lower brachial plexus paralysis?

○ Skeleton

Carpal Bones – “Some lovers try positions that they cannot handle”

Start at thumb on lower level

Proximal - Scaphoid (skiff boat), Lunate, Triquetrum (3 sides), Pisiform (you can feel this?)

Distal – Trapezium, Trapezoid, Capitate (little head), Hamate (hook)

Metacarpals – I-V starting with thumb

Phalanges – Proximal, Middle and Distal (though thumb only has proximal and distal)

Note – radius is big at the wrist

Scaphoid Fracture

Scaphoid bone is the most common wrist bone to be fractured if you catch fall with hands

Blood comes into scaphoid at its distal end and so if fracture happens below that circulation may be

compromised and nonunion or avascular necrosis could develop

○ This can lead to arthritis

○ Surgery necessary to treat this

○ Movements of the Wrist and Fingers

Wrist – remember that the palm is face up in anatomical position

Extension/Flexion

Abduction (radial deviation)/Adduction (ulnar deviation)

Fingers – think of the middle finger as the midline

Abduction (away from middle finger)/Adduction (toward middle finger)

Extension/Flexion

Thumb

Extension/Flexion – tricky, „main flexion action of thumb‟

Abduction (move thumb anterior to 4 fingers)/adduction

Opposition – movement unique to thumb and pinky

○ Joints of the Fingers

Metacarpophalangeal Joint (MP Joint) – 1st knuckle

Proximal Interphalangeal Joint (PIP Joint) – 2nd

knuckle

Distal Interphalangeal Joint (DIP Joint) – Knuckle sandwich

○ Aponeurosis and Synovial Sheaths

Palmar Aponeurosis – a condensation of deep fascia which protects the palm

Comes from the tendon of palmaris longus

Common Sheath – underneath palmar aponeurosis and protects tendons, contains synovial fluid

Fibrous Digital Sheaths – on inner side of fingers, contains synovial fluid

○ Muscles

Muscles of the Hand

Origin Insertion Action Nerve

Superficial Muscles – Hypothenar Muscles

Abductor digiti

minimi

Pisiform Proximal phalanx Abductor Ulnar

(deep

branch) Flexor digiti

minimi

-Hamulus

-Flexor retinaculum

Proximal phalanx Flexor

Opponens digiti

minimi

-Hamulus

-Flexor retinaculum

5th metacarpal Oppose

Superficial Muscles – Thenar Muscles

Abductor pollicis

brevis

-Scaphoid -Trapezium

-Flexor retinaculum

Pro

xim

al

Phal

anx

Abductor Median nerve

(recurrent

branch)

Except

deep

head, it

is ulnar

Flexor pollicis

brevis

Superficial Head: flexor retinaculum

Flexor

Deep Head: capitate &

trapezium

Opponens pollicis Trapezium 1st metacarpal Oppose

Deep Muscles Dorsal

interosseous mm

(4)

Metacarpals -Proximal Phalanx

-dorsal expansion

“extensor hood”

Abducts Ulnar

(deep

branch)

Palmar interosseus

mm (3)

Metacarpals -Proximal Phalanx

-dorsal expansion “extensor hood”

Adducts

Adductor pollicis -Metacarpal III

-Capitate

Proximal phalanx of

thumb

Adducts

Lumbricals (4) Tendons of flexor digitorum profundum

Extensor hood -Flexes MP joint -Extends DIP and PIP Joints

Ulnar and

Median

Dorsal interosseous mm – “DAB” – dorsal interosseous abducts

Proximal interosseous mm – “PAD” – palmar interosseous adducts

Note – note the number of each deep muscle

Note – lumbricals on palmar side, superficial to interosseous

○ Extensor Hood

Muscles attaching to it

Lumbricals, dorsal interosseous, palmar interosseous,

abductor digiti minimi, adductor pollicis, abductor pollicis

brevis

Lots of the muscles involved in handwriting

○ Arterial Supply

Radial and Ulnar arteries anastamose on the palmar side of

the wrist and give off branches for the fingers

Both are underneath palmar aponeurosis

Superficial Palmar Arch – a little more distal than deep palmar arch

Mainly supplied by ulnar artery

Ulnar artery → Superficial palmar arch → common palmar digital arteries (single in the middle)

→ proper palmar digital arteries (two on sides)

○ "USC Poonani"

Deep Palmar Arch – proximal to superficial palmar arch

Mainly supplied by radial artery (which is on the thumb side)

Deep palmar arch → palmar metacarpal arteries → proper palmar digital arteries

○ Nerves

Superficial Branch of Radial Nerve – sensory only in

hand

Ulnar Nerve

Deep Branch of Ulnar – motor to intrinsic hand

muscles

Superficial Branch of Ulnar – sensory

Palmal Branch of Ulnar – sensory

Median Nerve

Recurrent Branch of Median – supplies thenar

muscles

○ Goes through carpal tunnel

Palmar Branch of Median – sensory

○ Goes through carpal tunnel

Digital Branch of Median – sensory

Dermatome Hotspots

C6 – palmar tip of thumb

C7 – palmar tip of index finger

C8 – palmar tip of pinky

○ Carpal Tunnel

Flexor retinaculum covers palmar area containing tendons and nerves

Connects to Scaphoid (1), Pisiform (4), Trapezium (5) and Hamate (8)

Contents

4 Tendons of flexor digitorum superficialis – superficial

4 Tendons of flexor digitorum profundus – deeper

Median Nerve – thumb side near surface (except digital branch)

Tendon of flexor pollicis longus – thumb side deeper than median

Other Tunnels not part of Carpal Tunnel

Ulnar Tunnel – contains ulnar artery and nerve, is above the flexor retinaculum

Tendon of flexor carpi radialis – inside flexor retinaculum on thumb side

○ Anatomical Snuff Box

Boundaries

Palmar – tendons of extensor pollicis

brevis and abductor pollicis longus

Dorsal – tendon of extensor pollicis

longus

Proximal – extensor retinaculum

Floor – scaphoid & trapezium

Roof – superficial fascia containing

branches of superficial branch of radial nerve

Contains the radial artery

○ Clinical Connections

Brachial Plexus Injuries

Erb-Duschenne Palsy – upper plexus injury (C5-6)

○ Caused by stretching arm or neck in funny ways

○ Nerves

Injures axillary, musculocutaneous & suprascapular nerves

Suprascapular prone to injury because it is fixed at suprascapular notch

○ Note - Supraspinatous and infraspinatous muscles are paralyzed most often

○ Symptoms

Arm lacks normal abduction and external rotation

Arm cannot be raised over head because deltoid (axillary) and supra- infraspinatous muscles

(suprascapular) are paralyzed

Elbow flexion weakened because biceps (musculocutaneous) is paralyzed

If roots damaged above their junction then additional paralysis of rhomboids (dorsal scapular)

and serratus anterior (long thoracic) producing weakness in scapular retraction and protraction

Klumpke Paralysis – lower plexus injury (C8-T1), much less common, short hand muscles

affected

○ Results in claw hand

Median Nerve Paralysis – results in atrophy of thenar muscles – Abductor pollicis brevis, Opponens

pollicis

Flexor pollicis brevis maintains some function because deep head is innervated by ulnar

Ulnar Nerve Paralysis – results in interosseous muscle atrophy

Wrist deviates to radial side since no flexor carpi ulnaris

Hyperextension of 4th and 5

th MP joints

Flexor digitorum profundus weakend – cannot flex 4th and 5

th DIP

Flexion of 2nd

and 3rd

DIP

Dupuytren’s Contracture – thickening of palmar aponeurosis

Shortening and thickening of digital bands pulls fingers into flexion (esp ring and pinky)

Colle’s Fracture – fracture of wrist resulting from falling on outstretched hand

Force transmitted through thenar eminence to lateral carpal bones and end of radius

Distal fragment displaced posteriorly („dinner fork deformity‟)

Development of the Skeletal System ○ Objectives

Understand how mesoderm and neural crest contribute to skeletal system formation

Understand the basic processes involved in development of the axial skeleton

Understand the principal molecules and genes involved in somite differentiation that relate to skeleton development

Vertebrae and Ribs ○ Describe how vertebrae and ribs are formed by endochondral ossification of sclerotome regions of somites

○ Describe the formation of intervertebral discs

○ Understand the principal molecules and genes involved in development of vertebral column

What are brevicollis, spina bifida, and scoliosis; what are some of the causes for these defects

○ Describe how ribs form from lateral processes of thoracic vertebrae

○ Describe how the sternum and clavicle are formed

What is cleidocranial dysplasia?

Understand the basic processes involved in development of the appendicular skeleton

Describe how somatic lateral plate mesoderm forms the skeleton of the appendages – the limb bones and appendicular

girdles

Describe how the appendicular skeleton is formed by endochondral ossification of cartilage models

Understand the role of the apical ectodermal ridge (AER), zone of polarizing activity (ZPA), and the molecules that establish axes of polarity in the limb

Describe how digits (fingers and toes) are formed. What is the role of cell death?

Describe limb rotation and the consequences for muscle compartments

What are Amelia, meormelia, and achondroplasia?

What are the epiphyses and diaphyses and what are their significance?

Describe how synovial joints are formed

○ Derivatives of Mesoderm

Paraxial Mesoderm – forms somites (mesoderm around a small cavity)

Gives rise to sclerotome which forms the axial skeleton

Intermediate Mesoderm – connects paraxial and lateral plate mesoderm

Lateral Plate Mesoderm – lines intraembryonic cavity, becomes parietal and visceral layers

Forms appendicular skeleton

○ Skeletal Development

Begins during week 4

Many develop from pre-existing cartilage

○ Development of Axial Skeleton

Somitic sclerotome – forms all cartilages and bones of axial skeleton

Somite Development and Axial Skeleton

Somites develop into dermomyotome (which becomes dermatome and myotome) and sclerotome

Cells migrate ventromedially (toward notochord) to make sclerotome

Sclerotome formation induced by notochord and neural tube via noggin and sonic hedgehog

Sclerotome then expresses Pax1 which initiates cartilage and bone forming gene expression

Origin of Specific Bones

Vertebrae

○ Formed by endochondral ossification

○ Develops in cranial → caudal sequence from 42-44 somite pairs

Which vertebrae a somite becomes influenced by cominations of Hox genes

4 Occipital Somites – 1 degenerates

8 Cervical Somites – the 1st cervical and remaining 3 occipital fuse to form skull base

12 Thoracic

5 Lumbar

5 Sacral – fuse to form sacrum

8-10 – coccygeal fuse to form coccyx (last 5-7 degenerate)

○ Development of Individual Vertebra

Sclerotome from each side of body converge to make each vertebrae and disc

Developing spinal nerve splits each somite and causes Cranial + Caudal parts of adjacent

somites to combine and form vertebra

Ventromedial part of each vertebra forms centrum (future vertebral body)

○ Influenced by sonic hedgehog

Dorsal part of each vertebra forms costal processes (future TP) and vertebral arch

○ Influenced by roof plate of neural tube

Why Resegment?

○ Causes myotomes to span intervertebral discs (allows muscles to move vertebra)

○ Intersegmental arteries (which were originally between sclerotomes) pass over middle of

vertebral body

○ Spinal nerves near intervertebral disks pass through intervertebral foramen

○ Development of Intervertebral Discs

Developed from lower somite (ex. C5-C6 disc is from C6 somite)

Nucleus Pulposis – derived from notochord (notochord regresses from area of vert. body)

Annulus Fibrosis – formed by condensation of other sclerotome cells

Thus, the disc has two origins, notochord and sclerotome

○ Vertebral Defects

Klippel-Feil Syndrome (Brevicollis) – congenital failure to segement cervical vert

(especially C2 & C3)

○ Causes – short neck, ↓ cervical motion, low hairline, scoliosis, hearing loss

○ Gene locus on Ch 8

Faulty Hox Gene Expression

○ Due to ↑ retinoic acid consumption or metabolic disturbances in mother

○ Results in messed up cranial-caudal gradient

Ex. If ↑ retinoic acid then type of vertebrae shift more caudally

Spina Bifida – incomplete development of vertebral arch

○ 1° Cause – failure of normal vertebral induction

○ 2° Cause – failure of neural tube to close dorsally

○ Can result in herniation of spinal cord and/or meninges

Scoliosis – defective formation of one side of vertebral column

Formation of Atlas and Axis

○ The last occipital somite and the first cervical combine to form proatlas which makes

basioccipital bone and the top of the dens

○ Remember that the atlas does not form a vertebral body (called centrum in dev), thus cells that

would normally form the centrum of C1 fuse with axis of C2 to form the dens

Ribs – form as outgrowths of thoracic vertebrae during month 2

○ Sclerotome cells migrate within somatic lateral plate mesoderm around body curvature toward

ventral surface

Sternum – forms from unification of ventral aspect of ribs 1-7 (via migrating sclerotome cells)

○ Join with two vertical cartilaginous bands

○ Costal Cartilage joins ribs to sternum

○ Then segments into elements

○ Split xiphoid process is a common malformation

Clavicle

○ Forms by intramembranous ossification (different from most others)

○ Ossification begins earlier than most bones (weeks 5-6) and is the last to complete the process

(around 21-25 years)

○ Cleidocranial Dysplasia – aplasia or hypoplasia (poorly formed) clavicles

Also affects development of head (flat nose) and teeth (too many and they don‟t fall out)

○ Note - somitic mesoderm is in somites, somatic mesoderm is in the body

○ Origin of Appendicular Skeleton

Made of appendicular girdles (shoulder and pelvic) and intrinsic limb bones

All formed by endochondral ossification except clavicle

All formed from somatic lateral plate mesoderm (including cartilage)

Note – upper limbs form before lower limbs

Overview of Limb Development Mesenchyme core develops

Ectoderm surrounds and apical ectodermal ridge is formed

Limb bud develops

Cartilage mesenchyme condenses

Cartilage models begin to form

Cartilage models completed and ossification begins

Active ossification of fetal limbs

Limb Bud

Initially consists of:

○ Mesenchyme from lateral plate mesoderm – forms skeleton, CT and some BV

○ Mesenchyme from somites – forms muscle

○ Neural crest cells – form Schwann cells and melanocytes

Apical ectodermal ridge (AER) – thickened distal border which prevents mesenchyme from

differentiating and instead causes it to proliferate rapidly (so that limb elongates)

○ Expresses SER2

○ Causes limb outgrowth and induced by factors from lateral plate mesoderm

These factors are different depending on which limb it is

○ If AER is experimentally removed then limb will stop proliferating and start differentiating

The entire limb bud is covered by ectoderm

○ Dorsal part expresses radical fringe

○ Ventral part expresses engrailed (just know that different things are expressed on either side)

The Process (mainly just understand the point)

○ Bone morphogenic factors (BMPs) in ventral ectoderm induce AER formation

○ AER restricted to distal tip of limb by radical fringe

○ Radical fringe induces SER2 expression in AER

○ Engrailed represses expression of radical fringe to maintain the polarization

○ AER then expresses FGF4 & 8 to proliferate cells

○ As limb elongates, the proximal mesenchymal cells start to differentiate as the AER gets farther

away from them

Zone of Polarizing Activity (ZPA) – cluster of cells at caudal border of limb that establish the

cranio-caudal polarization (proper location of digits etc.)

○ Produces retinoic acid which initiates expression of sonic hedgehog

Absence of SHH causes regression of AER (Why???)

○ As limb grows the ZPA moves distal to keep up with the AER

Dorsoventral Axis – regulated by BMPs in ventral ectoderm

○ BMPs cause expression of engrailed on ventral side, which represses stuff that is secreted by

dorsal side

○ LMX1 specifies cells to be dorsal

HOXd Expression Patterns in Limb

○ Pattern limb along proximodistal axis

○ Influenced by combinations of SHH and others

○ ↑ number means more distal

Development of Digits

○ Process

Apoptosis in specific parts of AER creates separate ridge for each digit

Apoptosis in interdigital spaces separates digits

○ If cell death does not occur → syndactyly (abnormal digit formation, too many or too few)

○ Apoptosis also important for separation of radius/ulna & tibia/fibia & axilla

○ Digit Specification - BMP concentration is highest between digit 4&5 and this causes digit 4 to

be digit 4. BMP concentration is lowest between 1&2 and this causes 1 to become 1

Limb Rotation

○ At first all limbs are oriented so that flexors are on one side and extensors on the other

○ Then upper limb rotates laterally and lower limb rotates medially so that the muscles are in the

right spot

Amelia – complete absence of limbs

Meromelia – partial absence of limb

○ Phocomelia – proximal structures small or absent

Epiphyseal Plates – temporary plate of cartilage between the diaphysis (middle of bone) and

epiphysis (end of bone)

○ Long bones have one at each end, small bones only have one, irregular bones have multiple

○ Achondroplasia (dwarfism) – abnormal ossification of cartilage that mainly affects long bones

Epiphyseal growth retarded and ceases early

Joint Formation

○ Cartilage present and differentiated

○ Joint “interzone” created by cells proliferating and increasing in density

○ Joint cavity formed by cell death, but surrounding cells stay to form joint capsule

Blood

○ Objectives (she emphasized these)

Identify the components of the blood and describe their functions

Identify sites of hematopoesis and describe what happens there

Explain the importance of stem cells and how they relate to hematopoiesis

Describe the functional anatomy of the bone marrow

Distinguish the developmental stages of formed elements

Describe the functions of granulocytes

○ Funciton – transport gases, buffer, transport hormones, produce & transport antibodies

○ Hematocrit – RBC % after centrifugation

Usually 45% RBCs, though in women it is lower

1% of it is WBCs and platelets, forming buffy coat

○ neutrophils > lymphocytes > monocytes > eosinophils > basophils

○ Granular leukocytes – neutrophils, eosinophils, basophils

○ Agranular leukocytes – monocytes, lymphocytes (T cells, B cells)

○ Nice picture??

The other 65% is plasma, just water, proteins and solutes

7% proteins – created in liver and confined to bloodstream

○ albumin – maintains blood osmotic pressure

○ immunoglobulins – antibodies

○ fibrinogen – for clotting

1-2% - electrolytes, nutrients, hormones, waste products, gases

○ RBCs

Important Structures

Band 3 – ion transporter & site for ankyrin to hold onto

Spectrin + Band 4.1 + actin – lets RBC be pliable

Reticulocytes – immature RBCs in circulation

Identifiable because they have a thin band of ribosomes

Anemia – deficiency in hemoglobin

Normochromic anemia

○ Hereditary spherocytosis – abnormal spectrin causes RBC shape deformity

○ Sickle Cell Disease – Valine substituted for glutamate. Can have reverisibly and non-reversibly

sickled RBCs

Hypochromic anemia – Iron deficiency of some sort (poor diet, blood loss)

Polycythemia – net increase in RBCs resulting in ↑ hematocrit and ↑ blood viscosity

Can be caused by stem cell disorder or ↑ erythropoietin

○ WBCs

Type Picture % Diameter Targets Nucleus Look

Neutrophils

60-70 10-12 -Bacterial first

defense

-phagocytes

multilobed Clear granules

you can‟t see

Eosinophils

2-4 10-12 -antiparasitic

-inhibits

histamine

-phagocytizes

antigen-antibody

complexes

Bilobed Pink granules

Basophils

<1 12-15 -Inflammatory

-Allergic

bilobed Dark blue

granules

Lymphocytes

20 7-8 T-Cells

B-Cells

Takes up

much of

the cell

Big nucleus,

very dark

because of

dense chromatin

Monocytes

3-8 14-17

biggest

-precursors to

macrophages

Kidney

shaped

-can find

nucleolus in

each lobe

-chromatin

not condensed

Megakaryocyte

Huge -doesn‟t

circulate

-makes platelets

Complex,

multilobed,

<64N

Note – neutrophils don‟t circulate, they marginate in capillaries and organs and sit there until needed

Note – eosinophil chemoattraction inhibited by steroids

Note – basophils involved with inflammatory response by release of histamine, heparin and serotonin

Serotonin and heparin are main culprits for anaphylactic shock since they help relax muscles?

Basophils also involved with allergic response via release of leukotrienes

Note – Monocytes are antigen presting cells, osteoclasts in bone, and Kupffer cells in liver (which help

recycle RBCs)

Lymphocytes

T-Lymphocytes – cell mediated immunity, many made as children and live forever

○ immune memory, 90% in blood

○ Present antigen to B-Cells

B-Lymphocytes – 4-10% in blood, mediate humoral immunity

○ Synthesize and secrete antibodies

Platelets

Hyalomere – outer visible ring containing microtubules allowing it to be contractile

Granulomere – internal structure of platelet (no nucleus)

○ Surface-opening tubule – where granules are released

○ Dense tubular system – machinery of platelets

Cytoplasm of megakaryocytes just buds off and platelets are formed

Thromboembolism – platelets blocking vessels

Coagulation disorders can be caused by Vitamin K deficiency, hemophilia

Thrombocytopenia – low # of platelets

○ Can be caused by leukemia, cancer, chemo drugs

○ Can result in petichiae (little bruises) and ecchymoses (big hemorrhages)

Types of Granules

All granulocytic leukocytes have azurophilic granules which are part of the lysosome and are clear

Neutrophils have three types of granules, but all are clear

Major Basic Protein – a specific granule found in eosinophils that helps fight against parasites

○ Bone Marrow

Clavicle is 1st place where bone marrow is formed

Cells in bone marrow ↓ with age

All cells in bone marrow are derived from one stem cell?

Megakaryocytes are always located near sinuses

Erythroblastic island – where RBCs are formed

Nurse cell – in the middle that phagocytizes old RBCs (a macrophage)

Hematopoetic cord – the cellular part

Adventitial Cells – can make fat and turn marrow into yellow marrow, this is reversible if necessary

These are the big clear cells in bone marrow

Reticular fiber used to hold everything together

Hematopoesis

Stem cells can make anything

Progenitor cells – high mitotic activity, self-renewing. Often have „forming cell‟ in the name

Precursor cells – high mitotic activity, not self-renewing. Often have „blast‟ or „myelocyte‟ in name

Mature cells - no mitotic activity, first cells to be seen in blood

Erythropoiesis

○ Cell gets smaller at each stage

○ Amount of RNA ↓ and amount of hemoglobin ↑ as process progresses

○ Proerythroblast – first cell you can visually identify

Responds to erythropoietin (only one to do so) which is released by kidney

○ Basophilic erythroblast – lots of protein (hemoglobin) and RNA synthesis

○ Polychromatophilic erythroblast – RNA becomes visible and nucleus darkens

Concentration of ribosomes and hemoglobin is equal

○ Orthochromatophilic erythroblast - Mitosis occurs up until this stage, afterwards nucleus is

extruded and mitosis stops

Nucleus is near one side

Granulopoiesis

○ Promyelocyte – gives rise to all granule cells. oval nucleus with nucleoli

○ Myelocyte stage – granules specific to each cell begin to form

○ Metamyelocyte stage – nucleus changes shape, more granules present

○ (Band Cell) – specific to neutrophils, nucleus like a horseshoe

○ Mature phenotype

Monopoiesis (difficult to find)

○ Monoblast → promonocyte → monocyte → differentiates into macrophage

○ Promonocyte has well developed golgi, RER, mitochondria, lysosomes

Lymphopoiesis (hard to identify)

○ Lymphoblast → prolymphocyte → T-cell & B-Cell

○ T-Cells differentiate outside bone marrow, B-Cells differentiate inside bone marrow