Introduction to human anatomy. Introduction A strong, yet light, internal support for the human body...
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Transcript of Introduction to human anatomy. Introduction A strong, yet light, internal support for the human body...
Introduction to human anatomy
Introduction A strong, yet light, internal support for
the human body The skeleton is adapted for the
protection, locomotor, and manipulative functions
The upright stance increases the ability of the skeletal muscle to resist gravity
Introduction The skeleton maintains its upright
position through a series of compensating curves
The skeleton accounts for approximately 20% of the body mass
The 206 bones of the body are grouped into the axial and appendicular skeleton
Introduction
Axial skeleton Forms the long axis
of the body 80 bones in three
major regions– skull
– vertebral column
– bony thorax• Ribs
• Sternum
Appendicular Bones of upper &
lower extremities and girdles
126 bones in three major regions– Girdles
• Shoulder girdle
• Pelvic girdle
– upper extremity
– lower extremity
The Skull The skull is the body’s most complex
bony structure It is formed by two sets of bones, the 8
cranial bones and the 14 facial bones These 22 bones combine to form the
cranial cavity and the facial features In addition, there are 3 bones in each
inner ear to assist in sound transmission
The Skull: Introduction The bones of the skull provide . . .
– A case to house the brain, the cranium– A framework for the face– Cavities to house the organs of sight, taste,
and smell– Passages for air and food– Attachment sites for the teeth– Attachment sites for muscle
The Skull: Introduction Most bones of the skull are flat bones Except for the mandible, all bones are firmly
united by interlocking sutures The major sutures of the skull are . . .
– Coronal (Between Frontal & Parietal)– Sagittal (Between Parietal bones) – Squamosal (Between Parietal & Temporal)– Lambdoidal (Between Parietal & Occipital)
Other skull sutures connect facial bones and are named after these structures
________________________________________________SagittalSagittal
CoronalCoronal
LambdoidLambdoid
SquamousSquamous
Overview of Skull Geography
Facial bones form the anterior aspect The cranial bones enclose the brain
Vault The cranial vault
or calvaria forms the superior, lateral, and posterior aspects of skull
The cranial base forming the inferior aspect of skull
Cranial Base Cranial base forms
the skull’s inferior aspect
Three prominent ridges divide the base into fossae
The brain rests on these cranial fossae completely enclosed by the cranial vault
The brain occupies the cranial cavity
Cavities of the Skull In addition to the large cranial cavity
there are many smaller cavities– Middle and inner ear cavities– Nasal cavity– Orbits of the eyes– Several bones contain air filled sinuses
• Sinuses surrounding the nasal cavity are referred to as the paranasal sinuses
Study Note
As you read about the bones of the skull, locate each bone on the different skull views in Figures 7.2, 7.3, 7.4
The skull bones and their important markings and features are summarized in Table 7.1 on pages 213-214
Cranium
The 8 cranial bones include; 2 parietal, 2 temporal frontal, occipital, sphenoid, ethmoid
Cranium is self- bracing allowing the bones to be thin, yet strong
Frontal bone Forms the
anterior portion of the cranium, the forehead, roofs of the orbits, and most of the anterior cranial fossa
Frontal bone - landmarks Frontal
squama Supraorbital
margins Supraorbital
foramen Orbits Anterior
cranial fossa Glabella Frontal
sinuses
Parietal bones Forms most of
the superior & lateral aspects of the skull
Articulates with other cranial bones to form four major sutures
ParietalParietal
Parietal bones - landmarks
The four largest sutures cranial sutures, Coronal, Sagittal, Lambdodial, Squamosal
Occipital bone Forms most of
the posterior wall and base of skull
Articulates with parietal & temporal
Joins w/ sphenoid in the cranial floor
Forms internal walls of posterior cranial fossa
Occipital bone - Ext. landmarks Foramen magnum,
Occipital condyles, External occipital protuberance, Nuchal lines, External occipital crest
Occipital bone - Int. landmarks
Hypoglossal canal, Posterior cranial fossa
Temporal Bone Forms the infero-
lateral aspects of the skull
Parts of the cranial floor
Divided into four regions; squamous tympanic, mastoid, and petrous-(int)
Temporal Bone The internal
petrous region contributes to the cranial base
The petrous region and the sphenoid bone form the middle cranial fossa
Temporal Bone - landmarks Zygomatic
process– Meets the
zygomatic bone
– Forms the cheek
Mandibular fossa– Receives
condyle of mandible
Temporal Bone - landmarks External
Auditory Meatus– Middle and
inner ear Styloid
process– Muscle of
tongue Mastoid
process– Muscles of
neck
Temporal bones - landmarks Jugular
foramen– Entry point for
the Jugular artery
Internal acoustic meatus– Entry point for
the auditory nerve
Jugular ForamenJugular Foramen
Temporal bones - landmarks Stylomastoid
foramen– exit for facial
nerve Carotid canal
– entrance for the carotid artery which supplies blood to cerebral hemispheres
Sphenoid bone Bone spanning the
width of middle cranial fossa
Articulates as central wedge of all cranial bones
Consists of central body and three processes; greater and lesser wings and pterygoid process (pos. view)
Sphenoid - landmarks
Sella turcica (enclosure for pituitary gland) Optic foramina (passage of optic nerves) Superior orbital fissure (Nerves III, IV, V enter orbit) Foramen rotundum & ovale (Cranial Nerve V to face) Foramen spinosum (Middle meningeal artery)
Ethmoid bone Forms most of
the area between the nasal cavity & orbits of eyes
Lies between nasal bones & sphenoid
Complex shape gives rise to nasal septum, sinuses and cribiform plate
Ethmoid bone - landmarks Cribiform plates
– Forms roof of nasal cavity
Olfactory formina– Olfactory nerves
enter brain Crista galli
– Attachment of the dura mater which secures brain in cavity
Ethmoid bone - landmarks Perpendicular
plate– Forms superior
part of nasal septum
Lateral mass– House ethmoid
sinuses Nasal concha
– Project into nasal cavity
Orbital plates– Medial walls of
orbits
Facial bones Consists of 14
bones w/ only mandible and vomer unpaired
Others include maxillae, lacrimals, nasals, zygomatics, inferior nasal conchae, and palatines (not pictured)
Mandible Forms the lower
jaw Largest,
strongest bone of the face
It has a body and two upwardly projecting sections called rami
Houses lower dentition
Mandible - landmarks Mandibular angle Mandibular notch Coronoid process Mandibular
condyle Alveolar margin Mandible formina Mental formina Ramus of
mandible
Maxillary bone Forms upper
jaw and central portion of facial skeleton
Fused medially Articulates with
all facial bones except mandible
Upper dentition Forms 2/3 of
hard palate of the mouth
MaxillaryMaxillarybonebone
Zygomatic Zygomatic processprocess
Maxillary bones - landmarks Alveolar margin
– Upper dentition Frontal process
– Forms lateral aspects of nose
Zygomatic process– Articulates with
zygomatic bone Maxillary
sinuses – (Fig. 7.11)
Maxillary bones - landmarks Palatine
processes– Forms roof of
mouth Incisive fossa
– Passage of nerves and blood vessels
Infraorbital foramen– Infraorbital
nerve and blood vessel to face
Palatine ProcessPalatine Process
Maxillary bones - landmarks Inferior
orbital fissure– Located deep
within the orbit
– Permits passage of the zygomatic nerve, maxillary nerve, and blood vessels to reach face
Zygomatic bones Commonly called
the cheekbones Form prominences
of cheeks and inferolateral margins of orbits
Articulate with the Zygomatic process of temporal bone and Zygomatic process of maxallae
Zygomatic Zygomatic bonebone
ZygomaticZygomaticProcess of Process of TemporalTemporal
Nasal bones Forms bridge of
the nose Thin,
rectangular shape
Fused medially Articulate with
the frontal bone and maxillary bones laterally
Nasal cartilages– (Fig. 6.1)
Lacrimal Bones Forms part of
the medial border of each orbit
Articulates with frontal, ethmoid & maxillae
Forms part of Lacrimal fossa– Permits tears to
drain from orbit to nasal cavity
Lacrimal Bones Lacrimal fossa
– Permits tears to drain from orbit to nasal cavity
Palatine bones The horizontal
plates forms the posterior portion of hard palate
Vertical plate forms part of the posterolateral wall of nasal cavity and a small portion of orbit
Palatine bones - landmarks Horizontal plate
– Posterior section of hard palate
Vertical plate– Part of the
posteriolateral walls of nasal cavity
Orbital surface– Part of inferior
medial aspect of orbit
Vomer Forms part of
the nasal septum
Discussed with the nasal cavity
Vomer - landmarks Plow shape
– Divides nasal septum into right and left parts
Inferior Nasal Conchae Form lateral
walls of nasal cavity
Project medially from the lateral walls of nasal cavity
Largest of nasal conchae
Inferior Nasal Conchae - Landmark
The Inferior nasal conchae is just one of three in the nasal cavity
Superior and middle concha are on the Ethmoid bone
The Orbits The orbits are bony cavities within which
the eyes are encased and cushioned by fatty tissue
The muscles that move the eyes and the tear producing lacrimal glands are housed within the orbit
Formed by frontal, sphenoid, maxilla, zygomatic, lacrimal palatine & ethmoid
Contain superior & inferior orbital fissures Optic foramina
The Orbits
Nasal cavity The nasal cavity is constructed of bone
and hyaline cartilage The cavity is divided into right and left
parts by the nasal septum Superior, middle and inferior nasal
concha project into the cavity The nasal septum and conchae are lined
with mucus-secreting mucosa
Nasal cavity Roof of the
cavity is the cribriform plates of ethmoid
Lateral walls are the superior, middle, and inferior conchae, and vertical plates of palatines
CribriformCribriformplateplate
Nasal cavity Floor of cavity is
formed by palatine processes of the maxillae and the palatine bones
Septum is formed by vomer and the perpendicular plate of ethmoid
Paranasal sinuses Five skull bones; frontal, sphenoid,
ethmoid, and the paired maxillary contain mucus-lined, air-filled sinuses
Cluster around nasal cavity Connected to nasal cavity to allow air to
enter and mucus to drain Lighten skull, warm and humidify air,
enhance voice resonance
Paranasal sinuses Note positioning
around nasal cavity
Paranasal sinuses Sphenoid sinus Frontal sinus Ethmoid sinus Maxillary
sinuses
Hyoid bone Not really a part of the skull, it is unique
in that it is the only bone that does not articulate with any other bone
Positioned just inferior to the mandible Anchored by stylohyoid ligaments to the
styloid processes of temporal bone Acts as a movable base for the tongue
Hyoid bone
Body– Neck muscle
attachment Greater horn
– Neck muscle attachment
Lesser horn
THE VERTEBRAL COLUMN
SECTION II
Vertebral Column:General Characteristics
Formed from 26 irregular bones It contains four distinct curvatures It provide axial support for the trunk Transmits weight of trunk to lower limbs Protects spinal cord Attachment site for ribs and muscles Separated by intervertebral discs There are 24 vertebrae, a sacrum (5 fused)
and a coccyx (4 fused)
General Characteristics Alignment
– Anterior/ posterior
– Lateral Curvatures
– Compensatory curves
Features– Weight bearing
– Muscle attachment
– Protection
RegionalCharacteristics Cervical C1-C7
– Neck / movable Thorasic T1-T12
– Rib cage / limited movement
Lumbar L1-L5– Low back / movable
Sacral 5 fused– Joins the pelvis
Coccyx 4 fused– Terminus
Clinicaldeviations Scoliosis
– An abnormal lateral curvature of the spinal column
– Curvature can occur in an “S” or “C” deviation
Clinical deviations Kyphosis
– An exaggerated dorsal curvature in the dorsal region
– Common is aged individuals because of osteoporosis
Clinical deviations Lordosis
– Accentuated lumbar curvature
– Being overweight or pregnant causes an excessive load up front
Curves develop in response to:Curves develop in response to:Upright postureUpright postureWeight bearingWeight bearing
MusculatureMusculature
Characteristics - Ligaments Ligaments hold the
vertebral column in an upright position– The broad Anterior
Longitudinal Ligament prevents hyperextension and is quite strong
– The cord like Posterior Longitudinal Ligament prevents hyperflexion and is relatively weak
Characteristics - Ligaments Ligaments
also connect specific vertebra and support disc position– Supraspinos
ligament
– Ligamentum flavum
– Interspinous ligament
Intervertebral Discs Intervertebral discs are cushion like pads
interposed between vertebra The discs provide elasticity and
compressibility Compression flattens discs Discs are thickest in the cervical and
lumbar to provide flexibility
Characteristics - discs Annulus fibrosus
surrounds the outer margin– Collagen fibers
Nucleus pulposus is the semi fluid substance which shifts under body weight & pressure
Herniation of disc Herniation Herniation of diskof disk
General structure of vertebrae Common pattern
– Body or centrum
– Vertebral arch• lamina
• pedicle
– Vertebral foramen
– Spinous process• Muscles attach
– Transverse process
• Muscles attach
General structure of vertebrae Interlocking
pattern– Superior and
inferior processes interlock
– The inferior from above and the superior from the vertebrae below form a movable joint
– The movement contributes to spinal rotation
Superior ArticularSuperior ArticularProcessProcess
General structure Pedicles have
notches on their superior and inferior borders
Lateral openings are called intervertebral foramen– Spinal nerves
from spinal cord exit through these foramina
Regional Characteristic: Cervical Body is oval, but wide
side to side C3 - C7 Spinous process is
short and bifid (split) except in C7
Vertebral foramen is triangular
Transverse processes contain foramina for blood vessels leading to brain
Cervical Vertebrae C1 and C2 The first two cervical vertebrae are named
the atlas and axis respectively There is no intervertebral disc between
them They are highly modified for carrying the
skull on top of the vertebral column The atlas (C1) functions are a cradle to
support the head The axis (C2) functions as a pivot point for
the rotation of the atlas
Cervical Vertebrae C1
Lateral masses articulates with the occipital condyles of the skull
Cervical Vertebrae C1
Inferior articular surface articulates with C2 below
Body of the Body of the Vertebrae is Vertebrae is
missing missing
Cervical Vertebrae C2 The axis has the
odontoid process or dens is its unique feature
The dens is the missing body of the atlas which fuses with the atlas during embryonic development
Regional Characteristic: Cervical Spinous processes
project directly posteriorly
Superior facets directed superoposteriorly
Inferior facets directed inferoanteriorly
Flexion/extension, lateral flexion and rotation
Regional Characteristic: Thoracic
Body is larger than cervical; heart shaped
Spinous process is long and sharp
Vertebral foramen is circular
Transverse processes project posteriorly and bear facets for ribs
Regional Characteristic: Thoracic Body bears two
costal demifacets Spinous processes
projects inferiorly Superior facets
directed posteriorly Inferior facets
directed anteriorly Rotation, limited
lateral flexion, flexion/extension prevented
Regional Characteristic: Lumbar
Body is massive and kidney shaped
Spinous processes are short and blunt
Vertebral foramen is triangular
Transverse processes are perpendicular to spinous process but has no special features
Regional Characteristic: Lumbar Spinous process
projects posteriorly Superior facets
directed medially Inferior facets
directed laterally Flexion/extension,
some lateral flexion, rotation prevented
Sacrum The triangular shaped structure formed
by five fused vertebrae Forms the posterior wall of the pelvis Articulates with L5 of the vertebral
column Articulates with the iliac bone of the
pelvic girdle Transfers the weight of the upper torso
and limbs to the lower extremities
Sacral Ala are fused remnants
of transverse processes that articulate with hip bones to form the sacro iliac joints of the pelvis
Sacral promontory – Center of gravity is 1 cm
posterior of this point Transverse line are sites
of vertebral fusion Sacral foramina
transmit blood vessels and nerves
SacralSacralpromontorypromontory
AlaAla
Sacral On the posterior aspect
median sacral crest are fused spinous processes
The vertebral canal continues inside the sacrum as the sacral canal
Sacral hiatus is at the inferior end of the sacral canal
Superior articular surface form a joint with the spinal column
Coccyx
Coccyx articulates with sacrum
The Bony Thorax The thorax is the chest which includes
– Thoracic vertebrae posteriorly– The ribs laterally– The sternum and costal cartilages anteriorly
It is cone shaped with its broad opening inferiorly
The thorax forms a bony cage around the heart, lungs and major blood vessels
Functions of The Bony Thorax Protection Attachment point for muscles of the
back, chest, and shoulders The intercostal muscles attach to the
thorax to lift and depress the thorax during respiration
The Sternum The sternum lies in the
anterior midline of the thorax
It is three fused bones – Manubrium
• Jugular notch
• Clavicular notch
– Sternal body• Sternal angle
– Xiphoid process• Xiphisternal joint
Bony Thorax Thorax is the chest and its bony
underpinnings is called the thoracic cage Elements consist of the thoracic vertebrae,
ribs, sternum, and costal cartilages which secure ribs to the sternum
A cone opening inferiorly, the thorax provides a protective cage around the vital organs of the thoracic cavity (heart, lungs, great blood vessels)
Bony Thorax - continued
Provides support for the shoulder girdles Bony attachment points for muscles of the
back, chest and shoulders Intercostal spaces between ribs are occupied
by the intercostal muscles which lift and depress the thorax during breathing
Sternum Located on the anterior
midline of the thorax Consists of three fused
bones; manubrium, body, and xiphoid process
Manibrium articulates with clavicle & 2 ribs
Body with ribs 2 - 7 Xiphoid attachment site
for abdominal muscle
Thorax to Vertebral Column
Ribs
Ribs Twelve pairs forming thoracic cage All attach posteriorly to thoracic vertebrae Curve inferiorly toward anterior body surface Ribs 1-7 attach directly to sternum by
separate costal cartilages and are referred to as true ribs
Ribs 8-10 attach indirectly to sternum by attaching to costal cartilages immediately above
Ribs 11-12 have no anterior attachments and are referred to as floating ribs
Ribs Ribs are bowed
flat bones Long shaft Tear drop shaped
with a costal groove on inner surface
Head of rib has 2 facets to articulate with its vertebrae as well as the one above
Ribs Neck is just
beyond the head Angle of rib Costal cartilages
attach rib to sternum
Attachments are secure but flexible
Ribs Tubercle of rib
articulates with transverse process
Ligaments secure rib to transverse process
Note how the transverse processes of thoracic vertebrae are angled posteriorly
The Appendicular Skeleton Appended to the axial skeleton Pectoral girdle is for manipulation and is
a lighter, less heavily reinforced structure Pelvic girdle is for weight bearing and
locomotion and is a heavier, more robust structure
Differences appear in bone structure, joint structure, ligaments, and muscle