Skeletal SystemOsteology

Types of Bones

Axial Skeleton

Appendicular Skeleton

Arthrology

Bone DisordersCartilage

Bone Formation

Classification of Bones

Function of Bone

Facial Bones

Skull

Bone Fractures

Osteology – The Science of Bones

Bone are composed of: Cells, Fibers and a Matrix ( Ca2+)

The Matrix of the Bone is referred to as an

Hydroxyapatite

The Chemical Composition of the bone matrix is

(Ca2+)10(PO4)6 (OH)2 return

Bone is living tissue it grows and changes throughout your life.

You completely replace your entire skeleton

about every ten years.

Figure 07.01Structure of a

Long Bone

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Bone Formation

Two Types -

1. Intramembranous – Develops in the connective tissue membranes in the embryo called Mesenchyma – embryonic CT

2. Endochrondral Bone Formation – Bone forms in cartilage

A cartilage model of the skeleton is in place and the cartilage is removed and bone is laid down.

NOTE : Bone is NOT calcified cartilage

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Formation of bone is called Ossification -

it starts in the embryo and continues to age 18 in females and 20 in males.

Within the cartilage skeleton model of the embryo are ossification centers.

This is where the cartilage is being destroyed and the bone is being made.

Ossification takes place in the middle of the bone shaft first and then at the ends. The bone develops moving very slowly toward the ends of the bone.

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Two types of bone are produced :

Spongy Bone – Contains a lot of cavities this structure reduces weight and increases strength of the bone.

This is the region that is effected by osteoporosis the most.

Hemopoietic tissue (makes blood) fills the cavities of spongy bone.

Compact Bone - Dense strong bone that makes up the outer surface of the bone.

Compact bone is composed of millions of subunits called:

Haversian Systems or Osteons

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Figure 07.02

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Volksman Canal

Articular Cartilage

Spongy Bone with Hemopoietic Tissue

Epiphyseal Plate or Growth Plate

Epiphysis

Diaphysis

Three types of Bone Cells

1. Osteoblasts – Makes new bone

2. Osteocytes – Maintain existing bone if damage occurs. Live inside calcified bone in lacuna (“little pond” in Latin)

3. Osteoclasts – Remove bone, act like white blood cells. They are triggered by parathormone from the thyroid to breakdown bone to increase calcium level in blood.

Their action can lead to osteoporosis – Loss of bone mass due to lack of calcium. Bones can become weak and brittle.

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Haversian Canal Systems

Haversian System

or OsteonLamella of bone

OsteocyteHaversian Canal

Canaliculi

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Function of Bones

1. Support

2. Motion – Muscle Attachment

3. Protection – Skull protects Brain

Ribs & Sternum protects Heart & Lungs

4. Calcium Storage – There is a constant exchange between bones and blood.

5. Bone Marrow – Process called Hemopoisis is the making of Red and White blood cells.

In the infant red marrow is found in most of the bones.

In the adult it is only found in 1. Sternum and Ribs

2. Hip Bones (iliac Crest) Take marrow samples here

3. Bodies of Vertebrae

4. Proximal end of Long Bonesreturn

Classification of Bones

1. Long Bones

Upper Extremities - Humerus

Radius & Ulna

Lateral Medial

Palm - Metacarpals

Fingers - Phalanges

Lower Extremities - Femur

Tibia & Fibula

Medial Lateral

Foot - Metatarsals and Phalanges

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2. Short Bones - Wrist - Carpal bones or carpus

Ankle - Tarsals bones or Tarsus

3. Irregular Bones - Vertebrae & Skull

may be movable or immovable

contain many irregular bones

4. Flat Bones - Scapula – Shoulder blade

Clavicle – Collar bone

Skull - Frontal & Parietal bones of skull

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5. Sesamoid Bones “seed” – small, nodular found within tendon ex: patella (knee cap)

Identifying Characteristics of Bones

1. Fossa – Depression in a bone

ex: TMJ (Temporal Mandibular Joint) forms a fossa

2. Sinus – Cavity in a bone

ex: maxillary sinus – cavity above upper jaw

3. Foramen – Hole in a bone

ex: Foramen Magnum – hole for spinal cord in skull

4. Meatus – Tubular structure in bone

ex: External auditory meatus let sound enter skull

5. Condyles – Large smooth curved surfaces that touches another bone.

ex: Distal end of femur

6. Trochanter – A large projection on a bone for muscle attachment

Lec 1return

Table 07.02

Figure 07.09

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Appendicular Skeleton

Axial Skeleton

Skeleton

Axial Skeleton - Skull

Ossicles (ear bones)

Hyoid

Sternum & Ribs

Vertebral column

Appendicular Skeleton - Upper Extremities

Pectoral Girdle - clavicle & scapula (attachment to axial skeleton)

Lower Extremities

Pelvic Girdle – ilium, ischium, pubic bone

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SkullTwo major components –

1. Skull Cap - Calvarium or cranium contains 8 bones that enclose the brain.

2. Facial Bones – 14 bones that support muscles of the face.

Bones of the Calvarium –

1. Frontal – forehead – Anterior fossa of base of skull

2. Parietal – 2 – means “walls”- top of skull

3. Temporal – 2 – sides of skull

4. Occipital – posterior part of skull

5. Sphenoid

6. Ethmoid

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12

35

4

6

Temporal Bone - Four Parts

1. Squamous – Flat/thin part of skull ( Don’t get hit here)

2. Mastoid Process – “breast” – contain sinus for middle ear.

3. Zygomatic Process – “bar” – posterior portion of cheek bone

4. Petrous portion – “hard” – houses the inner ear

Occipital Bone – Thick Bone

Contains the Foramen Magnum “Big Hole”

Articulates with first cervical vertebra - Atlas

Greek god Atlas Return

Sphenoid – Floor of skull – called the keystone of the skull keeps the other bones in place.

Holds the Pituitary Gland in the “Turkish Saddle” formed by the four Clinoid processes.

Ethmoid Bone – “sieve” contains holes for olfactory nerves to pass through. This is called the Cribriform Plate.

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EthmoidSphenoid

Looking down into skull

Petrous portion

Pituitary would be here

V shape of Occipital is called a

Lambdoidal Shape

Clinoid Processes

“Turkish Saddle”

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Squamous

The immovable joints between the bones of the skull are called

Sutures

Anterior

Posterior Return

Infant Skull – Contains areas of connective tissue called

Fontanelles

Allows the skull to move during birth and accommodates rapid growth of brain.

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Facial Bones

There are two of each of the facial bones

1. Maxilla – Upper Jaw called keystone of face all facial bone touch the maxilla except mandible.

2. Zygomatic Process – Anterior roof of mouth formed by maxilla

3. Nasal Bones – Forms bridge of nose

4. Lacrimal Bones – Inferior medial orbit

5. Zygomatic Bones – Middle of cheek

6. Palatine Bones – Posterior portion of the roof of the mouth

7. Vomer – Bone of lower septum of nasal cavityReturn

1

2

34

57

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The Cheek is made up of :

Zygomatic Process - Maxilla

Zygomatic Bone

Zygomatic Process - Temporal

The roof of the mouth is called the Hard Palate

It is composed of the: Maxilla - Anterior

Palatine - Posterior

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Nose –

Lateral Nose - Two inferior Conchae in the Inferior lateral nasal cavity

Medial Nose - Vomer – medial nasal cavity (called the Septum)

Mandible – Jaw bone only moveable joint of skull

Condyloid Process

Part of TM Joint

Ramus “branch”

Angle

Body

Coronoid Process

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Figure 07.12

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Teeth—Humans have a heterodont dentition ( Different Teeth)

Figure 07.17C1

C7

T1

T12

L1

L5

Ribs attach to all the Thoracic Vertebrae

Figure 07.18

Muscle attachment

Rib attachment

Laminectomy – Cut through this part of the vertebra to get to the spinal cord

Spinal cord found here

Thoracic is area most common for tumors

Largest bodies in Lumbar region due to carrying all of the body’s weight

Longest spinous processes in Thoracic region

C1 – Atlas

C2 – Axis

Odontoid Process “tooth” connects these two together allows you to rotate your head

Vertebral Column –

Posterior Lateral

AnteriorCervical

Thoracic

Lumbar

Sacral

Coccyx

Scoliosis

Abnormal Curves –

Kyphosis – Hunchback – Accentuated Thoracic Curve

Lordosis – Swayback – Accentuated Lumbar Curve

Scoliosis – Lateral curve in Thoracic region more common in females begins during puberty.

Intervertebral Discs –

Rings of Fibrocartilage between the vertebrae

Annulus Fibrosis

Stiff cartilage ring Nucleus Pulposus –

Soft gelatinous center

Slipped Disc -

When someone has a slipped disc the disc doesn’t really move. The Annulus tears and the soft gelatinous center gets squeezed out. Sort of like putting pressure on a jelly donut the jelly squeezes out.

Best cure is bed rest and to let the ring heal and the center to regenerate.

Figure 07.21

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Humerus – Bone of Arm

Surgical Neck

Deltoid Tuberosity

Figure 07.25

Distal

Proximal

Lateral Medial

Semilunar notch

Figure 07.29

Male

Female

Figure 07.30For muscle attachment, you can see how active person is by looking at this area of a bone.

Common fracture siteFemur

Patella in tendon found here

Figure 07.31Articulates with femur

Articulates with Talus Bumps on side of ankle

Figure 07.33

Dancer’s Fracture

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Box Figure 07.01aBone

Fractures

Repair of Bone Fracture

1. Severe Bleeding

2. Blood clot forms in the bone

3. Cells from the Periosteum produce Osteoblasts that produce new bone.

4. New bone fragment + Blood clot form a Callus

5. Bone forms between fracture ends called a Bony Collar

6. Osteoclasts remove excess bone

Box Figure 07.01b

Arthrology – Science of Joints

1. Fibrous Joints – Contain very little connective tissue between the bones.

ex: sutures of the skull

2. Cartilaginous Joints – Fibrocartilage between bones – strong joints

ex: Intervertebral Discs, Pubic Symphysis

3. Synovial Joints – Connections between bones of appendicular skeleton “ with egg white” ex: Humerous & Glenoid fossa, Femur & Acetabulum

Synovial Fluid is there to reduce friction in the joint and to moisten and nourish the cartilage. Cartilage doesn’t have blood vessels so the cartilage celled get nourish by synovial fluid.

A Bursa is a bag of synovial fluid attached to a joint that is there to reduce friction. Inflammation of the bursa is called Bursitis.

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Figure 07.35

Produces Synovial Fluid

Made of Hyaline Cartilage

Figure 07.37

Types of Joints

Movement of a Joint

Flexion - Decrease an angle

Extension - Increase an angle

Adduction - Bring limb toward the midline

Abduction - Move limb away from midline

Circumduction - Circular motion

Dorsiflexion – Lift foot toward shin

Supination / Pronation- rotate hand palm up or palm down

Arthritis

Rheumatoid Arthritis – “discharge” of synovial fluid. Disorder of the immune system, joints swell with stiffness and pain due to excess of synovial.

Osteoarthritis – Breakdown of articular cartilage so bone grind on bone with pain and reduced movement

Bone Loss

Osteoporosis - Loss of bone mass more frequent in women. Return

Plate 10

Table 07.01