SKELETAL SYSTEM

Functions:

1. framework

2. locomotion

3. attachment of muscles

4. protection

5. hemopoises

General

Characteristics:

• periosteum –

protective covering

• matrix is hard and

rigid due to

deposition of

calcium phosphate

• osteon / haversian

canal system –

structural and

functional unit

haversian canal

concentric

lamellae

osteocytes

canaliculi

Volkmann’s

canal

Types of bones:

1. long bones

2. short bones

3. flat bones

4. irregular bones

5. sesamoid bones

Divisions of the skeletal system

I. Axial

A. Skull

a. Bones of the cranium

1. Occipital - 1

2. Parietal - 2

3. Frontal - 1

4. Temporal - 2

5. Ethmoid - 1

6. Sphenoid - 1

b. Bones of the face:

1. Nasal - 2

2. Vomer - 1

3. Inferior nasal conchae - 2

4. Lacrimal - 2

5. Palatines - 2

6. Zygomatic - 2

7. Maxillae/upper jaw - 2

8. Mandible /lower jaw - 1

Bones of the Middle Ear:

1. maleus

2. incus

3. stapes

c. Fontanels – membranous tissue

between the cranial

bones at sutures

B. Vertebral column – consists of vertebrae

about 18 inches in

length

functions:

1. Support

2. Attachment of ribs

3. Protects and encloses the spinal cord

Regions of the

vertebral column:

1. Cervical/neck region

a. Atlas

b. Axis/epistropheus

c. c3,c4,c5,c6

d. vertebra

prominens (c7)

2. Thoracic region =12

3. lumbar region =5

4. Sacral region = 5

5. Coccygeal region = 4

Poor standing posture leads to

exaggerated curves of the vertebral

column and are called as curvatures

1. Kyphosis - exaggerated thoracic

curve/humpback

2.Lordosis –increased lumbar curve/hollow

back

3. Scoliosis – exaggerated lateral

curvature

C. Ribs – 12 pairs

Kinds of ribs based on

attachment:

1. Trueribs/vertebro-

sternal = 1-7

2. False ribs/:

a. vertebrochondral

=8,9,10

b. floating = 11-12

D. Sternum or breastbone

II. Appendicular

Division

Girdles:

1. Pectoral or

shoulder girdle

a. Clavicle or collar

bone

b. Scapula or

shoulder blade

2. Pelvic girdle

a. Hip bone:

• ilium

• ischium

• pubis

b. Sacrum

Limb

a. Forelimb

1. Humerus

2. Radius

3. Ulna

4. Carpals

5. Metacarpals

6. phalanges

b. Hindlimbs

1. Femur/thigh bone

2. Patella or knee cap

3. Tibia or shin bone

4. Fibula or calf bone

5. tarsals

6. Metatarsals

7. phalanges

Joints or articulations

1. Immovable or

synarthroses

e.g. sutures

2. Slightly movable or amphiarthroses

e.g. pubic symphysis

3. Movable

e.g. between phalanges

Kinds of posture:

1. plantigrade

2. digitigrade

3. unguligrade