بوابة الثانوية العامة المصرية - المحاضرات التأهيليه لكليه الطب

بعد أما الإمتحانات خلصت والحمد لله

دلوقتي إن شاء الله هكمل المحاضرات التأهيليه ..

Skeletal system

The skeleton s composed of two types of tissue cartilage & bone.

Cartilage:

It is softer than bone , less rigid & slightly elastic

Bone:

Rigid tissue hardened by calcium & phosphorus . The bone cells (osteocytes) are present in lacunae .

Forms of bones

The bone exists in two forms :

Compact (hard or ivory) bone:

It is hard , dense & forms the surface layer of all bones & the tubular shafts of long bone

Spongy , cancellus bone:

Its like a sponge which is usually filled with red bone marrow .

Parts of skeleton

Axial skeleton :

Skull :cranium 8 bones , face 14 bones , auditory ossicles 6 bones (28)

Hyoid:1 bone

vertebral column :33 vertebrae (7 cervical , 12 thoracic , 5 lumbar ,5 sacral , 4 coccygeal ) the sacral & coccygeal are fused in 2 masses so the count is (26)

sternum : 3 peices

ribs :12 pairs

Appendicular skeleton :

upper limb

shoulder girdle :2 scapula & 2 clavicle (4)

(2)arm bones :1 humerus in each side

forearm bones :1 ulna & i radius in each side (4)

wrist bones : 8 carpal bones in each wrist (16)

hand bones : 5 metacarpals in each hand (10)

finger bones : 14 phalanges in each hand , 2 in each tumb and 3 in each of other fingers (28)

lower limb

Hip girdle : hip bone one in each side (2)

Thigh bone : 1 femur in each thigh (2)

Leg bones : 1 tibia & 1 fibula in each leg (4)

Ankle & foot bones : 7 tarsala & 5 metatarsals in each foot . (24)

Toe bones : 14 phalages in each foot , 2 in the great toe and 3 in each of other toes (28).

functions of the skeleton :

1-Support the soft parts of the body.

2-gives shape to the body as a whole by the arrangement of bones.

3- allows movement by the muscles which pull the jointed bones into different directions .

4-lever action.

5-protiction of the dalicate parts of the body e.g.

the cranium proctects the brain.

the vertebral column protects the spinal cord.

the thoracic cage protects the heart and lungs.

6-bone marrow helps in the formation of blood.

7-a store for calcium and phosphorus for the time of need.