The skeletal system is divided into the axial skeleton and appendicular skeleton. The axial skeleton forms the body's central axis and includes the skull, vertebral column, and thoracic cage. The skull protects the brain and is formed from flat cranial and facial bones joined by sutures. The vertebral column extends from the skull to the pelvis and is composed of 33 vertebrae including 7 cervical, 12 thoracic, 5 lumbar, the sacrum, and coccyx. The appendicular skeleton attaches to the axial skeleton and includes the pectoral girdle, pelvic girdle, and bones of the upper and lower limbs.

1. SKLETAL SYSTEM
•
It is divided into two
parts :
•
Axial.
•
Appendicular.

2. AXIAL SKELETON
•
It forms the
longtudinal axis of the
body.
•
It is divided into three
parts :
•
Skull.
•
Vertebral Column.
•
Bony thorax.

3. SKULL
•
It is formed of two
sets of bones :
•
Cranium.
•
Facial bones.
•
Most of Its bones
are flat.

4. CRANIUM
•
it encloses and
protects the brain.
•
It is formed of eight
large flat bones.
•
Two of them are
paired and the others
are single.

5. CRANIUM
•
The bones are :
•
Frontal.
•
Parietal.
•
Temporal.
•
Occipital.
•
The bones are joined
together by sutures.

6. FACIAL BONES
•
They hold the eyes in
an anterior position.
•
They are (14) bones.
•
Twelve are paired and
only the mandible and
vomer are single.
•
They are : maxillae,
palatine,zygomatic,
lacrimal, nasal, vomer
and mandible.

7. VERTEBRAL COLUMN
•
It is the axial support
of the body.
•
It extends from the
skull which it supports
to the pelvis, where it
transmits the weight
of the body to the
lower limbs.

8. VERTEBRAL COLUMN
•
It is formed of (24)
single bones
(Vertebrae) :
•
Cervical vertebrae
(7).
•
Thoracic
vertebrae(12).
•
Lumbar vertebrae (5).
•
Sacrum (fused 5
vertebrae).
•
Coccyx (fused 4
vertebrae).

9. VERTEBRAL COLUMN
•
The single vertebrae
are separated by
pads of flexible
fibrocartilage (inter
vertebral discs).
•
The intervertebral
discs absorb shocks
and allow the spine
flexibility.

10. TYPICAL VERTEBRA
•
It is formed of :
•
Body.
•
Vertebral arch: laminae
and pedicle.
•
Vertebral foramen.
•
Transverse process.
•
Spinous process.
•
Superior and inferior
articular processes.
•
THEY ARE IRREGULAR
BONES.

11. DIFFERENT VERTEBRAE
•
Cervical :smallest ,
the spine is divided
into two branches.
Transverse process
contain foramen.
•
Thoracic : body is
heart shaped and has
two costal facets.
•
Lumbar : massive
block like bodies.

12. BONY THORAX
•
It is formed of the
sternum,ribs and
thoracic vertebrae.
•
It protects the organs
of the thoracic cavity.
•
Sternum
•
Manubrium.
•
Body.
•
Xiphoid process.

13. RIBS
•
They are (12) pairs
which are divided as
follows :
•
True (7) : attach
directly to the
sternum.
•
False (5) : either
attach indirectly to the
sternum or not at all.
•
Floating : last two
pairs.

14. APPENDICULAR SKELETON
•
It is formed of :
•
Pectoral girdle.
•
Pelvic girdle.
•
Bones of the upper
and lower limbs.

15. PECTORAL GIRDLE
•
It is formed of :
•
CLAVICLE : it holds
the arm away from
the thorax.
•
SCAPULA (WING).

16. UPPER LIMB
•
ARM :Humerus.
•
FORE ARM: Radius
& Ulna.
•
Long bones :
•
They are formed of :
•
Epiphysis : on each
end.
•
Diaphysis : a tubular
shaft. It is covered
externally by the
periosteum.

17. HAND
•
WRIST : Carpal
bones.
•
PALM : Metacarpal
bones.
•
FINGERS :
Phalanges.
•
They are examples of
short bones.

18. PELVIC GIRDLE
•
Formed of the two
HIP bones.
•
Each hip bone is
formed of three parts :
•
ILium.
•
Ischium.
•
Pubis.
•
The hip bones and
the sacrum form the
bony pelvis.

19. LOWER LIMB
•
THIGH : Femur.
•
LEG : Tibia & Fibula.

20. FOOT
•
TARSUS : Tarsal
bones.
•
Metatarsals.
•
Phalanges.