Skeletal system

1. PROF.Dr. MONA HASSAN MOHAMMED ALI
prof. AND HEAD AND of Anatomy &
Embryolgy
FOMSCU

2. At the end of the lecture, the students should be able to:
 Enumerate the functions of bone
 Classify bones according to shape, structure & development
 Enumerate the bones of axial and their functions
INTENDED LEARNING OUTCOMES

3.  Definition of bone:
- it is a hard type of connective tissue which forms the
skeleton.
BONE

4. 1. Support:
• Due to its rigidity and hardness, it
provides the strength that keep the rigid
framework that support the body.
2. Protection:
• Protect vital delicate internal organs vital
for life.
• Examples: the skull protects the brain and
the thoracic cage protects heart and lungs
from external shocks.
3. Levers:
• Providing anchoring points for muscles to
facilitate their movements at the joints.
FUNCTIONS OF BONE

5. • Serves as a reservoir for minerals
(calcium and phosphate)
• Occurs within the marrow
cavities of certain bones like the
sternum and heads of the tibia
FUNCTIONS OF BONE

6. • The vertebral column transmits the
weight of the head and the trunk to
the bony pelvis then to the bones of
the lower limb to the feet and lastly to
the ground.
• To make important part of the
locomotor system
FUNCTIONS OF BONE

7. • It is the system of bones
associated with cartilages
and joints of the human
body.
• Together these structures
form the human skeleton.
• It describes the form and
organization of the body
parts.
SKELETAL SYSTEM

8. • It consists of 206 bones.
• It can be studied in two
parts:
• A- Exoskeleton: Nail,
enamel of the teeth.
• B- Endoskelton:
1- Axial skeleton
2- Appendicular skeleton
HUMAN SKELETON

9. • It consists of 80 bones
• Consists of the bones that lie
around the longitudinal axis
of the human body.
- Skull, mandible
- Ossicles of the middle ear
- Hyoid bone
- Thoracic cage
- Vertebral column
1- AXIAL SKELETON

10. 1- AXIAL SKELETON

11. Consists of the (126) bones of the
upper and lower limbs
(extremities):
Upper Extremity (64)
 Shoulder Girdle
 Skeleton of the upper limb
Lower Extremity (62)
 Pelvic Girdle
 Skeleton of the lower limb
2- APPENDICULAR SKELETON

12. 1- According to the microscopic
structure:
 Forms outer layer of the long bone
 Very hard and dense
 Consist of delicate trabeculae filled
with red or yellow marrow
 Withstand stress and support shifts in
weight
CLASSIFICATIONS OF BONES

13. Compact and spongy bones
CLASSIFICATIONS OF BONES

14.  Compact bones  Cancellous bones
CLASSIFICATIONS OF BONES

15. 2- According to development
(bone formation):
 Ossification: Process of
converting other tissues to
bone
 Two types of ossification
processes occur during
embryological formation:
▪ Membranous
▪ Cartilagenous
CLASSIFICATIONS OF BONES

16.  Bones develop in membrane from mesenchymal cells
 Examples: most bones of the skull cap and the clavicle
CLASSIFICATIONS OF BONES

17.  Occurs in long bone,
vertebrae, ribs.
 The mesenchyme is
changed first into a
cartilage model, then
the cartilage is
dissolved and
disappear and
changed into bone.
CLASSIFICATIONS OF BONES

18. 3- According to the shape of bones :
 Long bones
 Short bones
 Flat bones
 Irregular bones
 Sesamoid bones
 Pneumatic bones
CLASSIFICATIONS OF BONES

19.  Length greater
than width
 Composed of two
ends (epiphyses)
and a shaft
(diaphysis)
e.g. femur,
radius, ulna, etc.
CLASSIFICATIONS OF BONES

20.  Consist of spongy bone
covered by a thin layer of
compact bone.
Cube shaped
 e.g. carpal, tarsal
bones
CLASSIFICATIONS OF BONES

21. Cont..
Thin, flattened, a bit
curve e.g. ribs, sternum,
skull bones, scapula, etc
CLASSIFICATIONS OF BONES

22. Cont..
Complicated irregular shapes e.g. verterbrae,
facial bones, hip bone.
CLASSIFICATIONS OF BONES

23.  Embedded in some muscle tendons , (e.g: patella)
 Diminish the friction between the tendon and the
underlying bones.
CLASSIFICATIONS OF BONES

24.  These are bones containing air cavities
 Example: some bones of the skull: Maxilla, Sphenoid,
Ethmoid
CLASSIFICATIONS OF BONES

25. CLASSIFICATIONS OF BONES
 According to bone
marrow:
 Red.
 Yellow.

26. Gross Anatomy
of a Long Bone
 Diaphysis
 Shaft
 Composed of compact
bone
 Epiphysis
 Ends of the bone
 Composed mostly of
spongy bone
Figure 5.2a

27. Structures of a Long Bone
 Periosteum
 Outside covering of the
diaphysis
 Fibrous connective
tissue membrane
 Sharpey’s fibers
 Secure periosteum to
underlying bone
 Arteries
 Supply bone cells with
nutrients
Figure 5.2c

28. Structures of a Long Bone
 Articular cartilage
 Covers the external
surface of the epiphyses
 Made of hyaline
cartilage
 Decreases friction at
joint surfaces
Figure 5.2a

29. Structures of a Long Bone
 Medullary cavity
 Cavity of the shaft
 Contains yellow marrow
(mostly fat) in adults
 Contains red marrow (for
blood cell formation) in
infants
Figure 5.2a

30. MAJOR BONES OF SKELETON

31. SKULL
• It is made up of 22 bones and 6 ear
ossicles:
• Paired bones Unpaired bones
• Temporal Frontal
• Parietal Occipital
• Maxilla Sphenoid
• Lacrimal Ethmoid
• Palatine Vomer
• Zygomatic Mandible
• Nasal
• Inferior concha
• Bones of middle ear cavity
• Incus
• Malleus
• Stapes.

32. VERTEBRAL COLUMN
• It is made up of 33 vertebrae,
namely, 7 cervical, 12 thoracic,
5 lumbar, 5 sacral and 4
coccygeal vertebrae.

33. THORACIC CAGE
• It consists of 12 thoracic
vertebrae, 12 pairs of ribs with
their costal cartilages, sternum
and xiphoid process.

34. TYPICAL THORACIC VEREBRA

35. Clinical Anatomy by Systems, 8th Edition,
Richard S. Snell.
B.D . Chaurasia’s General anatomy.
REFERENCES

36. THANK YOU