The skeletal system consists of bones and joints that perform several important functions. There are two main types of bone - compact bone forming the hard outer layers, and spongy bone found internally. Bones can be classified based on their structure, shape, or location in the body. The axial skeleton includes the skull, vertebral column, ribs, and sternum. It supports the trunk and protects the brain, spinal cord, and organs. The appendicular skeleton comprises the bones of the upper and lower limbs. It includes long bones like the femur and phalanges, short bones like the carpals, and irregular flat bones.

1. SKELETAL SYSTEM
BONES & JOINTS

3. Functions of the Bones
1. Support
2.Protection
3. Movement
4.Storage
5.Hematopoiesis

5. Table. 6.1

6. 2 Types of Bone
Compact bone
Spongy bone

7. CLASSIFICATION of BONES
• According to structure
1. compact = solid mass; dense & hard
= forms the outer layer of bone structure
= functional unit --- Haversian system
2. cancellous or spongy = contain spaces
filled with bone marrow
= incomplete Haversian system

9. CLASSIFICATION of BONES
• According to shape
1. long bones = length is greater than breadth
= consists of shaft (diaphysis) &
two extremities (epiphysis)
diaphysis = filled with yellow marrow
= cylindrical, large space or canal at the center
= periosteum
epiphysis = made up of cancellous tissue
e.g.: femur, humerus, tibia, fibula, radius, ulna, phalanges
Membranes: 1. periosteum
2. endosteum

10. CLASSIFICATION of BONES cont’n.
• According to shape
2. short bones = cuboidal in shape
= spongy bone with thin coat of compact bone
= sesamoid bone -- short bone embedded in a
tendon e.g.: patella
e.g.: carpals (wrist), tarsal (ankle) bones
3. flat bones = broad or elongated flat plates
= for protection & muscle attachments
composition: 2 thin layers of compact tse. enclosing
a thin layer of spongy bone
e.g.: bones of the skull, sternum, ribs, scapula

11. CLASSIFICATION of BONES cont’n.
• According to shape
4. Irregular bones = all other bones not assigned to
the previous groups
e.g.: vertebrae
pelvic bones
bones of the base of the skull

12. CLASSIFICATION of BONES cont’n.
• According to location
A X I A L
skull 22
hyoid 1
ossicles 6
vertebrae 26
ribs & sternum 25_
80

13. CLASSIFICATION of BONES cont’n.
• According to location
APPENDICULAR
Upper Extremities Lower Extremities
clavicle 2 hip bone 2
scapulae 2 femur 2
humerus 2 patella 2
radius 2 tibia 2
ulna 2 fibula 2
carpals 16 tarsals 14
metacarpals 10 metatarsals 10
phalanges 28__ phalanges 28__
64 62

14. Fig. 6.10

15. AXIAL SKELETON
I. SKULL
= skeleton --- head & face
= united by joints (sutures)
cranium -- skull minus mandible
cavities: a. Cranial - contains the brain
b. Orbital - contains eyeball
& accessory organs
c. nasal

18. Fig. 6.14

19. Fontanelle
= membrane filled spaces found in the skull of
newborn infants
e.g.: 1. anterior = largest
2. posterior
3. anterolateral (sphenoidal)
4. posterolateral (mastoid)

21. Fig. 6.37

22. AXIAL SKELETON
I. VERTEBRAL COLUMN
= long, curved, slightly movable pillar
= united together by cartilage & ligaments
= formed by series of bones -- vertebrae
FUNCTION:
1. support of the trunk
2. contains & protects the spinal cord &
nerves

23. VERTEBRAL COLUMN
Classification of vertebra
cervical 7
thoracic 12
lumbar 5
sacral 5
coccygeal 4
33
Intervertebral discs = flattened plates of fibrocartilage that
are interposed between the adjacent surfaces of the
bodies of vertebrae
FUNCTION: 1. uniting medium between vertebrae
2. main shock absorber
3. give flexibility & movement to the whole
vertebral column

24. VERTEBRAL COLUMN
a. Cervical vertebrae (7) = forms the skeleton of
the neck
atypical cervical vertebrae:
1. atlas -- 1st
2. axis = 2nd
3. 7th cervical vertebrae = spinous process
b. Thoracic vertebrae (12) = costal pits - for rib
attachment

26. VERTEBRAL COLUMN
c. Lumbar vertebrae (5)
= triangular vertebral foramen
d. Sacrum = inverted triangular bone
situated between hip bones
e. Coccygeal vertebrae (1) = 4 small
incomplete vertebrae fused to form the
coccyx / tail bone; triangular

27. Fig. 6.17

28. Fig. 6.18

29. Fig. 6.20

30. AXIAL SKELETON
I. STERNUM (breast bone)
= flat bone, found -- anterior thoracic wall
PARTS: a. Manubrium
b. Body
c. Xiphoid process
2. RIBS (12 pairs)
= narrow arched flat bones with 2
ends
1. vertebral - posterior; attaches with thoracic
2. sternal - anterior; attaches with costal
cartilages

31. Fig. 6.21

32. Classification of ribs:
a. true ribs (1st to 7th)
- ribs whose costal cartilages are directly
attached to sternum
b. false ribs (8th to 12th)
- ribs whose costal cartilages are not attached
directly to the sternum but to 7th

33. APPENDICULAR SKELETON
BONES of the UPPER EXTREMITY (UE)
1. Clavicle (collar bone)
2. Scapula (shoulder blade)
3. Humerus (arm bone)
4. Radius - lateral bone of the forearm
5. Ulna - medial bone of the forearm
6. Carpals (wrist bone) - 8 bones arranged into 2 rows - proximal
& distal rows
7. Metacarpals (bones of the hand)
8. Phalanges (bones of the fingers) long bones of the fingers

36. Fig. 6.26

37. Fig. 6.22

38. Fig. 6.27

39. APPENDICULAR SKELETON
BONES of the LOWER EXTREMITY (LE)
1. Hip bone (innominate bone)
right & left hip bones + sacrum = pelvic girdle
3 bones: 1. ilium
2. ischium
3. pubis
2. Femur (thigh) = longest, strongest, largest bone in
the body
3. Tibia (shin bone) = long bone; anterior, medial,
4. Fibula (peroneal bone) = long slender bone placed
parallel with the tibia but located laterally

40. Fig. 6.29

41. Fig. 6.30

42. Fig. 6.33

43. Fig. 6.34

44. APPENDICULAR SKELETON
BONES of the LOWER EXTREMITY (LE) cont’n
5. Tarsals (ankle bone) = short bones;
2 rows: internal & external rows
6. Metatarsals (bones of foot) = 5 long bones
numbered from medial to lateral
7. Phalanges (bones of toes) = similar to bones of
the fingers

45. Fig. 6.35

46. END OF LECTURE

47.  It is impossible for a man to learn what he thinks
he already knows
 Epictetus.