1. Skeletal system: BONE & CARTILAGE Bpharm semester I lecture 2
Dr Abubakr H Mossa
Sr. Instructor Anatomy
3/10/12

2. Lecture outline: Parts of skeletal system (skeleton): Bone:
Axial
Appendicular
Bone:
Bone as a living tissue
Composition of bone
Functions of bone
Types of bone tissue
Ossification: bone formation
Bones classification
Cartilage: composition and types

3. Skeletal system Parts of Skeletal system: Bone (skeleton): Cartilage
Axial
Appendicular
Cartilage
Joints

4. Skeleton
The skeleton has two parts: the axial skeleton and the appendicular skeleton.
The axial skeleton includes the:
skull,
the hyoid bone,
the vertebral column (spine, sacrum, and coccyx),
the sternum
the ribs.
Its components are aligned along the long axis of the body.

5. Skeleton The appendicular skeleton includes the bones of the:
Upper extremities:
Arm: humerus
Forearm: radius & ulna
Hand: carpals (8), metacarpals (5) & phalanges (14)
The pectoral (shoulder) girdle: clavicle & scapula
The pelvic girdle: hip bone
bones of the lower extremities:
Thigh: femur ( in the knee :patella)
Leg: tibia & fibula
Foot: tarsals (7), metatarsals (5) & phalanges (14)
Its components are outside the body main axis.

7. Bone Bone as a living tissue: It has blood vessels and nerves.
Self repairing
Constantly remodeled

8. Bone Functions of bone: Supporting framework necessary for movement
Protection of internal organs
Calcium and phosphate store
Site of formation of blood (red bone marrow) in the marrow cavity.
In adult the red marrow is restricted to the bones of skull, vertebrae, sternum, ribs, shoulder girdle, hip and the proximal ends of the long bone.
What happens to the red marrow in the shaft of the long bones in adult?

9. Bone tissue Types of bone tissue:
Initially all bones are woven but later on they differentiate into two main types:
Compact bone: hard and heavy, forms the outer layer (cortex) of all bones
Cancellous (spongy): lighter and found in the ends of long bones and in the irregular bones

10. Bone: Composition of bone: Cells Intercellular matrix: Collagen fibers
Inorganic crystals (Calcium salts)

12. Bone Ossification: bone formation
Bone develops from embryonic connective tissue which differentiate (ossify) in two ways:
Endochondral (cartilage replacing) ossification: a model of cartilage is replaced by bone.
Intramembranous (dermal) ossification: ossification starts directly in a membrane of connective tissue (without a preceding cartilage model)
Compare the two types of ossification with respect to the following:
Mechanism
Duration
Bones formed by each mechanism

13. Bone Classification: Axial or appendicular According to the shape;
Long and short limb bones
Flat and irregular axial bones
Pneumatic bones (of skull)
Sesamoid bones

14. Bone Long bone: Parts: Formed by endochondral ossification
Shaft (diaphysis): cortex of compact bone and marrow cavity inside.
Ends (epiphysis): thin shell of compact bone and interior of spongy bone
Junction between the two called metaphysis
Formed by endochondral ossification

16. Bone Short bones: Flat bones:
Carpal and tarsal bones of the wrist and the foot, respectively.
Flat bones:
Has two layers of compact bone : inner and outer table
Diploe: layer of spongy bone between the two tables
Develops as dermal bone
Irregular bones: vertebrae, hip and basal cranial bone
Pneumatic bone: cranial bones in which air sinuses are found (maxilla, sphenoid ..)
Sesamoid bone:
A bone develops within a tendon when it rubs against a bony surface.
Patella of the knee

19. Cartilage: Composition: Types: Cells called chondrocytes
matrix : consists of fibers & semi-rigid ground substance
Types:
Hyaline: found in costal cartilages, epiphyseal plates (important for growth) & articular cartilage
Fibrocartilage: as in the intervertebral discs
Elastic cartilage: forms the cartilage of ear & nose

21. Thanks