Bone

Q 1: Define bone and classify it into different types.

Bone is a hard, calcified, and flexible tissue that provides support, protection, and movement to the human body. Bones are classified into two main types:

1. Long bones: e.g. femur, humerus, tibia, fibula, etc.
2. Short bones: e.g. carpal bones, tarsal bones, etc.
3. Flat bones: e.g. sternum, ribs, scapula, etc.
4. Irregular bones: e.g. vertebrae, ethmoid bone, etc.

Q 2: Explain the structure of a long bone and its features.

A long bone consists of:

1. Diaphysis (shaft): the main weight-bearing part of the bone.
2. Epiphysis (head): the end of the bone that forms the joint.
3. Metaphysis: the region between the diaphysis and epiphysis.
4. Cortex: the outer layer of compact bone.
5. Endosteum: the inner layer of spongy bone.

Q 3: Describe the process of bone formation and remodeling.

Bone formation (osteogenesis):

1. Osteoblasts → Bone matrix → Mineralization → Bone formation

Bone remodeling:

1. Osteoclasts (break down bone tissue)
2. Osteoblasts (build new bone tissue)

Q 4: Explain the process of bone healing.

Bone healing:

1. Inflammation → Soft callus formation → Hard callus formation → Bony union

Q 5: Describe the blood supply to the bone.

Blood supply to bone:

↓ (arterial supply)

1. Artery → Periosteal vessels → Endosteal vessels ↓ (venous drainage)
2. Vein → Periosteal veins → Endosteal veins

Q 6: Explain the nerve supply to the bone.

Nerve supply to bone:

↓ (innervation)

1. Nerve → Periosteal nerves → Endosteal nerves

Q 7: Describe the types of joints and their classification.

Types of joints:

1. Synarthroses (immovable joints)
2. Ampiarthroses (slightly movable joints)
3. Diarthroses (freely movable joints)

Q 8: Explain the structure of a synovial joint.

Synovial joint:

1. Articular cartilage (covers the joint surface)
2. Synovial membrane (lines the joint capsule)
3. Joint capsule (encloses the joint)

Q 9: Describe the structure of a hyaline cartilage and its functions.

Hyaline cartilage:

1. Fibrocartilage (strong and flexible)
2. Elastic cartilage (flexible and elastic)
3. Hyline cartilage (smooth and slippery)

Q 10: Explain the functions of bones.

Functions of bones:

1. Support: provides structural support to the body

2. Protection: protects internal organs

3. Movement: allows for movement and locomotion

4. Blood cell production: produces blood cells

5. Mineral storage: stores mineral ions

6. Describe Haversian system

• Basic structural unit of compact bone called osteon
• Central Haversian canal contains blood vessels and nerves
• Concentric lamellae arranged around the canal
• Lacunae lie between lamellae and contain osteocytes
• Canaliculi connect lacunae for nutrient exchange
• Volkmann’s (perforating) canals connect one Haversian canal to another
• Entire osteon lined internally by endosteum and externally covered by periosteum

2. Describe microscopic structure of LS and TS of compact bone LS of compact bone

• Haversian canal seen as a long vertical tube
• Concentric lamellae arranged around it
• Lacunae appear between lamellae with osteocytes
• Volkmann’s canals appear crossing horizontally

TS of compact bone

• Haversian canal appears as a central circular opening
• Lamellae appear as circular rings around the canal
• Lacunae appear as tiny dark spots on the rings
• Canaliculi radiate outward from lacunae
• Volkmann’s canals appear as small side openings

3. Describe microscopic structure of spongy bone

• Made up of a network of trabeculae
• Trabeculae are thin, irregular bony plates
• Spaces between trabeculae form marrow cavities
• Marrow cavities contain red or yellow marrow
• Osteocytes lie in lacunae within trabeculae
• No Haversian system present
• Trabeculae surfaces lined by endosteum
• Periosteum absent on trabeculae