Skeleton

Question 1

Define Bone

Answer 1

Bone is a vascular living constantly changing mineralized connective tissue.

Question 2

What is bone?

Answer 2

It is 1/3rd connective tissue. It is impregnated with calcium phosphate and calcium carbonate and other salts making it hard and rigid capable of bearing impact forces of jumping and compressive forces of weight bearing
The organic connective tissue (collagen fibres) make them tough and resilient to the tensile forces.
- it shows characteristic growth and has a greater regenerative power than any other tissue in the body except for blood,

Question 3

Functions of bone

Answer 3

• Bones give shape and support to the body and resists any form of stress
• These provide surface for attachment of muscles, tendons, ligaments etc
• Serve as levers for muscular actions
• The skull, vertebral column and thoracic cage protect the brain, spinal cord and thoracic viscera respectively
• Bone marrow manufactures the Blood cells
• Store 97% of bodies calcium and phosphate
• Bone marrow contains the reticulo-endothelial cells which are phagocytic in nature and take part in immune response of the body
• The larger paranasal air sinuses affect the timber of the voice

Question 4

Classify bones according to their shape

Answer 4

1. Long bone - Each bone has an elongated shaft called the diaphysis and two extended ends called epiphysis which are smooth and articular. The shaft typically has three borders and 3 surfaces, nutrient foramen directed away from the growing end and a central medullary canal
   a. typical long bones - humerus, radius, ulna, femur, tibia, fibula
   b. Miniature Long bones - One epiphysis - Metacarpals, Metatarsals, Phalanges
   c. Modified Long bones - Clavicle - no medullary cavity
2. Short bones - Shape is usually cuboid, cuneiform, trapezoid or scaphoid - Carpals and tarsals
3. Flat bones - Shallow plates and form boundaries of certain body cavities - Scapula, Bones in vault of skull, ribs and sternum
4. Irregular bones - Vertebra, hip bone, and the base bones of the skull
5. Pneumatic bones - have large air spaces lined by epithelium - Maxilla, Sphenoid, ethmoid, etc - help in making skull lighter, resonance of sound and act as air conditioning chambers
6. Sesamoid bones - Bony nodules found embedded in the tendon or joint capsules. No periosteum and ossify after birth. Related to articular or non-articular bony surface and the surfaces of contact are covered with hyaline cartilage and lubricated by a bursa or synovial membrane - examples- patella, pisiform, fabella
7. Accessory (Supernumerary) bones - Occur due to ununited epiphyses and develop from extra centres of ossification- Sutural bones, os trigonum, os vesalianum etc
8. Heterotopic bones - develop in soft tissue - riders bone in the adductor muscles

Question 5

Functions of sesamoid bones

Answer 5

To resist pressure
to minimize friction
to alter the direction of pull of the muscle
to maintain the local circulation