Bone

Question 1

Bone functions

Answer 1

1. Framework for support of the skeleton.
2. Protection e.g. brain, spinal cord, lungs, and heart.
3. Serve as levers for the muscles attached to them via tendons.
4. Reservoir for minerals, e.g. calcium, magnesium, phosphates, etc.

Question 2

Bone matrix

Answer 2

The extracellular matrix (ground substance and fibers) consists of inorganic material (65%) e.g. calcium phosphate, calcium carbonate and organic component (35%) is mostly type I collagen (95%) which gives bone
slight flexibility and ground substance.

Question 3

Periosteum

Answer 3

A vascular, fibrous layer, which surrounds bone except over articular surfaces. It has 2 layers:
1. The outer layer is collagen with some elastic fibers. This layer distributes vascular and nerve supply to bone.
2.The inner layer is cellular that gives rise
to new bone.
- The central cavity of a bone is lined with endosteum

Question 4

Bone matrix development

Answer 4

1. Bone starts as osteoid, which is collagen and GAG’s with no minerals.
2. Bone becomes mineralised.
3. Bone starts to remodel as the adult form.

Question 5

Blood and nerve supply is the bone

Answer 5

Bones have periosteal vessels, which penetrate the bone of the diaphysis of long bones and divide into branches that enter the Haversian systems. These vessels supply the osteocytes embedded in the calcified matrix.

Small myelinated and unmyelinated nerves go into the Haversian canals

Question 6

Intramembranous Bone Formation

Answer 6

The process involves mesenchyme to bone directly.

• Locations: flat bones e.g. the skull, mandible, and clavicle

Question 7

Endochondral Bone Formation

Answer 7

1. A miniature hyaline cartilage model is formed in the region where bone is to grow within the embryo
2. The cartilage model grows appositionally and interstitially and serves as a structural scaffold for bone development, is then resorbed, and replaced by
   bone (all the cartilage is replaced by bone).
   Locations: long, short bones, pelvis, and vertebrae.

Question 8

Synarthroses

Answer 8

Union of bones by dense CT. E.g. tibiofibular, radioulnar

Question 9

Synchondrosis

Answer 9

Junction by cartilage e.g. symphysis pubis

Question 10

Synostosis

Answer 10

Joint united by bone. E.g. sutures