Human Anatomy - Human Bone Structure
Bone is a relatively hard and lightweight composite material , formed mostly of calcium phosphate in the chemical arrangement termed calcium hydroxyapatite. It has relatively high compressive strength but poor tensile strength . While bone is essentially brittle, it does have a degree of significant elasticity contributed by its organic components (chiefly collagen ). Bone has an internal mesh -like structure, the density of which may vary at different points .
Bone can be either compact or cancellous (spongy). Cortical (outer layer) bone is compact; the two terms are often used interchangeably. Cortical bone makes up a large portion of skeletal mass; but, because of its density, it has a low surface area. Cancellous bone is trabecular (honeycomb structure), it has a relatively high surface area, but forms a smaller portion of the skeleton.
Bone can also be either woven or lamellar . Woven bone is put down rapidly during growth or repair. It is so called because its fibres are aligned at random, and as a result has low strength. In contrast lamellar bone has parallel fibres and is much stronger. Woven bone is often replaced by lamellar bone as growth continues.
Human Anatomy - Bone Terminology
| process | A relatively large projection or prominent bump. |
| articulation | The region where adjacent bones contact each other-a joint . |
| articular process | A projection that contacts an adjacent bone. |
| eminence | A relatively small projection or bump. |
| tuberosity | A projection or bump with a roughened surface. |
| tubercle | A projection or bump with a roughened surface, generally smaller than a tuberosity. |
| trochanter | One of two specific tuberosities located on the femur . |
| spine | A relatively long, thin projection or bump. |
| suture | Articulation between cranial bones. |
| malleolus | One of two specific protuberances of bones in the ankle . |
| condyle | A large, rounded articular process. |
| epicondyle | A projection near to a condyle but not part of the joint. |
| line , ridge | A long, thin projection, often with a rough surface. |
| crest | A prominent ridge. |
| facet | A small, smooth articular surface. |
| foramen | An opening through a bone. |
| fossa | A broad, shallow depressed area. |
| canal | A long, tunnel-like foramen, usually a passage for notable nerves or blood vessels. |
| meatus | A short canal. |
| sinus | A cavity within a cranial bone. |
There are also names for specific parts of long bones.
| diaphysis , shaft | The long, relatively straight main body of the bone; region of primary ossification. |
| epiphyses | The end regions of the bone; regions of secondary ossification. |
| epiphyseal plate | The thin sheet of bone marking the fusion of epiphyses to the diaphysis (adults only). |
| head | The proximal articular end of the bone. |
| neck | The region of bone between the head and the shaft. |