Bone Anatomy

Human Bone Structure and Anatomy

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.

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.

Radiology School Topics

RADIOLOGY COURSES

Cross Sectional Anatomy	Radiographic Positioning	Radiographic Physics
Fluoroscopy	Radiographic Anatomy	Radiation Biology
Contrast Media	Radiographic Principles	Radiation Safety
PACS and Digital Imaging		Radiographic Film Critique