Joints - Anatomy & Physiology

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Joints comprise broadly two categories:

• Synarthroses form joints that are relatively rigid
• Diarthroses form joints that are freely movable

Joint Function:

• Absorb force of impact, transfer force via cartilage to bone
• Allow a variable degree of movement

Fibrous Joints

• Most occur in the skull: known as sutures
  • Key in development: allow extension of individual bones during growth
  • Gradually eliminated as ossification progresses
• Syndesmoses: facing areas of two bones joined by connective tissue ligaments, very limited movement allowed
  • Eg. Joints of the metacarpus in the horse
• Gomphosis: attachment of tooth to bone within its socket

Cartilaginous Joints

• Synchondroses: eg. joints between epiphyses and diaphyses of juvenile long bones, disappear on maturity
  • Permanent synchondroses: the joint between the skull and hyoid
• Symphysis: articulating bones are divided by a succession of tissues, with cartilage covering the bones or the tissue between
  • Eg. mandibular, pelvic, vertebral

Synovial Joints

• Articulating joints are separated by a fluid-filled joint cavity, which is bounded by a synovial membrane
• Often the synovial membrane is reinforced by a fibrous capsule and ligaments restricting joint movement
• Cartilage covers the articular surfaces
  • Usually, this is Hyaline, although Fibrocartilage or fibrous tissue can substitute

Joint Pathology

For links to joint pathology, go here