Enthesis

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Enthesis (plural: entheses) is the point at which a tendon inserts into bone, where the collagen fibers are mineralized and integrated into bone tissue. These insertion points are commonly called Sharpey's fibers.

[edit] Classification

There are two types:

  • Fibrous entheses
  • Fibrocartilaginous entheses

In a fibrous enthesis, the collagenous tendon or ligament directly attaches to the bone, whilst the fibrocartilaginous enthesis displays 4 zones during the transition from tendon/ligament to bone:

  • i) tendinous area displaying longitudinally oriented fibroblasts and a parallel arrangement of collagen fibres
  • ii) a fibrocartilaginous region of variable thickness where the structure of the cells changes to chondrocytes
  • iii) an abrupt transition from cartilaginous to calcified fibrocartilage - the so-called 'tidemark' or 'blue line'
  • iv) bone

[edit] Pathology

A disease of the entheses is known as an "enthesopathy" or "enthesitis" and is characteristic of spondyloarthropathy but present in other pathology as well.

[edit] External links

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Musculoskeletal system, connective tissue: bone and cartilage
Cartilage
Bone