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.

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

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

• Image of enthesis at Medscape
• Enthesopathy and Soft Tissue Shadows at chiroweb.com
• Resnick D, Niwayama G (1983). “Entheses and enthesopathy. Anatomical, pathological, and radiological correlation”. Radiology. 146 (1): 1–9. PMID 6849029.
• Template:Medcyclopaedia
• Origin of phrase at rheuma21st.com at rheuma21st.com

Template:Bone and cartilage

Template:WikiDoc Sources