synovium

Definition: The synovial membrane is a specialized connective tissue that lines the inner surface of capsules of synovial joints and tendon sheath.

Components

 synovial cells / synoviocytes
 connective tissue

Localization

 articular synovium
 synovial bursa
 tendon sheath

Functions

The synovial membrane makes direct contact with the synovial fluid lubricant, which it is primarily responsible for maintaining.

In contact with the synovial fluid at the tissue surface are many rounded macrophage-like synovial cells (type A) and fibroblast-like (type B) synovial cells.

Type A cells maintains the synovial fluid by removing wear-and-tear debris and type B cells produces hyaluronan among other extracellular components in the synovial fluid.

Cases

 Case 258 : Normal synovium

Structure

The synovial membrane is variable but often has two layers :

 The inner layer (in contact with synovial fluid), or intima, consists of a sheet of cells thinner than a piece of paper, the synovial cells.

 The outer layer, or subintima, can be of almost any type of connective tissue – fibrous (dense collagenous type ), adipose tissue (fatty; e.g. in intra-articular fat pads ) or areolar tissue (loose collagenous type ).

Pathology

 synovial pathology

• synovial anomalies
• synovial diseases
• synovial tumors

Examples

 synovial proliferative disorders

• pigmented villonodular synovitis
• giant cell tumor of tendon sheath
• hemosiderotic synovitis
• fatty infiltration of the synovial membrane

 intrasynovial cartilaginous lesions

• primary and secondary synovial chondromatosis

 crystal deposition diseases
 response of synovial tissues to implanted foreign materials used in large and small joint arthroplasty

See also

 joints

• synovial fluid

 synovitis

• tenosynovitis

Open References

 Pathology of the Synovium

• https://pdfs.semanticscholar.org/a746/480349a3af3fc47f61287d24fa3191d244b2.pdf