Articular capsule

An articular capsule (or joint capsule) is an envelope surrounding a synovial joint.

Layers
Each capsule consists of two layers:
 * an outer layer (stratum fibrosum) composed of avascular white fibrous tissue
 * an inner layer (stratum synoviale) which is a secreting layer, and is usually described separately as the synovial membrane.

On the inside of the capsule, articular cartilage covers the end surfaces of the bones that articulate within that joint.

The outer layer is highly innervated by the same nerves which perforate through the adjacent muscles associated with the joint.

Fibrous membrane
The fibrous membrane of articular capsule (fibrous capsule) is attached to the whole circumference of the articular end of each bone entering into the joint, and thus entirely surrounds the articulation.

Pathology
Frozen shoulder (adhesive capsulitis) is a disorder in which the shoulder capsule becomes inflamed.

Plica Syndrome is a disorder in which the synovial plica becomes inflamed and causes abnormal biomechanics in the knee.