Subcutaneous calcaneal bursa

The subcutaneous calcaneal bursa is a superficial bursal structure located between the skin and the posterior aspect of the calcaneal tuberosity, overlying the insertion of the Achilles tendon. It is distinct from the retrocalcaneal bursa, which lies deeper between the anterior surface of the Achilles tendon and the calcaneus. The subcutaneous calcaneal bursa is typically thin and difficult to visualize in healthy individuals, but becomes more apparent when inflamed or distended, as seen in bursitis.

Anatomically, the subcutaneous calcaneal bursa is situated within the superficial retrocalcaneal pad, which is compartmentalized and has a histological continuum with the superficial lamina of the crural fascia. Cadaveric studies have demonstrated that the bursa may have variable locations, with up to five potential sites identified in historical anatomical tables, and is closely associated with a superficial retrocalcaneal nerve plexus at the Achilles tendon-fat pad interface. The bursa is lined by a synovial membrane and functions to reduce friction between the skin and the underlying calcaneal prominence, especially during repetitive motion or pressure.