Subacromial bursa

The subacromial bursa is the synovial cavity located just below the acromion, which communicates with the subdeltoid bursa in most individuals, forming the so-called subacromial-subdeltoid bursa (SSB). The SSB bursa is located deep to the deltoid muscle and the coracoacromial arch and extends laterally beyond the humeral attachment of the rotator cuff, anteriorly to overlie the intertubercular groove, medially to the acromioclavicular joint, and posteriorly over the rotator cuff. The SSB decreases friction, and allows free motion of the rotator cuff relative to the coracoacromial arch and the deltoid muscle. French anatomist and surgeon Jean-François Jarjavay is credited as the first to desc (Wikipedia)