Subacromial bursa

The subacromial bursa sits like a flattened balloon containing fluid under the hard cap of bone (the acromion) at the shoulder, where it acts to lubricate shoulder movement and to protect the tendons lying underneath in the ‘subacromial’ space. A tendon attaches a muscle to a bone and there are four main tendons that sit under the bursa and can be involved in so called ‘impingement syndrome’. Together they form the ‘rotator cuff’ and help to stabilise the head or ‘ball’ of the humerus (the upper arm bone) against the smaller ‘socket’ (glenoid fossa or cavity) on the shoulder blade (scapula).