Subacromial-Subdeltoid Bursa (Detail)

bursa subacromialis subdeltoidea (complex)

The subacromial-subdeltoid bursa is a single continuous bursal space providing frictionless sliding of the supraspinatus tendon beneath the coracoacromial arch. It is the most commonly injected bursa in clinical practice — subacromial injection is the standard diagnostic and therapeutic intervention for subacromial pain syndrome (impingement). Bursal thickening on ultrasound (>2 mm) or MRI indicates subacromial bursitis.

Region: Shoulder

Biomechanics

Function & Actions

The largest bursa in the body (with the iliopsoas bursa) — allows frictionless motion of the rotator cuff under the coracoacromial arch during shoulder elevation

Clinical Relevance

Clinical Notes

The subacromial bursa is injected from the posterolateral shoulder with the needle directed anteriorly under the posterior acromion. Ultrasound-guided injection is more accurate than landmark-based injection and achieves higher rates of intrabursal needle placement. The bursal fluid is sampled to exclude septic bursitis (turbid/purulent fluid, elevated WBC) before steroid injection.

Pathology

Common Injuries & Conditions

Subacromial Bursitis

Rotator cuff-coracoacromial arch friction bursal inflammation producing painful arc managed with subacromial injection and physiotherapy.