The suprascapular nerve innervates the supraspinatus and infraspinatus muscles, two of the four rotator cuff muscles, making it one of the most functionally important nerves of the shoulder. It passes through two anatomical bottlenecks where it is vulnerable to compression: the suprascapular notch for the supraspinatus branch and the spinoglenoid notch for the infraspinatus branch. Paralabral cysts from SLAP tears commonly compress the nerve at the spinoglenoid notch.
| Origin | Upper trunk of the brachial plexus (C5, C6) |
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Suprascapular nerve neuropathy presents with posterior shoulder pain, weakness of shoulder abduction (supraspinatus) and external rotation (infraspinatus), and atrophy of the corresponding fossae that is visible clinically. MRI reveals both the nerve compression and the resulting muscle atrophy. Paralabral cysts at the spinoglenoid notch causing isolated infraspinatus denervation (preserved supraspinatus) are a recognised consequence of posterior SLAP tears. Surgical decompression involves releasing the transverse scapular ligament at the suprascapular notch.
Nerve compression at the suprascapular or spinoglenoid notch producing shoulder weakness and posterior deltoid atrophy, commonly caused by paralabral cysts from SLAP tears and managed with cyst aspiration or surgical decompression.
