Anatomy

Anatomy of the n. suprascapularis

The n. suprascapularis arises from the upper trunk of the brachial plexus, mainly from the C5 and C6 nerve roots. From the lateral neck, it runs posterolaterally toward the scapula and enters the suprascapular notch, where it usually passes beneath the superior transverse scapular ligament.

After entering the supraspinous fossa, the nerve travels deep to the m. supraspinatus and gives motor branches to this muscle. It then continues laterally and posteriorly around the scapular spine through the spinoglenoid notch into the infraspinous fossa, where it supplies the m. infraspinatus.

The n. suprascapularis therefore innervates two key rotator cuff muscles:

m. supraspinatus – initiates shoulder abduction and contributes to glenohumeral stability.
m. infraspinatus – produces external rotation of the shoulder and also contributes to dynamic stabilization of the humeral head.

In addition to its motor function, the n. suprascapularis provides sensory articular branches to the glenohumeral joint and acromioclavicular joint, which makes it clinically important in shoulder pain and suprascapular nerve entrapment.