Which nerve innervates the infraspinatus muscle?

Which nerve innervates the infraspinatus muscle?

• A. Axillary nerve
• B. Suprascapular nerve
• C. Upper subscapular nerve
• D. Long thoracic nerve

Answer: (B)

The infraspinatus is innervated by the suprascapular nerve, which comes from the upper trunk of the brachial plexus (C5–C6). After branching, the nerve travels through the suprascapular notch to reach the supraspinatus and then continues around the spine of the scapula to the infraspinatus, giving motor input to it. This nerve supplies the rotator cuff muscle responsible for external rotation of the arm. The other nerves listed innervate different muscles (axillary to deltoid and teres minor, upper subscapular to subscapularis, and long thoracic to serratus anterior), so they do not innervate the infraspinatus.

The infraspinatus is innervated by the suprascapular nerve, which comes from the upper trunk of the brachial plexus (C5–C6). After branching, the nerve travels through the suprascapular notch to reach the supraspinatus and then continues around the spine of the scapula to the infraspinatus, giving motor input to it. This nerve supplies the rotator cuff muscle responsible for external rotation of the arm. The other nerves listed innervate different muscles (axillary to deltoid and teres minor, upper subscapular to subscapularis, and long thoracic to serratus anterior), so they do not innervate the infraspinatus.