Corpus: Dorsal scapular nerve

The dorsal scapular nerve is a branch of the brachial plexus, primarily arising from the C5 segment, with occasional contributions from C4 and C6.

The dorsal scapular nerve originates near the intervertebral foramen between the fourth and fifth cervical vertebrae. It may share a common trunk with the long thoracic nerve. The nerve crosses, or sometimes pierces, the scalenus medius muscle and runs parallel to the accessory nerve. It then runs medially and caudally, piercing the levator scapulae muscle, to which it may give a branch. The nerve continues along the medial border of the scapula, innervating its target muscles.

The dorsal scapular nerve innervates the following muscles:

• Rhomboid major muscle
• Rhomboid minor muscle
• Levator scapulae muscle (occasionally)

Damage to the dorsal scapular nerve is rare and usually results from trauma. Injury to this nerve can cause scapula alata, where the scapula lifts off from the thorax. This is accompanied by atrophy of the rhomboid muscles on the affected side. Atrophy of the levator scapulae may occur but is often masked by the trapezius muscle.