Brachial Plexus Practice Test

Latissimus dorsi is motor-innervated by the thoracodorsal nerve, a branch of the posterior cord of the brachial plexus. This nerve carries fibers from C6 through C8 (with occasional contribution from nearby levels) and travels to reach the latissimus dorsi to provide its motor input. The muscle’s actions are to extend, adduct, and medially rotate the arm, which you’ll feel when you pull yourself up or perform strokes like swimming; the thoracodorsal nerve is essential for those powerful pulling movements. The other nerves listed don’t supply this muscle. Upper and lower subscapular nerves serve the subscapularis and, in the case of the lower subscapular, teres major. The axillary nerve supplies deltoid and teres minor. So the thoracodorsal nerve is the correct innervation for latissimus dorsi.