Which plexus largely innervates muscles of the shoulder and upper limb?

• A. Brachial Plexus
• B. Lumbar Plexus
• C. Lumbosacral Plexus
• D. Dorsal Cavities

Answer: (A)

The shoulder and upper limb receive their motor and sensory innervation primarily from the brachial plexus, a network formed by the ventral rami of spinal nerves C5 through T1. This plexus organizes into roots, trunks, divisions, and cords, giving rise to major nerves such as the axillary, musculocutaneous, radial, median, and ulnar nerves that innervate the shoulder girdle and arm muscles. In contrast, the lumbar and lumbosacral plexuses supply the lower limb and trunk, not the upper limb, and the dorsal cavities are not nerve networks. So, for muscles of the shoulder and upper limb, the brachial plexus is the principal source of innervation.