The musculocutaneous nerve is a major nerve of the upper limb, primarily responsible for innervating the muscles in the anterior compartment of the arm. It arises from the brachial plexus, specifically from the C5, C6, and C7 spinal nerves. This nerve plays a crucial role in the movement of the arm, particularly in flexing the elbow. In addition to motor functions, the musculocutaneous nerve also provides sensory innervation to the skin of the lateral forearm. It branches into the lateral cutaneous nerve of the forearm, allowing for sensation in this area. Damage to this nerve can lead to weakness in arm flexion and sensory loss.