The musculocutaneous nerve is a major nerve of the upper limb, primarily responsible for innervating the muscles in the front of the arm. It arises from the brachial plexus, specifically from the spinal nerves C5, C6, and C7. 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 forearm. It branches into the lateral cutaneous nerve of the forearm, which supplies sensation to the lateral aspect of the forearm. This dual role makes the musculocutaneous nerve essential for both movement and sensation in the arm.