Musculocutaneous nerve is derived from the lateral cord. Axillary nerve is derived from the posterior cord. Motor innervation is deltoid and teres minor muscles that act on the shoulder joint. Sensory innervation is from the skin just below the point of the shoulder. Radial nerve is also derived from the posterior cord.
Sensory innervation is from the skin on the dorsum of the hand on the radial side.
Usually leads to loss of nerve function Entrapment Nerve passing though a muscle or defined space Musculocutaneous nerve passing through coracobrachialis muscle Carpal Tunnel Syndrome Diminished function but no total loss Spinal Cord lesion All muscles supplied by spinal nerves below the site of the lesion are paralyzed Loss of sensation below the site of the lesion Lesions are referred to as the lowest portion of the spinal cord that functions a C5 spinal cord lesion means all spinal nerves below the 5th. All muscles supplied by a given nerve root will be weakened most muscles receive their innervation from axons derived from more than one spinal segment. Lateral, Medial, Posterior Cords 4. Understand embryological origin of the brachial plexus. Know the branches originating from the plexus , their component fibers and their distribution.