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The C8 nerve contributes to the motor innervation of many of the muscles in the trunk and upper limb. Its primary function is the flexion of the fingers, and this is used as the clinical test for C8 integrity, in conjunction with the finger jerk reflex.
The muscle is inserted onto the radial sesamoid bone of the metacarpophalangeal joint. It acts to flex, adduct, and abduct the thumb, and is therefore also able to oppose the thumb. The superficial head is innervated by the median nerve, while the deep head is innervated by the ulnar nerve (C8-T1). [6]
The ulnar nerve originates from the C8-T1 nerve roots (and occasionally carries C7 fibers which arise from the lateral cord), [5] [6] which then form part of the medial cord of the brachial plexus, and descends medial to the brachial artery, up until the insertion point of coracobrachialis muscle (middle 5 cm over the medial border of the humerus).
A myotome is the group of muscles that a single spinal nerve innervates. [1] Similarly a dermatome is an area of skin that a single nerve innervates with sensory fibers. Myotomes are separated by myosepta (singular: myoseptum). [2] In vertebrate embryonic development, a myotome is the part of a somite that develops into muscle.
The cervical plexus innervates muscles of the neck and areas of skin on the head, neck and chest. The deep branches innervate muscles, while the superficial branches supply areas of skin. A long branch (primarily of fibers of C4 and with contributions of fibers from C3 and C5; nervus phrenicus) innervates muscles of the diaphragm.
The medial pectoral nerve (also known as the medial anterior thoracic nerve) is (typically) a branch of the medial cord of the brachial plexus and is derived from spinal nerve roots C8-T1. It provides motor innervation to the pectoralis minor muscle, and the lower half (sternal part) of the pectoralis major muscle. It runs along the inferior ...
The anterior interosseous nerve classically innervates 2.5 muscles: which are deep muscles of the forearm flexor pollicis longus; pronator quadratus; the radial (lateral) half of flexor digitorum profundus (inserting on the second and third digits) and the inferior radioulnar, wrist and carpal joints.
The brachial plexus is a network of nerves (nerve plexus) formed by the anterior rami of the lower four cervical nerves and first thoracic nerve (C5, C6, C7, C8, and T1).This plexus extends from the spinal cord, through the cervicoaxillary canal in the neck, over the first rib, and into the armpit, it supplies afferent and efferent nerve fibers to the chest, shoulder, arm, forearm, and hand.