Brachial plexus

The brachial plexus is a network (plexus) of nerves (formed by the ventral ramus 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 and hand.(see below) 1st and 2nd lumbrical muscles. muscles of the thenar eminence by a recurrent thenar branch The brachial plexus surrounds the brachial artery.Nerves in the infraclavicular portion of the right brachial plexus in the axillary fossa.The outermost (distal) part of the brachial plexus shown from a dissected cadaveric specimen.Brachial plexusMind map showing branches of brachial plexusSpinal cord. Brachial plexus. Cerebrum.Inferior view.Deep dissection.Diagram of the brachial plexus using colour to illustrate the contributions of each nerve root to the branches.The brachial plexus, including all branches of the C5-T1 ventral primary rami. Includes mnemonics for learning the plexus's connections and branches. The brachial plexus is a network (plexus) of nerves (formed by the ventral ramus 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 and hand. The brachial plexus is divided into five roots, three trunks, six divisions (three anterior and three posterior), three cords, and five branches. There are five 'terminal' branches and numerous other 'pre-terminal' or 'collateral' branches, such as the subscapular nerve, the thoracodorsal nerve, and the long thoracic nerve, that leave the plexus at various points along its length. A common structure used to identify part of the brachial plexus in cadaver dissections is the M or W shape made by the musculocutaneous nerve, lateral cord, median nerve, medial cord, and ulnar nerve. The five roots are the five anterior rami of the spinal nerves, after they have given off their segmental supply to the muscles of the neck.The brachial plexus emerges at five different levels; C5, C6, C7, C8, and T1. C5 and C6 merge to establish the upper trunk, C7 continuously forms the middle trunk, and C8 and T1 merge to establish the lower trunk.Prefixed or postfixed formations in some cases involve C4 or T2, respectively.The dorsal scapular nerve comes from the superior trunk and innervates the rhomboid muscles which retract the scapula. The subclavian nerve originates in both C5 and C6 and innervates the subclavius, a muscle that involves lifting the first ribs during respiration. The long thoracic nerve arises from C5, C6, and C7. This nerve innervates the serratus anterior, which draws the scapula laterally and is the prime mover in all forward-reaching and pushing actions. These roots merge to form the trunks: Each trunk then splits in two, to form six divisions: These six divisions regroup to become the three cords or large fiber bundles. The cords are named by their position with respect to the axillary artery. The branches are listed below. Most branch from the cords, but a few branch (indicated in italics) directly from earlier structures. The five on the left are considered 'terminal branches'. These terminal branches are the musculocutaneous nerve, the axillary nerve, the radial nerve, the median nerve, and the ulnar nerve. Due to both emerging from the lateral cord the musculocutaneous nerve and the median nerve are well connected. The musculocutaneous nerve has even been shown to send a branch to the median nerve further connecting them.There have been several variations reported in the branching pattern but these are very rare. Bold indicates primary spinal root component of nerve. Italics indicate spinal roots that frequently, but not always, contribute to the nerve.