These structures are named by their relative anatomical location: TrunksĪt the base of the neck, the roots of the brachial plexus converge to form three trunks. The anterior rami of vertebral levels C5-C8 and T1 make up the roots of the brachial plexus. Fig 2 - The spinal cord outflow at each vertebral level. The roots of the brachial plexus are formed by the anterior rami of spinal nerves C5-T1 (the posterior divisions innervate the skin and musculature of the intrinsic back muscles).Īfter their formation, these nerves pass between the anterior and medial scalene muscles to enter the base of the neck. They leave the spinal cord via the intervertebral foramina of the vertebral column.Įach spinal nerve then divides into an anterior and a posterior ramus. These are the anterior rami of spinal nerves C5, C6, C7, C8, and T1.Īt each vertebral level, paired spinal nerves arise. The ‘roots’ refer the anterior rami of the spinal nerves that comprise the brachial plexus. There are no functional differences between these divisions - they are simply used to aid explanation of the brachial plexus. The brachial plexus is divided into five parts roots, trunks, divisions, cords and branches (a good mnemonic for this is Read That Damn Cadaver Book). In this article, we shall look at the anatomy of the brachial plexus - its formation and anatomical course through the body. This is position is known as ‘ waiter’s tip’ and is characteristic of Erb’s palsy. The wrist is weakly flexed due to the normal tone of the wrist flexors relative to the weakened wrist extensors. The forearm is pronated due to the loss of biceps brachii. The affected limb hangs limply, medially rotated by the unopposed action of pectoralis major.
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