Middle finger drawing skin#

For simplicity, the smaller branches of the brachial plexus are not shown. Fig 3 - Diagrammatic representation of the brachial plexus. The cords give rise to the major branches of the brachial plexus. The anterior division of the inferior trunk.The posterior division of the inferior trunk.The posterior division of the middle trunk.

The posterior division of the superior trunk.

The anterior division of the middle trunk.

The anterior division of the superior trunk.

Once the anterior and posterior divisions have entered the axilla, they combine together to form three cords, named by their position relative to the axillary artery. They recombine into the cords of the brachial plexus. These divisions leave the posterior triangle and pass into the axilla. We now have three anterior and three posterior nerve fibres. Thus, they are known as the anterior and posterior divisions. One division moves anteriorly (toward the front of the body) and the other posteriorly (towards the back of the body). DivisionsĮach trunk divides into two branches within the posterior triangle of the neck. The trunks traverse laterally, crossing the posterior triangle of the neck.

Inferior trunk - combination of C8 and T1 roots.

Superior trunk - a combination of C5 and C6 roots.

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.

Middle finger drawing skin#

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. Sensory functions affected – sensation over the lateral aspect of upper limb (C5-6 dermatomes).Motor functions affected – abduction at shoulder, lateral rotation of arm, supination of forearm, and flexion at shoulder.Muscles affected – supraspinatus, infraspinatus, subclavius, biceps brachii, brachialis, coracobrachialis, deltoid and teres minor.This includes the musculocutaneous, axillary, suprascapular, and nerve to subclavius. Nerves affected – the peripheral nerves derived from C5-6 roots are most affected.

It most commonly occurs as a result of a stretching injury during a difficult vaginal delivery. There are no functional differences between these divisions – they are simply used to aid explanation of the brachial plexus.Ĭlinical Relevance: Upper Brachial Plexus Injury (Erb’s Palsy)Įrb’s palsy refers to an injury to the upper roots of the brachial plexus (typically C5-6). In this article, we shall look at the anatomy of the brachial plexus – its formation and anatomical course through the body. The plexus is formed by the anterior rami (divisions) of cervical spinal nerves C5, C6, C7 and C8, and the first thoracic spinal nerve, T1. It begins in the root of the neck, passes through the axilla, and runs through the entire upper extremity. The brachial plexus is a network of nerve fibres that supplies the skin and musculature of the upper limb.

8 Clinical Relevance: Lower Brachial Plexus Injury (Klumpke’s Palsy).

7 Clinical Relevance: Upper Brachial Plexus Injury (Erb’s Palsy).

5.6 Practical Relevance: Dissecting the Brachial Plexus.