Brachial Plexus Anatomy Quiz

Study Notes

Brachial Plexus Components

The brachial plexus is a network of nerves that originates from the spinal cord and innervates the upper limb.
The brachial plexus is formed by the ventral rami of spinal nerves C5-T1.

Nerve Formation

The five roots (C5-T1) merge to form three trunks: superior, middle, and inferior.
Each trunk divides into an anterior and posterior division.

Anatomical Arrangement

The anterior divisions of the upper, middle, and lower trunks combine to form the lateral cord.
The posterior divisions of the upper, middle, and lower trunks combine to form the posterior cord.
The anterior division of the lower trunk combines with the medial division of the middle trunk to form the medial c

Nerve Distribution

The brachial plexus gives rise to five terminal branches: musculocutaneous, axillary, radial, median, and ulnar nerves.

Specific Nerves and Function

The musculocutaneous nerve originates from the lateral cord and provides innervation to the biceps brachii, coracobrachialis, and brachialis muscles.
The axillary nerve originates from the posterior cord and innervates the deltoid and teres minor muscles.
The radial nerve originates from the posterior cord and innervates the triceps brachii muscle and extensor muscles of the forearm and hand.
The median nerve originates from the medial and lateral cords and provides motor and sensory innervation to the forearm and hand.
The ulnar nerve originates from the medial cord and provides motor and sensory innervation to the hand, particularly the medial part of the hand.

Key Facts

The rhomboid muscles are innervated by the dorsal scapular nerve.
The musculocutaneous nerve is well connected to the median nerve.
The brachial plexus provides nerve supply to the shoulder, upper arm, forearm, and hand.
The spinal accessory nerve supplies the trapezius muscle.
The pectoralis major muscle, a large muscle in the chest, is the prime mover in all forward-reaching and pushing actions.
In the anatomical position, the anterior divisions are superficial to the posterior divisions.

Clinical Relevance

Thoracic outlet syndrome can occur when the brachial plexus is compressed between the clavicle and first rib.
Erb's palsy, a condition that affects the shoulder and arm, is caused by damage to the upper roots of the brachial plexus, often associated with birth injury.

Description

Test your knowledge of the anatomy of the brachial plexus, a network of nerves formed by the lower cervical and first thoracic nerves, supplying nerve fibers to the chest, shoulder, arm, forearm, and hand.