What is the correct order of components in the brachial plexus?

The brachial plexus is a network of nerves that originates from the spinal roots and is essential for motor and sensory function in the upper limb. Understanding the correct order of its components is critical for students of anatomy and those in related fields.

The proper sequence starts with the roots, which are formed by the anterior rami of spinal nerves C5, C6, C7, C8, and T1. Following the roots, these converge to form the trunks. There are three trunks: upper, middle, and lower. Each trunk then divides into anterior and posterior divisions, and these divisions regroup to form the cords. The cords are named based on their position relative to the axillary artery: lateral, posterior, and medial. Finally, the cords give rise to the branches, which innervate the muscles of the shoulder, arm, and hand.

This order—roots, trunks, divisions, cords, and branches—helps in the understanding of how nerve signals are transmitted and how injuries in the plexus can affect different muscle groups and sensory areas. Knowledge of this sequence is also crucial for clinical practice, especially in diagnosing nerve injuries or planning surgical interventions.