What is the brachial plexus and what does it do?

The brachial plexus is a network of nerves formed by the anterior rami of spinal nerves C5–T1, with minor contributions from C4 and T2. It provides motor and sensory innervation to the entire upper limb.

What are the main parts of the brachial plexus?

The brachial plexus is organized into four key components: Roots (C5 to T1), Trunks (upper, middle, and lower), Divisions (each trunk splits into anterior and posterior), and Cords (lateral, medial, and posterior).

What are the common variations in the brachial plexus?

Variations include a prefixed plexus (includes C4 and lacks T2) and a postfixed plexus (includes T2 and lacks C4). These affect the spinal nerve contributions.

What is Erb's paralysis and what causes it?

Erb's paralysis results from injury to the upper trunk (C5–C6), often due to excessive head-shoulder separation like a fall or birth injury. It leads to a 'waiter's tip' position with adduction, medial rotation of the arm, extended elbow, and pronated forearm.

What is Klumpke's paralysis and how does it present?

Klumpke's paralysis involves injury to the lower trunk (C8–T1), typically from arm hyperabduction. It causes a 'claw hand' deformity due to intrinsic hand muscle paralysis and may be associated with Horner's syndrome.

Which nerves arise from the posterior cord of the brachial plexus?

The posterior cord gives rise to several important nerves, including the upper and lower subscapular nerves, thoracodorsal nerve, axillary nerve, and radial nerve.

What structures are at risk during axillary surgery?

During procedures like axillary lymph node excision, key structures at risk include the intercostobrachial nerve, long thoracic nerve, thoracodorsal nerve, and thoracodorsal artery.

Brachial Plexus Anatomy – Roots, Trunks, Cords & Branches

❓ Frequently Asked Questions