The Brachial plexus is formed by the ventral primary rami of the lower four cervical nerves and the first thoracic nerves (C5–T1). It has roots & trunks (in the neck), divisions (passing behind clavicle), cords and branches (in the axilla). It is covered by a prolongation of prevertebral fascia (axillary sheath) around the nerves in the axilla.
Following Video will help you draw the Brachial Plexus in less than 10 seconds and learn it faster than any others! Just practice it, since it is always and always asked in First Year MBBS Anatomy exams.
Two branches are given directly from the roots in the neck:
- Dorsal scapular nerve (C5), which supplies rhomboid major & monor levator scapulae muscles.
- Long thoracic nerve of Bell (C5–C7), which is given in the neck, enters axilla and descends on the external surface of the serratus anterior muscle and supplies it.
Lateral cord gives three branches (LML), medial and posterior cords give 5 branches each. Radial nerve is a branch of posterior cord (STARS) and supplies posterior (extensor) compartment of upper limb. Ulnar nerve is a branch of medial cord (UM4) and runs on the ulnar (medial) side of the limb. Median nerve runs in the midline of the limb and has contributions from both medial and lateral cords.
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