Brachial Plexus - Key Terms (Vocabulary)

Vocabulary-style flashcards covering key terms and definitions related to the Brachial Plexus as presented in the notes.

Brachial Plexus

A major network of nerves that supplies the upper limb.

Roots (brachial plexus)

Five ventral rami from C5 to T1 (C5–T1) that form the roots and give rise to several nerves.

Trunks

Three trunks: Superior (C5–C6), Middle (C7), Inferior (C8–T1).

Divisions

Each trunk splits into an anterior and a posterior division; anterior divisions mainly supply flexors, posterior divisions supply extensors.

Cords

Three bundles: Lateral, Posterior, and Medial, formed from the divisions and giving rise to major peripheral nerves.

Lateral cord

Formed from the anterior divisions of the upper and middle trunks; gives rise to Musculocutaneous nerve and contributes to the Median nerve.

Medial cord

Formed from the anterior division of the inferior trunk; gives rise to Ulnar nerve and contributes to the Median nerve, plus other medial branches.

Posterior cord

Formed from all three posterior divisions; gives rise to Axillary and Radial nerves, plus posterior branches like thoracodorsal and subscapular nerves.

Musculocutaneous nerve

Branch from the lateral cord; innervates forearm flexors (e.g., biceps, brachialis) and provides sensation to the lateral forearm.

Median nerve

Formed from contributions of the lateral and medial cords (C5–T1); supplies most forearm flexors and some hand muscles; sensory in lateral hand.

Ulnar nerve

Branch from the medial cord (C8–T1); innervates most intrinsic hand muscles; sensory to the medial hand.

Axillary nerve

Branch from the posterior cord (C5–C6); motor to deltoid and teres minor; sensory to regimental badge area of the shoulder.

Radial nerve

Branch from the posterior cord (C5–T1); motor to posterior arm/forearm muscles; sensory to posterior arm/forearm and dorsolateral hand.

Suprascapular nerve

Branch from the superior trunk (C5–C6); supplies supraspinatus and infraspinatus.

Nerve to subclavius

Branch from the superior trunk (C5–C6); innervates the subclavius muscle.

Lateral pectoral nerve

Branch from the lateral cord; innervates the pectoralis major.

Medial pectoral nerve

Branch from the medial cord; innervates the pectoralis major and minor.

Upper subscapular nerve

Branch from the posterior cord; innervates the subscapularis.

Lower subscapular nerve

Branch from the posterior cord; innervates subscapularis and teres major.

Thoracodorsal nerve

Branch from the posterior cord (also called middle subscapular); innervates the latissimus dorsi.

Cervico-axillary canal

Pathway from the neck to the axilla through which the brachial plexus travels.

Boundaries of the cervico-axillary canal

Clavicle anteriorly, first rib and superior scapula posteriorly.

Thoracic Outlet region

Region from the intervertebral foramina to the pectoralis minor; contains the brachial plexus, subclavian artery and vein.

Interscalene triangle

Anatomical space between anterior and middle scalene muscles where the brachial plexus exits the neck.

Supraclavicular nerves

Nerves (C3–C4) supplying skin above the clavicle; include divisions of the plexus in the neck region.

Axillary sheath

Fibrous sleeve enclosing the axillary artery, axillary vein, and cords of the brachial plexus.

Axillary artery parts

Three parts of the axillary artery (1st, 2nd, 3rd) with key branches: 1st–superior thoracic; 2nd–thoracoacromial and lateral thoracic; 3rd–subscapular, anterior circumflex humeral, posterior circumflex humeral.

Shoulder/upper limb innervation pattern

Dermatomal and peripheral nerve distributions supplying motor and sensory function to the upper limb.

Upper Plexus vs. Lower Plexus

Upper Plexus (C5–6) affects shoulder/upper arm; Lower Plexus (C7–T1) affects lower arm/hand.

Injury mechanisms to the brachial plexus

Stretch/traction injuries, rupture, transection, blunt trauma, birth injury, trauma from sports, MVAs, gunshot wounds.