BRACHIAL PLEXUS

• Brachial plexus is formed by confluences of nerve roots from C5 to T1.

• It is surrounded by fascia derived from prevertebral fascia.

• The plexus consists of roots, trunks, divisions, cords and branches.

Roots:

• These are constituted by anterior primary rami of spinal nerves C5, C6, C7, C8,T1.

Trunks:

• Roots C5 and C6 joint to formupper trunk. Most common injury is of upper trunk.

• Root C7 forms the middle trunk.

• Root C8 and T1 join to form lower trunk.

• Each trunk divides into ventral and dorsal divisions which join to form cords.

Cords:

• The lateral cord is formed by the union of ventral divisions of the upper and middle trunks.

• The medial cord is formed by the ventral division of the lower trunk.

• The posterior cord is formed by union of the dorsal divisions of all the three trunks (upper, middle & lower trunks).

BRANCHES OF BRACHIAL PLEXUS

• Branches of Brachial plexus arises from different anatomical segments:-

A) BRANCHES OF THE ROOTS

• Nerve to serratus anterior (long thoracic nerve) (C5,C6,C7).

• Nerve to rhomboideus (dorsal scapular nerve) (C5).

• Nerve to scalene and longus colli (C5-C8).

• Branch to phrenic nerve (C5).

B) BRANCHES OF THE TRUNKS

• These arise only from the upper trunk which gives two branches:-

– Suprascapular nerve (C5,C6)

– Nerve to subclavius (C5,C6)

C) BRANCHES OF THE CORDS

a) Branches of lateral cord

• Lateral pectoral (C5-C7)

• Musculocutaneous (C5-C7)

• Lateral root of median (C5-C7)

b) Branches of medial cord

• Medial pectoral (C5-T1)

• Medial cutaneous nerve of arm (C8,T1)

• Medial cutaneous nerve of forearm (C8,T1)

• Ulnar (C7,C8,T1). C7 fibres reach by a communicating branch from lateral root of median nerve.

• Medial root of median (C8,T1).

c) Branches of posterior cord

• Upper subscapular (C5,C6)

• Nerve to latissimus dorsi (thoracodorsal) (C6, C7,C8)

• Lower subscapular (C5,C6)

• Axillary (circumflex) (C5,C6)

• Radial (C5-C8,T1)  LARGEST BRANCH OF BRACHAL PLEXUS

• If the contribution of C4 nerve root also occurs, it is called prefixed to plexus.

• If the contribution of T2 nerve root also occurs, it is called postfixed to plexus.

• Branches of brachial plexus, which arise from roots & trunk are supraclavicular branches (above the clavicle).

• Branchs of brachial plexus, which arise from the cords are infraclavicular branches (below the clavicle).