Brachial plexus – part 1.

Formed by the ventral rami of C5 down to T1 providing the entire nerve supply of the shoulder and upper limbs. The plexus extends inferolaterally either side of the last four cervical and first thoracic vertebrae, proceeding to pass over the first rib, behind the clavicle and in to the axilla before continuing along the arms.

The brachial plexus consists of 5 components: roots, trunks, divisions, cords and branches (Rob Taylor drinks cold beer).

brachial plex 1


– Roots of C5 and 6 pass down between anterior and medial scalenes, then unite to form the superior trunk.
– The root of C7 passes through the scalenes muscles and emerges at the lateral border of the anterior scalenes as the medial trunk.
– Roots the C8 and T1 unite behind Sibson’s fascia, beneath the subclavian artery to form the inferior trunk.

All three trunks traverse the supraclavicular fossa, protected by cervical and scalene muscles.

Each trunk splits in two to form anterior and posterior divisions.


– The posterior cord is formed of the three posterior divisions of the trunks (C5 – T1).
– The lateral cord is formed of the anterior divisions of the superior and medial trunk (C5 – 7).
– The medial cord is the anterior division of the inferior trunk continued (C8 – T1).

The cords pass through the thoracic outlet and give off major branches.


Lateral cord (LML):
– Lateral pectoral nerve (C5 – 7).
– Musculocutaneous nerve (C5 -7).
– Lateral head of Median nerve (C5 -7).

Medial cord (M4U):
Medial pectoral nerve (C8 – T1).
Medial cutaneous nerve of the arm (C8 – T1).
Medial cutaneous nerve of the forearm (C8 – T1).
– Medial head of the median nerve (C8 – T1).
– Ulnar nerve (C7 – T1).

Posterior cord (ULNAR):
– Subscapular nerve (upper and lower) (C5 – C7).
– Thoraco-dorsal nerve (nerve to latissimus dorsi)(C5 – 7).
– Axillary nerve (C5 – 6).
– Radial nerve (C5 – 8).

brachial plex 2


One thought on “Brachial plexus – part 1.

  1. Pingback: Brachial plexus – part 2. | Epsom tissue techniques

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