The brachial plexus is formed from the ventral rami of cervical and upper thoracic spinal nerves. It divides into trunks, divisions, cords and terminal branches that innervate the muscles and skin of the upper limb. The brachial plexus transmits signals from C5-T1 spinal nerves to form the major nerves of the arm and forearm, including the median, ulnar, radial and musculocutaneous nerves.

1. Formation & branches Brachial plexus
Root
(ventral rami)
Trunk Division Cord terminal
Branch
C5.
C6. Lat root of median
nerve
C7. Median nerve
C8. Med root of
median nerve
T1.
Upper.Tr.
Middle.Tr.
Lower.Tr.
a.d.
a.d.
Lat.C.
Medial C.
p.d. Post.C.

2. Lateral C Post C Medial C
Lat Pectoral Nerve Med pectoral nerve Upper Subscapular nerve
Musculocutaneous Nerve Med cutaneous nerve of
arm
Lower subscapular nerve
Lat root of median nerve Med cutaneous nerve of
forearm
Thoracodorsal nerve
Med root of median nerve Axillary nerve
Ulnar Nerve Radial Nerve