Neuroanatomy of Brachial Plexus: All about brachial plexus in one page, easy to remember & recall

First mnemonic to be remembered is RTDC

RTDC stands for Roots, Trunks, Divisions and then Cord.

C5, C6, C7, C8, T1 Nerve roots contribute in the formation of brachial plexus.

Draw first diagram as given below to depict the nerve roots in a simple manner.

C5---------

C6-----------

C7-----------

C8----------

T1-----------

 
Then join the C5 and C6 root to make upper trunk.

C7 root to continue as middle trunk

Join C8 and T1 to form the lower trunk.

Then each trunk divides into anterior and posterior divisions.

Anterior division of upper trunk and anterior division of middle trunk join to form Lateral cord.

Anterior divison of the lower trunk forms the Medial cord.

Posterior divisions of all the three trunks join to form the Posterior cord.

Once you understand the formation and nomenclature of RTDC, then it will be easy to remember the names and root values of nerves of the upper limb which are the branches of the brachial plexus.

Another mnemonic to be remembered : LLM, 4 MU & ULTRA

LLM are the nerves arising from the lateral cord ( Lateral Pectoral Nerve, Lateral root of Median nerve and Musculo cutaneous nerve). Since C5,6 & 7 roots had contributed in the formation of lateral cord, so the root value Lateral pectoral nerve and Musculocutaneous nerves are C5,6 & 7. Usculocutaneous nerve supplies all three muscles of the flexor compartment of arm( BBC,i.e., Biceps, Brachialis and Coracobrachialis).

4MU are the nerves from the Medial Cord. Medial Pectoral Nerve, Median root of median Nerve, Medial cutaneous nerve of arm , Medial cutaneous nerve of forearm, and Ulnar Nerve ( Root value C7,T1)

ULTRA is the mnemonic for the nerves of the posterior cord. ULTRA stands for Upper subscapular nerve, Lower subscapular nerve, Thoracodorsal nerve ( Nerve to Latissimus dorsi muscle, root value C7, C8), Radial nerve and Axillary nerve. Radial nerve is basically the continuation of the posterior cord and because posterior cord is formed by joining of the posterior divisions of all, upper, middle and lower trunks, the root value of radial nerve is C5 to T1.

Once you understood the basic detail about the formation of brachial plexus, then you should also remember that two nerves arise from the root itself. These two nerves are Dorsal scapular nerve and Long thoracic nerve.

Dorsal scapular nerve root value is C5

Long Thoracic Nerve arises form C5, C6 and C7 and it supplies to serratus anterior muscle. Its injury results in winging of scapula.

Two nerves arise from the trunk: Suprascapular nerve and nerve to subclavius. These two nerves arise from the upper trunk. Now, it is easy to recall that the C5 and C6 roots join to form the upper trunk which divides into anterior and posterior division. But, trunk it self gives origin to suprascapular nere and Nerve to subclavius.