T2 contributions to the brachial plexus

Recent advancements in neurotization and nerve grafting procedures have led to an increasing need for knowledge of the detailed anatomy of communicating branches between peripheral nerves. Although the surgical anatomy of the axilla has been well described, little is known regarding the degree or frequency of potential contributions to or communications with the brachial plexus. The aim of our study, therefore, was to explore extrathoracic, as well as potential intrathoracic, contributions to the brachial plexus from T2.

The anatomy of the ventral primary ramus of T2 and the second intercostal nerve, including its lateral cutaneous contribution as the intercostobrachial nerve, was examined in 75 adult human cadavers (150 axillae), with particular emphasis on the communications with the brachial plexus.

Extrathoracically, communications were observed to occur in 86% of specimens. These contributions arose variably from either the intercostobrachial nerve or one of its branches and communicated with the medial cord (35.6%), medial antebrachial cutaneous nerve (25.5%), or posterior antebrachial cutaneous nerve (24%). Whereas the majority of specimens (68.2%) were observed to have only one extrathoracic communication, 31.7% of specimens exhibited two. Intrathoracically, communications were observed to occur in 17.3% of specimens. These communications always arose from the ventral primary ramus of T2. When combining and comparing data within individual specimens, it was observed that those axillae without an extrathoracic contribution from the intercostobrachial nerve always contained an intrathoracic communication.

Based on our findings, we conclude that 100% of specimens contained a communication branch between T2 and the brachial plexus. Considering the possible implications of this data, with regards to sensory innervation of the arm and axilla, further studies in this area of research could prove extremely beneficial.