The gross anatomy of the extrathoracic course of the intercostobrachial nerve.

Recent reports emphasize the importance of preserving the intercostobrachial nerve (ICBN) during surgical procedures (i.e., mastectomy, axillary clearance). However, a limited number of scientific reports explore the surgical anatomy of this nerve. We dissected 100 adult human formalin-fixed cadavers (200 axillae). In all the cadavers the ICBN was present with variant contributions from intercostal nerves T1, T2, T3, and T4. The arrangements of the ICBN were typed as I through VIII. The components of Type I (45% or 90 of our specimens) included a branch to the posterior antebrachial cutaneous nerve, a branch to the anterior and lateral parts of the axilla, a branch to the medial side of the arm, and a branch to the medial antebrachial cutaneous nerve. Type II (25%) describes the ICBN arising from T2 and giving off a branch to the brachial plexus. In Type III (10%), lateral cutaneous branches of T2 and T3 fuse as a common trunk and then split immediately after exiting the intercostal space to form an ICBN. In type IV (5%), T2 and T3 join distally to form an ICBN that ends as its terminal branches. Type V (5%): T3 joins T2 from the same intercostal space proximally, with Type VI (3%) showing a very proximal branching of the sensory terminal nerves. Type VII (5%) displayed a contribution from T3 and a branch to the brachial plexus with multiple terminating branches. A contribution from T3 and T4 and a branch to the brachial plexus with multiple branches of termination comprised Type VIII (2%).