Mapping axillary sensory cutaneous nerves for enhanced analgesic approaches in axillary surgery: a cadaveric study

Background Innervation of the breast includes branches of thoracic intercostal nerves, the superficial cervical plexus, the brachial plexus, and the intercostobrachial nerve (ICBN). Commonly used blocks for breast surgery provide incomplete analgesia of the axillary region. This cadaveric study aims to identify and map the axillary sensory cutaneous nerves. Methods We conducted nine axillary dissections on cadavers of both sexes with cadavers in supine position and upper limbs abducted. Incisions along the anterolateral thorax and superior clavicle created laterally reflecting skin flaps, allowing visualization of the ICBN and brachial plexus. Photographs were taken during dissections to enabled three-dimensional reconstruction using imaging software 3D Slicer. Results In all dissections, an ICBN and a branch of the posterior cord were identified entering axillary subcutaneous tissue. A branch of the medial cord was identified entering axillary tissue in 5/9 (56%) cadavers. The ICBN remained localized to the anterior axillary base but demonstrated various extrathoracic branching patterns. The posterior cord branch arose from the proximal posterior cord before penetrating the axillary base at its posterior margin in all cadavers. When present, the medial cord branch arose from the proximal medial cord before penetrating the axillary base along the midaxillary line. Conclusion In addition to the ICBN, two branches of the brachial plexus were identified entering axillary subcutaneous tissue. These branches are not currently considered when providing analgesia for breast surgery and may contribute to pain following surgery that involves axillary dissection.