The long thoracic nerve, its origin, branching pattern and relation with scalenus muscles

Abstract

The purpose of this dissection study was to explore the anatomy of the long thoracic nerve (LTN) and its origin, configuration, branching pattern and relation with scalenus muscles. Fifteen embalmed cadavers (30 sides) were used. Bilateral neck, brachial plexus and chest wall were dissected. The LTN origin trajectory, branches and relation with middle scalenus muscle were explored. The serratus anterior muscle was dissected, the portions were separated, and their LTN branches were investigated. Most common form of the long thoracic nerve is formed by an upper portion origin from the C5 and C6 nerve roots and a lower portion origin from the C7 nerve root. In one case, the LTN was forming C6, C7 and C8, in which C6 nerve root forms upper portion and C7, C8 nerves root form lower portion. In some cases, the long thoracic nerve was formed only by C5 and C6 or C6 and C7 nerve roots. We defined four different types for these LTN configurations. When we look relationship between the roots of the nerve and scalenus muscle; nerve roots mostly (C5 and C6 components or upper portion of the LTN) lay between the middle and posterior scalene muscles, sometimes traveled through the middle scalene muscle, less frequently course over the middle scalenus muscle. The C7 contribution (lower portion of the LTN) to the LTN was always located anterior to the middle scalene muscle. The C8 (in one case) also was found over the middle scalenus muscle. Each of the LTN has 7–13 branches and 0–4 branches arising directly from the nerve roots or before exact nerve configuration, 5–7 branches origin from the main trunk of the nerve. We defined these branches as ribs and intercostals spaces. We hope that this study will be helpful for many neurosurgical procedures and anatomic studies.