A Cadaveric Investigation of the Long Thoracic Nerve

Introduction: Entrapment of the long thoracic nerve (LTN) is associated with pain in the thorax and back. Entrapment can occur at many places along the pathway of the LTN, including the cervical spine and the scalene muscles, which can make it hard to diagnose. The purpose of this study was to document the LTN's anatomy and measure the course it takes with regard to the serratus anterior muscle. Method: From 4 previously dissected, adult cadavers, 8 LTNs were documented regarding the nerve's anatomical route and muscular innervation. A transverse plane through the cricothyroid membrane was established and a t-pin was pierced into the nerve at that plane and measurements were taken using Vernier calipers. Results: The average length from the spinal origin of LTN to the insertion into the serratus anterior muscle was the width of 10.3 thumb interphalangeal joint (IPJ) on the right side and 9.75 IPJ on the left side. The average length from the origin to the cricothyroid membrane was 5.15 IPJ on the right side and 4.4 IPJ on the left side. The average length from the cricothyroid membrane to the serratus anterior insertion on the right side was 5.15 IPJ and 5.35 IPJ on the left side. Conclusion: Knowing the average lengths of the LTN can better help treat the entrapment with manual therapy, topical injections, or even surgery. The results will assist to help improve clinicians' ability to locate the site of LTN entrapment so appropriate management can be implemented.