Anatomy of the Long Thoracic Nerve in Relation to Thoracotomy for Spinal Approaches: How to Avoid Nerve Injury?

Thoracotomy and thoracoscopy are commonly used to access the thoracic spine in cases of vertebral fractures, tumors, spinal deformities, or symptomatic thoracic disc herniations. These procedures involve incisions in the intercostal spaces, which may place the lateral thoracic nerve (LTN) at risk. The LTN is a motor nerve that innervates the serratus anterior muscle, and its injury can result in winging of the scapula. The objective of this study was to describe the anatomic course of the LTN in relation to thoracotomy and thoracoscopic approaches to the thoracic spine.

Ten cadaveric specimens embalmed in formaldehyde were dissected bilaterally. Initial dissection was performed in the supine position, followed by repositioning into lateral decubitus. The LTN's location was measured relative to the lateral border of the scapula and the anterior aspect of the spine from the second to seventh intercostal spaces.

The LTN exhibited 3 to 5 branches (mean 3.8 ± 1.0), most frequently at the fourth intercostal space. At the level of the third rib, the nerve's average width was 2.9 ± 0.9 mm. The LTN was located 15.5 to 20.4 mm ventral to the lateral scapular border at the fifth to seventh intercostal spaces and 7.8 to 13.1 mm at more cranial levels. The distance between the nerve and the anterior spinal aspect ranged from 9.9 to 24 mm.

To minimize LTN injury, thoracotomy incisions should be placed approximately 15 mm from the scapular border at the second and third intercostal spaces and 35 mm at the fourth to seventh spaces. For thoracoscopy, portal incisions should be made more ventrally, aligned with the anterior spinal border to reduce nerve injury risk.