Lateral Branches of Posterior Rami of Thoracic Nerves (Left)

Description

The posterior ramus of the thoracic nerve divides into medial and lateral branches lateral to the zygapophyseal joint. The lateral branch continues laterally, coursing between the superior costotransverse and intertransverse ligaments. As it reaches the medial border of levator costarum, the lateral branch travels inferoposteriorly.

The upper lateral branches (T1-T6) remain intramuscular, supplying the levator costarum, longissimus and iliocostalis muscles, while the lower lateral branches (T7-T12) also contribute to cutaneous innervation of the back and the anterior part of the gluteal region. These lower branches can descend a distance of four ribs to become cutaneous.