Posterior Rami of Thoracic Spinal Nerves (Left)

Description

The posterior rami of the thoracic nerves are the dorsal branches of the T1 to T12 spinal nerves. They are one of the two terminal branches of these spinal nerves, the other being the anterior (ventral) rami.

The posterior rami are mixed nerves conveying both sensory and motor information to and away from the central nervous system. Autonomic fibers will also travel in the posterior rami.

The posterior rami branch off the spinal nerves shortly after the nerve emerges from the transverse foramen. As it reaches the epaxial musculature, the posterior rami split into medial and lateral branches which target the transversospinal and deep segmental back muscles (medial branches) and erector spinae muscles (lateral branches). Some references will also include an intermediate branch which supplies the more medial erector spinae muscles.