Upper thoracic dorsal rami: anatomic study of their medial cutaneous branches.

The authors describe the distribution of the medial branches of the upper thoracic dorsal rami (T1 to T5 levels). At each level, after travelling through the erector spinae, they become superficial, and reach the apex of the spinous process of the corresponding vertebra. They then spread out laterally, innervating the skin. They can occasionally be compressed by paravertebral tendons, and this possibly contributes to certain forms of dorsal pain. Anastomosis of the dorsal cutaneous branch of the second thoracic nerve (T2) with the descending lateral branch of the accessory nerve has been observed. Its presence could explain the occasional clinical situations where there is no resultant paralysis from accidental surgical section of the latter nerve.