Diagram Of The Upper Intercostal Nerve

Illustration from 'Surgical Anatomy: The Treatise of the Human Anatomy and Its Applications to the Practice of Medicine and Surgery, volume III' (by Dr. John Blair Deaver) shows the intercostal nerves are the anterior divisions (rami anteriores; ventral divisions) of the thoracic spinal nerves, 1903. The upper intercostal nerves run outward in the interspaces, at first between the internal intercostal fascia and the pleura, and then between the external and internal intercostal muscles, till the mid-axillary line is reached. (Photo by VintageMedStock/Getty Images)