# What is the thoracic nerves?

Gray’s Anatomy (1918) describes the thoracic nerves as follows: The anterior divisions of the thoracic nerves ( rami anteriores; ventral divisions ) are twelve in number on either side.

## What it means

- The anterior divisions of the thoracic nerves ( rami anteriores; ventral divisions ) are twelve in number on either side. Eleven of them are situated between the ribs, and are therefore termed intercostal; the twelfth lies below the last rib. Each nerve is connected with the adjoining ganglion of the sympathetic trunk by a gray and a white ramus communicans.
- The intercostal nerves are distributed chiefly to the parietes of the thorax and abdomen, and differ from the anterior divisions of the other spinal nerves, in that each pursues an independent course, i. e., there is no plexus formation. The first two nerves supply fibers to the upper limb in addition to their thoracic branches; the next four are limited in their distribution to the parietes of the thorax; the lower five supply the parietes of the thorax and abdomen.
- The twelfth thoracic is distributed to the abdominal wall and the skin of the buttock. The First Thoracic Nerve. —The anterior division of the first thoracic nerve divides into two branches: one, the larger, leaves the thorax in front of the neck of the first rib, and enters the brachial plexus; the other and smaller branch, the first intercostal nerve, runs along the first intercostal space, and ends on the front of the chest as the first anterior cutaneous branch of the thorax.
- Occasionally this anterior cutaneous branch is wanting. The first intercostal nerve as a rule gives off no lateral cutaneous branch; but sometimes it sends a small branch to communicate with the intercostobrachial. From the second thoracic nerve it frequently receives a connecting twig, which ascends over the neck of the second rib. The Upper Thoracic Nerves ( nn. intercostales ).
- —The anterior divisions of the second, third, fourth, fifth, and sixth thoracic nerves, and the small branch from the first thoracic, are confined to the parietes of the thorax, and are named thoracic intercostal nerves. They pass forward in the intercostal spaces below the intercostal vessels.
- At the back of the chest they lie between the pleura and the posterior intercostal membranes, but soon pierce the latter and run between the two planes of Intercostal muscles as far as the middle of the rib.

## Sources

- [Gray's Anatomy of the Human Body (1918)](https://www.bartleby.com/lit-hub/anatomy-of-the-human-body/6c-the-thoracic-nerves/)

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