Thoracic nerves

The thoracic nerves are the twelve spinal nerves emerging from the thoracic vertebrae.

Each thoracic nerve T1 -T12 originates from below each corresponding thoracic vertebra.

Branches also exit the spine and go directly to the paravertebral ganglia of the autonomic nervous system where they are involved in the functions of organs and glands in the head, neck, thorax and abdomen.

Anterior divisions: The intercostal nerves come from thoracic nerves T1-T11, and run between the ribs.

At T2 and T3, further branches form the intercostobrachial nerve. The subcostal nerve comes from nerve T12, and runs below the twelfth rib.

Posterior divisions:

The medial branches (ramus medialis) of the posterior branches of the upper six thoracic nerves run between the semispinalis dorsi and multifidus, which they supply; they then pierce the rhomboid and trapezius muscles, and reach the skin by the sides of the spinous processes.

This sensitive branch is called the medial cutaneous ramus.

The medial branches of the lower six are distributed chiefly to the multifidus and longissimus dorsi, occasionally they give off filaments to the skin near the middle line.

This sensitive branch is called the posterior cutaneous ramus.