Vessels and nerves of the thoracic wall

There are numerous vessels and nerves that course throughout the bony and muscular architecture of the thoracic wall, and they provide innervation and blood supply to the structures within and around the thoracic cage.

First, let’s have a look at the contents of the intercostal space, specifically the neurovascular bundle containing the intercostal nerve, artery and vein.

It is important to remember the order of these structures, with the most superior structure being the intercostal vein and below it comes the artery and below the artery, the nerve.

To easily remember this, think V-A-N or think about a VAN that’s blue at the top, red in the middle and yellow in the inferior part.

The inferior portion of the ribs also have a costal groove which only provides partial protection for these structures, so they can be damaged during penetrating intercostal injuries or any intervention that requires intercostal access

Now, let’s talk about the nerves.

There are 12 pairs of thoracic spinal nerves which supply the thoracic wall.

They leave the intervertebral foramina as soon as they are formed, dividing into anterior and posterior rami.

Now, the anterior rami of nerves T1 through T11 form the intercostal nerves that run along the intercostal spaces along the inferior borders of the ribs, with the third intercostal nerve travelling between the third and fourth ribs.

The anterior ramus of nerve T12 that courses inferior to the 12th rib is the subcostal nerve.

The intercostal nerves give anterior and lateral cutaneous branches to innervate the thorax and abdominal wall, muscular branches to supply the muscles of the thoracic wall, and they give rami communicantes or communicating branches that connect the intercostal nerves to a sympathetic trunk on the same side.

The posterior rami of thoracic spinal nerves pass posteriorly, lateral to the articular processes of the vertebrae in order to supply the joints, deep back muscles and skin of the posterior thoracic region.

Now, the intercostal nerves are either typical or atypical, and the typical ones are the 3rd through the 6th pair.

These nerves enter the medial-most parts of the posterior intercostal spaces.