Nerves of the trunk in 3D

How the trunk is innervated

At every level an anterior and a posterior root join beyond the spinal ganglion to form a spinal nerve, which divides almost at once into a posterior ramus for the deep back muscles and skin, and an anterior ramus. In the thoracic region the anterior rami stay separate as intercostal nerves running under each rib.

In the cervical, lumbar and sacral regions the anterior rami join into plexuses: the brachial plexus for the upper limb, the lumbar plexus with the iliohypogastric, ilio-inguinal, genitofemoral and obturator nerves, and the sacral plexus with the pudendal nerve. The sympathetic trunk and the vagus nerve carry autonomic fibres to the organs.

What the 3D model shows

The nerves view has 87 parts: thoracic, lumbar and sacral spinal cord segments with anterior and posterior roots, a spinal ganglion and the cauda equina; intercostal nerves; the sympathetic trunk with its ganglia; the vagus and accessory nerves; the trunks, divisions and posterior cord of the brachial plexus with the long thoracic, thoracodorsal, pectoral and axillary nerves; and the iliohypogastric, ilio-inguinal, genitofemoral, obturator and pudendal nerves. The second view adds the trunk muscles.

How to study the trunk nerves

In the nerves view, take one thoracic segment and follow it outward: spinal cord segment, roots, spinal ganglion, then the intercostal nerve along its rib. Turn to the lateral view to see the sympathetic trunk lying in front of the rib heads. Then open the nerves and muscles view and pair nerves with their targets: long thoracic nerve with serratus anterior, pectoral nerves with the pectoral muscles, axillary nerve with teres minor, pudendal nerve with the external anal sphincter. Recall each pair from memory afterwards.