The thoracic nervus longus is also called the long thoracic nerve. This is a nerve that originates from the brachial plexus. The nerve originates more specifically from the pars supraclavicularis and contains nerve roots of the spinal cord segments C5, C6 and C7 from the neck. Its function is limited to the innervation of a muscle. This means that it is a purely motor nerve and does not perform any sensitive tasks.
Course of the thoracic longus nerve
After the nerve roots have united to form the brachial plexus, purely motor fibers of the spinal cord segments C5, C6 and C7 separate from it above the clavicle and form the thoracic nerve longus. This nerve then penetrates the scalenus medius muscle from the center. This penetration is located a short distance below the scapular dorsal nerve.
The nerve then runs over the first rib and bends caudally towards the abdomen. From there, the nerve lies mainly between the latissimus dorsi muscle and the serratus anterior muscle, relatively far superficially on the thorax. To each of the nine muscle bellies of the anterior serratus muscle, the thoracic longus nerve releases several motor branches, so-called rami musculares, for innervation. The ninth muscle belly of the musculus serratus anterior is located on the ninth rib, which is why the nerve can reach a considerable length for its location close to the trunk in large people.
Function of the thoracic nerve longus
The sole function of the thoracic long nerve is the motor innervation of the anterior serratus muscle. For this purpose, signals from the spinal cord are transmitted via the nerve cells of the nerve into the muscle, through which they are processed and executed. The muscle has an important function for the movement of the shoulder blade and thus also for the movement of the upper arm. If the nerve is damaged, this results in a restriction of movement.
Pain
Pain caused by damage to the long thoracic nerve is not very common. This usually results in persistent, slight pain in the area of the shoulder blade or the lateral thorax. Damage can be caused by various factors.
Most often, after wearing a rucksack or a bag with a belt for a long time, a pressure lesion occurs with subsequent complete or incomplete loss of function. After the end of the load, improvement often occurs. In rare cases, the functional impairment and pain persist. Furthermore, pain can occur after a direct trauma caused by a blow or a stab wound, but this is not significantly different from the pain resulting from a pressure lesion.
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