Anatomy of the spinal cord nerves arising from the cervical vertebrae and their paths

There are eight pairs of nerves that grow from the spinal cord and exit the cervical vertebrae. One pair emerges from the two foramina of the first vertebra and diverges in the muscles of the head alone. This pair is small and narrow, because at the place of its exit it is safest for it to be narrow, as we already said in the section on bones.

The exit point of the second pair is between the first and second holes - I mean the holes mentioned in the section on bones.

The larger part of this pair gives the head a sense of touch, as it rises obliquely to the top of the back of the head, folds forward and diverges along the outer covering of the ears. This pair completely compensates for the shortcomings of the first pair, due to its small size and inability to diverge and spread over adjacent areas.

The rest of this pair goes to the muscles behind the neck and to the broad muscle and gives them the ability to move. The origin and exit of the third pair is the opening between the second and third vertebrae. Each nerve of this pair branches into two branches. One branch diverges in the depths of the muscles that have branches here, and, in particular, in the muscle that turns the head and neck backwards, then rises to the spines of the vertebrae and, being opposite them, sticks to their roots.

Then it rises to the heads of the spines and membranous ligaments extending from these spines are mixed with it. Then the nerves of this pair pass further, turning towards the ears. Not in humans, but in animals they end at the ears and set the ear muscles in motion.

The second branch goes forward until it reaches the vastus muscle. At the beginning of the ascent, vessels and muscles are wrapped around this branch, which cover it so that it is stronger in itself. In animals, these nerves merge with the temporal and auricular muscles, but most often they diverge only in the muscles of the cheeks.

As for the fourth pair, it emerges from the hole between the third and fourth vertebrae and is divided, like the previous pair, into an anterior part and a posterior part. Its front part is small and therefore it merges with the fifth pair.

They say that a branch arises from it, thin as a spider's web, which stretches along the carotid artery until it reaches the dividing septum, passing along both compartments of the barrier that bisects the chest. And most of this pair folds back and plunges deep into the muscles, releasing itself at the spines. It sends a branch to the muscle common to the head and neck and takes its path forward. In animals, this pair is adjacent to the muscles of the cheek and ears. They say that branches descend from it to the spine.

The fifth pair emerges from the foramen between the fourth and fifth vertebrae and also branches into two branches. One of the branches, namely the anterior one, is smaller. It reaches the muscles of the cheeks, the muscles that tilt the head forward, and other muscles common to the head and neck.

The second branch splits into two branches. One of them, namely the branch, located in the middle between the first branch and the second branch, goes to the top of the scapula, and part of the sixth and seventh pairs of nerves merges in it.

The second branch merges with the branches of the fifth, sixth and seventh pairs and runs to the middle of the thoraco-abdominal barrier.

As for the sixth, seventh and eighth pairs, they emerge sequentially from other openings, and the exit point of the eighth pair is located in the common opening of the last vertebra of the neck and the first vertebra of the ridge, and their branches come close together; but most of the sixth pair of nerves approaches the surface of the scapula, and the other part - larger than part of the fourth pair, and smaller than part of the fifth pair - goes to the thoraco-abdominal barrier.

Most of the seventh pair goes to the humerus, although some of its branches go to the muscles of the head, neck and spine, accompanying the branch of the fifth pair, and also extends to the thoraco-abdominal obstruction.

The eighth pair, after intertwining and accompanying the other pairs, goes to the skin of the hand and forearm, and no part of it goes to the thoraco-abdominal barrier. However, the part of the sixth pair that goes to the arm does not extend beyond the scapula, and the seventh pair does not extend beyond the humerus, and those nerves that go from the scapula to the forearm belong to the eighth pair in connection with the beginning of the nerves coming from the thoracic vertebrae.

It is these nerves that are allocated to the thoraco-abdominal barrier, and not the spinal nerves located below them, so that the nerves coming to the thoraco-abdominal barrier descend from a higher place and are well distributed, especially since their first target is the membrane dividing the chest. The spinal nerves would not be able to go there straight without forming an angular bend.

If all the nerves descending to the thoraco-abdominal barrier descended from the brain, then their path would undoubtedly be lengthened. The place where these nerves end on the thoraco-abdominal barrier is precisely its middle, because they could not spread and disperse along the thoraco-abdominal barrier fairly and equally if they reached its edge, and not the middle, or reached the entire periphery. This would distort the necessary path of the nerves, since the muscles carry out the movement of organs precisely through the ends of the nerves.

Further, the moving part of the thoraco-abdominal barrier is precisely its periphery, where the ends of the nerves should be located, and not their beginning. Since the nerves are not supposed to go to the middle, they must of necessity be suspended and should be protected and covered for safety. Therefore, the nerves are covered, for the sake of protective protection, by a membrane dividing the chest in half, which accompanies them, and they rest on this membrane.

Since the work of this organ is important, its nerves have many origins created so that they would not cease to function if damage were to occur to a single origin.