Answer:
medulla
Step-by-step explanation:
When we think of the nervous system we usually think almost exclusively of the brain.
Focusing on this organ is logical because of its special relevance, but it is often forgotten that the nervous system is precisely a system, that is, a set of interrelated elements. In other words, not everything is the brain. Moreover, within the nervous system there are two major divisions, central nervous system and autonomic nervous system.
In addition to the king organ, in the central nervous system we can also find another great component: the spinal cord, through which most of the body's innervations pass.
The spinal cord is the most caudal part of the central nervous system, beginning in the medulla and ending in the lower back.
It is the lower part of the neuroaxis, in a slightly flattened and asymmetrical cylindrical shape that, like the brain, is strongly protected by being surrounded by the spine. Likewise, it also enjoys the protection of the meninges and cerebrospinal fluid, which prevent most of the damage caused by the surrounding elements.
In a sense, it is a part of the nervous system that is not completely anatomically separated from the brain, but that many of the elements involved in the latter work at the same time in the spinal cord. Anyway, it is possible to identify the beginning of this structure just below the brain stem.
This part of the nervous system is the point of connection between the brain and the rest of the organism, passing the vast majority of nerve fibers through the medulla. The transmission of information is usually given by a single neuron, but as a general rule, neurons configuring different nerves of the body make one or more intermediate synapses, is within the bone itself or outside it (as with nerve ganglion neurons).