Nervous Ganglion: Types And Functions Of This Part Of The Nervous System
A nervous ganglion is the group of neuronal bodies that are located outside the central nervous system and that fulfills very important functions to transport electrical impulses connecting the brain with specific organs.
In this article we will see what a nerve ganglion is how it is composed and what are the two main types into which it is divided.
In biology, the term “ganglion” is used to designate the masses of tissue that form in cellular systems. Specifically in neurology, this term usually refers to a mass or group of nerve cell bodies present in most living organisms. Its main function is to carry nerve impulses from the periphery to the center, or vice versa.
In this sense, a “nervous ganglion” is the agglomeration of somas or neuronal bodies that are located in the autonomic nervous system It is mainly responsible for connecting the peripheral nervous system with the central nervous system, both in an efferent sense (from the central nervous system to the sensory organs) and afferent sense (from the sensory organs to the central nervous system).
Therefore, a nervous ganglion is broadly composed of cell bodies of afferent nerves, cell bodies of efferent nerves, and neuronal axons Likewise, it can be divided into two large subtypes according to the specific function they perform within the peripheral nervous system.
Types of nerve ganglion
The nervous ganglia are located outside the central nervous system, that is, in the autonomic nervous system. Depending on the specific part of the autonomic nervous system to which they belong, as well as according to the specific path they follow to transmit nerve impulses, These ganglia can be divided into sensory and autonomic ganglia
The sensory nerve ganglion acts by receiving signals from the periphery and sending them to the brain, that is, it has an afferent function. It is also known as the somatic ganglion, sensory ganglion, or spinal ganglion, since it is located in the back of other structures called spinal nerves. These last ones are the nerves that form the dorsal and ventral roots of the spinal cord For this reason, the sensory nerve ganglion is also known as the spinal ganglion.
It extends through these roots or branches, crossing different parts of the body, and is responsible for activating electrical impulses from the skin and the muscles of the back (dorsal branches). In fact, another name that these ganglia commonly receive is “dorsal root ganglia.”
2. Autonomous or vegetative nerve ganglion
The autonomic nervous ganglion acts in the opposite direction to the sensory nervous ganglion, that is, in an efferent manner: it receives signals from the central nervous system and sends them to the periphery. It is also called the vegetative ganglion, and since it belongs to the autonomic nervous system, what it does is regulate motor activity. They are located near the viscera on which it acts although keeping distance from them, and are in turn divided into two types of ganglia:
2.1. parasympathetic ganglia
These are the ganglia that are part of the parasympathetic nervous system. They are located in the wall of the viscera that they innervate, that is, in the specific area of the body in which the nerve acts. Due to the proximity they maintain with the organs on which they act, They are also known as intramular lymph nodes (except for those that act on the neck and head). They are made up of three different roots depending on the route that the nerve fibers follow: motor root, sympathetic root or sensory root.
In turn, these nerve fibers make up different cranial nerves, including the oculomotor, facial, glossopharyngeal, vagus and pelvic splanchnic nerves.
2.2. sympathetic ganglia
As their name indicates, they are part of the sympathetic nervous system. They are found on both sides of the spinal cord, forming long nerve chains. These are the ganglia that They are found around the celiac trunk (arterial trunk that originates from the aorta, specifically in the abdominal part of this artery). The latter are the prevertebral sympathetic ganglia, and they can innervate the organs that make up the abdominal and pelvic region, or.
On the other hand, there are the paravertebral ganglia, which form the paravertebral chain and go from the neck to the thoracic cavity, acting especially on the viscera.
Among its main functions is the transmission of information about events that may be risky for the organization. In this sense, they are related to stressful situations and constitute one of the elements responsible for responding to them, either through flight or through aggression.
