Pons Varolio: anatomy, characteristics and functions

The pons of Varolio, also known as the annular pons or pons, It is a structure of the central nervous system (CNS) located in the brain stem. Specifically, it is the most prominent region of this structure and its function is to connect and communicate to the midbrain and medulla oblongata.

In other words, the pons annular function is to connect the spinal cord and the medulla oblongata with the cerebral hemispheres and the cerebellum. So, If damaged, it could cause serious consequences, even causing sudden death or entering a coma. Below, its structure, characteristics and functions are described in depth.

Anatomy of the Varolio Bridge

The annular protuberance has the shape of a thick roller placed transversely and two faces are distinguished in it: anterior and posterior. The anterior has a groove (basilar groove) arranged vertically in the center and is formed by vertebral arteries. The posterior surface is not visible, since it is hidden by the cerebellum and is part of the rhomboid fossa.

The nerves are arranged around it cranial. Specifically, on the sides of the anterior surface the trigeminal nerves (fifth cranial nerve) emerge, which extend towards the cerebellum. And through the anterior groove are the abductor (VI), facial (VII) and cochlear (VIII) nerves.

Its structure It is divided, functionally, into two sets of nuclei: the nuclei associated with cranial nerves and the nuclei themselves, not associated with nerves. Thus, the nerves associated with cranial nerves are the following:

Sensitive: pontine trigeminal nucleus, nucleus of the solitary tract, vestibular and cochlear nuclei.Visceral motors: special motor nucleus of the trigeminal, special motor nucleus of the facial and somatic motor nucleus of the abductor.Vegetative and general visceral motor: superior salivatory nucleus.

For their part, the proper nuclei are located in the ventral area. The afferents from the cerebral cortex arrive at these and leave for the cerebellum. That is to say, The proper nuclei are responsible for receiving and sending information between the cerebral cortex and the cerebellum. through the brain stem.

Characteristics

The Varolio Bridge, which measures approximately 2.5 centimetersis mainly characterized by:

It is the point of origin of constituent fibers. That is, most of the fibers that make up the middle cerebellar peduncles emerge from it, which contain the white matter of the brain.Contains Purkinje cells from the cerebellum that descend through the brain stem bridge vertically to the spinal cord. In relation to the previous ones, the annular pons presents a mechanism of direct action on the cerebellumconnecting it with the cerebral hemispheres.It is made up of neurons and gliaalthough some areas lack synapses.

Features

The structure and location of the Varolio Bridge make it a essential nucleus for communication of the nervous system, its main function. Thus, it is considered both a conduction center and a functional center.

The sensory pathways from the spinal cord to the brain circulate through it, and vice versa. Afferent fibers reach this region, cross and leave for the destination organ.. This also means that it is in the pons where the crossing of fibers occurs, causing the left hemisphere to control the right side of the body and the right hemisphere to control the left side.

It is considered a functional center because it constitutes an information transmission station. Thanks to the protuberance, various vital areas communicate at the vegetative and motor levels. Likewise, It plays a fundamental role in automatic muscle coordination. Thus, without this structure or without its correct functioning, the body could not, for example, remain standing, falling immediately.

In addition, the Varolio bridge intervenes in the expression of emotions and feelings. In this case, emotions such as joy, anger or sadness are manifested through specific facial expressions. Thanks to the regulation of the nerves that pass through the pons, these expressions can be controlled, although most of the time it is done automatically.

Also It intervenes in the perception of hearing, pain, taste and touch, as well as the secretion of saliva and tears. Although, it is pertinent to emphasize that these functions are not developed exclusively in this area, but are combined with other areas of the brain and work together.

And, as if that were not enough, it also plays a role in physiological phenomena: such as respiratory or cardiovascular functioning, controlling processes such as the beating of the heart. It is also involved in temperature regulation and the regulation of circadian cycles. of sleep and wakefulness and, therefore, in consciousness.

In summary

The pons or annular protuberance is a small brain region that It is involved in major vital functions, In addition to serving as a communication linkn among other structures of the nervous system. Therefore, injuries to this area could lead to serious diseases such as Millard-Gübler Syndrome, which causes hemiplegia on one side of the body or face. Or Foville Syndrome, which also causes gaze paralysis.

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