Silvian Aqueduct: Characteristics Of This Brain Canal
The Sylvian aqueduct is a duct or canal located in a structure of our brain called the midbrain and whose function is to transport, from one ventricle to another, the cerebrospinal fluid, which acts as a shock absorber and protects us from blows to the head, among other relevant functions for our body.
In this article we explain what the Silvio aqueduct is, what its characteristics are, where it is located, what functions it performs, how it develops and what are the main disorders associated with a malfunction of this brain structure.
In neuroanatomy, it is known as the Sylvian aqueduct, cerebral aqueduct or aqueduct of the midbrain to the brain. conduit located in the midbrain that is responsible for connecting the third and fourth ventricles of the brain, and through which the cerebrospinal fluid passes (CSF) that permeates the brain and spinal cord.
CSF is a liquid substance that fulfills basic functions in our nervous system, among which are: acting as a protector against head trauma; provide hydropneumatic support; eliminate residual metabolites from the nervous system; and act as a homeostatic mechanism when certain hormonal imbalances occur in the body.
Currently, the name Silvio aqueduct is in disuse and In current anatomical nomenclature, the name given to this brain structure is the aqueduct of the midbrain or, simply, the cerebral aqueduct However, throughout this article we will use the term Silvio aqueduct to refer to it.
Location and structure
The Sylvian aqueduct is located within the mesencephalon or midbrain, one of the parts that make up the brain stem. This brain structure is located above the pons or pons and below the diencephalon (composed of the thalamus and hypothalamus, among other structures), and is made up of the tectum (or roof), located in the dorsal part; and the tegmentum (or integument), located just below the tectum.
The midbrain or mesencephalon is made up of various neuronal nuclei : the periaqueductal gray matter, involved in the processing of pain or threatening stimuli; the red nucleus, which controls various motor processes; and the substantia nigra, a component of the basal nuclei whose functions are related to motor control, learning, and reward mechanisms.
The Silvio aqueduct, as we mentioned at the beginning of the article, is a channel that connects the third and fourth ventricles, in a system of four cavities or ventricles. The two lateral ventricles are located along the cerebral hemispheres and connect to the third ventricle through the interventricular foramen or Monro’s foramen.
Regarding the third ventricle, it should be noted that it is a cavity located in the midline of the brain and is limited on each side by the thalamus and hypothalamus. In its front part it communicates, as we have mentioned, with the lateral ventricles and, in the posterior part, with the Sylvian aqueduct.
For its part, The fourth ventricle is the one located at the lowest level of the four cerebral ventricles It extends from the Sylvian aqueduct to the central canal at the upper end of the spinal cord, with which it communicates through several orifices: the Luschka foramina, located on the sides; and the Magendie foramen, located in the center and between the two Luschka foramina.
Features and development
The Silvio aqueduct, as its name indicates, is a canal or cerebrospinal fluid irrigation system that connects the third and fourth ventricles and which, together with the lateral ventricles, constitute the ventricular system that protects the brain, among other functions.
The development of the ventricular system occurs in parallel with the rest of the central nervous system. The cerebral ventricles are derived from the embryonic neuroepithelium. Both the ventricles, the Sylvian aqueduct and the central canal of the spinal cord are covered by an epithelial layer of cubic and cylindrical cells, called ependymal cells.
From the fifth week of embryonic development, the brain vesicles are differentiated into: telencephalon, diencephalon, mesencephalon, metencephalon and myelencephalon. These vesicles are hollow inside and maintain their cavities until their development is complete in adulthood: what we know as cerebral ventricles.
In the sixth week, the division of the brain vesicles is clearer; The forebrain has already differentiated into the telencephalon and the diencephalon. The midbrain, for its part, has not been divided and its largest cavity progressively narrows in the early stages, while the Sylvian aqueduct is formed, which connects the third with the fourth ventricle.
The midbrain or mesencephalon is the structure that undergoes the least changes during development, except for its most caudal part. Finally, the length of the Silvio aqueduct is approximately 18 millimeters.
Related disorders
Hydrocephalus is a group of diseases caused by an increase in cerebrospinal fluid (CSF) inside the cranial cavity. Its incidence is 1 or 2 cases per 1000 births and it occurs more frequently due to congenital causes than acquired ones. In cases in which congenital hydrocephalus occurs, teratogenic factors, malnutrition, toxins, etc. may play a role.
There are three main types of hydrocephalus: communicating or non-obstructive, which arise when CSF absorption is not adequate; non-communicating or obstructive ones, which occur when the flow of CSF is blocked in one or more channels that connect one ventricle to another; and normotensive, in which an increase in CSF is generated in the ventricles, with a slight increase in intracranial pressure.
One of the most common disorders related to damage or obstruction of the Sylvian aqueduct is known as hydrocephalus due to congenital aqueductal stenosis (HSAS) This disease, associated with a phenotype that is part of the clinical spectrum of the X-linked L1 syndrome, causes severe obstructive hydrocephalus, generally of prenatal onset, which produces signs of intracranial hypertension, thumb abduction, symptoms of spasticity and a severe deficit intellectual.
In children, one of the most typical symptoms involves a rapid increase in head circumference or size. Other autonomic or somatic symptoms may also occur and may include vomiting, irritability, dreams, and seizures.
Although the consequences of hydrocephalus vary from patient to patient depending on age, disease progression, and individual differences in CSF tolerance, it should be noted that hydrocephalus due to stenosis of the Sylvian aqueduct represents the most severe extreme of the condition. spectrum and has an unflattering prognosis.
