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The fornix, anatomy, function and disorders

The fornix, anatomy, function and disorders

There is an important structure composed of white matter It connects different regions of the brain. Is the call fornix whose functions are fundamental for the correct cognitive functioning. Today we will talk about the anatomy, functions and problems that can cause damage in this interesting structure of the brain.

Content

  • 1 What is the fornix?
  • 2 Anatomy of the fornix
  • 3 Functions of the fornix
  • 4 Fornix disorders and problems

What is the fornix?

The fornix is ​​a C-shaped structure that originates from the hippocampus extending from there to the frontal area of ​​the brain being arched around the hypothalamus. The word fornix means “arch” in Latin and for a long time, through the discoveries of neuroanatomist James Papel, it was claimed that the fornix was part of the Papez circuit, a set of brain regions that according to the scientist constituted the "anatomical basis of emotions".

The circuit of Papez was constituted by the hippocampus, the anterior nucleus of thalamus, the cingulate twist, the turn paracampal and the mammillary bodies. The fornix was the connector of the structures of this circuit and its participation was and remains essential. Later, the circuit of Papez gave rise to what today is known as limbic system, whose functions are so broad that they range from emotional processing to movement.

Fornix Anatomy

The fornix is ​​made up of white matter a substance formed by myelinated nerve fibers or axons of neurons, which is also found in very important structures of the brain such as the cerebellum, the thalamus or the hypothalamus. The fornix is ​​in the telencephalon, in the middle of both cerebral hemispheres. Its structure is divided into several areas where we can find the body, two anterior and two subsequent projections, hence it is usually also known as a "four-pillar vault." These anterior columns connect with the mammillary bodies, while the posterior columns connect with the tonsil bodies.

In addition, the fornix connects with the structures that are part of both the limbic system and the cerebral cortex being connected structures such as the hippocampus, the thalamus or the Brodmann area, located in the frontal lobe. That is why it acts as a connector that allows the proper functioning of the brain as a whole.

Functions of the fornix

The clearest function of the fornix is ​​that of connect the different structures allowing the transmission of information, being an essential communicator in the brain. Without normal preservation of this structure, cognitive functioning would be impaired.

The fornix acts as the main exit route of the hippocampus, a key structure for memory formation. That is why the fornix is ​​commonly associated with the participation of the process of memory consolidationIn fact, when damage occurs in this structure, problems are often triggered in this cognitive process.

Fornix disorders and problems

Although it is strange that it happens, there are cases in which there is a congenital absence of this fibrous structure. It is the case of the holoprosencephaly, a cerebral malformation in which there is a division of the anterior deficit brain. In addition there are problems that can affect the fornix such as tumors, herpes simplex or multiple sclerosis leading to different problems in this structure.

When fornix damage occurs, mainly deficit in the declarative memory, the type of memory that allows us to remember events or events voluntarily, such as when we remember an important moment in our lives. Within the problems in declarative memory, it is specifically the episodic memory that to which a damage to the fornix can affect to a greater extent. In this type of memory, there is an autobiographical record through which we can remember specific events that are part of our history.

In addition, problems in this structure are associated with a type of amnesia known as anterograde amnesia, a loss of memory that prevents us from forming new memories and learning, even if our past memory remains intact.

During the disease of Alzheimer's specifically, there is a neurodegeneration of this structure that is usually associated with the cognitive deterioration that this disease produces in its affected. This degeneration usually occurs at the beginning of the disease and can indicate and predict its subsequent development, preceding the degeneration of the hippocampus, a region whose degeneration is associated in an important way with the cognitive symptoms of this disease.

Links of interest

//pubs.rsna.org/doi/full/10.1148/rg.314105729
//www.healthline.com/human-body-maps/body-of-fornix
//www.ncbi.nlm.nih.gov/pubmed/9210244