In the brain

Brain

The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

, the interventricular foramina (or foramina of Monro) are channels that connect the paired lateral ventricles with the third ventricle

Third ventricle

The third ventricle is one of four connected fluid-filled cavities comprising the ventricular system within the human brain. It is a median cleft between the two thalami, and is filled with cerebrospinal fluid ....

 at the midline of the brain. As channels, they allow cerebrospinal fluid

Cerebrospinal fluid

Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...

 (CSF) produced in the lateral ventricles to reach the third ventricle and then the rest of the brain's ventricular system

Ventricular system

The ventricular system is a set of structures containing cerebrospinal fluid in the brain. It is continuous with the central canal of the spinal cord.-Components:The system comprises four ventricles:* right and left lateral ventricles* third ventricle...

. They also contain choroid plexus

Choroid plexus

The choroid plexus is a structure in the ventricles of the brain where cerebrospinal fluid is produced...

, a specialized CSF-producing structure, that is continuous with that of the lateral and third ventricles.

Anatomy

The crescent-shaped interventricular foramina are located on the medial

Anatomical terms of location

Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...

 and inferior aspect of the lateral ventricles. Each foramen is bounded by the fornix and thalamus

Thalamus

The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...

. The lumens of the foramina have a diameter of several millimeters.

Clinical relevance

Inflammation

Inflammation

Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...

, tumor

Tumor

A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...

, or other conditions that may occlude the foramina may lead to internal hydrocephalus

Hydrocephalus

Hydrocephalus , also known as "water in the brain," is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head,...

.

History

The foramina were named after

Eponym

An eponym is the name of a person or thing, whether real or fictitious, after which a particular place, tribe, era, discovery, or other item is named or thought to be named...

 the Scottish

Scotland

Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

 physician Alexander Monro

Alexander Monro (secundus)

Alexander Monro of Craiglockhart and Cockburn was a Scottish anatomist, surgeon and medical educator. To distinguish him as the second of three generations of physicians of the same name, he is known as secundus. His students included the naval physician and abolitionist Thomas Trotter...

, who first described the structures in his 1783 publication, Observations on the Structure and Functions of the Nervous System. They had previously been identified by the 17th century anatomist Raymond Vieussens

Raymond Vieussens

Raymond Vieussens was a French anatomist from Vigan. He studied medicine at the University of Montpellier where he earned his degree in 1670. He later became head physician at Hôtel Dieu Saint-Eloi in Montpellier...

.