Claustrum

Anatomical structure

The claustrum is defined as a bilateral slender sheet of gray matter which only comprises about 0.25% of the cerebral cortex. 

The term ‘claustrum’ originates from the Latin ‘claud’ which translates to mean ‘hidden away’ or ‘enclosed’, perfectly describing this concealed structure. The claustrum is located within the inner surface of the neocortex of the pallium, deep to the insula and separated from it by the extreme capsule. It is separated medially from the putamen by a narrow layer of white matter known as the external capsule. Although situated adjacent to structures of the basal ganglia, such as the putamen, the claustrum does not fall under this category.

The anterior portion of the claustrum is generally thin and is formed by ‘islands’ of grey matter, whereas it’s posterior aspect is considerably thicker and more clearly defined. The claustrum does not span throughout the entirety of the cerebral cortex but is mainly limited to the general region of the insular cortex. 

The claustrum is said to take on the appearance of a leaf with two segments. Each segment extends anteriorly, one to the frontal lobe and the other towards the temporal lobe. The claustrum can be identified in both the horizontal and coronal sections of the brain. Within a horizontal section the claustrum appears to be a linear structure which spans the length of the insular cortex. A coronal section of the brain highlights the ‘curves’ of the claustrum as it follows the contour of the brain. 

It can be hard to wrap your head around the structures of the brain. Check out the study units below on the structures of the brain from a horizontal and coronal perspective.

Blood supply of the claustrum

The claustrum is vascularized by branches of both the superficial and deep components of the middle cerebral artery. The insular and anterolateral central branches of the middle cerebral artery have been reported to provide partial arterial supply to the claustrum.

Function of the claustrum

The function of the claustrum remains relatively unknown. Previous research has identified numerous neuronal connections between the claustrum and the surrounding cerebral cortex. All cortical areas of the brain have been reported to reciprocally connect to the claustrum. Meaning that the claustrum is involved in many processes of the cerebral cortex, while its precise role remains unknown. Current research suggests that the claustrum may function in the area of knowledge processing specifically in differentiating between irrelevant and relevant facts and information. 

Due to its multiple neural connections, the claustrum is also thought to play a role in synchronizing perceptual, cognitive and motor processes.

As the last step in your learning process, why not have a go at identifying some structures in a coronal section through the brain with our quiz!