If we look at a photograph of a human brain, probably the first thing we see is the outermost layer, a grayish wrinkled mass. This outermost and most superficial part is the cerebral cortex, and the aforementioned folds its convolutions or twists and furrows.

These folds emerge during the brain development of the fetus little by little, involving the neuronal matter from which they are formed in different brain functions of great importance for our day to day. One of them easily identifiable is the precentral gyrus , which we will talk about throughout this article.

Precentral gyrus: description and neuroanatomical location

The pre-central gyrus is one of the various cerebral gyres or convolutions present in the cerebral cortex, the part that on an observational level protrudes outwards from these folds. This gyrus is part of the primary motor area , so it is important to link it to the ability to generate movement.

This region of the brain can be located in the frontal lobe , just in front of Rolando’s fissure or central furrow that separates the front from the parietal. For this reason, another name for the pre-central gyrus is the pre-Rolandic gyrus or circumvolution.

The pre-central gyrus is present in both hemispheres , bordering Silvio’s fissure at the bottom. Just after the fissure we would find the post-central gyration, while in a more rostral way we would find the precentral fissure or furrow.

Functionally speaking it would be deeply communicated with the secondary motor cortex and the supplementary motor cortex, which allow planning and programming the movement, and the Broca area, which allows programming language related movements. In addition, it also has connections with other brain areas such as the cingulate or hypothalamus .

In the pre-central gyre and part of the central furrow or Rolando’s we can see represented Penfield’s homunculus, being both areas essential for the realization of the voluntary movement. Specifically, it is considered that the lower areas of the precentral gyrus control or innervate the regions of the head and face, while the upper parts would be in charge of innervating the legs.

Another aspect to highlight of this turn is that in it we can find some of the biggest pyramidal cells of the whole body, the Betz cells, reaching their axons to the spinal cord.

Associated functions

The pre-central gyrus is a region of the brain that is very important in enabling normative functionality and human behaviour , being involved in various functions. Among them we highlight the following.

1. Voluntary movement

It is considered that in the precentral gyrus, identified with the primary motor cortex, there is the motor representation and the first connections in charge of allowing the movement of different body regions. This brain region is largely responsible for the impulse and the capacity for movement , both simple and complex.

2. Displacement capacity

The capacity to move or simply to interact with the environment physically is, due to the need for movement to be carried out, one of the different functions in which there is a participation of the pre-central gyre.

3. Language and Communication

Our ability to communicate with others depends largely on the ability to move our voluntary musculature, which depends largely on the action of the motor cortex of which the pre-central turn of the face is a part in order to be able to speak (something which requires, among other things, movement of the lips and tongue) or communicate by means of gestures (muscles of the face and extremities).

4. Response to stimulation

Although the somatosensory system corresponds more to the post-central gyre, it has been observed during experiments with monkeys that in the pre-central gyre we can also find regions in charge of giving motor response to stimulation, specifically in order to seek protection or defence against possible threats . This effect has been observed with non-family stimuli, with the brain responding less or not at all to stimuli to which one is already accustomed.

Problems generated by your injury

The presence of injuries in the pre-central gyrus can have, as can be imagined from the importance of its functions, serious repercussions on the life of those who suffer them. An example of this is the presence of paralysis in the form of monoplegia, hemiplegia, paraplegia or tetraplegia , which may lose the ability to move different parts of the body.

It has also been observed that it influences the praxias or the performance of complex movements, causing the lesion of this turn the appearance of apraxias. Likewise, the lesion of the precentral gyrus has also been associated with the presence of Broca’s aphasia, making it impossible or complicated to produce the movements necessary to express oneself fluently.

Bibliographic references:

  • Graziano, M.S.A.; Alisharan, S.R.; Hu, X. & Gross, C.G. (2002). The clothing effect: Tactile neurons in the precentral gyrus do not respond to the touch of the familiar primate chair. PNAS, 99 (18): 11930-33.