Posterior commissure of the Great Brain

The prefrontal cortex, along the anterior branches of its frontal part, forms a thin border with the lateral surface of the greater commissure of the gyrus, which in the posterior direction runs somewhat obliquely backward and gives the brain a slightly bean-shaped shape. Like the greater commissure, the posterior commissure can serve as a fiber decussation site for the central motor tracts. The transverse fibers of this bundle located near the medulla oblongata can intersect the muscle fibers of the trunk, which in humans makes it impossible for a person to utter words by voluntary effort of the tongue to chew food. To study speech using PET tomography, it is necessary to experimentally create interference with motor planning. So, for example, you can ask a subject to name the numbers from 1 to 9, and if the subject pronounces the numbers unconsciously, without going over them in his mind, this is an indicator of the presence of interference from motor planning and can be characterized as a violation of initiation. If the subject carefully thinks about each answer, then, due to the action of the defense mechanism, he will try to classify all numbers as prime or composite, “two-digit” or “three-digit”, and will pronounce the numbers only after the classification process is completed. In this case, we should talk about a violation of maintaining conscious activity during initiation. Taking into account the above, PET can be considered a method for studying cognitive disorders.

The prefrontal root along the anterior branches of its frontal part forms a thin border with the side of the liquoritis, a large root riddled, in the posterior direction going slightly obliquely to the back and giving the brain a slightly bean-shaped shape. Both the anterior and dorsal roots can be sites of decussation of fibers for the central motor tract. Located near the bridge, the transverse fibers of these bundles are able to cross the muscle fiber of the trunk, which makes it possible for a person to voluntarily use the tongue to pronounce phrases and chop food.