Why does your brain have crevises?

Your brain does not have crevices, it has sulci and gyri.

The brain is a complex organ, and its surface is not smooth. Instead, it is covered in a series of folds and ridges, called sulci and gyri. These folds and ridges increase the surface area of the brain, which allows it to pack more neurons into a smaller space.

The sulci are the grooves that separate the gyri, while the gyri are the ridges that rise between the sulci. The gyri are typically named after the region of the brain in which they are located. For example, the frontal gyrus is located in the frontal lobe of the brain.

The sulci and gyri are an important part of the brain's structure. They help to organize the brain into different regions, and they also provide a pathway for blood vessels and nerves to reach the brain.