Final answer:
Ridges of tissue on the surface of the cerebral hemispheres are called gyri. The correct answer is option 1).
Step-by-step explanation:
Ridges of tissue on the surface of the cerebral hemispheres are called gyri. The cerebral cortex, a layer of gray matter, covers the cerebrum and is folded into these ridges called gyri and valleys called sulci. The gyri and sulci create a distinctive pattern of folds that increases the brain's surface area, allowing for a greater amount of gray matter within the cranial cavity.
These patterns form important functional areas of the brain and are used to map the cerebral cortex into four major regions or lobes. For instance, the central sulcus separates the frontal and parietal lobes. The most prominent sulcus is the longitudinal fissure, which divides the cerebrum into the left and right cerebral hemispheres.
While the corpus callosum, a thick bundle of nerve fibers, connects these two hemispheres. The folding of the cortex during embryonic development follows a regular pattern of growth leading to a similar pattern of gyri and sulci in everyone's brain.