Superior to the lateral sulcus are the parietal lobe and frontal lobe, which are separated from each other by the central sulcus.

The lateral sulcus that separates the temporal lobe from the other regions is one such landmark. Using these landmarks, the cortex can be separated into four major regions, or lobes ( Figure 14.3.2). The surface of the brain can be mapped on the basis of the locations of large gyri and sulci. During embryonic development, as the telencephalon expands within the skull, the brain goes through a regular course of growth that results in everyone’s brain having a similar pattern of folds. The folding of the cortex maximizes the amount of gray matter in the cranial cavity. If the gray matter of the cortex were peeled off of the cerebrum and laid out flat, its surface area would be roughly equal to one square meter. Extensive folding in the cerebral cortex enables more gray matter to fit into this limited space.

The head is limited by the size of the birth canal, and the brain must fit inside the cranial cavity of the skull. The pattern of these folds of tissue indicates specific regions of the cerebral cortex. A gyrus (plural = gyri) is the ridge of one of those wrinkles, and a sulcus (plural = sulci) is the groove between two gyri. This thin, extensive region of wrinkled gray matter is responsible for the higher functions of the nervous system. The cerebrum is covered by a continuous layer of gray matter that wraps around either side of the forebrain-the cerebral cortex. The limbic cortex is the region of the cerebral cortex that is part of the limbic system, a collection of structures involved in emotion, memory, and behavior. The basal forebrain contains nuclei that are important in learning and memory. The basal nuclei are responsible for cognitive processing, the most important function being that associated with planning movements. In mammals, the cerebrum comprises the outer gray matter that is the cortex (from the Latin word meaning “bark of a tree”) and several deep nuclei that belong to three important functional groups. The cerebrum of the most primitive vertebrates is not much more than the connection for the sense of smell. The complexity of the cerebrum is different across vertebrate species. Many of the higher neurological functions, such as memory, emotion, and consciousness, are the result of cerebral function. Deep within the cerebrum, the white matter of the corpus callosum provides the major pathway for communication between the two hemispheres of the cerebral cortex.įigure 14.3.1 – The Cerebrum: The cerebrum is a large component of the CNS in humans, and the most obvious aspect of it is the folded surface called the cerebral cortex. It separates the cerebrum into two distinct halves, a right and left cerebral hemisphere. There is a large separation between the two sides of the cerebrum called the longitudinal fissure. The wrinkled portion is the cerebral cortex, and the rest of the structure is beneath that outer covering. The iconic gray mantle of the human brain, which appears to make up most of the mass of the brain, is the cerebrum ( Figure 14.3.1). The coordination of reflexes depends on the integration of sensory and motor pathways in the spinal cord. The regulation of homeostasis is governed by a specialized region in the brain. A person’s conscious experiences are based on neural activity in the brain. The spinal cord is a single structure, whereas the adult brain is described in terms of four major regions: the cerebrum, the diencephalon, the brain stem, and the cerebellum. The brain and the spinal cord are the central nervous system, and they represent the main organs of the nervous system. Explain the arrangement of gray and white matter in the spinal cord.Recognize the complex connections within the subcortical structures of the basal nuclei.Describe the connections between the cerebrum and brain stem through the diencephalon, and from those regions into the spinal cord.Name the major regions of the adult brain.By the end of this section, you will be able to:

Parts of the brain stem