Nursing Entrance Exam

cerebral surface area. Depressions, or grooves, separate the gyri. The shallow depressions are called sulci, and deeper ones are fissures. The cerebrum is where the higher mental functions occur. These functions include conscious thoughts, sensations, intellect, memory, and complex movements. The second-largest part of the brain, the cerebellum, is partially hidden by the cerebral hemispheres. Like the cerebrum, the cerebellum contains hemispheres, which are covered by a layer of gray matter, referred to as the cerebellar cortex. The cerebellum adjusts continuous movements by comparing arriving sensations with previous sensory information to allow for the performance of the same movements. The diencephalon integrates incoming information. The left and right thalamus make up the walls of the diencephalon. Each thalamus holds relay and processing centers for sensory information. The hypothalamus is the floor of the diencephalon, and contains centers involved with emotions, autonomic function, and hormone production. A narrow stalk, the infundibulum, connects the hypothalamus to the pituitary gland, which is a component of the endocrine system. The nervous and endocrine systems work together to maintain homeostasis through integration by the hypothalamus and the pituitary gland. The processing centers and nuclei of the brainstem relay information headed to or from the cerebrum or cerebellum. The brainstem includes the mesencephalon, pons, and medulla oblongata. The mesencephalon, or midbrain, processes visual and auditory information, and control reflexes triggered by these stimuli. Some centers in this region help maintain consciousness. The pons connects the cerebellum to the brainstem; the pons also contains nuclei involved with somatic and visceral motor control. The brain and spinal cord connect at the medulla oblongata. Information is relayed to the thalamus and to other centers in the brainstem by the medulla oblongata. Key centers that regulate autonomic functions – such as heart rate, blood pressure, and digestion – send instructions from this region of the brain. 7.1.2 Embryology of the Brain The central nervous system (CNS) is derived from the embryological layer called the ectoderm. During initial development, this layer curves into a hollow cylinder known as the neural tube. Three prominent enlargements develop in the cephalic portion of the neural tube to become the primary brain vesicles. The three primary brain vesicles are named for their relative regions: the prosencephalon, (forebrain), the mesencephalon (midbrain), and the rhombencephalon (hindbrain). The prosencephalon and rhombencephalon further divide into secondary brain vesicles. The prosencephalon is comprised of the telencephalon and the diencephalon. The telencephalon forms the cerebrum of the adult brain. The portion of the rhombencephalon adjacent to the mesencephalon forms the metencephalon. The dorsal portion of the metencephalon will become the cerebellum, and the ventral portion develops into the pons. The portion of the rhombencephalon closer to the spinal cord forms the myelencephalon, which will become the medulla oblongata.

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