Human Anatomy 3B

March 8th, 2004

The cerebrum is the largest part of the brain. Also, it is the most visible part. It also dominates the adult brain. Most of it is in processing somatic sensory and motor information. Two types of matter are located in the cerebrum. Gray matter is a substance known as the cerebral cortex. It is located in the cerebral nuclei. White matter is deep in the neural cortex and by the cerebral nuclei. Gray matter is the part of the brain that is responsible for processing information. White matter is different. It is responsible for the transmission of information. Areas of gray matter are known as basal ganglia. They are dispersed throughout the white matter. The white matter contains association fibers, commissural fibers, and projection fibers. A coat of neural cortex covers the two hemispheres. Elevated forms of ridges of the brain are called gyri. They are separated by depressions called sulci or fissures. The surface area of the two hemispheres is about two and one half feet. Longitudinal fissures separate the hemispheres. Each hemisphere is divided into lobes. They are like fingerprints, they are all different. On each hemisphere, the central sulcus divides the frontal lobe from the temporal lobe. The primary motor cortex of the gyrus directs voluntary movements. The primary sensory cortex receives somatic sensory information. The general interpretive area receives information from all the sensory association areas. The parieto-occipital sulcus divides the parital lobe from the occipital lobe. Each hemisphere receives sensory information, and sends motor command to the opposite side of the body. They also look the same, but have many different functions. The frontal lobe is a voluntary control of skeletal muscles. The parietal lobe is the perception of touch, pressure, vibration, pain, temperature, and taste. It also controls conscious thoughts and memory. The occipital lobe is the perception of visual stimuli. The temporal lobe is the perception of auditory and olfactory stimuli. All of the lobes function in the processing of sensory data, and initiation of motor activities. The somatic motor association area coordinates learned movements. The general interpretive area receives information from all of the sensory association areas. It is only present in the left hemisphere of the brain. The speech center regulates the patterns of breathing and vocalization needed for normal speech. The prefrontal cortex coordinates information from the secondary and special association areas of the entire cortex and performs abstract functions. The cerebral nuclei in the white matter of the cerebrum are the caudate nucleus, amygdaloid body, globus pallidus, and putamen. They control muscle tone and coordinate learned movement patterns and other somatic motor activities. Some symptoms from it are aphasia, dyslexia, and disconnection syndrome. Aphasia is a disorder that affects the ability to speak and read. Dyslexia is a disorder that affects the use of words. Disconnection syndrome is when the corpus callosum is cut. If this happens, the two hemispheres work on their own and are unaware of motor commands. Someone could touch something, but not say what it is while knowing the object.