Anatomy & Physiology I and II

Anatomy & Physiology Study Guide

©2018 Achieve Test Prep Page 131 of 367 The medulla oblongata is the most inferior of the brain regions. This organ includes the attachment sites for 11 of the 12 pairs of cranial nerves. The medulla oblongata is a very busy place—all communication between the brain and spinal cord involves the medulla oblongata. In addition, the medulla oblongata is a center for the coordination of autonomic reflexes and visceral functions. The medulla oblongata includes three groups of nuclei. The autonomic nuclei that control visceral activities are located in the medulla oblongata. The reticular formation is a loosely organized mass of gray matter that contains embedded nuclei. The portion of the reticular formation in the medulla oblongata contains nuclei and centers responsible for the regulation of vital autonomic functions. These reflex centers receive inputs from cranial nerves, the cerebral cortex, and the brain stem. The cardiovascular centers adjust the heart rate, the strength of cardiac contractions, and the flow of blood through peripheral tissues. 12.10 Integrative Centers Integrative centers receive information from many association areas and direct extremely complex motor activities. These centers also perform complicated analytical functions. Integrative centers are found in the lobes and cortical areas of both cerebral hemispheres. Integrative centers concerned with the performance of complex processes, such as speech, writing, mathematical computation, and being aware that spatial relationships, are restricted to either the left or the right hemisphere. The general interpretive area, or the Wernicke area , also called the gnostic area, receives information fromall the sensory association areas. Destruction to the general interpretive area disturbs the ability to interpret what is visualized or heard, even when the words are understood as individual entities. Hemispheric Lateralization Each of the two cerebral hemispheres is responsible for specific functions that are not ordinarily performed by the opposite hemisphere. This regional specialization has been called hemispheric lateralization. In many people, the left hemisphere encompasses the general interpretive and speech centers and is accountable for language-based skills. For example, reading, writing, and speaking are dependent on processing in the left cerebral hemisphere. The left hemisphere plays a role in performing analytical tasks, such as mathematical calculations and logical decision making. The left cerebral hemisphere is called the dominant hemisphere or the categorical hemisphere. The right cerebral hemisphere analyzes sensory information and relates the body to the sensory environment. Interpretive centers in this hemisphere permit the identification of familiar objects by sight, taste, touch, smell, or feel. For example, the right hemisphere plays a dominant role in recognizing faces and in understanding three-dimensional relationships. Nine percent of the human population is left-handed people. In most cases, the primary motor cortex of the right hemisphere controls motor function for the dominant hand, and the centers involved with speech and analytical function are in the left hemisphere. 12.11 Brain Functions Medulla Oblongata