Central Nervous System PDF Lecture Slides

PowerPoint® Lecture Slides prepared by Vince Austin, University of Kentucky The Central Nervous System Part A...

PowerPoint® Lecture Slides prepared by Vince Austin, University of Kentucky The Central Nervous System Part A 12 Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Central Nervous System (CNS) ▪ CNS – composed of the brain and spinal cord ▪ Cephalization ▪ Elaboration of the anterior portion of the CNS ▪ Increase in number of neurons in the head ▪ Highest level is reached in the human brain ▪ Brian: ▪ Composed of wrinkled, pinkish gray tissue ▪ Surface anatomy includes cerebral hemispheres, cerebellum, and brain stem Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Embryonic Development ▪ During the first 26 days of development: ▪ Ectoderm thickens along dorsal midline to form the neural plate ▪ The neural plate invaginates, forming a groove flanked by neural folds ▪ The neural groove fuses dorsally and forms the neural tube Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Embryonic Development Anterior (rostral) end Level of section Surface ectoderm (a) 19 Neural plate days Neural folds Neural groove (b) 20 days Neural crest (c) 22 days Surface ectoderm Neural tube (d) 26 days Figure 12.1 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Basic Pattern of the Central Nervous System ▪ Spinal Cord ▪ Central cavity surrounded by a gray matter core ▪ External to which is white matter composed of myelinated fiber tracts ▪ Brain ▪ Similar to spinal cord but with additional areas of gray matter ▪ Cerebellum has gray matter in nuclei ▪ Cerebrum has nuclei and additional gray matter in the cortex Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Basic Pattern of the Central Nervous System Figure 12.4 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Ventricles of the Brain ▪ Arise from expansion of the lumen of the neural tube ▪ The ventricles are: ▪ The paired C-shaped lateral ventricles ▪ The third ventricle ▪ The fourth ventricle Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Ventricles of the Brain Figure 12.5 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Cerebral Hemispheres ▪ Form the superior part of the brain and make up 83% of its mass ▪ Contain ridges (gyri) and shallow grooves (sulci) ▪ Contain deep grooves called fissures Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Major Lobes, Gyri, and Sulci of the Cerebral Hemisphere ▪ Deep sulci divide the hemispheres into several lobes: ▪ Frontal, parietal, temporal, & occipital ▪ Central sulcus – separates the frontal and parietal lobes Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Major Lobes, Gyri, and Sulci of the Cerebral Hemisphere ▪ Parieto-occipital sulcus – separates the parietal and occipital lobes ▪ Lateral sulcus – separates the parietal and temporal lobes ▪ The precentral and postcentral gyri border the central sulcus Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Cerebral Cortex ▪ The cortex – superficial gray matter; accounts for 40% of the mass of the brain ▪ It enables sensation, communication, memory, understanding, and voluntary movements ▪ Each hemisphere acts contralaterally (controls the opposite side of the body) ▪ Hemispheres are not equal in function ▪ No functional area acts alone; conscious behavior involves the entire cortex Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Functional Areas of the Cerebral Cortex ▪ The three types of functional areas are: ▪ Motor areas – control voluntary movement ▪ Sensory areas – conscious awareness of sensation ▪ Association areas – integrate diverse information Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Functional Areas of the Cerebral Cortex Figure 12.8a Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Cerebral Cortex: Motor Areas ▪ Primary (somatic) motor cortex ▪ Premotor cortex ▪ Broca’s area ▪ Frontal eye field Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Primary Motor Cortex ▪ Located in the precentral gyrus ▪ Composed of pyramidal cells whose axons make up the corticospinal tracts ▪ Allows conscious control of precise, skilled, voluntary movements ▪ Motor function Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Primary Motor Cortex Figure 12.9.1 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Premotor Cortex ▪ Located anterior to the precentral gyrus ▪ Controls learned, repetitious, or patterned motor skills ▪ Coordinates simultaneous or sequential actions ▪ Involved in the planning of movements Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Broca’s Area ▪ Broca’s area ▪ Located anterior to the inferior region of the premotor area ▪ Present in one hemisphere (usually the left) ▪ A motor speech area that directs muscles of the tongue ▪ Is active as one prepares to speak Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Frontal Eye Field ▪ Frontal eye field ▪ Located anterior to the premotor cortex and superior to Broca’s area ▪ Controls voluntary eye movement Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Sensory Areas ▪ Primary somatosensory cortex ▪ Somatosensory association cortex ▪ Visual and auditory areas ▪ Olfactory, gustatory, and vestibular cortices Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Sensory Areas Figure 12.8a Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Primary Somatosensory Cortex ▪ Located in the postcentral gyrus, this area: ▪ Receives information from the skin and skeletal muscles ▪ Exhibits spatial discrimination ▪ Somatosensory sensory function Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Primary Somatosensory Cortex Figure 12.9.2 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Somatosensory Association Cortex ▪ Located posterior to the primary somatosensory cortex ▪ Integrates sensory information ▪ Forms comprehensive understanding of the stimulus ▪ Determines size, texture, and relationship of parts Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Visual Areas ▪ Primary visual cortex ▪ Seen on the extreme posterior tip of the occipital lobe ▪ Receives visual information from the retinas ▪ Visual association area ▪ Surrounds the primary visual cortex ▪ Interprets visual stimuli (e.g., color, form, and movement) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Auditory Areas ▪ Primary auditory cortex ▪ Located at the superior margin of the temporal lobe ▪ Receives information related to pitch, rhythm, and loudness ▪ Auditory association area ▪ Located posterior to the primary auditory cortex ▪ Stores memories of sounds and permits perception of sounds ▪ Wernicke’s area Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Association Areas ▪ Prefrontal cortex ▪ Language areas ▪ General (common) interpretation area ▪ Visceral association area Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Association Areas Figure 12.8a Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Prefrontal Cortex ▪ Located in the anterior portion of the frontal lobe ▪ Involved with intellect, cognition, recall, and personality ▪ Necessary for judgment, reasoning, persistence, and conscience ▪ Closely linked to the limbic system (emotional part of the brain) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings