a & p exam 3

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a & p exam 3
2010-11-07 22:22:25
Central Nervous System TRACS handout

a&p exam 3 CNS
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  1. The three types of functional areas of the Cerebral Cortex are
    Motor, Sensory, and Association Areas
  2. Motor Areas
    control voluntary movement
  3. Sensory areas
    conscious awareness of sensation
  4. association areas
    integrate diverse information
  5. entire cerebtal cortex
    conscious behavior
  6. Motor Areas
  7. • Primary (somatic) motor cortex
    • • Premotor cortex
    • • Broca’s area
    • • Frontal eye field
  8. Primary Motor Cortex
    • • Large pyramidal cells of the precentral gyri
    • • Long axons → pyramidal (corticospinal) tracts
    • • Allows conscious control of precise, skilled, voluntary movements
  9. Premotor Cortex
    • • Anterior to the precentral gyrus
    • • Controls learned, repetitious, or patterned motor skills
    • • Coordinates simultaneous or sequential actions
    • • Involved in the planning of movements that depend on sensory feedback
  10. Broca’s Area
  11. * 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
  12. Frontal Eye Field
    • • Anterior to the premotor cortex and superior to Broca’s area
    • • Controls voluntary eye movements
  13. Sensory Areas
  14. • Primary somatosensory cortex
    • • Somatosensory association cortex
    • • Visual areas
    • • Auditory areas
    • • Olfactory cortex
    • • Gustatory cortex
    • • Visceral sensory area
    • • Vestibular cortex
  15. Primary Somatosensory Cortex
    • • In the postcentral gyri
    • • Receives sensory information from the skin, skeletal muscles, and joints
    • • Capable of spatial discrimination: identification of body region being stimulated
  16. Somatosensory Association Cortex
    • • Posterior to the primary somatosensory cortex
    • • Integrates sensory input from primary somatosensory cortex
    • • Determines size, texture, and relationship of parts of objects being felt
  17. Visual Areas
    • • Primary visual (striate) cortex
    • • Extreme posterior tip of the occipital lobe
    • • Most of it is buried in the calcarine sulcus
    • • Receives visual information from the retinas
    • • Visual association area
    • • Surrounds the primary visual cortex
    • • Uses past visual experiences to interpret visual stimuli (e.g., color, form, and movement)
    • • Complex processing involves entire posterior half of the hemispheres
  18. Auditory Areas
    • • Primary auditory cortex
    • • Superior margin of the temporal lobes
    • • Interprets information from inner ear as pitch, loudness, and location
    • • Auditory association area
    • • Located posterior to the primary auditory cortex
    • • Stores memories of sounds and permits perception of sounds
  19. OIfactory Cortex
    • • Medial aspect of temporal lobes (in piriform lobes)
    • • Part of the primitive rhinencephalon, along with the olfactory bulbs and tracts
    • • (Remainder of the rhinencephalon in humans is part of the limbic system)
    • • Region of conscious awareness of odors
  20. Gustatory Cortex
    • • In the insula
    • • Involved in the perception of taste
  21. Visceral Sensory Area
    • • Posterior to gustatory cortex
    • • Conscious perception of visceral sensations, e.g., upset stomach or full bladder
  22. Vestibular Cortex
    • • Posterior part of the insula and adjacent parietal cortex
    • • Responsible for conscious awareness of balance (position of the head in space)
  23. Multimodal Association Areas
  24. • Receive inputs from multiple sensory areas
    • • Send outputs to multiple areas, including the premotor cortex
    • • Allow us to give meaning to information received, store it as memory, compare it to previous
    • experience, and decide on action to take
  25. Multimodal Association Areas
    • * Three parts
    • • Anterior association area (prefrontal cortex)
    • • Posterior association area• Limbic association area
  26. Anterior Association Area (Prefrontal Cortex)
    • • Most complicated cortical region
    • • Involved with intellect, cognition, recall, and personality
    • • Contains working memory needed for judgment, reasoning, persistence, and conscience
    • • Development depends on feedback from social environment
  27. Posterior Association Area
    • • Large region in temporal, parietal, and occipital lobes
    • • Plays a role in recognizing patterns and faces and localizing us in space
    • • Involved in understanding written and spoken language (Wernicke’s area)
  28. Limbic Association Area
    • • Part of the limbic system
    • • Provides emotional impact that helps establish memories
  29. Cerebral White Matter
    • •Myelinated fibers and their tracts
    • •Responsible for communication
    • •Commissures (in corpus callosum)—connect gray matter of the two hemispheres
    • •Association fibers—connect different parts of the same hemisphere
    • •Projection fibers—(corona radiata) connect the hemispheres with lower brain or spinal cord
  30. Functions of Basal Nuclei
    • •Though somewhat elusive, the following are thought to be functions of basal nuclei
    • •Influence muscular control
    • •Help regulate attention and cognition
    • •Regulate intensity of slow or stereotyped movements
    • •Inhibit antagonistic and unnecessary movements
  31. Thalamic Function
    • •Gateway to the cerebral cortex
    • •Sorts, edits, and relays information
    • •Afferent impulses from all senses and all parts of the body
    • •Impulses from the hypothalamus for regulation of emotion and visceral function
    • •Impulses from the cerebellum and basal nuclei to help direct the motor cortices
    • •Mediates sensation, motor activities, cortical arousal, learning, and memory
  32. Hypothalamic Function
    • •Autonomic control center for many visceral functions (e.g., blood pressure, rate and force of
    • heartbeat, digestive tract motility)
    • •Center for emotional response: Involved in perception of pleasure, fear, and rage and in biological
    • rhythms and drives
    • •Regulates body temperature, food intake, water balance, and thirst
    • •Regulates sleep and the sleep cycle
    • •Controls release of hormones by the anterior pituitary
    • •Produces posterior pituitary hormones
  33. Epithalamus
    • •Most dorsal portion of the diencephalon; forms roof of the third ventricle
    • •Pineal gland—extends from the posterior border and secretes melatonin
    • •Melatonin—helps regulate sleep-wake cycles
  34. Brain Stem
    • •Three regions
    • •Midbrain
    • •Pons
    • •Medulla oblongata
  35. Midbrain
    • •Located between the diencephalon and the pons
    • •Cerebral peduncles
    • •Contain pyramidal motor tracts
    • •Cerebral aqueduct
    • •Channel between third and fourth ventricles
  36. Midbrain Nuclei
    • •Nuclei that control cranial nerves III (oculomotor) and IV (trochlear)
    • •Corpora quadrigemina—domelike dorsal protrusions
    • •Superior colliculi—visual reflex centers
    • •Inferior colliculi—auditory relay centers
    • •Substantia nigra—functionally linked to basal nuclei
    • •Red nucleus—relay nuclei for some descending motor pathways and part of reticular formation
  37. Pons
    • •Forms part of the anterior wall of the fourth ventricle
    • •Connect higher brain centers and the spinal cord
    • •Relay impulses between the motor cortex and the cerebellum
    • •Origin of cranial nerves V (trigeminal), VI (abducens), and VII (facial)
    • •Some nuclei of the reticular formation
    • •Nuclei that help maintain normal rhythm of breathing
  38. Medulla Oblongata
    • •Joins spinal cord at foramen magnum
    • •Forms part of the ventral wall of the fourth ventricle
    • •Contains a choroid plexus of the fourth ventricle
    • •Pyramids—two ventral longitudinal ridges formed by pyramidal tracts
    • •Decussation of the pyramids—crossover of the corticospinal tracts
    • •Inferior olivary nuclei—relay sensory information from muscles and joints to cerebellum
    • •Cranial nerves VIII, X, and XII are associated with the medulla
    • •Vestibular nuclear complex—mediates responses that maintain equilibrium
    • •Several nuclei (e.g., nucleus cuneatus and nucleus gracilis) relay sensory information
    • •Autonomic reflex centers
    • •Cardiovascular center
    • •Cardiac center adjusts force and rate of heart contraction
    • •Vasomotor center adjusts blood vessel diameter for blood pressure regulation
    • •Respiratory centers
    • •Generate respiratory rhythm
    • •Control rate and depth of breathing, with pontine centers
    • •Additional centers regulate
    • •Vomiting, Hiccuping, Swallowing, Coughing, Sneezing
  39. Cerebellar Processing for Motor Activity
    • •Cerebellum receives impulses from the cerebral cortex of the intent to initiate voluntary muscle
    • contraction
    • •Signals from proprioceptors and visual and equilibrium pathways continuously “inform” the
    • cerebellum of the body’s position and momentum
    • •Cerebellar cortex calculates the best way to smoothly coordinate a muscle contraction
    • •A “blueprint” of coordinated movement is sent to the cerebral motor cortex and to brain stem nuclei
  40. Cognitive Function of the Cerebellum
    • •Recognizes and predicts sequences of events during complex movements
    • •Plays a role in nonmotor functions such as word association and puzzle solving