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Human Anatomy and Physiology Test #5 review presentation


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Chapters 11 and 12 from Marieb 10e
Personal review for an exam

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Human Anatomy and Physiology Test #5 review presentation

  1. 1. Test Five Review
  2. 2. 1. List and describe the characteristics of the major subdivisions of the nervous system
  3. 3. 2. List, describe and give the functions of the neuroglia found in the CNS and the PNS.
  4. 4. Neuroglia • Provide the support for neurons via glia cells • Six types – In the CNS • • • • Astrocytes Microglia Ependymal cells Oligodendrocytes – In the PNS • Satellite cells • Schwann cells
  5. 5. Astrocytes (CNS) • Most abundant, versatile & highly branched glia cells • They cling to neurons w/ their synaptic endings & cover capillaries • Function: – Support and brace neurons – Anchor neurons to their nutrient supplies – Guide migration of young neurons – Control the chemical environment
  6. 6. Microglia (CNS) 1. Small ovoid cell w/ “thorny” processes that touch nearby neurons 2. Function: • Monitor health (migrate to injured) • Transform into phagocytes when invading organisms or dead neurons are present • IMP b/c immune system cannot reach CNS
  7. 7. Ependymal Cells (CNS) 1. Range in shape from squamous to columnar 2. Line central cavities of the brain & spinal column forming a permeable barrier between cerebrospinal fluid (CSF) & tissue fluid • Help circulate CSF
  8. 8. Oligodendrocytes (CNS) 1. Produce myelin sheaths • Insulating coverings
  9. 9. Peripheral Nervous System (PNS) 1. Satellite Cells: function still unknown 2. Schwann Cells • Form myelin sheaths around nerve fibers • Vital to damage of PNS
  10. 10. 3. Diagram, label and give the functions for the parts of a typical neuron.
  11. 11. Processes of Neurons • Arm like processes extend from the cell body of all neurons – Bundles in the CNS= tracts – Bundles in the PNS= Nerves • Two types of processes: – Dendrites – Axons
  12. 12. Dendrites 1. Main receptive regions that convey incoming information towards the cell body • Information moves as graded potentials; not action potentials 2. Short, tapering, diffusely branching 3. Contain same organelles as cell body (ex. No golgi)
  13. 13. The Axon 1. Each neuron has a single axon • Can be short or long 1. Long = nerve fiber 2. Arises from the axon hillock • Extension off the cell body 3. Axon collaterals • Branching, especially at end (terminal branches) 4. Axon Terminal • Endings of terminal branches • Also called synaptic knobs
  14. 14. The Axon, continued • Two regions – Conducting region • Generates and transmits nerve impulses – Secretory region • At the axon terminals • When stimulated by the preceding nerve impulses releases neurotransmitters (can be + or -)
  15. 15. The Axon, continued • Organelles – Contains same organelles as cell body and dendrites – Except NO nissil bodies and golgi apparatus • Depends on cell body for these functions • Axolemma – Axon plasma membrane
  16. 16. The Axon, continued • Movement of substances – Anterograde-toward axon terminal • Mitochondria, cytoskeletal elements, membrane components, enzymes – Retrograde-toward cell body • Organelles being returned for destruction • Intracellular communication • Certain viruses or bacteria
  17. 17. 4. Classify neurons based on their structure and function.
  18. 18. *Classification of Neurons • Structurally – Multipolar – Bipolar – unipolar • Functionally – Sensory (afferent) – Motor (efferent) – Interneurons or association
  19. 19. Classification of Neurons (structurally) 1. Multipolar • 3 + processes • m/c; esp. in the CNS
  20. 20. Classification of Neurons (structurally) 1. Bipolar • 2 processes 1. Axon + dendrite • Extend from opposites sides of the cell body • Rare 1. Found in special senses (retina of eye/nose)
  21. 21. Classification of Neurons (structurally) 1. Unipolar • Single process that divides • Peripheral process 1. More distal a)Sensory receptors • Central process 2. Enters CNS • Called psuedounipolar b/c originally was a bipolar neuron
  22. 22. Functional Classification • Sensory (afferent) neurons – Transmit impulses from sensory receptors in the skin or internal organs toward the CNS – Most are unipolar – Cell bodies located in sensory ganglia outside the CNS – Peripheral processes can be very long
  23. 23. Functional Classification • Motor (efferent) neurons – Carry impulses away from the CNS to the effector organs (muscles and glands) – Multipolar – Cell bodies located in the CNS
  24. 24. Functional Classification • Interneurons or Association neurons – Lie b/w motor and sensory neurons in neural pathways – Multipolar – 99% of neurons in the body
  25. 25. 5. Describe resting membrane potential and describe how it is created and maintained.
  26. 26. Resting Membrane Potential 1. Potential difference in a resting neuron (Vr) • (-70mV) – minus sign indicates the cytoplasmic side (inside) is negatively charged relative to the outside • The membrane is said to be polarized • Can vary from -40 to -90 mV
  27. 27. Resting Membrane Potential 1. Due to differences in the ionic makeup of the intracellular & extracellular fluids • K+ most important role 2. Also, due to the differential permeability of the plasma membrane to those ions 3. Inside the cell • Lower conc. Na+, higher conc. K+ 4. Outside the cell • It is balanced by Cl-
  28. 28. Resting Membrane Potential 1. At rest • The membrane is impermeable to large proteins • Slightly permeable to Na+ • Very permeable to K+ & Cl• Always leaking occurring
  29. 29. 6. Define action potential and be able to draw and label a typical neuronal action potential.
  30. 30. Action Potentials (nerve impulse) 1. The way neurons send signals over long distances 2. Brief reversal of the membrane potential • -70 mV → +30 mV 3. Depolarization phase → repolarization phase → hyperpolarization phase 4. Must be stimulated to open voltage-gated channels • Graded potential → action potential 1. Location: axon hillock
  31. 31. Phases of the Action Potential 1. 1 – resting state 2. 2 – depolarization phase 3. 3 – repolarization phase 4. 4 – hyperpolarization Figure 11.12
  32. 32. Resting State 1. Voltage-gated channels are closed • Only leakage channels are open • Na+ channels have 2 gates 1. Activation gate: closed at rest 2. Inactivation gate: blocks channel when open
  33. 33. Depolarizing Phase 1. Increase in Na+ permeability & reversal of membrane potential 2. Na+ channels open letting Na+ into the cell 3. If -55 mV reached = threshold • AP starts & is cont. • Positive feedback 4. Membrane potential reaches +30 mV
  34. 34. Repolarizing Phase 1.Decrease in Na+ permeability • Inactivation gates start to close 2.Increase in K+ permeability • K+ leaves the cell
  35. 35. Hyperpolarization 1. K+ permeability continues • Making the cell very negative • Undershooting the resting potential (-70) • Sodium potassium pumps restore normal ion distribution
  36. 36. 7. List the events involved in the initiation and propagation of an action potential.
  37. 37. Propagation of an Action Potential (Time = 0ms) 1. Na+ influx causes a patch of the axonal membrane to depolarize 2. Positive ions in the axoplasm move toward the polarized (negative) portion of the membrane 3. Sodium gates are shown as closing, open, or closed
  38. 38. Propagation of an Action Potential (Time = 0ms) Figure 11.13a
  39. 39. Propagation of an Action Potential (Time = 2ms) Figure 11.13b
  40. 40. Propagation of an Action Potential (Time = 4ms) 1. The action potential moves away from the stimulus 2. Where sodium gates are closing, potassium gates are open and create a current flow Figure 11.13c
  41. 41. 8. Define all or none response in neurons.
  42. 42. Threshold 1. Not all local depolarization events produce APs 2. Must reach threshold (-55 mV) • Outward current of K+ = inward current of Na+ 3. Weak (subthreshold) stimuli potentials • are not relayed into action potentials 4. Strong (threshold) stimuli • are relayed into action potentials 5. All-or-none phenomenon – action potentials either happen completely, or not at all
  43. 43. 9. Compare absolute and relative refractory periods.
  44. 44. Absolute Refractory Period 1. Time from the opening of the Na+ activation gates until the closing of inactivation gates 2. The absolute refractory period: • Prevents the neuron from generating an action potential • Ensures that each action potential is separate • Enforces one-way transmission of nerve impulses
  45. 45. Absolute and Relative Refractory Periods Figure 11.15
  46. 46. Relative Refractory Period 1. The interval following the absolute refractory period when: • • • • Sodium gates are closed Potassium gates are open Repolarization is occurring Need a very strong stimulus to initiate an action potential
  47. 47. 10. Compare rate of impulse conduction on myelinated and unmyelinated neurons.
  48. 48. Conduction Velocities of Axons 1. Conduction velocities vary widely among neurons 2. Rate of impulse propagation is determined by: • Axon diameter – the larger the diameter, the faster the impulse • Presence of a myelin sheath – myelination dramatically increases impulse speed, prevents leakage
  49. 49. Saltatory Conduction 1. Current passes through a myelinated axon only at the nodes of Ranvier 2. Voltage-gated Na+ channels are concentrated at these nodes 3. Action potentials are triggered only at the nodes and jump from one node to the next 4. Much faster than conduction along unmyelinated axons
  50. 50. Saltatory Conduction Figure 11.16
  51. 51. Multiple Sclerosis (MS) 1. An autoimmune disease that mainly affects young adults 2. Symptoms: visual disturbances, weakness, loss of muscular control, and urinary incontinence 3. Nerve fibers are severed and myelin sheaths in the CNS become nonfunctional scleroses 4. Shunting and short-circuiting of nerve impulses occurs of
  52. 52. 11. Define graded potential an give examples of types of graded potentials.
  53. 53. Graded Potentials 1. Short-lived, local changes in membrane potential 2. Decrease in intensity with distance 3. Magnitude varies directly with the strength of the stimulus 4. Sufficiently strong graded potentials can initiate action potentials • Can be depolarization or hyperpolarization
  54. 54. Graded Potentials • Receptor potential or generator potential– when the receptor of a sensory neuron is excited by some form of energy (heat, light or other • Postsynaptic potential—when the stimulus is a neurotransmitter released by another neuron.. The neurotransmitter is released into a fluid-filled gap called a synapse and influences the neuron beyond (post) the synapse
  55. 55. 12. Compare graded and action potentials.
  56. 56. 13. Describe the structure of electrical and chemical synapses.
  57. 57. The Synapse 1. Presynaptic Neuron • Neuron conducting the impulses • Info sender 2. Postsynaptic Neuron • Neuron transmitting the electrical signal away from the synapse • Info receiver • May be another neuron or effector cell (muscle or gland)
  58. 58. Electrical Synapses • Are less common than chemical synapses • Correspond to gap junctions found in other cell types • Are important in the CNS in: – Arousal from sleep – Mental attention – Emotions and memory – Ion and water homeostasis
  59. 59. Chemical Synapses • Specialized for the release and reception of neurotransmitters • Typically composed of two parts: – Axonal terminal of the presynaptic neuron, which contains synaptic vesicles • Contain neurotransmitters – Receptor region on the dendrite(s) or soma of the postsynaptic neuron
  60. 60. 14. List the events in nerve-nerve chemical synaptic transmission.
  61. 61. 15. Distinguish between temporal summation and spatial summation.
  62. 62. Summation • A single EPSP cannot induce an AP – But multiple hits can increase the probability – Adding together = summate – Two types • Temporal summation • Spatial summation
  63. 63. Summation • Temporal summation – When one or more presynaptic neurons transmits impulses in rapid bursts • Releases NTs quickly • Spatial Summation – When the postsynaptic neurons is stimulated by a large # of terminals from the same or multiple neurons
  64. 64. Summation • IPSPs can also summate with EPSPs, canceling each other out • Neurons can also be facilitated – More easily excited by successive depolarization events b/c they are already near threshold
  65. 65. Summation Figure 11.20
  66. 66. 16. Describe the structure and function of the spinal cord.
  67. 67. Spinal cord • CNS tissue is enclosed within the vertebral column from the foramen magnum to the first Lumbar vertebrae • Provides two-way communication to and from the brain • Protected by bone, meninges, and CSF • Epidural space- space between the vertebrae and the dural sheath (dura mater) filled with fat and a network of veins
  68. 68. Spinal Cord • Spinal nerves – 31 pairs attach to the cord by paired roots • Cervical and lumbar enlargements – sites where nerves serving the upper and lower limbs emerge
  69. 69. Spinal Cord • Conus medullaris – Termination of spinal cord • Filum terminale – fibrous extension of the pia mater; anchors the spinal cord to the coccyx • Cauda equina – collection of nerve roots at the inferior end of the vertebral canal
  70. 70. 17. List the three meninges that surround the brain and spinal cord and their functions.
  71. 71. Meninges • Three connective tissue membranes lie external to the CNS—dura mater, arachnoid mater, and pia mater • Functions of the meninges – Cover and protect the CNS – Protect blood vessels and enclose venous sinuses – Contain cerebrospinal fluid (CSF) – Form partitions within the skull
  72. 72. Meninges Figure 12.24a
  73. 73. Dura Mater • Leathery, strong meninx composed of two fibrous connective tissue layers • The two layers separate in certain areas and form dural sinuses • Three dural speta extend inward and limit excessive movement of the brain – Falx cerebri—fold that dips into the longitudinal fissure – Falx cerebelli—runs along the vermis of the cerebellum – Tentorium cerebelli—horizontal dural fold extends into the transverse fissure
  74. 74. Dura Mater Figure 12.25
  75. 75. Arachnoid Mater • The middle meninx, which forms a loose brain covering • It is separated from the dura mater by the subdural space • Beneath the arachnoid is a wide subarachnoid space filled with CSF and large blood vessels • Arachnoid villi protrude superiorly and permit CSF to be absorbed into venous blood
  76. 76. Arachnoid Mater Figure 12.24a
  77. 77. Pia Mater • Deep meninx composed of delicate connective tissue that clings tightly to the brain
  78. 78. 18. Know the three dural septa (in the powerpoint) and where they are located.
  79. 79. Dura Mater • Leathery, strong meninx composed of two fibrous connective tissue layers • The two layers separate in certain areas and form dural sinuses • Three dural speta extend inward and limit excessive movement of the brain – Falx cerebri—fold that dips into the longitudinal fissure – Falx cerebelli—runs along the vermis of the cerebellum – Tentorium cerebelli—horizontal dural fold extends into the transverse fissure
  80. 80. Dura Mater Figure 12.25
  81. 81. 19. Know the features of CSF and its functions.
  82. 82. Cerebrospinal Fluid (CSF) • Watery solution similar in composition to blood plasma • Forms a liquid cushion that gives buoyancy to the CNS organs • Prevents the brain from crushing under its own weight • Protects the CNS from blows and other trauma • Nourishes the brain and carries chemical signals throughout it • Runs in subarachnoid space
  83. 83. Circulation of CSF Figure 12.26b
  84. 84. 20. List the major regions of the brain (functional areas i.e. cortices, association areas, language areas) and their functions.
  85. 85. Functional areas of the Cerebral Cortex • The three types of functional areas are: – Motor areas—control voluntary movement • Mostly anterior to central sulcus – Sensory areas—conscious awareness of sensation • Most posterior to central sulcus – Association areas—integrate diverse information
  86. 86. Cerebral Cortex: Motor Areas • • • • Primary (somatic) motor cortex Premotor cortex Broca’s area Frontal eye field
  87. 87. Primary Motor Cortex • Located in the precentral gyrus • Pyramidal cells whose axons make up the corticospinal tracts • Allows conscious control of precise, skilled, voluntary movements of skeletal muscles
  88. 88. Primary Motor Cortex Homunculus Figure 12.9.1
  89. 89. 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 movement
  90. 90. • Broca’s area Broca’s Area – Located 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
  91. 91. Frontal Eye Field • Frontal eye field – Located anterior to the premotor cortex and superior to Broca’s area – Controls voluntary eye movement
  92. 92. Sensory Areas • • • • Primary somatosensory cortex Somatosensory association cortex Visual and auditory areas Olfactory, gustatory, and vestibular cortices
  93. 93. Sensory Areas Figure 12.8a
  94. 94. Primary Somatosensory Cortex • Located in the postcentral gyrus, this area: – Receives information from the sensory receptors in skin and proprioceptors in skeletal muscles, joints, tendons – Exhibits spatial discrimination
  95. 95. Primary Somatosensory Cortex Homunculus Figure 12.9.2
  96. 96. Somatosensory association cortex • Located posterior to the primary somatosensory cortex • Integrates sensory information • Forms comprehensive understanding of the stimulus (memory of objects) • Determines size, texture, and relationship of parts • Temperature, pressure, etc.
  97. 97. Visual Areas • Primary visual (striate) cortex – Seen on the 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 – Interprets visual stimuli (e.g., color, form, and movement)
  98. 98. 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 sound and permits perception of sounds – Wernicke’s area
  99. 99. Others • Olfactory Cortex (Smell) – Medial aspect of temporal lobe • Piriform lobe – specifically the uncus • Gustatory cortex (taste) – Insular lobe • Visceral Sensory area – Back part of insular lobe • Vestibular cortex – Insular and parietal cortex
  100. 100. Association Areas • Prefrontal cortex • Language areas • Visceral association area
  101. 101. Prefrontal Cortex • Located in the anterior portion of the frontal lobe • Involved with intellect, cognition, recall, and personality • Necessary for judgment, reasoning, persistence, and consciences • Closely linked to the limbic system (emotional part of the brain)
  102. 102. Association Areas Figure 12.8a
  103. 103. Language Areas • Located in a large area surronding the left (or language-dominant) lateral sulcus • Major parts and functions: – Wernicke’s area—sounding out unfamiliar words – Broca’s area—speech preparation and production – Lateral prefrontal cortex—language comprehension and word anaylysis – Lateral and ventral temporal lobe—coordinate auditory and visual aspects of language
  104. 104. Visceral Association Area • Located in the cortex of the insula • Involved in conscious perception of visceral sensations
  105. 105. Functional areas of cerebral cortex • Motor areas: – Primary motor and premotor cortices of the frontal lobe – The frontal eye field, and Broca’s area in the frontal lobe of one hemisphere (usually left) • Sensory areas – Primary somatosensory cortex and somatosensory association cortex in the parietal lobe – Visual areas in the occipital lobe – Olfactory and auditory areas in the temporal lobe – Gustatory, visceral, and vestibular areas in the insula • Association areas – Anterior association areas in the frontal lobe – Posterior and limbic association areas spanning several lobes
  106. 106. 21. List the different lobes, gyri, and sulci discussed in class and what each separate or are associated with.
  107. 107. Major Lobes, Gyri, and Sulci of the Cerebral Hemisphere • Deep sulci divide the hemispheres into five lobes: – Frontal, parietal, temporal, occipital, and insular • Central sulcus—separates the frontal and parietal lobes – The precentral and postcentral gyri border the central sulcus • Parieto-occipital sulcus—separates the parietal and occipital lobes • Lateral sulcus—separates the parietal and temporal lobes
  108. 108. 22. Know the features of the cerebral cortex.
  109. 109. 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 oppisite side of the body) • Hemispheres are not equal in function • No functional area acts alone; conscious behavior involves the entire coretex
  110. 110. 23. List the parts to the diencephalon and their functions.
  111. 111. Diencephalon • Central core of the forebrain • Consists of three paired structures – Thalamus – Hypothalamus – Epithalamiums • Encloses the third ventricle
  112. 112. Diencephalon Figure 12.12
  113. 113. Thalamus • Paired, egg-shaped masses that form the superolateral walls of the third ventricle • Connected at the midline by the intermediate mass • Contains 4 groups of nuclei—anterior, ventral, dorsal, and posterior • Nuclei project and receive fibers from the cerebral cortex • *afferent impulses from all senses and all parts of the body converge on the thalamus and synapse
  114. 114. Hypothalamus • Located below the thalamus, it caps the brainstem and forms the inferolateral walls of the third ventricle • Mammillary bodies – Small, paired nuclei bulging anteriorly from the hypothalamus – Relay station for olfactory pathways • Infundibulum—stalk of the hypothalamus; connects to the pituitary gland – Main visceral control center of the body • homeostasis)
  115. 115. Hypothalamic Nuclei Hypothalamus Pituitary Gland Mammillary body Figure 12.13b
  116. 116. Hypothalamic Function • Regulates blood pressure, rate and force of heartbeat, digestive tract motility, rate and depth of breathing, and many other viceral activities • Perception of pleasure, fear, and rage – Close connection w/ limbic system • Maintains normal body temperature • Regulates feelings of hunger and satiety (satisfaction *fullness) • Regulates sleep and the sleep cycle
  117. 117. Endocrine functions of the hypothalamus • Releasing hormones control secretion of homones by the anterior pituitary gland – GH, TSH, LH, FSH, ACTH • The supraoptic and paraventricular nuclei produce ADH and oxytocin – Which is released form the posterior pituitary gland
  118. 118. Epithalamus • Most dorsal portion of the diencephalon; forms roof of the third ventricle • Pineal gland—extends from the posterior border and secretes melatonin – Melatonin—hormone involved with sleep regulation, sleep-wake cycles, and mood • Choroid plexus—a structure that helps form cerebral spinal fluid (CFS)
  119. 119. Choroid Plexus Pineal Gland
  120. 120. 24. List the ventricles, their locations, how they are connected, and the source of cerebrospinal fluid in them, its functions, how is it circulated and how frequently is it replaced.
  121. 121. Ventricles of the Brain • Lateral Ventricles (w/in hemishperes) – Anterior separated by a septum pellucidum • Interventricular foramen (lateral3rd) • Third Ventricle (w/in diencephalon) • Cerebral Aqueduct – runs through midbrain (3rd-4th) • Fourth Ventricle (w/in hindbrain dorsal to the pons)
  122. 122. Ventricles • Continuous with one another and with central canal of spinal chord • Hollow chambers filled with CSF and lined by ependymal cells
  123. 123. Ventricles of the Brain Figure 12.5
  124. 124. CSF and Choroid Plexes – Properties of CSF slide 92. • choroid Plexuses – clusters of capillaries that form tissue fluid filters, which hang from the roof of each ventricle – Have ion pumps that allow them to alter ion concentrations of the CSF – Help cleanse CSF by removing wastes
  125. 125. Circulation of CSF Figure 12.26b
  126. 126. 25. Know the parts that make up the brainstem and what cranial nerves (CN) are associated with each along with the functions of each area.
  127. 127. Brain Stem • Consists of three regions—midbrain, pons, and medulla oblongata • Similar to spinal cord but contains embedded nuclei • Controls automatic behaviors necessary for survival • Provides the pathway for tracts between higher and lower brain centers • Associated with 10 of the 12 pairs of cranial nerves
  128. 128. Brain Stem: Ventral View Figure 12.15a
  129. 129. Brain Stem: Left Lateral View Figure 12.15b
  130. 130. Brain Stem: Dorsal View Figure 12.15c
  131. 131. Midbrain • Located between the diencephalon & the pons • Midbrain structures include: • Cerebral peduncles – 2 structures that contain descending pyramidal motor tracts • Cerebral aqueduct – tube connects the 3rd & 4th ventricles • Various nuclei
  132. 132. Midbrain Nuclei • CN Nuclei III & IV • Corpora quadrigemina – 4 domelike protrusions of the dorsal midbrain – Superior colliculi • visual reflex centers – Inferior colliculi • Auditory relay • Superior cerebellar peduncles
  133. 133. Midbrain Nuclei • *substantia nigra – Functionally linked to basal nuclei – Contains melanin-precursor to dopamine – Related to Parkinson's • Red nucleus – Largest nucleus of the reticular formation; red nuclei are relay nuclei for some descending motor pathways
  134. 134. Midbrain Nuclei: Cross Section of Midbrain Figure 12.16a
  135. 135. Pons • Between midbrain and the medulla oblongata • Forms part of the anterior wall of the 4th ventricle • Fibers of the pons: – Connect higher brain centers and the spinal chord – Pontine nuclei fibers • Relay impulses between the motor cortex and the cerebellum • Middle cerebellar peduncles • Origin of cranial nerves V (trigeminal), VI (abducens), and VII (facial) • Contains nuclei of the reticular formation
  136. 136. Pons Figure 12.16b
  137. 137. Medulla Oblongata • Most inferior part of the brain stem • Along with the pons, forms the ventral wall of the fourth ventricle • Contains a choroid plexus of he fourth ventricle • Pyramids-two longitudinal ridges formed by cortiocospinal tracts • Decussation of the pyramids—crossover points of the corticospinal tracts • Cranial nerves VII, IX, X, XI, AND XII are associated with the medulla
  138. 138. Medulla Nuclei • Cardiovascular control center- adjusts force and rate of heart contraction • Respiratory centers- control rate and depth of breathing • Additional centers- regulate vomiting, hiccouping, swallowing, coughing, and sneezing
  139. 139. Brain Stem: ventral view Figure 12.15a
  140. 140. 26. Know the anatomy of the cerebellum and the functions of it.
  141. 141. The Cerebellum Figure 12.17b
  142. 142. Anatomy of the Cerebellum • Two bilaterally symmetrical hemispheres connected medially by the vermis • Folia- transversely oriented gyri • Each hemisphere has three lobes- anterior, posterior, and flocculondular • Neural arrangement- gray matter cortex, internal white matter, scattered nuclei • Arbor vitae—distinctive treelike pattern of the cerebellar white matter
  143. 143. Cerebellar Processing • Cerebellum recieves impulses of the intent to initiate voluntary muscle contraction – Proprioceptors and visual signals “inform” the cerebellum of the body’s position – Cerebellar cortex calculates the best way to perform a movement – A “blueprint” of coordinated movement is sent to the cerebral motor cortex and spinal cord neurons • Cognitive function – Recognizes and predicts sequences of events – Word association and puzzle solving