Neuroanatomy: Central Nervous System Structure
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Questions and Answers

What is the primary function of the Thalamus?

  • To control respiratory and cardiovascular functions
  • To regulate muscle tone and equilibrium
  • To integrate and transmit sensory information to various cortical areas (correct)
  • To coordinate voluntary movement

    • What is the main function of the Archicerebellum?

  • To control autonomic functions
  • To maintain equilibrium (correct)
  • To regulate muscle tone
  • To coordinate voluntary movement

    • What is the function of the Reticular Activating System in the Brainstem?

  • To control respiratory functions
  • To maintain consciousness (correct)
  • To coordinate voluntary movement
  • To regulate cardiovascular functions

    • Which cranial nerve arises from the superior part of the spinal cord?

    <p>CN XI</p> Signup and view all the answers

    What is the role of voltage-gated Ca++ channels in neurotransmission?

    <p>To allow the vesicles to release the neurotransmitter into the synaptic cleft</p> Signup and view all the answers

    Which of the following cranial nerves is NOT responsible for parasympathetic output?

    <p>CN XI</p> Signup and view all the answers

    What is the primary function of Glutamate in the brain?

    <p>To act as an excitatory neurotransmitter</p> Signup and view all the answers

    What is the primary function of the Hippocampus in the cerebrum?

    <p>Memory and learning</p> Signup and view all the answers

    What is the major inhibitory neurotransmitter in the spinal cord?

    <p>Glycine</p> Signup and view all the answers

    What is the primary function of the Amygdala in the cerebrum?

    <p>Emotion, appetite, and response to pain/stressors</p> Signup and view all the answers

    What is the primary function of astrocytes in the CNS?

    <p>Supporting neuronal function</p> Signup and view all the answers

    Which of the following glial cells is responsible for reuptake of neurotransmitters?

    <p>Astrocytes</p> Signup and view all the answers

    What is the name of the fissure that divides the cerebral hemispheres?

    <p>Medial longitudinal fissure</p> Signup and view all the answers

    What is the function of the Neocerebellum?

    <p>To coordinate voluntary movement</p> Signup and view all the answers

    What is the composition of Gray matter in the CNS?

    <p>Cell bodies</p> Signup and view all the answers

    What percentage of parasympathetic activity is performed by the Vagus Nerve (X)?

    <p>75%</p> Signup and view all the answers

    What is the name of the structure that connects the two cerebral hemispheres?

    <p>Corpus Callosum</p> Signup and view all the answers

    What is the primary function of the Cerebellum?

    <p>Regulation of movement and coordination</p> Signup and view all the answers

    What is the primary function of the Blood-Brain Barrier?

    <p>Keeping the brain's environment in homeostasis</p> Signup and view all the answers

    What is the name of the layer of the cerebrum that is responsible for cognition, movement, and sensation?

    <p>Cerebral cortex</p> Signup and view all the answers

    What is the name of the fissure that divides the temporal lobe from the frontal and parietal lobes?

    <p>Lateral fissure of Sylvius</p> Signup and view all the answers

    What are the Structurally distinct areas of the cerebral cortex called?

    <p>Brodmann areas</p> Signup and view all the answers

    What is the effect of moderate hypothermia on electrophysical activity?

    <p>Reduces electrophysical activity</p> Signup and view all the answers

    What is the effect of 1°C change in temperature on CMR?

    <p>5% change in CMR</p> Signup and view all the answers

    What is the paradox of glucose during cerebral ischemia?

    <p>Glucose availability is detrimental to the ischemic brain</p> Signup and view all the answers

    What is the result of hyperglycemia during ischemia?

    <p>Worse neurologic outcomes</p> Signup and view all the answers

    What is the goal of induction in neuroanaesthesia?

    <p>To prevent increases in ICP and decreases in CPP</p> Signup and view all the answers

    What is the effect of moderate hypothermia on protein kinase?

    <p>Decreases protein kinase</p> Signup and view all the answers

    What is the goal of maintenance in neuroanaesthesia?

    <p>To provide adequate substrate delivery and control brain tension</p> Signup and view all the answers

    What is the significance of CBF in neuroanaesthesia?

    <p>It is used to manipulate CBV</p> Signup and view all the answers

    What is the effect of benzodiazepines on CBF and CMR?

    <p>Decrease CBF and CMR</p> Signup and view all the answers

    Which opioid is an exception in maintaining autoregulation and cerebral CO2 responsiveness in neuroanesthesia?

    <p>Meperidine (Demerol)</p> Signup and view all the answers

    What is the effect of ketamine on CBF?

    <p>Increase CBF by up to 60%</p> Signup and view all the answers

    What is the primary concern with using ketamine in neuroanesthesia?

    <p>All of the above</p> Signup and view all the answers

    Which nondepolarizing muscle relaxant has significant histamine release?

    <p>Atracurium</p> Signup and view all the answers

    What is the effect of succinylcholine on ICP?

    <p>Increase ICP</p> Signup and view all the answers

    Why is ketamine historically not used in neuroanesthesia?

    <p>All of the above, except it provides protection against neuronal cell death</p> Signup and view all the answers

    What is the primary advantage of opioid-based anesthetic techniques in neuroanesthesia?

    <p>Hemodynamic stability and predictable emergence</p> Signup and view all the answers

    Which part of the brain is responsible for fine movement?

    <p>Basal Ganglia</p> Signup and view all the answers

    What is the function of the Corpus Callosum in the brain?

    <p>Connects the cerebral hemispheres</p> Signup and view all the answers

    Which structure is responsible for dividing the temporal lobe from the frontal and parietal lobes?

    <p>Lateral fissure of Sylvius</p> Signup and view all the answers

    What is the primary function of the Diencephalon?

    <p>Midline structure between the hemispheres</p> Signup and view all the answers

    Which part of the brain is responsible for emotion, appetite, and response to pain/stressors?

    <p>Amygdala</p> Signup and view all the answers

    What is the primary function of the Cerebral cortex?

    <p>Cognition, movement, and sensation</p> Signup and view all the answers

    What is the function of the Central sulcus of Rolando?

    <p>Divides the frontal and parietal lobes</p> Signup and view all the answers

    What is the name of the structurally distinct areas of the cerebral cortex?

    <p>Brodmann areas</p> Signup and view all the answers

    What is the primary mechanism by which CSF helps to maintain normal ICP?

    <p>Translocating to the more distensible spinal subarachnoid space</p> Signup and view all the answers

    Which of the following is a common symptom of intracranial hypertension?

    <p>Mydriasis</p> Signup and view all the answers

    What is the primary cause of ischemic damage in the brain?

    <p>Reduced energy availability</p> Signup and view all the answers

    What is the result of cerebral ischemia on ATPase ion pumps?

    <p>They begin to fail</p> Signup and view all the answers

    What is the primary function of calcium in cellular metabolism?

    <p>Activating enzymes</p> Signup and view all the answers

    What is the result of increased intracellular calcium levels in neurons?

    <p>Depolarization and release of excitatory neurotransmitters</p> Signup and view all the answers

    What is the result of Cushing's triad?

    <p>Hypertension, bradycardia, and irregular respirations</p> Signup and view all the answers

    What is the result of intracranial hypertension on oxygen delivery?

    <p>Decreased oxygen delivery</p> Signup and view all the answers

    Which part of the brain integrates afferent information from other areas of the CNS and PNS to transmit to the cerebral cortex and lower motor neurons for muscle tone, equilibrium, and voluntary movement coordination?

    <p>Cerebellum</p> Signup and view all the answers

    What is the primary function of the neurons that innervate muscles and glands?

    <p>To innervate muscles and glands</p> Signup and view all the answers

    Which part of the brain contains the Reticular Activating System, which is responsible for consciousness?

    <p>Brainstem</p> Signup and view all the answers

    Which neurotransmitter is released into the synaptic cleft upon depolarization of the nerve terminal?

    <p>All of the above</p> Signup and view all the answers

    Which type of neuron is responsible for transmitting sensory information?

    <p>Pseudounipolar sensory neurons</p> Signup and view all the answers

    Which part of the brain is responsible for autonomic functions, including respiratory and cardiovascular control?

    <p>Brainstem</p> Signup and view all the answers

    What is the function of the cerebellar peduncles?

    <p>To contain both efferent and afferent pathways</p> Signup and view all the answers

    Which type of glial cell is responsible for the majority of CNS functions?

    <p>Astrocytes</p> Signup and view all the answers

    What is the effect of volatile anesthetics on CBF in a dose-related manner?

    <p>Increase in a concentration-dependent manner</p> Signup and view all the answers

    What is the effect of halothane on CBF compared to isoflurane and sevoflurane?

    <p>Greatest increase in CBF</p> Signup and view all the answers

    What is the effect of isoflurane on CMR?

    <p>40% decrease in CMR</p> Signup and view all the answers

    What is the effect of volatile anesthetics on autoregulation?

    <p>Attenuation of autoregulation</p> Signup and view all the answers

    What is the effect of nitrous oxide on CBF and CMR?

    <p>Increase in CBF and CMR</p> Signup and view all the answers

    What is the effect of volatile anesthetics on CSF formation and absorption?

    <p>Decrease in CSF formation and absorption</p> Signup and view all the answers

    What is the 'luxury perfusion' phenomenon?

    <p>Redistribution of blood away from ischemic areas</p> Signup and view all the answers

    What is the effect of high concentrations of volatile anesthetics on autoregulation?

    <p>Abolition of autoregulation</p> Signup and view all the answers

    What is the primary advantage of using benzodiazepines in neuroanesthesia?

    <p>Anxiolytic, anticonvulsant, and amnestic effects</p> Signup and view all the answers

    Which of the following opioids is an exception in maintaining autoregulation and cerebral CO2 responsiveness in neuroanesthesia?

    <p>Meperidine</p> Signup and view all the answers

    What is the effect of ketamine on cerebral physiology?

    <p>Increase in CBF and CMR</p> Signup and view all the answers

    What is the primary concern with using ketamine in neuroanesthesia?

    <p>Increase in ICP</p> Signup and view all the answers

    Which nondepolarizing muscle relaxant has significant histamine release?

    <p>Atracurium</p> Signup and view all the answers

    What is the effect of succinylcholine on ICP?

    <p>Increase in ICP</p> Signup and view all the answers

    Why is ketamine historically not used in neuroanesthesia?

    <p>It increases ICP</p> Signup and view all the answers

    What is the primary advantage of opioid-based anesthetic techniques in neuroanesthesia?

    <p>Hemodynamic stability and predictable emergence</p> Signup and view all the answers

    Study Notes

    Neuroanatomy

    • The Central Nervous System (CNS) structurally consists of the brain and spinal cord.
    • The brain is divided into four structural components: Cerebrum, Diencephalon, Brainstem, and Cerebellum.
    • Cerebrum is divided into four lobes: Frontal (Primary Motor cortex), Parietal (Pain & touch sensory), Occipital (Vision cortex), and Temporal (Auditory and speech centers).
    • The Cerebral Cortex is the outer 3mm layer of cerebral hemispheres, divided into structurally distinct areas called Brodmann areas.
    • The Diencephalon consists of the Thalamus, Hypothalamus, Epithalamus, and Subthalamus.
    • Thalamus is the "Relay Station" that integrates and transmits sensory information to various cortical areas via separate pathways.
    • Hypothalamus is the primary neurohumoral organ.

    Cerebellum

    • Cerebellum integrates afferent information received from other areas of CNS & PNS to be transmitted to the cerebral cortex and to lower motor neurons for muscle tone, equilibrium, and voluntary movement coordination.
    • Cerebellum is connected via cerebellar peduncles which have both efferent and afferent pathways.
    • Archicerebellum maintains equilibrium, Paleocerebellum regulates muscle tone, and Neocerebellum coordinates voluntary movement.

    Brainstem

    • Brainstem consists of midbrain, pons, and medulla.
    • Brainstem is responsible for consciousness, autonomic functions, and many reflexes.
    • Contains ascending and descending fiber tracts and extends to Foramen Magnum.

    Electrophysiology

    • There are two primary CNS cell types: Neurons and Glial Cells.
    • Neurons conduct antegrade impulses from dendrites to soma to axon to synaptic terminals.
    • Gray matter is composed of cell bodies, and White matter is composed of axons.
    • The majority of CNS neurons are either Multipolar motor neurons or Pseudounipolar sensory neurons.

    Neurons

    • Nerve terminals contain neurotransmitters within vesicles.
    • Upon depolarization, voltage-gated Ca++ channels open, allowing vesicles to release neurotransmitters into the synaptic cleft.
    • Excitatory neurotransmitters (e.g., Glutamate) hypopolarize the postsynaptic neuron, while Inhibitory neurotransmitters (e.g., GABA, Glycine) hyperpolarize the postsynaptic neuron.

    Cranial Nerves

    • Cranial nerves are made up of sensory and/or motor neurons.
    • Cranial nerves exit the cranial cavity through foramina in the cranium, except for CN XI which arises from the superior part of the spinal cord.

    Glial Cells

    • Glial cells are more abundant (5x) and supportive in nature, maintaining ionic environment, modulating action potential conduction, controlling reuptake of neurotransmitters, and repairing neurons.
    • Glial cell subtypes include Astrocytes, Ependymal cells, Oligodendrocytes, and Microglia.

    Blood-Brain Barrier

    • The Blood-Brain Barrier maintains homeostasis, reducing electrophysical activity, decreasing Ca++ entry, glutamate release, and protein kinase activity, while stabilizing proteins and slowing enzymatic activity.

    Neuroanesthesia

    • Neuroanesthesia is the practice of applied cerebrovascular physiology and pharmacology, using techniques and agents to control CMR & CBF, which subsequently manipulates CBV.
    • Induction goal is to prevent increases in ICP and decreases in CPP, while Maintenance goal is to provide adequate substrate delivery and control brain tension by controlling CBF/CBV.

    Goodies

    • Benzodiazepines are useful anesthetic adjuncts due to their anxiolytic, anticonvulsant, and amnestic effects, with reductions in CBF and CMR.
    • Opioid-based anesthetic techniques are popular in neuroanesthesia because they provide hemodynamic stability and a predictable emergence, with minimal effects on CBF and CMR.
    • Ketamine causes a dramatic increase in CBF (up to 60%) and a lesser increase in CMR, with impeded CSF absorption, leading to increased ICP.

    Neuromuscular Blocking Agents

    • Nondepolarizing muscle relaxants have a direct effect on cerebral physiology due to histamine release, which dilates the cerebral vasculature.
    • Succinylcholine can produce increases in ICP, attenuated with a defasciculating dose of nondepolarizers.

    Neuroanatomy

    • The Central Nervous System (CNS) consists of the brain and spinal cord.
    • The brain is divided into four structural components:
      • Cerebrum
      • Diencephalon
      • Brainstem
      • Cerebellum
    • Cerebrum:
      • Consists of the cerebral cortex, which is responsible for cognition, movement, and sensation.
      • Divided into four lobes: frontal, parietal, occipital, and temporal.
      • Can be further divided into structurally distinct areas called Brodmann areas.
    • Diencephalon:
      • Located midline between the two hemispheres.
      • Consists of the thalamus, hypothalamus, epithalamus, and subthalamus.
      • Thalamus acts as a "relay station" for integrating and transmitting sensory information to various cortical areas.
    • Cerebellum:
      • Integrates afferent information from other areas of the CNS and PNS.
      • Transmits information to the cerebral cortex and lower motor neurons for muscle tone, equilibrium, and voluntary movement coordination.
      • Connected to the brain via cerebellar peduncles.
      • Divided into three parts: archicerebellum, paleocerebellum, and neocerebellum.
    • Brainstem:
      • Consists of the midbrain, pons, and medulla.
      • Responsible for consciousness, autonomic functions, and many reflexes.
      • Contains ascending and descending fiber tracts.

    Electrophysiology

    • There are two primary CNS cell types: neurons and glial cells.
    • Neurons conduct antegrade impulses from the dendrites to the soma to the axon to the synaptic terminals.
    • Gray matter consists of cell bodies, while white matter consists of axons.
    • The majority of CNS neurons are either multipolar motor neurons or pseudounipolar sensory neurons.
    • Neurons release neurotransmitters into the synaptic cleft, which can be excitatory or inhibitory.

    Cranial Nerves

    • Cranial nerves are made up of sensory and/or motor neurons.
    • They exit the cranial cavity through foramina in the cranium.

    Intracranial Pressure

    • Intracranial hypertension results in reduced cerebral perfusion pressure (CPP) and oxygen delivery.
    • Cushing's triad: decreased CPP, hypertension, and bradycardia.
    • Other symptoms of intracranial hypertension include headache, N/V, papilledema, pupil dilation, focal deficits, seizure, and coma.
    • Intracranial hypertension can lead to cerebral ischemia and further decreased CPP.

    Cerebral Ischemia

    • The brain is highly sensitive to ischemia due to its high energy needs and limited storage capacity of essential substrates.
    • Ischemia results in inefficient glycolysis and reduced ATP production.
    • This leads to the release of excitatory neurotransmitters, further depolarization, and increased calcium influx.

    Anesthetic Considerations

    • Inhalation anesthetics decrease cerebral metabolic rate (CMR) in a concentration-dependent manner.
    • Volatile anesthetics are potent cerebrovascular dilators, increasing cerebral blood flow (CBF).
    • Isoflurane produces the greatest decrease in CMR and is the least potent cerebral vasodilator.
    • Nitrous oxide increases CBF, CMR, and intracranial pressure (ICP).
    • Opioid-based anesthetic techniques are popular in neuroanesthesia due to their hemodynamic stability and predictable emergence.
    • Ketamine causes a dramatic increase in CBF and ICP, but provides protection against neuronal cell death.

    Neuromuscular Blocking Agents

    • Nondepolarizing muscle relaxants have a direct effect on cerebral physiology due to histamine release.
    • Histamine directly dilates the cerebral vasculature.
    • Atracurium has significant histamine release, while pancuronium demonstrates sympathetic effects on induction.
    • Succinylcholine can produce increases in ICP, which can be attenuated with a defasciculating dose of nondepolarizers.

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