Cerebral White Matter Fibers
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Questions and Answers

What type of cerebral white matter fibers connect one part of the cerebral cortex to another part in the same hemisphere?

  • Association fibers (correct)
  • Limbic fibers
  • Commissural fibers
  • Projection fibers

    • Which part of the corpus callosum connects the frontal cortices?

  • Rostrum
  • Splenium
  • Genu (correct)
  • Body

    • What is the largest bundle of nerve fibers in the association fibers?

  • Cingulum
  • Superior longitudinal fasciculus (correct)
  • Uncinate fasciculus
  • Inferior longitudinal fasciculus

    • Which type of fibers connect the cerebral cortex to the subcortical nuclei in the cerebral hemispheres?

    <p>Projection fibers</p> Signup and view all the answers

    What is the function of the uncinate fasciculus?

    <p>Connects the inferior frontal lobe gyri to the temporal lobe</p> Signup and view all the answers

    Which part of the corpus callosum connects the occipital cortices?

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

    What type of fibers connect one part of a hemisphere to the corresponding part of the opposite hemisphere?

    <p>Commissural fibers</p> Signup and view all the answers

    What is the name of the bundle of nerve fibers that connects the frontal and parietal lobes with the parahippocampal gyrus?

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

    Which tracts are present in the anterior limb of the internal capsule?

    <p>Frontopontine fibers and corticonuclear fibers</p> Signup and view all the answers

    What is the location of the corticospinal fibers for the upper and lower limbs and trunk?

    <p>Posterior limb</p> Signup and view all the answers

    Which of the following fibers are present in the retrolentiform part of the internal capsule?

    <p>Parietopontine and temporopontine fibers</p> Signup and view all the answers

    What can occur as a result of pin-point lesions of the internal capsule?

    <p>Widespread derangements of the body</p> Signup and view all the answers

    Which of the following tracts is NOT present in the posterior limb of the internal capsule?

    <p>Optic radiation</p> Signup and view all the answers

    What is the location of the anterior part of the superior thalamocortical fibers?

    <p>Anterior limb</p> Signup and view all the answers

    Which part of the visual pathway receives fibers from the lower retinal quadrants?

    <p>Upper lip of the calcarine sulcus</p> Signup and view all the answers

    What is the function of the superior colliculus in the visual pathway?

    <p>Mediation of light reflexes</p> Signup and view all the answers

    Where do the cochlear fibers end in the auditory pathway?

    <p>Cochlear nuclei</p> Signup and view all the answers

    What is the function of the medial geniculate body in the auditory pathway?

    <p>Receiving the inferior brachium from the inferior colliculus</p> Signup and view all the answers

    What is the term used to describe the group of structures that lie in the border zone between the cerebral cortex and the hypothalamus?

    <p>Limbic system</p> Signup and view all the answers

    What is the name of the thin layer of grey matter that lies in contact with the dorsal surface of the corpus callosum?

    <p>Indusium griseum</p> Signup and view all the answers

    What is the main function of the limbic system?

    <p>Regulation of behaviors related to primitive life</p> Signup and view all the answers

    What is the function of the midline commissurotomy (Corpus callosotomy)?

    <p>To prevent epileptic seizures from spreading from one half of the brain to the other</p> Signup and view all the answers

    What is the name of the cortex that surrounds the corpus callosum and follows the lateral ventricle?

    <p>Limbic lobe</p> Signup and view all the answers

    What is the term for the fibers of the corpus callosum in the horizontal plane?

    <p>Commissural fibers</p> Signup and view all the answers

    Where do the auditory radiations arise from in the auditory pathway?

    <p>Medial geniculate body</p> Signup and view all the answers

    What is the name of the structure that lies ventrally to the corpus callosum?

    <p>Septum pellucidum</p> Signup and view all the answers

    What is the name of the sinus that lies dorsally to the corpus callosum?

    <p>Inferior sagittal sinus</p> Signup and view all the answers

    What is the term for the two longitudinally directed strands of fibers in the indusium griseum?

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

    What is the name of the part of the corpus callosum that lies between the body and splenium?

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

    What is the caudal relation of the corpus callosum?

    <p>Posterior horn of lateral ventricle</p> Signup and view all the answers

    What is the primary function of the amygdala in the limbic system?

    <p>Signals the cortex of motivationally significant stimuli</p> Signup and view all the answers

    Which part of the limbic system is involved in the formation of recognition memory?

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

    What is the main function of the hippocampal formation?

    <p>Conversion of short-term memories to long-term memories</p> Signup and view all the answers

    Which disorder is associated with damage to the mammillary bodies?

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

    What is the primary function of the insular cortex?

    <p>Social emotions</p> Signup and view all the answers

    Which part of the limbic system is involved in rewarding and pleasurable activities?

    <p>Septal nuclei</p> Signup and view all the answers

    What is a common disorder associated with damage to the hippocampal formation?

    <p>Anterograde amnesia</p> Signup and view all the answers

    What is the primary function of the anterior thalamic nucleus?

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

    Study Notes

    Types of Cerebral White Matter Fibers

    • Association (Arcuate) Fibers: connect one part of the cerebral cortex to another part in the same hemisphere
    • Commissural Fibers: cross the midline and connect one part of a hemisphere to the corresponding part of the opposite hemisphere
    • Projection Fibers: connect the cerebral cortex to the subcortical nuclei in the cerebral hemispheres and with nuclei in the diencephalon, brainstem, and spinal cord

    Association Fibers

    • Short Association Fibers: U-shaped, pass from one part of a gyrus to another part of the same gyrus or adjacent gyrus of the same lobe
    • Long Association Fibers: run long distances between cortical areas of different lobes, forming visible nerve bundles
      • Superior Longitudinal Fasciculus: connects the anterior part of the frontal lobe to the occipital and temporal lobes
      • Cingulum: within the white matter of the cingulate gyrus, connects frontal and parietal lobes with the parahippocampal gyrus
      • Inferior Longitudinal Fasciculus: from the occipital to temporal lobes
      • Uncinate Fasciculus: from inferior frontal lobe gyri to temporal lobe

    Commissural Fibers: Corpus Callosum

    • Rostrum: tapered anterior end connecting the orbital cortices
    • Genu: sharp backward bend from the rostrum, connecting frontal cortices
    • Body (Trunk): largest, convex upwards, connecting parietotemporal cortices
    • Splenium: thick rounded posterior end, connecting occipital cortices
    • Isthmus: the area between the body and splenium
    • Fibers in the Sagittal Plane:
      • Tapetum
    • Fibers in the Horizontal Plane:
      • Commissural fibers
    • Fibers in the Coronal Plane:
      • Supracallosal gyrus or Indusium Griseum
      • Medial and Lateral Longitudinal Striae (of Lancisi)
    • Median Relations:
      • Dorsally: Inferior Sagittal Sinus in the lower free border of the falx cerebri
      • Caudally: Inferior Sagittal Sinus joins the Great Cerebral Vein → Straight Sinus → Transverse Sinus
      • Ventrally: Septum Pellucidum, Interventricular Foramen (of Monro), Fornix (& its Commissure), Pineal Body
    • Paramedian Relations:
      • Dorsally: Pericallosal Branch of ACA, Cingulate Gyrus
      • Caudally: Post.Horn of Lateral Ventricles
      • Ventrally: Ant.Horn & Body of Lateral Ventricles

    Midline Commissurotomy (Corpus Callosotomy) & Split-Brain Syndrome

    • Prevents epileptic seizures from spreading from one half of the brain to the other

    Internal Capsule

    • Parts:
      • Anterior Limb
      • Genu
      • Posterior Limb
    • Fibers:
      • Descending Tracts:
        • Anterior Thalamocortical Fibers
        • Corticonuclear & Corticospinal Fibers
      • Ascending Tracts:
        • Optic Radiation
        • Auditory Radiation

    Visual Pathways

    • Medial smaller root of the Optic Tract forms the Superior Brachium which passes to the Midbrain and synapses in the Superior Colliculus (general light reflex) and Pretectal Nucleus (pupillary light reflex) to mediate the light reflexes

    Auditory Pathways

    • Cochlear Fibers end in the Cochlear Nuclei and 2 sets of fibers arise
    • Dorsal Fibers cross the Pontine Tegmentum to the Contralateral Lateral Lemniscus
    • Ventral Fibers synapse bilaterally in Superior Oliuary Nucleus Complex to the Bilateral Lateral Lemnisci
    • The Lateral Lemniscus ends at the Inferior Colliculus of the Midbrain
    • The Medial Geniculate Body (MGB) receives the Inferior Brachium from the Inferior Colliculus of the Midbrain
    • The Auditory Radiation arises from the MGB, passes through the Sublentiform Part of the Internal Capsule to reach the Auditory Cortex (Temporal Lobe)

    The Limbic System

    • Definition: a group of structures that lie in the border zone between the cerebral cortex and the hypothalamus, concerned with regulating behaviors related to the objectives of primitive life (Sustenance, shelter, and sex)
    • Cortical Areas: Anterior Thalamic Nucleus (Emotion), Mammillary Bodies (Facial Recognition)
    • Functions and Disorders:
      • Amygdala: signals the cortex of motivationally significant stimuli, related disorders: Anxiety, Autism, Depression, Post-Traumatic Stress Disorder, Phobias
      • Hippocampal Formation: Learning (Conversion of short-term memories to long-term memories), related disorders: Anterograde Amnesia, Alzheimer's Disease, Navigational Disability
      • Septal Nuclei: Reward & Pleasure Center, related disorders: Neuropsychiatric Disorders (Schizophrenia, Bipolar, OCD)
      • Mammillary Bodies: Formation of Recognition Memory, related disorders: Prosopagnosia (Face Blindness)
      • Insular Cortex: Social Emotions, related disorders: Addictive Behavior

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