Presentation on theme: "Lab 5: White Matter and the Ventricles"— Presentation transcript:
1Lab 5: White Matter and the Ventricles Wed. February 25th, 2015Describe the anatomic correlates pertinent to the production, flow and reabsorption of cerebrospinal fluid.Identify the following structures of the limbic system: fornix, amygdala, mammillary bodies and hippocampus.Identify intercortical, commissural and projection fibers on sections of the brain.Identify the internal capsule and the associated fibers in the anterior limb, posterior limb and genu.Name the major cerebrospinal fluid (CSF) containing structures, including the lateral ventricles and the intracranial cisterns created in the subarachnoid space.Christopher Ramnanan, Ph.D.
2The CSF containing ventricle system Lateral ventricles (LV):Associated with the caudate nucleusAnterior Horn: associated w/ Head caudate nucleusBody: associated w/Body of caudate nucleusInferior and Posterior Horns: associated w/ Tail of caudate nucleusInferiorHornAnterior HornBodyPosterior (Occipital) HornCerebral Aqueduct: associated w/ midbrain3rd Ventricle: associated with thalamus4th Ventricle:Associated with pons, medulla, cerebellum
3Production and Flow of CSF CSF is produced (~500 mL/day, adult) by the choroid plexus in all four ventricles.Typical description of flow:Lateral ventricles IV Foramen of Munro 3rd ventricle Cerebral Aqueduct 4th ventricle exits Foramen of Magendie (Median Plane) and Foramen of Luschka (Bilateral) Cisterna Magna to circulate around CNSCSF fluid is mainly reabsorbed in the venous sinus system system via arachnoid granulations (most easily seen in the superior sagittal sinus.Choroid Plexus, Lat. Ventr.Choroid Plexus; 3rd Ventr.Choroid Plexus, 4th Ventr.
5Prominent CSF cisterns Quadrigeminal (superior) cistern: posterior to midbrainInterpeduncular cistern (chiasmatic cistern): located anterior to the midbrain; contains optic chiasmCisterna manga (cerebellomedullary cistern): largest pool; located b/w the cerebellum and the medulla; receives CSF from Luschka/MagendiePontine (pre-pontine) cistern: located anterior to cistern
6These cisterns can best be approximated (where the CSF pools would have been, in life) in sagittal brain specimens with dura intact. The cisterns are useful landmarks in sagittal clinical images, as are the ventricle structures.MRI Ventricles and CSF cisterns – Sagittal view
7The cortex has white matter connections with other parts of the CNS including: Association fibers: connections to other regions of cortex within the same hemisphere;Projection fibers: connections to subcortical structures (thalamus, basal ganglia, brainstem, spinal cord) andCommissural fibers: connections to cortex within contralateral hemisphereWe won’t go into any detailed discussion of any particular association fibers, but we will discuss important commissural and projection fibers over the next few slides.
8Prominent Commissural Structure: The Corpus Callosum GenuRostrumSpleniumNote:-Corpus callosum larger in females than males; may relate to females > males in terms of multitasking-Agenesis of corpus callosum is a common congenital malformation (may affect motor milestones, social behaviour and cognitive functions in children; often misdiagnosed)-Corpus callosum surgical resection sometimes used in epileptic patients to limit incidents of secondary seizuresGenuSplenium
9FYI links:The story of Kim Peek, who inspired the autistic character in the movie Rain Man:https://www.psychologytoday.com/blog/the-superhuman-mind/201303/the-brain-the-real-rain-manPatients with partial or complete lack of corpus callosum share their experiences:How corpus callosum disorders can be diagnosed:
10Prominent Projection Structure: The Internal Capsule Includes most fibers (descending motor, ascending sensory) that travel between cortex and subcortical structures (thalamus, brainstem, spinal cord). We will identify structures passing through the anterior limb, the genu, and the posterior limb of the internal capsule. The optic radiations are associated with posterior aspect of the posterior limb.
11Internal Capsule, Coronal View Corona radiata fibers will continue as the internal capsule.Some fibers of the internal capsule descending from the precentral gyrus (ie. motor tracts) will continue as cerebral peduncles in midbrain.Corona radiataNote: In this coronal plane, you can see that internal capsule is landmark that separates the thalamus and head of the caudate nucleus (medial) from the lentiform nucleus (not well observed in this particular cut).
12Transverse View Through Internal Capsule: Major Components Ant. Limb passes b/w caudate head and lentiform nucleusTransverse View Through Internal Capsule: Major ComponentsAnterior limb-frontopontine tracts-thalamic radiations to prefrontal cortexGenu (the bend)-Corticobulbar motor tracts supplying facePosterior Limb1) descending corticospinal motor tracts supplying limbs2) thalamic somatosensory radiations to primary somatosensory cortex3) auditory radiations (medial geniculate nucleus to primary auditory cortex in temporal lobe)4) optic radiations (lateral geniculate nucleus to primary visual cortex in occipital lobe)Post. Limb passes b/w caudate head and lentiform nucleus
13The Internal Capsule includes: Sensory information (except olfaction) relayed from thalamus to cortex (thalamic or thalamocortical radiations ). Selected fibers include:Thalamus to Frontal Lobe:Prefrontal Cortex(Ant. Limb)Thalamus to Parietal Lobe:Primary Somatosensory Cortex(Post Limb)Thalamus to Temporal Lobe:Primary Auditory CortexThalamus to Occipital Lobe:Primary Visual CortexPost LimbGenuAnt Limb
14L A H The Internal Capsule includes: Descending motor tracts from the primary motor cortex (precentral gyrus):Corticopontine tracts (to pons)Corticobulbar tracts (to medulla)Corticospinal tracts (to spinal cord)H
15The Internal Capsule includes: Ascending sensory information that will be relayed (via the thalamus) to the primary somatosensory cortex (postcentral gyrus):The dorsal column/medial leminscus tract (fine touch/proprioception)The spinothalamic tract (pain/temperature)
16The Internal Capsule includes: The auditory radiations (from medial geniculate nucleus to primary auditory cortex of the temporal lobe; this is conceptual)Auditory radiations
17The Internal Capsule includes: The optic radiations (lateral geniculate nucleus to primary visual cortex of the occipital lobe)Medial (nasal side)optic tract fibers crossMost fibers terminate inThalamus (lateral geniculate bodies)Axons are relayed via optic radiations to visual cortex of occipital lobe
18The Limbic SystemToday’s objectives include selected structures that were previously introduced to you, in great detail, by Dr. Lau in the Psychiatry Block (Week 2; ‘Neuropsychiatry Workshop’ Session): hippocampus,fornix, amygdala, mammillary bodies, and cingulate gyrus (previously an objective in Lab 2).The limbic structures function in emotion, memory, motivation, and learning.
19Note: you are only responsible for identifying the cingulate gyrus Note: you are only responsible for identifying the cingulate gyrus. Note that this gyrus spans several lobes and is associated with corpus callosum.
21Inf. Horn, Lat. Vent. Hippocampus Note: you can use inferior horn, lat ventricle to ID tail of the caudate and the hippocampus (grey matter above and below ventricle, respectively).
22Note: you can use the uncus to approximate location of amygdala
23Fornix Mammillary Body Corpus Callosum (cut) Hippocampus Hippocampus The fornix is a white matter structure leaving the hippocampus that projects mainly to the mammillary bodies (hypothalamus) which, in turn, mainly projects to the thalamus via mammillothalamic tracts.FornixMammillary BodyCorpus Callosum (cut)HippocampusHippocampusThalamiFornixThalamusFornixLat. Ventricle, Inf. Horn.Mammillary Body
25* * * * * Main Afferents Main Efferents Cingulate cortex Association cortex, thalamusHippocampusCingulate cortex, Association cortexMammillary bodies (via fornix), AmygdalaMammillary BodiesThalamusAmygdalaHypothalamus
26FYI:The legacy of H.M.-In 1953, underwent bilateral medial temporal lobectomy to treat epilepsy-Epileptic seizures were effectively controlled but significant impact on aspects of memory, while other aspects of memory remained intact.-Maybe one of the most studied brains in history
27Dr. Lau (in psychiatry) and Dr Dr. Lau (in psychiatry) and Dr. Grimes (this slide, shown earlier this week) described limbic functions associated with the basal ganglia. While we studied the motor circuit of the basal ganglia, note that there is a limbic circuit as well.
28FornixAnt. Horn, Lat Vent.Inf. Horn of Lat. VentricleHippocampusInternal capsule
29Lateral View, Lentiform N. Internal capsuleFornixAnt. Horn, Lat Vent.Lateral View, Lentiform N.Post. Horn of Lat. VentricleInf. Horn of Lat. VentricleHippocampusDigital Anatomy Resource: ID-ventricles-limbic system structures-internal capsule components
30Digital Anatomy Resource: ID -ventricles-grey matter (including basal ganglia from last week)-white matter (internal capsule components, and what fibers run through each part)