Lab 5: White Matter and the Ventricles Christopher Ramnanan, Ph.D. [email protected] Describe the...
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Lab 5: White Matter and the Ventricles Christopher Ramnanan, Ph.D. [email protected] Describe the anatomic correlates pertinent to the production, flow
Lab 5: White Matter and the Ventricles Christopher Ramnanan,
Ph.D. [email protected] Describe 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. Wed. February 25 th, 2015
Slide 2
The CSF containing ventricle system Lateral ventricles (LV):
Associated with the caudate nucleus Anterior Horn: associated w/
Head caudate nucleus Body: associated w/ Body of caudate nucleus
Inferior and Posterior Horns: associated w/ Tail of caudate nucleus
3 rd Ventricle: associated with thalamus 4 th Ventricle: Associated
with pons, medulla, cerebellum Cerebral Aqueduct: associated w/
midbrain Anterior HornBody Inferior Horn Posterior (Occipital)
Horn
Slide 3
Production and Flow of CSF Choroid Plexus, Lat. Ventr. Choroid
Plexus; 3 rd Ventr. Choroid Plexus, 4 th Ventr. 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
3 rd ventricle Cerebral Aqueduct 4 th ventricle exits Foramen of
Magendie (Median Plane) and Foramen of Luschka (Bilateral) Cisterna
Magna to circulate around CNS CSF fluid is mainly reabsorbed in the
venous sinus system system via arachnoid granulations (most easily
seen in the superior sagittal sinus.
Slide 4
Slide 5
Prominent CSF cisterns Interpeduncular cistern (chiasmatic
cistern): located anterior to the midbrain; contains optic chiasm
Quadrigeminal (superior) cistern: posterior to midbrain Cisterna
manga (cerebellomedullary cistern): largest pool; located b/w the
cerebellum and the medulla; receives CSF from Luschka/Magendie
Pontine (pre-pontine) cistern: located anterior to cistern
Slide 6
MRI Ventricles and CSF cisterns Sagittal view These 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.
Slide 7
The cortex has white matter connections with other parts of the
CNS including: A)Association fibers: connections to other regions
of cortex within the same hemisphere; B)Projection fibers:
connections to subcortical structures (thalamus, basal ganglia,
brainstem, spinal cord) and C)Commissural fibers: connections to
cortex within contralateral hemisphere We wont go into any detailed
discussion of any particular association fibers, but we will
discuss important commissural and projection fibers over the next
few slides.
Slide 8
Prominent Commissural Structure: The Corpus Callosum Rostrum
Splenium Genu Splenium Note: -Corpus callosum larger in females
than males; may relate to females > males in terms of
multitasking http://cercor.oxfordjournals.org/content/23/10/2514
http://cercor.oxfordjournals.org/content/23/10/2514 -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 seizures Genu
Slide 9
FYI 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-man Patients with partial or complete lack of corpus callosum
share their experiences:
http://blogs.scientificamerican.com/observations/2012/12/20/patients-reflect-on-life-with-
a-common-brain-malformation How corpus callosum disorders can be
diagnosed: http://www.nodcc.org/how-a-dcc-is-diagnosed
Slide 10
Prominent 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.
Slide 11
Internal 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. Note: 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). Corona radiata
Slide 12
Transverse View Through Internal Capsule: Major Components
Anterior limb -frontopontine tracts -thalamic radiations to
prefrontal cortex Genu Genu (the bend) -Corticobulbar motor tracts
supplying face Posterior Limb 1) descending corticospinal motor
tracts supplying limbs 2) thalamic somatosensory radiations to
primary somatosensory cortex 3) 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) Ant. Limb passes b/w caudate head and
lentiform nucleus Post. Limb passes b/w caudate head and lentiform
nucleus
Slide 13
The 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 Cortex (Post Limb) Thalamus to Occipital
Lobe: Primary Visual Cortex (Post Limb) Genu Post Limb Ant
Limb
Slide 14
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 A L
Slide 15
The 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)
Slide 16
The Internal Capsule includes: The auditory radiations (from
medial geniculate nucleus to primary auditory cortex of the
temporal lobe; this is conceptual) Auditory radiations
Slide 17
Medial (nasal side) optic tract fibers cross Most fibers
terminate in Thalamus (lateral geniculate bodies) Axons are relayed
via optic radiations to visual cortex of occipital lobe The
Internal Capsule includes: The optic radiations (lateral geniculate
nucleus to primary visual cortex of the occipital lobe)
Slide 18
Todays 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. The Limbic
System
Slide 19
http://www.neuroanatomy.ca/flex_labs/Limbic_System/story.html
Note: you are only responsible for identifying the cingulate gyrus.
Note that this gyrus spans several lobes and is associated with
corpus callosum.
Slide 20
http://www.neuroanatomy.ca/flex_labs/Limbic_System/story.html
Note: Olfactory input projects to amygdala
Slide 21
http://www.neuroanatomy.ca/flex_labs/Limbic_System/story.html
Inf. 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).
Slide 22
http://www.neuroanatomy.ca/flex_labs/Limbic_System/story.html
Note: you can use the uncus to approximate location of
amygdala
Slide 23
Thalami Corpus Callosum (cut) Hippocampus Fornix Mammillary
Body Lat. Ventricle, Inf. Horn. Fornix fornix hippocampus
mammillary bodies 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. Hippocampus Fornix Thalamus Mammillary
Body
FYI: The legacy of H.M.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2649674/ -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
Slide 27
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.
Slide 28
Fornix Hippocampus Internal capsule Inf. Horn of Lat. Ventricle
Ant. Horn, Lat Vent.
Slide 29
Fornix Hippocampus Internal capsule Inf. Horn of Lat. Ventricle
Ant. Horn, Lat Vent. Post. Horn of Lat. Ventricle Lateral View,
Lentiform N. Digital Anatomy Resource: ID -ventricles -limbic
system structures -internal capsule components
Slide 30
Digital Anatomy Resource: ID -ventricles -grey matter
(including basal ganglia from last week) -white matter (internal
capsule components, and what fibers run through each part)