Download 2017 Anatomy White Matter STUDENT

White Matter and the Ventricles
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.
Christopher Ramnanan, Ph.D.
[email protected]
The CSF containing ventricle system
Lateral ventricles (LV):
Associated with the caudate
nucleus
Inferior
Horn
Anterior Horn
Anterior Horn: associated w/
Head caudate nucleus
Posterior
(Occipital)
Horn
Body: associated w/
Body of caudate nucleus
Inferior and Posterior Horns:
associated w/ Tail of
caudate nucleus
Basal Ganglia can
serve as landmarks
to identify ventricles
Body
Cerebral
Aqueduct:
associated w/
midbrain
3rd Ventricle:
associated with
thalamus
4th Ventricle:
Associated with pons,
medulla, cerebellum
Superior view, 3D model
Note:
-Caudate (Head) proximal to Ant. Horn of Lat. Vent.
-Tail of Caudate proximal to Post. Horn of Lat. Vent.
-Thalamus adjacent to 3rd ventricle
-Lentiform nucleus (Putamen + Globus Pallidus) lateral
to Internal Capsule
Caudate (Head)
Int. Capsule
Putamen
Globus Pallidus
(Int + Ext)
Thalamus
Caudate (Tail)
Key view: Transverse section through basal ganglia
Coronal view, 3D model
Note:
-Caudate (Body) proximal to Lat. Vent. (Body)
-Tail of Caudate proximal to Inf. Horn of Lat. Vent.
-Thalamus adjacent to 3rd ventricle
-Lentiform nucleus (Putamen + Globus pallidus)
lateral to internal capsule
Int. Capsule
Caudate (Body)
Putamen
Putamen
Thalamus
GPe
GPi
Globus Pallidus
(Int + Ext)
Caudate (Tail)
Key View: Coronal Section, through 3rd ventricle
Production and Flow of CSF
CSF is produced (~500 mL/day, adult)
by the choroid plexus in all four
ventricles.
Choroid Plexus,
Lat. Ventr.
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
CNS
CSF fluid is mainly reabsorbed in the
venous sinus system system via
arachnoid granulations (most easily
seen in the superior sagittal sinus).
Choroid Plexus;
3rd Ventr.
Choroid Plexus,
4th Ventr.
Prominent CSF cisterns
Quadrigeminal
(superior) cistern:
posterior to midbrain
Interpeduncular
cistern (chiasmatic
cistern): located
anterior to the midbrain;
contains optic chiasm
Pontine (pre-pontine)
cistern: located anterior to
pons
Cisterna magna
(cerebellomedullary
cistern): largest pool;
located b/w the
cerebellum and the
medulla; receives CSF
from Luschka/Magendie
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.
MRI Ventricles and CSF cisterns – Sagittal view
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 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.
Prominent Commissural Structure: The Corpus Callosum
Genu
Rostrum
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
Genu
-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
Splenium
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-realrain-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-witha-common-brain-malformation
How corpus callosum disorders can be diagnosed:
http://www.nodcc.org/how-a-dcc-is-diagnosed
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.
Internal Capsule, Coronal View
Corona radiata
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).
Ant. Limb passes b/w caudate
head and lentiform nucleus
Transverse View Through Internal
Capsule: Major Components
Anterior limb
-frontopontine tracts
-thalamic radiations to prefrontal cortex
Genu (the bend)
-Corticobulbar motor tracts supplying face
Post. Limb passes b/w
thalamus and lentiform
nucleus
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)
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)
Post Limb
Genu
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)
The Internal Capsule includes:
Descending motor tracts from the
primary motor cortex (precentral gyrus):
Corticobulbar tracts (to brainstem)
Corticospinal tracts (to spinal cord)
L
A
H
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)
The Internal Capsule includes:
The auditory radiations (from medial
geniculate nucleus to primary
auditory cortex of the temporal lobe;
this is conceptual)
Auditory radiations
The Internal Capsule includes:
The optic radiations (lateral geniculate
nucleus to primary visual cortex of the occipital
lobe)
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 Limbic System
Today’s objectives include selected structures that were previously introduced to you,
in some detail, in the Psychiatry Block:
hippocampus,fornix, amygdala, mammillary bodies, and cingulate gyrus
The limbic structures function in emotion, memory, motivation, and learning.
Note: you are only responsible for identifying the cingulate gyrus. Note that this
gyrus spans several lobes and is associated with corpus callosum.
http://www.neuroanatomy.ca/flex_labs/Limbic_System/story.html
Note: Olfactory input
projects to amygdala
http://www.neuroanatomy.ca/flex_labs/Limbic_System/story.html
FYI: Amygdala may be more than emotion/memory/motivation/fear center:
https://www.youtube.com/watch?v=42bLSZnVf0g
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).
http://www.neuroanatomy.ca/flex_labs/Limbic_System/story.html
Note: you can use the uncus to approximate location of amygdala
http://www.neuroanatomy.ca/flex_labs/Limbic_System/story.html
The hippocampal grey matter will have
a characteristic white swirl of white
matter associated with it (contrast to
amygdala, which will appear as a solid
block of grey matter).
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.
Fornix
Mammillary Body
Corpus
Callosum
(cut)
Hippocampus
Hippocampus
Thalami
Fornix
Thalamus
Fornix
Lat.
Ventricle,
Inf. Horn.
Mammillary Body
*
*
* *
*
Main Afferents
Main Efferents
Cingulate cortex
Association cortex,
thalamus
Hippocampus
Hippocampus
Cingulate cortex,
Association cortex
Mammillary bodies (via fornix),
Amygdala
Mammillary
Bodies
Hippocampus
Thalamus
Amygdala
Hippocampus
Hypothalamus
FYI:
The legacy of H.M., Henry Molaison
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
Ant. Horn,
Lat Vent.
Fornix
Inf. Horn of
Lat. Ventricle
Hippocampus
Internal capsule
Internal capsule
Fornix
Ant. Horn,
Lat Vent.
Lateral View,
Lentiform N.
Inf. Horn of
Lat. Ventricle
Post. Horn of
Lat. Ventricle
Hippocampus
Digital Anatomy Resource: ID
-ventricles
-limbic system structures
-internal capsule components
LAB 5 CHECKLIST – WHITE MATTER AND VENTRICLES
NB: Items italicized are conceptual, those denoted with a * are FYI
BRAIN MATTER and LANDMARKS
White Matter
- Corona radiata
- Internal capsule
- Anterior limb
- Frontopontine tracts
- Thalamic radiations to frontal cortex
- Genu
- Corticobulbar motor tracts
- Posterior limb
- Corticospinal motor tracts
- Thalamic radiations to 1o somatosensory cortex
(spinothalamic and dorsal column/medial
leminiscus pathways)
- Thalamic radiations to 1o auditory cortex
- Thalamic radiations to 1o visual cortex
- Optic radiations
- Cerebral peduncles
- Corpus callosum
- Rostrum
- Genu
- Splenium
VENTRICLES and CSF
- Lateral ventricles
- Anterior horn
- Body
- Inferior horn
- Posterior horn
- IV Foramen of Munro
- 3rd ventricle
- Cerebral aqueduct
- 4th ventricle
- Foramen of Magendie
- Foramen of Luschka
- Choroid plexus
- Arachnoid granulations
- Cisterns
- Interpeduncular cistern
- Pontine (pre-pontine)
- Cisterna magna
- Quadrigeminal cistern
Limbic System
- Hippocampus
- Amygdala
- Mammillary bodies
- Cingulate gyrus
- Fornix