Lab Anatomy 4
In this lecture , we will be talking about sections in the CNS with some commenting about the parts of
the lateral ventricle .
Angled horizontal Plane: is a section passing from the external ear to the orbit of the eye (also called
orbito-meatal plane i.e. between the orbits of the eye to the meatus of the ear)
This plane passes through:
1- Two parts of the lateral ventricle
a- Anterior horn of the lateral ventricle
b- Posterior horn of the lateral ventricle
2- Two parts of corpus callosum
4- Basal ganglia
a- Caudate nucleus medial
b- Lentiform ( Putamen + Globus Pallidus internal and external )
Caudate nucleus is formed of the following parts :
Head of caudate usually bulges in the anterior horn of the lateral ventricle from the lateral side
Atrophy in the caudate nucleus could be seen as absence of the bulging of its head into the
anterior horn .
Fornix and septum pellucidum form the medial aspect of the anterior horn of the lateral
Anterior limb : lies between caudate nucleus and lentiform
Posterior limb : lies between Thalamus and lentiform
Genu : lies between the two limbs ( anterior and posterior limb )
Retro-lentiform part : white matter containing the Optic Radiation as it is connected with
the visual area .
Remember: The most important part is the posterior limb , where cerebro-vascular accidents
(stroke ) could affect the pyramidal , extra pyramidal tracts and sensation temporarily .
Important notes for the practical exam on this slide :
This section is an angled horizontal section , not a coronal one .
Showing the parts we mentioned above .
e.g : showing : Thalamus , Caudate nucleus , Lentiform with its two parts ..
The lower figure is showing a horizontal section:
The caudate nucleus and the thalamus lying medially, and lentiform is lateral with its two parts
(having the putamen laterally and the globus palidus medially).
The caudate nucleus with its parts (head, body, tail and amygdaloid nucleus by the end of the
tail) is lying at the same level medially with the thalamus.
Amygdaloid nucleus is part of the basal gangilia found in the temporal lobe.
Slide 27 (lower figure)
Coronal sections depend on the level where the section is taken:
First Section: Shows the structures; Caudate and Putamen with the anterior limb of Internal
Second section: Shows Caudate , Putamen with anterior limb between then and Globus Palidus.
Third section: Shows Thalamus , Putamen And might show Globus palidus.
The first section is the most anterior section
As going posteriorly, thalamus starts to appear
At the level of the thalamus, Brain stem lies at the same level. (The sections in the practical part
showing the thalamus is almost always accompanied with the brain stem, as it is on the same
Mesencephalon lies at the same level of the Diencephalon and below it(midbrain , pons and
might show the medulla)
….line slide 28
Ventricles of the CNS:
1- Two lateral ventricles, inside the cerebral hemispheres.
2- Third ventricle, in the diencephalon.
3- Fourth ventricle, in the hindbrain.
Found in the cerebral hemispheres.
C-shaped having the following parts:
1- Anterior horn of the lateral ventricle
2- Body of the lateral ventricle
3- Posterior horn of the lateral ventricle
4- Inferior horn of the lateral ventricle
Notice that the lateral ventricle and the caudate nucleus are both C-shaped, so in showing the
boundaries for the parts of the lateral ventricles, they will be related.
Anterior horn of lateral Ventricle: Lies in the temporal lobe, anterior to the interventricular
foramen that lies below the anterior part of the fornix and forms a connection between the
lateral ventricle with the third ventricle.
Related to the Head of the caudate nucleus that forms the lateral boundary of Anterior horn of
the lateral ventricle.
Body of the lateral ventricle: lied in the parietal lobe, posterior to the interventricular foramen.
Related to the body of the caudate nucleus that forms the lateral boundary of the body of the
Posterior horn of the lateral ventricle: lies in the occipital lobe.
Inferior horn of the lateral ventricle: lies in temporal lobe.
Related to tail and the Amygdaloid nucleus of the caudate nucleus where the form the roof of
the inferior horn of the lateral ventricle.
Upper figure showing the anterior horn in the temporal lobe
Boundaries of the anterior horn of the lateral ventricle:
Roof: formed by Genu of Corpus Callosum
Medially: formed by Fornix and Septum Pellucidum.
Laterally: formed by Head of Caudate nucleus.
Note: As this section is more anterior. Laterally, the section shows putamen of lentiform with the
anterior limb of internal capsule lying between caudate and putamen. Please refer to slide 27.
Lower figure showing the body of the lateral ventricle in the parietal lobe
Boundaries of the body of the lateral ventricle:
Roof: formed by Body of Corpus Callosum.
Medially: formed by Fornix only.
Infrio-Laterally: formed by Body of Caudate nucleus and Thalamus.
Note: This section passes through the parietal lobe superiorly and the temporal lobe inferiorly ,
where the inferior horn of the lateral ventricle lies.
Lateral fissure separates the parietal from the temporal lobes.
The deepest part of the lateral fissure is Insula,which is a sub-merged cortex.
Boundaries of the inferior horn of the lateral ventricle:
Roof: formed by Tail and Amygdaloid nucleus of Caudate nucleus( with the Amygdaloid nucleus
being more anterior).
Medially: formed by choroid plexus.
Laterally: formed by Tapetum( continuation of the Splenium part of Corpus Callosum)
Floor: Hippocampal gyrus.
Note: As this section is more posterior. Laterally, the section shows globus palidus then putamen
(from medial to lateral). Please refer to slide27.
Boundaries of the posterior horn of the lateral ventricle:
Superio-lateral: formed by Tapetum.
Medially: formed by two bulges:
1- Bulb of the posterior horn
2- Calcar avis.
Coronal section at third level (in slide 27).
Showing the thalamus at the level of the mesencephalon (midbrain and pons).
Third ventricle lies inside the diencephalon
Parietal lobe and temporal separated by the lateral fissure.
Showing the body of the lateral ventricle (in the parietal lobe) and the inferior horn of the lateral
ventricle (in the temporal lobe).
In the cavity of the body of the lateral ventricle, Body of corpus callosum and thalamus bulge
from the lateral side of the cavity.
At the level of the midbrain the following parts can be seen:
1- substantia nigra appears in a moustache like appearance( it secretes Dopamine).
Note: deficiency in dopamine causes Parkinson disease. Parkinson disease patients are given L-
DOPA, which is transformed in the body into dopamine.
2- Cruss cerebri, where pyramidal, extra pyramidal and sensory tracts pass.
3- Red nuclei, that give rise to Rubro-spinal tract.
Slide 31 is a diagrammatic section showing a coronal section passing through the thalamus,
brain stem, parietal and temporal lobes. (The doctor mentioned that questions in the practical
exam could be on the natural sections and the diagrammatic sections )
Please read slide 31 as it summarizes all the parts in this coronal section (the doctor just went
over the names of the structures).