Neuroanatomy 3 SDL: Forebrain, Ventricles and CSF Flashcards
What is the forebrain/cerebrum made up of?
Cerebral hemispheres and diencephalon
Which are the four components of the diencephalon? Which two of those are the major components of the diencephalon?
- Thalamus (major)
- Hypothalamus (major)
- Epithalamus
- Subthalamus
Identify structures A-L
A: thalamus
B: hypothalamus
C: mamillary body
D: infundibulum/pituitary gland?
E: ?
F: ?
G: corpus callosum
H: septum pellucidum
I: anterior commissure
J: intermediate mass (thalamus)
K: fornix
L: pineal gland
Note the proximity of the pituitary to the optic chiasma. How might a patient with a tumour of the pituitary gland present? (i.e. what symptoms might an individual develop?)
Can cause compression of optic chiasma –> results in bitemporal hemianopia/tunnel vision. This is impaired peripheral vision in outer temporal halves of visual field of each eye (i.e. partial blindness affecting lateral halves of vision due to compression/lesions of optic chiasm)
Is the cerebral cortex made up of grey or white matter?
Consists of columns of gray matter neurons, with white matter located underneath.
What is meant by the terms sulci and gyri?
Sulci; grooves
Gyri; folds
Describe the lateral surface of the frontal lobe (gyri and sulci)
- Precentral gyrus
- Located immediately in front of the central sulcus.
- Superior, middle and inferior gyri
- Broad, parallel gyri that extend anteriorly from the precentral gyrus.
Describe the medial surface of the frontal lobe
The precentral and superior frontal gyri extend over onto the medial surface of the frontal lobe, which is completed by a portion of the cingulate gyrus.
Describe the inferior/orbital surface of the frontal lobe?
made up of a series of (mostly un-named) orbital gyri.
Describe the gyri found on the parietal lobe
- Postcentral gyrus extends over onto the medial surface of the parietal lobe
- Another portion of the cingulate gyrus forms an additional part of the medial surface of the parietal lobe
Describe the landmarks of the occipital lobe
- The occipital lobe has no gyri with commonly used names.
- Its medial surface is bisected by the calcarine sulcus.
- The primary visual cortex surrounds the calcarine sulcus and extends to the tip of the occipital pole.
Describe the landmarks of the temporal lobe
The temporal lobe is covered by five long parallel gyri:
- The superior, middle and inferior temporal gyri are on the lateral surface.
- The primary auditory cortex can be found in the superior temporal lobe.
- The medial edge of the temporal lobe is flanked by the parahippocampal gyrus, which at its anterior end folds back on itself to form a bump called the uncus.
- The parahippocampal gyrus is so-called because it is continuous with a cortical region called the hippocampus, which is rolled inside the temporal lobe, so it is visible mainly in sections.
Where is the primary auditory cortex located?
in the superior temporal lobe
What forms the limbic lobe?
The limbic lobe is formed by the cingulate gyrus and the parahippocampal gyrus and can only be appreciated in the medial surface of the brain.
Label the diagram below of the lateral surface of the hemispheres. Also indicate the approximate positions of the primary motor, somatosensory, visual and auditory cortices.
Label the diagrams below of the medial surface of the hemispheres
Which functional area(s) of cortex would be affected by blockage of the posterior cerebral artery?
the occipital lobe, the inferomedial temporal lobe, a large portion of the thalamus, and the upper brainstem and midbrain.
Which cerebral artery(ies) supply the primary projection cortex for general sensory information?
medial cerebral artery
Which cerebral artery(ies) supply the primary auditory cortex?
medial cerebral artery
What are the grey matter structures found deep inside each hemisphere collectively referred to as?
Basal nuclei (ganglia)
What are the 5 components of the basal ganglia?
- Caudate nucleus (major component)
- Putamen (major)
- Globus pallidus
- Substantia nigra
- Subthalamic nucleus
What is the corpus striatum?
A nucleus (a cluster of neurons) in the subcortical basal ganglia of the forebrain; a collective name given to the caudate nucleus and lentiform nucleus within the basal ganglia.
In very general terms, what is the major function of the basal ganglia?
responsible primarily for motor control, as well as other roles such as motor learning, executive functions and behaviors, and emotions.
In the diagram below of a horizontal slice through the forebrain:
- label the structures indicated
- colour the corpus striatum red
- colour the internal capsule yellow.
What forms the lentiform nucleus?
Comprises the putamen and the globus pallidus within the basal ganglia. With the caudate nucleus, it forms the striatum.
How would you describe the 3-dimensional shape of the caudate nucleus?
C-shaped structure with head, body and tail.
The fibres making up the white matter core of the cerebral hemispheres can be classified into three functional types. What are these 3 types?
- Association fibres
- Commissural fibres
- Projection fibres
Define each of these terms and give at least one example of each:
- Association fibres
- Commissural fibres
- Projection fibres
- Association:
- Axons that connect cortical areas within the same cerebral hemisphere
- E.g. uncinate fasciculus
- Commissural:
- Axons that connect the two hemispheres of the brain
- E.g. corpus callosum is the main commissural tract, anterior commissure, posterior commissure
- Projection:
- Axons that connects the cortex with other areas in the CNS, e.g. deep nuclei, brainstem, cerebellum or spine.
- E.g. corticospinal tract
What is the major commissure of the brain?
Corpus callosum
In horizontal section the internal capsule appears V-shaped, with the point of the V towards the midline.
Name the three anatomical subdivisions of the internal capsule.
Anterior limb, genu, posterior limb
Find out the names and functions of at least three fibre tracts which run in the internal capsule.
- The genu contains corticobulbar fibers, which run between the cortex and the brainstem.
- The posterior limb of the internal capsule contains corticospinal fibers, sensory fibers (including the medial lemniscus and the anterolateral system) from the body
- Thalamocortical radiations are the fibers that connect the medial and anterior nuclei of the thalamus to the frontal lobes (these are severed during a prefrontal lobotomy).
Each cerebral hemisphere contains an extensive, C-shaped cavity. What is this?
Lateral ventricle
Where is the whole ventricular system of the brain derived from?
The central canal of the embryonic neural tube.
Which component of the ventricular system is located in each of the following brain regions?
- Diencephalon -
- Midbrain -
- Pons -
- 3rd ventricle
- cerebral aqueduct
- 4th ventricle
Label the diagram below of the human ventricular system. Make sure you identify the various “horns” of the lateral ventricle.
which points the ventricular system communicate with the subarachnoid space?
- Lateral foramen of Luschka (x2)
- Median foramen of Magendie
These connect the 4th ventricle with the subarachnoid space.
What is choroid plexus?
The choroid plexus or plica choroidea, is a plexus of cells that arises from the tela choroidea in each of the ventricles of the brain. The choroid plexus produces most of the cerebrospinal fluid (CSF) of the central nervous system.
What are the functions of the CSF? List at least two.
- Cushion the brain within the skull and serve as a shock absorber for the central nervous system
- CSF circulates nutrients and chemicals filtered from the blood and removes waste products from the brain.
There are bottlenecks in the circulation of CSF, both inside and outside the ventricular system. If circulation is obstructed, CSF production continues unabated and a condition called … results?
Hydrocephalus
At which sites is the circulation of CSF most likely to become obstructed?
For each of these sites, work out which parts of the ventricular system would become enlarged as a result of a blockage there.
- Interventricular foramen –> corresponding lateral ventricle would become enlarged
- Cerebral aqueduct –> 3rd ventricle and both lateral ventricles would become enlarged
- Foramen of Luschka and foramen of Magendie –> 4th ventricle, 3rd ventricle and both lateral ventricles would become enlarged
