Neuroanatomy 3 SDL: Forebrain, Ventricles and CSF

Question 1

What is the forebrain/cerebrum made up of?

Answer 1

Cerebral hemispheres and diencephalon

Question 2

Which are the four components of the diencephalon? Which two of those are the major components of the diencephalon?

Answer 2

1. Thalamus (major)
2. Hypothalamus (major)
3. Epithalamus
4. Subthalamus

Question 3

Identify structures A-L

Answer 3

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

Question 4

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?)

Answer 4

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)

Question 5

Is the cerebral cortex made up of grey or white matter?

Answer 5

Consists of columns of gray matter neurons, with white matter located underneath.

Question 6

What is meant by the terms sulci and gyri?

Answer 6

Sulci; grooves

Gyri; folds

Question 7

Describe the lateral surface of the frontal lobe (gyri and sulci)

Answer 7

• 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.

Question 8

Describe the medial surface of the frontal lobe

Answer 8

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.

Question 9

Describe the inferior/orbital surface of the frontal lobe?

Answer 9

made up of a series of (mostly un-named) orbital gyri.

Question 10

Describe the gyri found on the parietal lobe

Answer 10

• 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

Question 11

Describe the landmarks of the occipital lobe

Answer 11

• 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.

Question 12

Describe the landmarks of the temporal lobe

Answer 12

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.

Question 13

Where is the primary auditory cortex located?

Answer 13

in the superior temporal lobe

Question 14

What forms the limbic lobe?

Answer 14

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.

Question 15

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.

Answer 15

Question 16

Label the diagrams below of the medial surface of the hemispheres

Answer 16

Question 17

Which functional area(s) of cortex would be affected by blockage of the posterior cerebral artery?

Answer 17

the occipital lobe, the inferomedial temporal lobe, a large portion of the thalamus, and the upper brainstem and midbrain.

Question 18

Which cerebral artery(ies) supply the primary projection cortex for general sensory information?

Answer 18

medial cerebral artery

Question 19

Which cerebral artery(ies) supply the primary auditory cortex?

Answer 19

medial cerebral artery

Question 20

What are the grey matter structures found deep inside each hemisphere collectively referred to as?

Answer 20

Basal nuclei (ganglia)

Question 21

What are the 5 components of the basal ganglia?

Answer 21

• Caudate nucleus (major component)
• Putamen (major)
• Globus pallidus
• Substantia nigra
• Subthalamic nucleus

Question 22

What is the corpus striatum?

Answer 22

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.

Question 23

In very general terms, what is the major function of the basal ganglia?

Answer 23

responsible primarily for motor control, as well as other roles such as motor learning, executive functions and behaviors, and emotions.

Question 24

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.

Answer 24

Question 25

What forms the lentiform nucleus?

Answer 25

Comprises the **putamen and the globus pallidu**s within the basal ganglia. With the caudate nucleus, it forms the striatum.

Question 26

How would you describe the 3-dimensional shape of the caudate nucleus?

Answer 26

C-shaped structure with head, body and tail.

Question 27

The fibres making up the white matter core of the cerebral hemispheres can be classified into three functional types. What are these 3 types?

Answer 27

1. Association fibres 2. Commissural fibres 3. Projection fibres

Question 28

# Define each of these terms and give at least one example of each: * Association fibres * Commissural fibres * Projection fibres

Answer 28

* 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

Question 29

What is the major commissure of the brain?

Answer 29

Corpus callosum

Question 30

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.

Answer 30

Anterior limb, genu, posterior limb

Question 31

**Find out** the **names** and **functions** of **at least _three_ fibre tracts** which run in the internal capsule.

Answer 31

* 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).

Question 32

Each cerebral hemisphere contains an extensive, C-shaped cavity. What is this?

Answer 32

Lateral ventricle

Question 33

Where is the whole ventricular system of the brain derived from?

Answer 33

The central canal of the embryonic neural tube.

Question 34

Which component of the ventricular system is located in each of the following brain regions? * Diencephalon - * Midbrain - * Pons -

Answer 34

* 3rd ventricle * cerebral aqueduct * 4th ventricle

Question 35

**Label the diagram below** of the human ventricular system. Make sure you **identify** the various "horns" of the lateral ventricle.

Answer 35

Question 36

which points the ventricular system communicate with the subarachnoid space?

Answer 36

* Lateral foramen of Luschka (x2) * Median foramen of Magendie These connect the 4th ventricle with the subarachnoid space.

Question 37

What is choroid plexus?

Answer 37

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.

Question 38

What are the functions of the CSF? List at least two.

Answer 38

* 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.

Question 39

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?

Answer 39

Hydrocephalus

Question 40

At which sites is the circulation of CSF most likely to become obstructed? ## Footnote **For each of these sites, work out which parts of the ventricular system would become enlarged as a result of a blockage there.**

Answer 40

* 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