The Cerebrum

Question 1

What is the largest part of the brain

Answer 1

The cerebrum

Question 2

Name the two cerebral hemispheres and what they are separated by

Answer 2

It consists of two cerebral hemispheres (left and right), separated by the falx cerebri of the dura mater.

Question 3

Embryologically, the cerebrum is derived from?

Answer 3

prosencephalon

Question 4

Describe the anatomical position of the cerebrum

Answer 4

The cerebrum is located within the bony cranium. It extends from the frontal bone anteriorly to the occipital bone posteriorly. Within the skull, the cerebrum fills the anterior and middle cranial fossae, and is located above the tentorium cerebelli inferoposteriorly.

Question 5

State what two types of tissue that the cerebrum is composed of

Answer 5

Grey matter and white matter

Question 6

State the function of white matter and what it forms

Answer 6

White matter forms the bulk of the deeper parts of the brain. It consists of glial cells and myelinated axons that connect the various grey matter areas.

Question 7

State the function of grey matter and what it forms

Answer 7

Grey matter forms the surface of each cerebral hemisphere (known as the cerebral cortex), and is associated with processing and cognition.

Question 8

Describe the external structure of the cerebrum

Answer 8

Externally, the cerebrum has a highly convoluted appearance, consisting of sulci (grooves or depressions) and gyri (ridges or elevations). It is divided into two anatomically symmetrical hemispheres by the longitudinal fissure – a major sulcus that runs in the median sagittal plane. The falx cerebri (a fold of dura mater) descends vertically to fill this fissure. The two cerebral hemispheres are connected by a white matter structure, called the corpus callosum.

Question 9

The cerebral hemispheres are connected by ?

Answer 9

a white matter structure called the corpus callosum.

Question 10

Name and describe the main sulci

Answer 10

Central sulcus – groove separating the frontal and parietal lobes.
Lateral sulcus – groove separating the frontal and parietal lobes from the temporal lobe.
Lunate sulcus – groove located in the occipital cortex.

Question 11

Name and describe the main gyri

Answer 11

The main gyri are:

Precentral gyrus – ridge directly anterior to central sulcus, location of primary motor cortex.
Postcentral gyrus – ridge directly posterior to central sulcus, location of primary somatosensory cortex.
Superior temporal gyrus – ridge located inferior to lateral sulcus, responsible for the reception and processing of sound.

Question 12

Describe the anatomical position of the frontal lobe

Answer 12

The frontal lobe is located beneath the frontal bone of the calvaria and is the most anterior region of the cerebrum. It is separated from the parietal lobe posteriorly by the central sulcus and from the temporal lobe inferoposteriorly by the lateral sulcus.

Question 13

What are the association areas in the frontal lobe responsible for

Answer 13

The association areas of the frontal lobe are responsible for:
higher intellect,
personality, mood,
social conduct and
language (dominant hemisphere side only).

Question 14

Describe the anatomical position of the parietal lobe

Answer 14

The parietal lobe is found below the parietal bone of the calvaria, between the frontal lobe anteriorly and the occipital lobe posteriorly, from which it is separated by the central sulcus and parieto-occipital sulcus, respectively. It sits superiorly in relation to the temporal lobe, being separated by the lateral sulcus.

Question 15

What are the association areas in the parietal lobe responsible for

Answer 15

Its cortical association areas contribute to the control of: language and calculation on the dominant hemisphere side, and visuospatial functions (e.g. 2-point discrimination) on the non-dominant hemisphere side.

Question 16

Describe the anatomical position of the temporal lobe

Answer 16

The temporal lobe sits beneath the temporal bone of the calvaria, inferior to the frontal and parietal lobes, from which it is separated by the lateral sulcus.

Question 17

What are the association areas in the temporal lobe responsible for

Answer 17

The cortical association areas of the temporal lobe are accountable for memory and language – this includes hearing as it is the location of the primary auditory cortex.

Question 18

Describe the anatomical position of the temporal lobe

Answer 18

The temporal lobe sits beneath the temporal bone of the calvaria, inferior to the frontal and parietal lobes, from which it is separated by the lateral sulcus.

Question 19

What are the association areas in the temporal lobe responsible for

Answer 19

The cortical association areas of the temporal lobe are accountable for memory and language – this includes hearing as it is the location of the primary auditory cortex.

Question 20

Describe the blood supply to the cerebrum

Answer 20

The blood supply to the cerebrum can be simply classified into 3 distinct paired arterial branches:

Anterior Cerebral Arteries – branches of internal carotid arteries, supplying the anteromedial aspect of the cerebrum.
Middle Cerebral Arteries – continuation of internal carotid arteries, supplying most of the lateral portions of the cerebrum.
Posterior Cerebral Arteries – branches of the basilar arteries, supplying both the medial and lateral sides of the cerebrum posteriorly.

Question 21

describe the venous drainage of the cerebrum

Answer 21

Venous drainage of the cerebrum is via a network of small cerebral veins. These vessels empty into the dural venous sinuses – endothelial lined spaces between the outer and inner layers of the dura mater.

Question 22

State the signs that manifest when the frontal lobe is damaged

Answer 22

Frontal lobe – a diverse range of presentations, often personality and behavioural changes occur and an inability to solve problems develops.

Question 23

State the signs that manifest when the parietal lobe is damaged

Answer 23

Parietal lobe – typically presents with attention deficits e.g. contralateral hemispatial neglect syndrome: where the patient does not pay attention to the side of the body opposite to the lesion.

Question 24

State the signs that manifest when the temporal lobe is damaged

Answer 24

Temporal lobe – presents with recognition deficits (agnosias) e.g. auditory agnosia: patient cannot recognise basic sounds, prosopagnosia: failure to recognise faces.

Question 25

State the signs that manifest when the occipital lobe is damaged

Answer 25

Occipital lobe – visual field defects: contralateral hemianopia or quadrantanopia with macular sparing.

Question 26

What signs persist when an individual has a global lesions

Answer 26

Global lesions – severe cognitive deficits (dementia), patients cannot answer simple questions such as their name, today’s date, where they are etc.