Session 1 - General Features

Question 1

The brain broadly consists of four parts:

Answer 1

Cerebrum, cerebellum, diencephalon and brainstem

Question 2

What is the Cerebrum?

Answer 2

• the largest part covering the superior and lateral aspects of the brain
• made up of two hemispheres each divided into four lobes.

Question 3

What is the Cerebellum (smaller)?

Answer 3

bulbous structure underneath the posterior part of the cerebrum. Cerebellum means ‘little brain’.

Question 4

Where is the Diencephalon?

Answer 4

• this area is deep within the brain
• beneath the cerebrum but above the brainstem.

Question 5

What does the Brainstem connect?

Answer 5

this part connects the cerebrum and diencephalon the spinal cord.

Question 6

What is the frontal and temporal lobes like?

Answer 6

• Frontal lobe – contains the primary motor cortex which is involved in conscious movement, and the prefrontal cortex which is involved in behaviour, personality and decision making.

• Temporal lobe – contains the primary auditory cortex and the hippocampus which is involved in the formation of memories.

Question 7

What is the function of the cerebellum and brainstem?

Answer 7

• Cerebellum – helps maintain posture and balance, and corrects fine movements.

• Brainstem – connects the rest of the brain to the spinal cord. It contains the nuclei of the cranial nerves and contains vital centres for regulating breathing and cardiovascular function.

Question 8

What are gyri and sulci?

Answer 8

• Gyri – folds (singular: gyrus).

• Sulci – this term means ‘furrow’. The sulci (singular: sulcus) grooves in between the gyri.

Question 9

Where is the lateral and central sulcus?

Answer 9

• Central sulcus – large sulcus running in the coronal plane that separates the frontal and parietal lobes. on both hemispheres.

• Lateral sulcus – another large sulcus that runs in the transverse plane - separates the temporal lobe (below) from the frontal and parietal lobes (above). on both hemispheres. It is also sometimes called the ‘Sylvian fissure’.

Question 10

What is inside the lateral sulcus?

Answer 10

Insula – part of cerebral cortex
- some resources, it is considered to be a fifth lobe.

• Opercula – this term means ‘lid’ or ‘cover’. It refers to the parts of the frontal, parietal and temporal lobes that cover the insula like lips around a mouth.

Question 11

What separates the two hemispheres?

Answer 11

Longitudinal fissure (interhemispheric fissure) – this large groove separates the two hemispheres.

Question 12

What is under the longitudinal fissure if separated?

Answer 12

Corpus callosum – this is a large bundle of white matter (axons) that connects the two hemispheres.

Question 13

What is the olfactory tracts and optic nerve like?

Answer 13

• Olfactory tracts – carry info on smell from the nasal cavity along the inferior surface of the frontal lobes on both sides.

• Optic nerves – carry visual information from the retinas. They’re also seen on the inferior surface of the frontal lobe and pass posteriorly and medially, to a point where they partly cross over each other (the optic chiasm).

Question 14

Where are the mammillary bodies and the hypothalamus?

Answer 14

• Mammillary bodies – found just behind the optic chiasm and pituitary gland. part of the diencephalon.

• Hypothalamus – part of the diencephalon and is only just visible behind the optic chiasm. The mammillary bodies are located on its most inferior surface.

Question 15

What is the crus cerebri and the interpenducular fossa?

Answer 15

• Crus cerebri – pillars of white matter next to mammillary bodies that connect the rest of the brain to the brainstem.
They form the most anterior part of the cerebral peduncles which are part of the midbrain.

• Interpeduncular fossa – the fossa between the cerebral peduncles. It may have a layer of arachnoid mater overlying it on some brain specimens.

Question 16

What is the brainstem like?

Answer 16

• Brainstem:
o Midbrain – the crus cerebri are located.
o Pons – central part of the brainstem.
o Medulla oblongata – tapers down to become the spinal cord inferiorly.

Question 17

What is the cerebellum like?

Answer 17

• Cerebellum – lined with many small fissures and is made up of two hemispheres connected by a central ‘vermis’. It connects to the brainstem.

Question 18

What is the frontal lobe?

Answer 18

Most posteriorly is the primary motor cortex - immediately anterior to the central sulcus. involved in movement (motor function)

anterior to this is the premotor cortex - responsible for preparation and planning of movements.

anteriorly is the prefrontal cortex. involved in personality, behaviour, problem solving, impulse control and inhibition, and social and sexual behaviour.

Broca’s area is found at the inferior frontal lobe of the dominant hemisphere (normally the left) and is important for spoken language production.

Question 19

What is the parietal lobe like?

Answer 19

extends from the central sulcus (anteriorly) to the parietooccipital fissure (posteriorly).

posterior to the central sulcus is the primary somatosensory cortex responsible for interpretation of sensory information.

The dominant parietal lobe (normally the left) is important for perception, and mathematical and language operations.

The non-dominant parietal lobe (normally the right) is important for visuospatial functions.

Question 20

What is the temporal lobe like?

Answer 20

Immediately below the lateral sulcus in the temporal lobe is the primary auditory cortex which is responsible for interpretation of auditory information.

Inferior and medially in the temporal lobe is the hippocampus which is instrumental in the formation of memory.

The amygdala is also located deep within the temporal lobe, and it has a role in the perception of fear.

Finally, Wernicke’s area is located in the most superior and posterior part of the dominant temporal lobe. It is important in understanding and coordinating spoken language.

Question 21

What is the occipital lobe like?

Answer 21

The most posterior part of the cerebrum is the occipital lobe, and it contains the primary visual cortex which is responsible for interpreting visual information received via the optic nerves giving us the perception of sight.

Question 22

What is the limbic system?

Answer 22

a group of structures found in the medial margins of the hemispheres

includes
the hippocampus
amygdala and
various parts of the cortex.
It also includes parts of the diencephalon.

As a group, they are involved in emotion, memory and behaviour. It has influence over the endocrine functions of the body and parts of it are specifically related to the sensations of fear, pleasure and rewarding behaviours.

Question 23

What is the homunculus?

Answer 23

Within the primary motor and sensory cortices, different parts of the body are represented by different parts of the gyri.

When displayed pictorially, this ‘mapping’ of specific parts of the body to parts of the cortex is called a homunculus. There is a homunculus for the motor and sensory cortices, but they are largely similar.

As an example, the face and mouth are represented on the lateral aspects of the primary motor and somatosensory cortices, whereas the upper limb and torso areas are located at the most superior part of the cortex. The most medial parts of the cortices (deep in the longitudinal fissure) represent the feet. This becomes particularly relevant when discussing lesions affecting the cortex, such as a stroke, which may only affect the lateral aspect of the hemisphere, instead of the superior or medial aspects, for example.

Question 24

What are the occipital and parietal lobes like?

Answer 24

• Parietal lobes – contains the primary somatosensory cortex which is involved in processing sensory information.

• Occipital lobe – contains the primary visual cortex which is responsible for processing visual information.