Week 6 - Cortical Organisation and Blood Supply to the brain

Question 1

What is the somatosensory cortex?

Answer 1

Located within the cerebral hemispheres

• Left SSC receives info. from right side of body
• Right SSC receives info. from left side of body

Question 2

What are sulci and gyri

Answer 2

Multiple folds

Question 3

What are the 4 lobes within the cerebral cortex?

Answer 3

Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe

Question 4

What is the cerebral cortex?

Answer 4

• Outer surface of the brain
• Associated with higher-level processes → consciousness, thought, emotion, reasoning, language + memory
• Each cerebral hemisphere can be sub-divided into 4 lobes
• Layer of grey matter
• Highly convoluted to form a series of ridges called gyri + furrows (sulci)

Question 5

Where is the frontal lobe and what is it responsible for?

Answer 5

→ Largest lobe of cerebral cortex
→Located at the front of the brain and behind the forehead

FUNCTIONS → higher cognitive functions e.g. decision making, conscious thoughts, problem-solving + attention

→ Frontal lobe is where our emotions and behaviours are controlled as well as personality and intelligence
→ Contain’s Broca’s area - essential for language production

Question 6

Where is the occipital lobe and what is it responsible for?

Answer 6

→ Located at the rear of the brain
→ Recieve sensory info. from retina of eyes

This information is then encoded into different visual data (colour, motion, orientation)

→ Also responsible for object and face recognition, assessing depth and distance as well as being able to map the visual world

Question 7

Where is the parietal lobe and what is it responsible for?

Answer 7

→ Situated between the frontal and occipital lobes above temporal lobe

→ Important for integrating body’s sensory info. - can build picture of the world around us

→ Allows us to perceive our bodies, an integrate somatosensory info. (touch, pressure, temp)

→ Allows us to coordinate movements in response to the environment through spatial mapping + attentional features

Question 8

Where is the temporal lobe and what is it responsible for?

Answer 8

→ 2nd largest

→ Associated w/memory, hearing, emotion and some aspects of language

→ Left temporal lobe (usually most dominant) associated with comprehending language, memorising verbal info, forming speech and learning + processing of auditory info to help us make sense of language

Question 9

What does the central sulcus do?

Answer 9

Separates frontal lobe from parietal lobe

Question 10

How are the 2 hemispheres joined together?

Answer 10

By the corpus callosum

Question 11

How are the 2 hemispheres separated?

Answer 11

great longitudinal fissure

Question 12

What is the somatosensory association area?

Answer 12

Responsible for interpretation, integration and understanding of sensory experiences.
e.g. ability to recognise objects by just touching them

Question 13

What is the sensory homunculus?

Answer 13

Description of how each body part is mapped to an area of the cerebral cortex within the primary somatosensory area.

→ Size of the body part representative of the richness of the sensory innervation.

→ Interpretation of sensory info.

→ Conscious awareness of the contralateral half of the body

→ A very sensitive area such as fingertips, lips and tongue have a much larger area within the primary sensory cortex and thus have a much larger body part as represented on the sensory homunculus.

Question 14

Outline of the blood supply of the brain?

Answer 14

Anterior circulation

Posterior circulation

Connected via the Circle of Willis:
- Posterior to anterior = R+L Posterior communicating arteries
- Right side and left side = Anterior communicating artery

Question 15

How is the right and left side blood supply connected?

Answer 15

R + L anterior circulation is connected via the anterior communicating artery.

The right anterior cerebral artery connects to the left anterior cerebral artery.

Question 16

How is the anterior and posterior blood supply connected?

Answer 16

The right posterior communicating artery connects the right posterior cerebral artery to the right middle cerebral artery.

Question 17

What is the circle of willis?

Answer 17

Encircles optic chiasma + the floor of the hypothalamus and the midbrain.

→ base of brain
→ purpose to compensate if any obstruction or narrowing leads to insufficient perfusion of the appropriate brain areas
→ circle of willis allow for the potential of continued blood flow to all major arteries of the brain

Question 18

What cerebral artery gives the largest blood supply?

Answer 18

The middle cerebral artery

Question 19

How does blood enter the cranial cavity?

Answer 19

𝐭𝐡𝐞 𝐜𝐚𝐫𝐨𝐭𝐢𝐝 𝐚𝐫𝐭𝐞𝐫𝐢𝐞𝐬 𝐚𝐧𝐭𝐞𝐫𝐢𝐨𝐫𝐥𝐲
- external and internal carotid
(internal supply the brain itself - anterior circulation)

𝐭𝐡𝐞 𝐯𝐞𝐫𝐭𝐞𝐛𝐫𝐚𝐥 𝐚𝐫𝐭𝐞𝐫𝐢𝐞𝐬 𝐩𝐨𝐬𝐭𝐞𝐫𝐢𝐨𝐫𝐥𝐲
- the vertebral arteries supply the posterior part of the brain → they come together to form basilar artery

Question 20

How will impaired bloody supply affect function?

Answer 20

Brain tissue requires oxygenated blood → lack of blood supply → O2 deprivation → neuronal cell death

Neurones die → loss of function → lead to physical disability

Question 21

What CNS symptoms does stroke cause?

Answer 21

brisk reflexes, reduced sensation, weakness, speech deficits, altered muscle tone

FAST

Question 22

Why may a stroke lead to some symptoms but not others?

Answer 22

Damage to a specific artery leads to specific symptoms and the symptoms depend on what that area of the brain is responsible for