The Cerebral Cortex: Gross and Functional Anatomy

Question 1

Broca’s area consists of what brain regions?

Answer 1

The triangular and opercular parts of the inferior frontal gyrus

Question 2

The frontal lobe accounts for what proportion of the cortical surface area?

Answer 2

40%

Divided into lateral, medial and orbital parts

Question 3

Label the gyri and sulci of the lateral frontal lobe.

Answer 3

k

Question 4

Label the orbital, triangular and opercular parts of the inferior frontal gyrus.

Answer 4

k

Question 5

What separates the superior frontal gyrus from the underlying cingulate gyrus?

Answer 5

Cingulate gyrus

Question 6

The postcentral gyrus is defined by which anterior and posterior boundaries?

Answer 6

Anterior - central sulcus

Posterior - pars marginalis

Question 7

Looking at the brain from an inferior view, identify the gyrus rectus, olfactory sulcus and lateral orbitofrontal cortex.

Answer 7

k

Question 8

Describe the main features of the prefrontal cortex.

Answer 8

• Large region of anterior frontal lobe - 30% of human cortex
• Orbital and medial regions implicated in behaviour, personality and social conduct
• Dorsolateral region more concerned with cognitive functions
• No precise anatomical boundaries
• All areas of frontal lobe that are not motor/premotor

Question 9

Which part of the primary motor cortex resembles an omega sign?

Answer 9

The motor hand area

Question 10

How can the central sulcus be indentified easily on a midsagittal section?

Answer 10

• Follow the cingulate sulcus posteriorly until you reach the pars marginalis
• The central sulcus lies directly in front of this, sloping down and backwards so that it makes a right angle with the pars marginalis

Question 11

Identify the superior parietal lobule, intraparietal sulcus and inferior parietal lobule from a lateral view of the brain.

Answer 11

k

Question 12

On a midsagittal brain section, identify the parieto-occpitial sulcus, calcarine sulcus, lingual gyrus and collateral sulcus.

Answer 12

k

Question 13

On a midsagittal brain section, identify the primary visual cortex and visual association cortex.

Answer 13

k

Question 14

Looking at the brain from a lateral view, identify the primary auditory cortex.

Answer 14

k

Question 15

What structures lie directly anterior to the lateral and medial motor strip?

Answer 15

Lateral - lateral premotor area

Medial - supplementary motor area (SMA)

Question 16

Describe the function of the somatosensory association cortex.

Answer 16

• Visuospatial representation of objects in extrapersonal space
• Recieves a projection from the visual cortex - the “where” pathway - concerned with trajectory and speed of objects and object interaction - reaching, grasping, rotating

Question 17

What is anosognosia?

Answer 17

Where patients (usually with severe neurological deficits) are unaware that their neurological problems exist - e.g. a patient claiming that a paralysed limb is function normally.

Question 18

What are praxes and how are they controlled?

Answer 18

• Praxes are semi-automatic motor sequences - e.g. to use scissors, tie shoelaces
• Praxes are stored in the premotor cortex but selected by the posterior parietal lobe
• Patients who have difficulty with praxes are said to have apraxia
• This may be caused by a lesion in either region or the white matter connections between them

Question 19

The inferior parietal region has been implicated in which abilities?

Answer 19

• Symbolic representation
• Concepts of number
• Mathematical and physics ability
• Reading and writing

Question 20

What is Gerstmann syndrome?

Answer 20

• Problems with simple arithmetic, left-right confusion and difficulty naming individual fingers
• Caused by lesions in the inferior parietal lobe

Question 21

Looking at a lateral view of the brain, identify the auditory cortex and the auditory association cortex.

Answer 21

k

Question 22

The precuneus, in the medial part of the parietal lobe, shows increased blood flow during what?

Answer 22

• Daydreaming
• Quiet contemplation
• Meditation
• Recall of personal memories

Question 23

In visual physiology, the “what pathway”, which provides information relating to colour and form, travels to which structures, and how do these integrate the visual information?

Answer 23

• The temporal lobe visual stream - “what”
• Passes inferiorly into the temporal lobe
• Information integrated by the lateral and inferior temporal cortex to identify and categorise objects
• Agnosia - failure to recognise objects

Question 24

Where is Wernicke’s area found?

Answer 24

Posterior third of the superior temporal gyrus

Question 25

Conduction aphasia, where a patient has problems repeating phrases, is thought to be caused by a lesion where?

Answer 25

The arcuate fasciculus

Question 26

What is Broca’s aphasia?

Answer 26

• Partial loss of the ability to speak
• Speech is effortful, disjointed, slow and hesitant, with marked word-finding difficulty
• Speech and language comprehension is usually preserved

Question 27

What is Wernicke’s aphasia?

Answer 27

• Difficulty understanding language and following instructions - speech comprehension
• Fluent speech with intact syntactic ability and effortless speech output
• Abnormal speech content, e.g. neologisms
• Patients often unaware that they are not making sense