ANA 303 Cerebrum & Circle of Willis

Question 1

What is the cerebrum?

Answer 1

The cerebrum, also called the telencephalon, refers to the two cerebral hemispheres (right and left) which form the largest part of the brain. It sits mainly in the anterior and middle cranial fossae of the skull.

Question 2

What are the unique grooves and ridges of the cerebrum?

Answer 2

gyri and sulci

Question 3

Discuss the white matter of the cerebrum

Answer 3

Deep to the cerebral cortex is an inner mass of white matter, which forms the bulk of the cerebrum and contains myelinated nerve fibers that convey information to or from the cerebral cortex

Question 4

Discuss the grey matter of the cerebrum

Answer 4

The grey matter surrounding the cerebrum is known as the cortex of the brain.
It is home to

Question 5

Lobes of the cerebral cortex

Answer 5

Frontal
Occipital
Parietal
Temporal

Question 6

Function of the frontal lobe

Answer 6

planning
organising
learning and recalling info
reasoning
social understanding
voluntary muscle movements
personality
decision-making

Question 7

Where is the primary site of motor control?

Answer 7

The motor cortex of the frontal lobe

Question 8

Function of the parietal lobe

Answer 8

processing sensory info e.g. feeling hot or cold, touch sensation
proprioceptors - is the sense of self-movement, force, and body position
kinesthesia
location awareness e.g. knowing if something is left or right
Learned movements e.g. writing

Question 9

Function of the temporal lobe

Answer 9

Processing auditory information
Processing olfactory information
Processing and development of memory
Associating visual and auditory information

Question 10

What is Broca’s area, history, it’s location, arterial supply and clinical anatomy?

Answer 10

aka motor speech area

Discovered in 1861 by French surgeon Pierre Paul Broca
Located: frontal lobe, brodmann brease 44 and 45, ususally in th left hemisphere

Function: A region of the frontal lobe where all speech patterns are formed
It controls the complex movements with your tongue and mouth to form words by carring info to the motor cortex
Helps make gestures whilst speaking and writing
Stuttering and delayed speech could be tied to a disorder in a person’s broca’s area

Clinical anatomy:
Lesions in Broca’s zones lead to severe expressive language deficits
There are also non-linguistic difficulties that lead to problems understanding signs and gestures

Broca’s aphasia syndrome
supplied by the middle cerebral artery

Question 11

What is Wernicke’s area, history, it’s location, arterial supply and colinal anatomy?

Answer 11

Discovered in 1874 by German Neurologist, Carl Wernicke, His patients were able to speak, but speech was meanignless, they couldn’t comprehend language
lesions were found in their ‘wernicke’s area’

An area of the parietal lobe
Interpreting speech
Leaning language and processing the meeaning of sounds

Location:
located in Brodmann area 22
in the superior temporal gyrus of left cerebrsl hemisphere

Supply:
supplied by the middle cerebral artery

Clinical Anatomy:
Aphasia: the loss or disruption of langauge skills that were already previosuly aquired and functional
It can be cuased by a brain injury, stroke, physical injury, tumor, dementia and infective brain disease

Question 12

Clinical anatomy of the frontal lobe

Answer 12

trauma
stroke
brain tumour
dementia
degenerative brain diseases

Question 13

The brain is supplied by which arteries?

Answer 13

The brain is supplied by:
two internal carotid
two vertebral arteries

Question 14

How do these arteries form the Circle of Willis?

Answer 14

The four arteries lie within the subarachnoid space, and their branches anastomose on the inferior surface of the brain to form the Circle of Willis

Question 15

The ICA forms from where and gives which terminal branches?

Answer 15

They arise in the neck from the common carotid artery
They give terminal branches which are:
Anterior cerebral arteries
Middle cerebral arteries

Question 16

The anterior cerebral arteries are joined together by the______________

Answer 16

anterior communicating artery

Question 17

The internal carotid arteries are joined by the ___________to_______________

Answer 17

posterior communicating arteries to the posterior cerebral arteries

Question 18

In addition to supplying branches to deeper parts of the brain, the cortical branches of each cerebral artery supply_________________

Answer 18

a surface and a pole of the cerebrum

Question 19

Describe the supply of the cortical branches (supply of the ant, mid and post cerebral artery)

Answer 19

Anterior cerebral artery supply most of the medial and superior surfaces of the brain and the frontal pole
Middle cerebral artery supply the lateral surface of the brain and the temporal pole
Posterior cerebral artery supply the inferior surface of the brain and the occipital pole

Question 20

The vertebral arteries arise and unite where?

Answer 20

They arise from the subclavian arteries
They unite at the lower border of the pons to form the basilar artery

Question 21

The basilar artery ends by dividing into_____________

Answer 21

two posterior cerebral arteries

Question 22

What branches arise from the basilar artery?

Answer 22

Other branches such as the anterior inferior cerebellar arteries, several small pontine arteries, and the superior cerebellar arteries arise from the basilar artery

Question 23

The basilar artery supply the________________

Answer 23

brainstem, cerebellum and cerebrum

Question 24

Describe the circle of Willis

Answer 24

The cerebral arterial circle (of Willis) is a roughly pentagon-shaped circle of vessels on the ventral surface of the brain
It is an important anastomosis at the base of the brain between the four arteries (two vertebral and two internal carotid arteries) that supply the brain

Question 25

The arterial circle is formed sequentially in an anterior to posterior direction by the:

Answer 25

Anterior communicating artery
Anterior cerebral arteries
Internal carotid arteries
Posterior communicating arteries
Posterior cerebral arteries

Question 26

Clinical anatomy of the circle of willis

Answer 26

an embolism in a major cerebral artery can cause ischemic stroke

Question 27

Describe the pathway for the anterior and posterior circulation of the circle of willis

Answer 27

Anterior circulation: internal carotid arteries, anterior cerebral arteries, anterior communicating artery and middle cerebral arteries (that supply the forebrain)

Posterior circulation: vertebral arteries, basilar artery, posterior cerebral arteries and posterior communicating arteries

Question 28

The inferomedial border is divided into________

Answer 28

an anterior part called the medial orbital border
a posterior part called the medial occipital border.

Question 29

What are the 3 pointed ends or poles can be recognized when the cerebral hemisphere is viewed from the lateral aspect?

Answer 29

1.the frontal pole anteriorly,
2. the occipital pole posteriorly
3. the temporal pole that lies between the frontal and occipital poles and points forward and downward.

Question 30

What are the 2 other lobes apart from the main 4 lobes?

Answer 30

insular lobe and limbic lobe

Question 31

A little anterior to the occipital pole the inferolateral border__________

Answer 31

shows a slight indentation called the preoccipital notch (or preoccipital incisure)

Question 32

A coronal section through the cerebral hemispheres shows that each hemisphere has three borders:

Answer 32

(1) superomedial
(2) inferolateral
(3) inferomedial

Question 33

What is the orbital part of the inferolateral border?

Answer 33

The orbital part of the inferolateral border is called the superciliary border (as it lies just above the level of the eyebrows)

Question 34

Each cerebral hemisphere has three surfaces

Answer 34

1. Superolateral surface between the superomedial border and the inferolateral border
2. Medial surface between the superomedial border and the inferomedial border.
3. Inferior surface between the inferolateral and
   inferomedial borders

Question 35

The inferior surface of the cerebrum is subdivided into_________

Answer 35

orbital and tentorial surfaces by the stem of the lateral sulcus

Question 36

Types of sulci

Answer 36

1. Limiting sulcus: Such a sulcus separates two
   functionally different areas, e.g. central sulcus.
2. Axial sulcus: some sulci develop along the axis of a rapidly growing/developing area e.g., the posterior part of calcarine sulcus.
3. Operculated sulcus: a sulcus may be between two structurally different areas and a third sulcus may lie in its wall and does not appear on the surface (e.g. lunate sulcus) e.g. the posterior part of calcarine sulcus which has a primary visual area in its
   depth and has peristriate and parastriate areas, secondary visual surface areas.
4. Complete sulcus: A sulcus, which is deep enough to produce an elevation on the ventricular wall is complete, e.g. collateral sulcus which produces collateral eminence in the floor of the inferior horn of
   lateral ventricle

Question 37

Parts of the frontal lobe

Answer 37

1. motor cortex
2. pre-motor cortex
3. prefrontal cortex
4. Broca’s area

Question 38

What are the sulci of the brain?

Answer 38

lateral sulcus
central sulcus
parieto-occipital sulcus

Question 39

Describe the lateral sulcus

Answer 39

Separates the temporal lobe from the frontal and parietal lobe

Question 40

Describe the central sulcus

Answer 40

serves as the posterior boundary of the frontal lobe
It separates the frontal and parietal lobe

Question 41

Describe the parieto-occipital sulcus

Answer 41

On the medial surface of the hemisphere, there is a “Y” shaped sulcus posteriorly. The upper limb of the “Y” shaped sulcus is called the parieto-occipital sulcus.
Separates the parietal and occipital lobe

Question 42

The lateral sulcus is also known as

Answer 42

Sylvian sulcus

Question 43

Broca’s area and Wernicke’s area are functionally interrelated because they can communicate with each other through

Answer 43

a pathway referred to as the arcuate fasciculus

Question 44

The anterior cerebral circulation supplies_______

Answer 44

Each gives rise to branches that supply the cortex and branches that penetrate the basal surface of the brain, supplying deep structures such as the basal ganglia, thalamus, and internal capsule

Question 45

Describe the supply of the posterior circulation

Answer 45

It supplies the posterior cortex, the midbrain, and the brainstem

•Midline arteries supply medial structures, lateral arteries supply the lateral brainstem, and dorsal-lateral arteries supply dorsal-lateral brainstem structures and the cerebellum

Question 46

Clinical correlates of the circle of willis

Answer 46

(Intracerebral) anuerysms ischemic and hemorhagic stroke

Question 47

Describe an aneurysm

Answer 47

an aneurysm is the dilatation of an artery or vein (resulting in a bulge and weakening of the vessel wall) which is greater than 50% of the normal diameter.
They are most likely to occur in the vessels contributing to the Circle of Willis
They are particularly dangerous producing a few symptoms until they rupture
Upon rupture (e.g. due to head trauma ( results in extravasation of blood into the subarachnoid space. blood typically accumulates in the subarachnoid space with a subsequent increase in ICP.
Once the artery has ruptured, it is a medical emergency, patient is likely to die unless treated swiftly.
Treatment is surgical

Question 48

Describe an ischemic and hemorrhagic stroke

Answer 48

A stroke can be caused by blockage of blood vessels ( occlusive/ischemic stroke )
or by bleeding from vessels ( hemorrhagic stroke ).

Ischemic strokes are generally caused by atherosclerotic lesions or thrombosis in blood vessels supplying the brain.

Hemorrhagic strokes are generally caused by long-standing high blood pressure or aneurysms in the vessels supplying the brain.
When bleeding occurs at the surface of the brain, it is called an extraparenchymal hemorrhage

Question 49

What are the main causes of cerebrovascular accidents?

Answer 49

Thrombosis: obstruction of blood vessels by a locally forming clot (thrombus)
Embolism: obstruction of blood vessels by an emobolus (any foreign material)
Hyperfusion: lack of blood supply to the brain due to low bp
Hemorrhage: accumulation of blood within the cranial cavity

Question 50

What is a cerebral herniation

Answer 50

A cerebral herniation or brain herniation is a serious medical condition that happens when brain tissues, blood and CSF, move from their normal postion within the skull.
It is usually caused when another condition (such as brain tumour, extradural or subdural haematoma, or abscesses in the supratentorial space)
Cerebral herniations are severe and need immediate treatment, if not treated immediately, it could be fatal

Question 50

Function of the insular lobe (island of Reil)

Answer 50

Lies in the depth of the lateral cortex and therefore hidden from surface view

processing and integration of taste sensation

Question 51

Function of the limbic lobe

Answer 51

modulation of emotions