Brain Blood Suuply And Venous Drainage

Question 1

The internal carotid artery has no branches into the neck.

How does it go directly into the skull and cranial cavity and what does it supply

Answer 1

It goes though the carotid canal and provides blood supply to the anterior portion of the brain

Question 2

When it comes to brain blood supply the external carotid artery does not supply the brain, what instead does it supply?

Answer 2

The meninges

Question 3

What is the blood supply to the internal capsule of the brain?

Answer 3

Branch of the middle cerebral arteries called the lenticulostriate

Question 4

A patient has had an artery occlude in their brain, this presenting symptoms are weakness and loss of sensation in lower limb ( upper unaffected) and inability to identify objects properly and personality change.

Which cerebral artery has been occluded here?

Answer 4

Anterior cerebral artery has been occluded.

If the occlusion is proximal to the artery collateral circulation is usually adequate to preserve circulation, however if the occlusion is distal these signs and symptoms will be shown

Question 5

If there is an occlusion in the middle cerebral artery which parts of the brain are likely to be affected and which symptoms would this present?

Answer 5

An occlusion here would affect the pre and post central gyri therefore there would be weakness in face and upper limb and there sensation on the contra-lateral side

Speech production would also be affected - aphasia

Question 6

If the middle cerebral artery occlusion affected the right hemisphere which key speech production areas would unlikely be affected?

Answer 6

Broca’s and Wernickes area

These are located in the left hemisphere therefore aphasia wouldn’t be a presenting symptom

Question 7

Which cerebral artery is the main blood supply to the Occipital lobe?

Answer 7

Posteior cerebral artery

Question 8

Why does there tend to be macular sparing (preservation of central visual fields) in a posterior cerebral artery occlusion?

Answer 8

This is because the occipital pole receiving collateral blood supply from the middle cerebral artery

Question 9

What are the dural venous sinuses and what is there function?

Answer 9

They are spaces which exist between peirostal and meningeal layers of dura, they are endothelium lined and are the venous drainage of the brain

Question 10

How is CSF resorbed in the sinuses

Answer 10

Via the anarchioid villi/granulations

Question 11

Which foramen do the venous sinus go through and which vein are they continues with

Answer 11

They go though the jugular foramen and become continuous with the internal jugular vein

Question 12

What is the confluence of sinuses and where does this happen

Answer 12

The straight, superior,and inferior saggital sinuses are found in the falx cerebri of dura mater and they converge at the confluence of sinuses which overlies internal Occipital protuberane

Question 13

Discuss the route from the confluence of sinuses to internal jugular vein

Answer 13

From the confluence the transverse sinus continues and curves into the Sigmoid sinus to meet the opening of the internal jugular vein

Question 14

The cavernous sinus does not converge at the confluence of sinuses.

What does this sinus drain and where can it be found and how does it reach the internal jugular vein

Answer 14

The cavernous sinuses drains the ophthalmic veins and is found on either side of the sella turcica.

From here it returns to the internal jugular vein via the superior and inferior petrosal sinuses

Question 15

What is the falx cerebri

Answer 15

It is a structure formed from invagination of the dura mater into the longitudinal fissure between the cerebral hemispheres

Question 16

What is the function of tentorium cerebella

Answer 16

It help maintain the anatomy of the brain by providing protection against pressure caused by the upper parts of the brain. It serrated the cerebrum from the cerebellum and brain stem

Question 17

What is the function of falx cerebri

Answer 17

Separates the cerebral hemispheres and houses the dural sinuses into which the blood and CSF Darin

Question 18

Why can an infection in the danger triangle spread into the cavernous sinus easily forming a thrombosis?

Answer 18

The cavernous sinus has small caverns so the blood flow is slow, due to this slow blood flow it allows bacteria to multiply in turn leading to clot formation - thrombosis.

Fever and swollen eye are the symptoms

Question 19

What are some common causes of a cavernous thrombosis

Answer 19

Usually comes from injury or an infection in the face

Can be from an infection in maxillary teeth

Question 20

What is an extradural(epidural) hematoma?

Answer 20

It is a collection of blood that forms between the inner surface of the skull and the outer layer of the dura (endosteal layer).
Blood clot on the OUTSIDE of the dura

Tends to be a rupture in the middle menigeal artery associated with head trauma or skull fracture

Question 21

What is a subdural haematoma

Answer 21

Collection of blood on the inner layer of the brain between the inner layer of the dura and the arachnoid mater of the meninges

Question 22

Why is a subdural haematoma more common in elderly people

Answer 22

This is because the veins that pass through the tough layer dura layer, in age, the walls of these veins become weaker.

A shock to the brain (fall) the tough layer of dura may rupture these veins and bleeding occurs into the space between the anarachnoid space and the dura.

Question 23

Why might it take a few days for symptoms to present in a subdural haematoma?

Answer 23

Because it is a venous bleed it may take a while for there to be sufficient pressure for the symptoms to develop.

Question 24

What is a subarachnoid haemorrhage?

Answer 24

This is a bleed into the space between the pia mater and the anarchnoid membrane

Question 25

What is the most common cause of a subarachnoid haemorrhage?

Answer 25

An aneurysm, the junction between arteries can be weaker and can balloon out and burst into the subarachnoid space