Blood supply to CNS

Question 1

How large is the brain and how much body ressources does it use?

Answer 1

2% of body mass by 20% of CO, 20% of O2 consumption, and 68% of glucose
So need a large blood supply

Question 2

What arteries go to the brain?

Answer 2

Internal carotid arteries and Vertebral arteries

They anastamose at the base of the brain to form the circle

Question 3

Where does the internal and external arteries branch?

Answer 3

Around the adams apple-
External goes to face and neck blood supply
Internal Goes uninterupted to the brain-arrive laterally to the brain and join with circle of willis

Question 4

Where does the vertebal arteries lie?

Answer 4

exit as first branch of subclavian-throught the cervical and exit by the magnum foramen. Join back at circle

Question 5

Describe the circle of willis

Answer 5

Vertebral artery arrives posteriorly, and forms the basilar artery-sits right in front of pons
Splits each side in Posterior cerebral artery
Internal carotid becomes middle cerebral artery-communicates with posterior cerbral with posterior communicating
Also anterior communicating bewteen two anterior cerebral artery (which connect with middle cerebral artery)

Question 6

What are the main venous drainages of the brain?

Answer 6

Cebreral veins join back up in numerous venous sinus-made by fold of dura mater (epidural)-then all collect at back of the head
Main one, along top is superior saggital sinus
Inferior saggital sinus becomes straight sinus and then join
exit via transverse sinus, then sigmoid sinus and then the carotid veins

Question 7

What is a stoke?

Answer 7

Also called CVA-rappidly developmig focal disturbance of brain function
85%-clot
15% - artherosclerosis

Question 8

What is a TIA?

Answer 8

Transient Iscaemic attack
Rapidly developing focal distrubance of brain function
BUT FULLY RESOLVE in 24H
Temporary blockage-bit of block but cleared
But suggest risks of stroke

Question 9

Define infarction

Answer 9

Degenerative changes in a tissue, following loss of blood supply-dead

Question 10

Define ischaemia

Answer 10

Lack of sufficient blood supply resulting in permanent damage - hypoxia/anoxia (only oxy) but ischeamia causes a lot more

Question 11

What are the 2 causes of occulusions

Answer 11

thrombosis-static blood anywhere starts thrombus and can migrate
Embolism-Plugging of small vessel by material (anything-like thrombi)-like heart artherosclerosis debros

Question 12

What changes could you observe on a patient with a vascular problem

Answer 12

Vascularture can be blown appart, yellow (fatty deposits) or can see infacted tissue (blacker) in brain

Question 13

What are the main risk factors for stroke?

Answer 13

Age, Hypertensions (hemorhagic stroke), Cardiac disease, Smoking, diabetes miellitus
Mostly lifestyle

Question 14

Which parts of the brain are perfused by which arteries?

Answer 14

Anterior cerebral artery does the top and front of brain and back until occipital lobe–supplies lower limbs
Middle cerebral artery-lateral fields and central brain (exept top strip)-torso, etc, and other
Posterior cerebral-mostly occipital and goes down and does part of temporal lobes

Question 15

What issues do you expect to see with some one with an anterior cerebral artery issue?

Answer 15

Paralysis of contralateral legs (over arms)
Distrubance of intellect, executive and function and judgment (front brain)
Loss of appropriate social behavior (front brain)

Question 16

What issues do you expect to see with some one with an middle cerebral artery issue?

Answer 16

“classic stroke”-Contralateral hemiplegia (arm>leg)
Contralateral hemisensory deficits
hemianopia (as eye fibers pass through)
Aphasia (On the L side only)

Question 17

What issues do you expect to see with some one with an posterior cerebral artery issue?

Answer 17

Visual deficits- 
Homymous (both sides in both eyes) Hemianopia (loss of visal field)
Visual agnosia (recognising what is in front of you)

Question 18

What issues do you expect to see with some one with an lacunar infarcts?

Answer 18

Lacunar infarcts represent strokes happening in life

associated with hypertension but not always symptomatic

Question 19

What are the 4 types of haemorrhagic stroke?

Answer 19

Extradural, subdural, subarachnoid, intracerebral

Question 20

What issues do you expect to see with some one with an haemorrhagic stroke?

Answer 20

Extradural-trauma-immediate-arterial-rupturing of bridging veins-blood creates the space.often central to where bone joint-increase of brain pressure until death
Subdural-venous-(already space there-where the blood accumulates)-Trauma-delayed. again rupture of bridging veins but sub dura. Often presents quite a while after head injury + loss of conciousness
Subarachnoid-where all the arteries vessels are-ruptured aneurysm (often born with weaknesses in vessels)
Intracerebral-spontaneous due to hypertension