FINAL: brain circulation and drainage

Question 1

What are the 3 main arteries heading towards the brain?

Answer 1

vertebral aa.
internal carotid aa.
middle meningeal aa.

Question 2

Where does the middle meningeal a. come from and through which foramen does it pass to enter the skull?

Answer 2

branches off of maxillary a. (from external carotid)
- thru foramen spinosum (sphenoid b.)

Question 3

How does the ICA enter the skull and where does it pass?

Answer 3

• enters via carotid canal
• passes anteriorly/medially thru cavernous sinus of sphenoid body

Question 4

What are the terminal branches of the ICA?

Answer 4

• ant. cerebral a. (and ant. communicating a.)
• middle cerebral a.

Question 5

Where do the vertebral aa. pass through to get into the skull?

Answer 5

• thru transverse foramina of C1-C6
• perforate dura and arachnoid
• pass thru foramen magnum

Question 6

What do the 2 vertebral aa. become and where?

Answer 6

Basilar a. (in front of pons)

Question 7

What is the vertebrobasilar arterial system also known as?

Answer 7

posterior circulation of the brain

Question 8

What does the basilar a. divide into? and how do these aa. join the ICA?

Answer 8

2 post. cerebral aa.
- join ICA via post. communicating aa.

Question 9

What do the ant. cerebral aa. supply?

Answer 9

most medial and superior surfaces of brain + frontal pole

Question 10

What do the middle cerebral aa. supply?

Answer 10

lateral surface of brain + temporal pole

Question 11

What is the Circle of Willis and what are the aa.?

Answer 11

anastomosis at base of brain
- post. cerebral aa.
- post. communicating aa.
- ICA
- ant. cerebral aa.
- ant. communicating aa.

Question 12

What does the Circle of Willis surround?

Answer 12

The hypothalamus

Question 13

What is the principle vessel receiving blood of the dural sinuses? and where does this vessel exit the skull?

Answer 13

Internal Jugular v. (exits thru jugular foramen)

Question 14

What is the collateral circulation if the internal jugular v. is occluded?

Answer 14

• angular v.
• pterygoid plexus
• suboccipital vv.

Question 15

What are the dural venous sinuses and where are they?

Answer 15

Endothelium lined spaces
- btwn periosteal and meningeal layers of the dura mater

Question 16

Large veins of the surface of the brain empty into the dural sinuses, ultimately draining all the blood into the:

Answer 16

internal jugula v.

Question 17

What is the confluence of sinuses made up of?

Answer 17

• sup. sagittal sinus
• straight sinus
• occipital sinus
• transverse sinus

Question 18

Where is the sup. sagittal sinus, where does it start/end?

Answer 18

• sup. border of falx cerebri
• starts: crista galli
• ends: near internal occipital protuberance at confluence of sinuses

Question 19

Where is the inf. sagittal sinus and where does it end?

Answer 19

inf. border of falx cerebri, ends in straight sinus

Question 20

What joins to form the straight sinus?

Answer 20

inf. sagittal sinus + great cerebral v.

Question 21

Where is the straight sinus and where does it end?

Answer 21

infero-posteriorly along line of attachment of falx cerebri and tentorium cerebelli
- joins confluence of sinuses

Question 22

Where is the transverse sinus, where does it start/end?

Answer 22

• starts at confluence
• goes laterally on occipital b. and posteroinferior angles of parietal b.
• ends: becomes sigmoid sinus (near petrous portion of temporal b.)

Question 23

Which transverse sinus is bigger? why?

Answer 23

Right bigger: sup. saggital sinus empties into right
(inf. sagittal sinus empties into straight and then left)

Question 24

Where is the sigmoid sinus and where does it start/end?

Answer 24

• starts: transverse sinus
• forms deep grooves in temporal and occipital b.
• continues inferiorly to jugular foramen
• ends: becomes internal jugular v.

Question 25

Where is the occipital sinus, where does it end, and what does it communicate with?

Answer 25

- lies in attached border of falx cerebelli - ends in confluence of sinuses - communicated w internal vertebral venous plexus

Question 26

Where is the cavernous sinus? where does it start/finish?

Answer 26

- middle cranial fossa - bilaterally on each side of sella turcica (sphenoid b.) - starts: sup. orbital fissue anteriorly - ends: apex of petrous portion of temporal b. posteriorly

Question 27

From where does the cavernous sinus receive blood?

Answer 27

- sup. opthalmic v. - inf. opthalmic v. - middle cerebral v. - sphenoparietal sinus

Question 28

Where does the cavernous sinus drain into?

Answer 28

- sup. petrosal sinus - inf. petrosal sinus - pterygoid plexus

Question 29

What are the contents of the cavernous sinus and what are the nerves ensheathed in the lateral wall?

Answer 29

Contents: - ICA - carotid plexus of sympathetic nerves - abducens n. (CVI) Ensheathed in lateral wall: - CIII: occulomotor - CIV: trochlear - CV1 (sometimes CV2): trigeminal opthalmic and maxillary

Question 30

Where is the superior petrosal sinus, where does it start/end and where does it attach (part of bone)?

Answer 30

- lies in anterolateral portion of tentorium cerebelli - starts: cavernous sinus - ends: where transverse sinus curves to form sigmoid sinus - attaches to: petrous portion of temporal b.

Question 31

Where is the inferior petrosal sinus, where does it start/end? (mention which part of the cavernous sinus it drains)

Answer 31

- runs btwn petrous portion of temporal b. and basilar portion of occipital b. - begins: posterior ends of vv. of cavernous sinus inferiorly - ends: Internal jugular vein (drains lateral cavernous sinus)

Question 32

What does the basilar plexus connect?

Answer 32

inf. petrosal sinus to internal vertebral venous network

Question 33

What do the emissary vv. connect?

Answer 33

dural venous sinuses with vv. outside cranium

Question 34

What is arachnoid granulation?

Answer 34

- collection of arachnoid villi - prolongation of arachnoid protruding through meningeal layer of dura into dural venous sinuses

Question 35

What does arachnoid granulation do?

Answer 35

- transport/drain CSF from subarachnoid space to venous system

Question 36

Where is arachnoid granulation usually found?

Answer 36

areas of sup. sagittal sinus and transverse sinus

Question 37

What is the pathway of CSF? start at the heart/lungs pumping arterial blood towards the ventricles.

Answer 37

Arterial blood from heart/lungs goes to: - lateral ventricle's choroid plexuses - 3rd ventricle's choroid plexus - 4th ventricle's choroid plexus Choroid plexuses create CSF which go to: - lateral ventricles - 3rd ventricle - 4th ventricle Lateral ventricles drain into 3rd ventricle through: interventricular foramina 3rd ventricle drains into 4th ventrical through: cerebral aqueduct 4th ventricle drains into subarachnoid space via: - lateral aperture (foramen of Luschka) - median aperture (foramen of Magendie) Note: sometimes it can go into central canal CSF in subarachnoid space enters the dural venous sinuses via: arachnoid villi Venous blood returns to heart/lungs.