Venous Drainage of the Brain

Question 1

Describe how the brain is drained?

Answer 1

By a series of veins which drain into viral venous sinuses. These sinuses are present between the periosteum and the cranial dura.

Question 2

How are the cerebral veins divided?

Answer 2

Into a superficial and deep group. Among the deep group the Great cerebral vein (of Galen) can be seen on were specimens and models.

Question 3

Which sinuses drain almost all of the blood from the brain?

Answer 3

Sagittal sinus (Superior and inferior)
Straight sinus
Two transverse sinuses

Question 4

How does the superior and inferior sagittal sinuses relate to the falx cerebri?

Answer 4

Inferior sagittal sinus run in its free border
The superior sagittal sinus runs in the falx cerebri’s attach border

(Blood flows from front to back)

Question 5

Into which vein in the neck do these dural venous sinuses drain into?

Answer 5

IJV

Question 6

Through which foramen in the skull does the internal jugular vein pass through?

Answer 6

Jugular foramen

Question 7

What is the importance of connections between intracranial sinuses and extrocranial veins?

Answer 7

These are not major routes for drainage of blood from brain but they can be potential routes of infection which may be carried in the blood i.e. flowing cut/abrasion to the scalp/face

These veins in the brain and the cranial venousness do not have valves to prevent backflow of blood from outside the cranium back into the cranium

Question 8

Name three important veins which connect intracranial veins with to extracranial veins

Answer 8

1. Superior ophthalmic veins
2. Emissary veins
3. Inferior petrosal sinuses

Question 9

What are the connections of the superior ophthalmic vein?

Answer 9

Superior ophthalmic veins drain into the cavernous sinus, and on the outside on the cranial cavity it is continuous with the facial vein

Question 10

What are the connections of the emissary veins?

Answer 10

They are small veins that connect the cranial venous sinuses with the dipole of the skull containing the blood sinuses in the bone marrow of the diploe, which in turn are continuous with the veins in the superficial fascia verifying the outer part of the skull

Question 11

What is the diploe of the skull bone?

Answer 11

Spongy cancellous beone separating the inner and outer later of cortical bone of the skull

Question 12

What are the connections of the inferior petrosal sinuses?

Answer 12

They lie at the base of the brain and are connected to each other (L and R) by the basilar sinus.

This small sinus also communicates inferiorly with the internal vertebral sinus

Question 13

What vein drains into the cavernous sinus?

Answer 13

Ophthalmic veins

Question 14

What structure in the skull base is the cavernous sinus closely related to?

Answer 14

Sella tunica

Question 15

Which nerves pass through the cavernous sinus?

Answer 15

Optic (CN II)
Occulomotor (CN III)
Trochlear (CN IV)
Abducens (CN VI)
Trigeminal - ophthalmic (CN V1) and maxillary (CN V2)

Question 16

Which artery passes through the cavernous sinus?

Answer 16

Internal carotid a

Question 17

Cavernous sinus thrombosis (CST) is a clinical condition due to spreading of infection from the nose, sinuses, ears or teeth. How might these infections spread from these regions?

Answer 17

Facial veins drain into cavernous sinus via super ophthalmic veins (from the danger triangle of the face)

Question 18

Why does cavernous sinus thrombosis (CST) result in bulging of the eyes and loss of vision?

Answer 18

Thrombosis blocks the veins so blood can’t drain out, and also causes paralysis of the nerves which pass through it, so the retina can swell up so light doesn’t get to rods and cones.

Question 19

Which artery are the posterior spinal arteries branches of?

Answer 19

Posterior inferior cerebellar arteries

Question 20

How do the anterior and posterior spinal arteries communicate?

Answer 20

Communicate freely with each other and form the internal vertebral (epidural) venous plexus lying in the epidural space.

Question 21

What structures does the internal venous plexus also communicate with?

Answer 21

Dural sinuses and veins within the skull

External vertebral venous plexus