Blood supply of the head & neck

Question 1

What are the venous sinuses?

Answer 1

Spaces between the otherwise closely adhered 2 layers of dura mater lined with vascular endotherlium into which superficial cerebral veins drain.

Question 2

What is the network of venous sinuses in the brain?

Answer 2

Question 3

What structure(s) are associated with the superior saggital sinus and where does it drain?

Answer 3

• Associated structure: Superior margin of the falx cerebri.
• Drains into: Right transverse sinus

Question 4

What structure(s) are associated with the inferior saggital sinus and where does it drain?

Answer 4

• Associated structure: Inferior margin of the falx cerebri.
• Drains into: Straight sinus.

Question 5

What structure(s) are associated with the straight sinus and where does it drain?

Answer 5

• Associated strucure: Junction of falx cerebri and tentorium cerebelli.
• Drains into: Left transverse sinus.

Question 6

What structure(s) are associated with the transverse sinuses and where does it drain?

Answer 6

• Associated structures: Lateral margins of tentorium cerebelli.
• Drains into: Sigmoid sinus.

Question 7

What structure(s) are associated with the sigmoid sinus and where does it drain?

Answer 7

• Associated structure: Petrous temporal bone, with mastoid air cells lying lateral.
• Drains into: Internal jugular vein.

Question 8

What structure(s) are associated with the cavernous sinus and where does it drain?

Answer 8

• Associated structure: Body of sphenoid bone.
• Drains into: Superior & inferior petrosal sinuses.

Question 9

What are the structures associated with the superior petrosal sinus?

Answer 9

• Associated structure: Anterior edge of tentorium cerebelli.
• Drains into: Transverse sinuses.

Question 10

What structure(s) are associated with the inferior petrosal sinus and where does it drain?

Answer 10

• Associated structure: Between occipital and petrous temporal bones.
• Drains into: Internal jugular vein.

Question 11

What are the structures associated with the cavernous sinus?

Answer 11

• Running through:
  1. Internal carotid artery
  2. Abducent nerve [VI]
• In lateral walls:
  1. Oculomotor nerve [III]
  2. Trochlear nerve [IV]
  3. Opthalmic (V₁) & maxillary (V₂) divisions of trigeminal nerve [V]

Question 12

Where does the spinal cord begin and end?

Answer 12

• Beginning: Foramen magnum
• Ending: L1 (conus medullaris)

Question 13

Why is the course of the ICA tortuous?

Answer 13

To reduce pressure of blood entering cerebral arteries, which are narrow and fragile.

Question 14

What is the course of the ICA?

Answer 14

1. Enters carotid foramen at base of skull.
2. Right-angled turn in anteromedial direction towards apex of petrous temporal bone.
3. Right-angled turn in superior direction into cavernous sinus.
4. After it pierces the cavernous sinus, it gives off the opthalmic artery.
5. Enters subarachnoid space and turns backwards at optic chiasm.
6. Turns to travel superiorly at the posterior clinoid process, giving off the anterior and middle cerebral arteries.

Question 15

What are the branches of the ECA?

Answer 15

• Superficial temporal artery
• Ascending pharyngeal artery
• Lingual artery
• Facial artery
• Occipital artery
• Posterior auricular artery
• Maxillary artery
• Superior thyroid artery

(Some Anatomists Like Freaking Out Poor Medical Students)

Question 16

What is significant about the venous drainage of the brain?

Answer 16

No veins run with the arteries. Instead, they drain into the dural venous sinuses separately and then eventually into the internal jugular vein.

Question 17

What are the main sources of arterial supply to the brain?

Answer 17

• Internal carotid artery (ICA, anterior cerebral circulation)
• Vertebral arteries (posterior cerebral circulation)

Question 18

What are the branches of the ICA?

Answer 18

1. Anterior cerebral artery (ACA)
2. Middle cerebral artery (MCA)

Question 19

What does the ACA supply?

Answer 19

• Medial aspects of frontal lobe
• Medial aspects of parietal/occipital lobe
• Medial aspects of motor/somatosensory cortex supplying lower limbs.

Question 20

What does the MCA supply?

Answer 20

• Basal ganglia
• White matter
• Motor/somatosensory cortex supplying the upper limbs/head and neck
• Internal capsule

Question 21

What are the branches of the vertebral artery?

Answer 21

1. Posterior inferior cerebellar artery (PICA)
2. Anterior & posterior spinal arteries

Question 22

At what level does the basilar artery form?

Answer 22

Junction between medulla and pons

Question 23

What are the branches of the basilar artery?

Answer 23

1. Posterior cerebral artery (PCA)
2. Anterior infereior cerebellar artery (AICA)
3. Superior cerebellar artery
4. Pontine arteries

Question 24

What does the PCA supply?

Answer 24

• Occipital lobe
• Infero-posterior surface of temporal lobe

Question 25

How is the circle of willis formed?

Answer 25

• ACA connected to each other by the anterior communicating artery.
• ICA/MCA connected to the posterior cerebral arteries by the posterior communicating arteries.

Question 26

What is the nature of venous drainage of the brain?

Answer 26

• Superficial veins → Venous sinuses
• Deep veins → Great cerebral vein

Question 27

Where are the major blood vessels supplying the brain mostly located?

Answer 27

Subarachnoid space

Question 28

Where does the common carotid artery bifurcate?

Answer 28

Upper border of thyroid cartilage

Question 29

What is the middle meningeal artery and its clinical significance?

Answer 29

• It is a branch of the maxillary artery.
• It enters skull through foramen spinosum.
• It bifurcates into anterior and posterior branches.
• Anterior branch runs deep to the pterion, where it can be torn in skull fracture of that area.