cranium, meninges and brain

Question 1

causes of herniation; give 3 types of cerebral herniation (superior to inferior)

Answer 1

space occupying lesion caused by blood, tumour, oedema, cyst in any compartment causing raised intracranial pressure and leading to herniation; subfalcine, transtentorial, tonsillar

Question 2

subfalcine herniation

Answer 2

cingulate gyrus from one hemisphere to the other, under the falx cerebri (push brain through underneath falx cerebri); not usually clinically significant

Question 3

transtentorial herniation

Answer 3

medial temporal lobe from the middle into the posterior fossa, across the tentorial opening (uncus of temporal lobe forced into gap between midbrain and edge of tentorium); pushes temporal lobe towards brainstem, so causes unconsciousness

Question 4

tonsillar herniation

Answer 4

compression of pons against clivus, causing displacement of cerebellar tonsils into foramen magnum (cerebellum enters foramen magnum); affects medulla causing cardiorespiratory failure

Question 5

arterial blood supply of cranium

Answer 5

circle of Willis

Question 6

circle of Willis

Answer 6

bilateral vertebral arteries (with small branches posteriorly to form bilateral anterior spinal arteries and bilateral posterior inferior cerebellar arteries) -> unilateral basillar artery (with bilateral anterior inferior cerebellar arteries bifurcating off at anastomosis, and with 5 bilateral pontine arteries leaving throughout) -> at anterior of basillar artery, split into bilateral superior cerebellar artery inferiorly and bilateral posterior cerebral artery superiorly -> bilateral posterior communicating arteries join bilateral middle cerebral arteries, which have anterior choroidal artery and opthalmic artery splitting off before becoming bilateral internal carotid arteries -> bilateral anterior cerebral arteries join anteriorly by unilateral anterior communicating artery

Question 7

what are dural venous sinuses

Answer 7

venous channels found between periosteal and meningeal layers of dura mater

Question 8

diagram of dural venous sinuses (including relevant vessels)

Answer 8

Question 9

diagram of cavernous sinus (lateral to pituitary gland)

Answer 9

• important as many structures associated with it, so bleeds in them can affect many cranial nerves travelling through it (largely to eye and front of face)

Question 10

diagram of sites of herniation

Answer 10

1. subfalcine herniation
2. transtentorial (uncal) herniation
3. tonsillar herniation

Question 11

what artery goes inside cranial cavity and supplies meninges, and significance of pterion fracture (pterion is where frontal, parietal, temporal and sphenoid bones join together, on side of skull, just behind temple)

Answer 11

middle meningeal artery, and if pterion fracture, large epidural bleed can occur

Question 12

what do dural venous sinuses receive blood from, and what do they drain into

Answer 12

receive blood from cerebral veins before draining into internal jugular vein before passing through neck and joining brachiocephalic vein

Question 13

other diagram of dural venous sinuses

Answer 13

• emissary veins important as traverse from outside of skull to inside of cranial cavity (vulnerable to infection)

Question 14

coronal section through hypothalamus

Answer 14

Question 15

horizontal section

Answer 15