Skull, Meninges, Ventricular System & CSF

Question 1

How many bones make up the skull?

Answer 1

22

Question 2

How is the skull split up?

Answer 2

Neurocranium (protecting brain)

Visceracranium (protecting face)

Question 3

What are the different sutures of the brain?

Answer 3

Coronal
Sagittal
Lambdoid

Question 4

What are the structures found in an infants skull that are no longer present in an adults?

Answer 4

Anterior fontanelle - closes at 18 mnths

Posterior fontanelle - closes at 3 months

Mastoid + sphenoidal fontanelle

Question 5

What is the pterion and why is this clinically important?

Answer 5

Weak spot where the parietal bone, squamous part of temporal bone and sphenoid join - middle meningeal artery lines underneath it so if it become damaged, the artery is at risk

Question 6

What bones make up the neurocranium?

Answer 6

Ethmoid 
Frontal 
Occipital
2 x parietal
Sphenoid
2 x temporal

Question 7

What bones make up the visceracranium?

Answer 7

2 of each: 
Inferior nasal concha 
Lacrimal bones 
Mandible
Maxilla 
Nasal bones 
Palatine bones 
Vomer
Zygomatic bones

Question 8

What is the difference in adult and neonatal skull appearances?

Answer 8

Neonatal skulls have a bigger calvarium and sutures are not fused in contrast to adult skulls

Question 9

What can fontanelles be used for?

Answer 9

US’s

Question 10

What is the ossification centre?

Answer 10

Where bones start to ossify so you can see radiations coming from these points e.g. in the skull

Question 11

What are the features of the flat skull bone?

Answer 11

Bone between scalp/pericardium and dura

Bone has an external and internal table with diploe in between

Question 12

What bone down the internal acoustic meatus sit in?

Answer 12

Petrous part of temporal bone

Question 13

What are the 3 cranial fossa’s?

Answer 13

1. Anterior
2. Middle
3. Posterior

Question 14

What comes out of the inferior orbital fissure?

Answer 14

CNVb comes out of this hole in the inferior part of the orbit bone

Question 15

What are the 3 meningeal layers (external to internal)?

Answer 15

1. Dura (periosteal and meningeal layer)
2. Arachnoid mater
3. Pia mater

Question 16

What are the cranial meninges continuous with?

Answer 16

Spinal meninges through the foramen magnum

Question 17

Damage to what vessel would cause a extradural haematoma?

Answer 17

Middle meningeal artery

Question 18

What would a extradural haematoma look like?

Answer 18

Lens like shape due to sutures preventing further spread

Question 19

How do you deal with brain bleeds?

Answer 19

Relieve pressure by draining it out

Question 20

Damage to what vessel would cause a subdural haematoma?

Answer 20

Bridging veins

Question 21

What would a subdural haematoma look like?

Answer 21

It would span the whole hemisphere on one side

Question 22

Damage to what vessel would cause a subarachnoid haemorrhage?

Answer 22

Cerebral arteries for e.g. due to an aneurysm

Question 23

What way could you detect a subarachnoid haemorrhage without scanning the brain?

Answer 23

Blood cells would be seen in a lumbar puncture sample as the subarachnoid space is where CSF is present

Question 24

What are dural reflections?

Answer 24

The meningeal layer of the dura forms several double-layered folds which project inwards, separating parts of the brain that help to stabilise and support CNS structures

Question 25

What dural reflections are present in the brain?

Answer 25

Falx cerebri (separates hemispheres) Tentorium cerebelli (over cerebellum) Falx cerebelli Diaphragm sellae

Question 26

What is the tentorial notch? Why is this clinically relevant?

Answer 26

Free edge of the tentorium cerebelli so this is a potential site of herniation of anything above the notch when there is raised ICP

Question 27

What are dural venous sinuses?

Answer 27

Valveless sinuses that are endothelial lined running between the 2 layers of dura mater that receive venous drainage from the cerebral cortex that goes through them ending up in the IJVs

Question 28

What are the venous sinuses?

Answer 28

``` Superior sagittal Inferior sagittal Straight Transverse Sigmoid Cavernous ```

Question 29

Where is the confluence of sinuses located?

Answer 29

connecting point of the superior sagittal, straight, and occipital sinus found deep to the occipital protuberance of the skull

Question 30

How can a boil on the forehead cause cavernous sinus thrombosis?

Answer 30

Infection can track back into the intracranial venous sinuses as the sinuses are valveless getting into the cavernous sinus and causing thrombosis as a blood clot forms to try and prevent infection spread - this can damage many CNs via compression and block important vessels

Question 31

Where is the cavernous sinus?

Answer 31

Lies laterally to the body of the sphenoid bone and sinus and pituitary fossa (pituitary gland and diaphragm sellae covering it) - also close to optic chiasm

Question 32

What is contained within the cavernous sinuses?

Answer 32

CNs III, IV, Va, Vb and VI ICA

Question 33

Where is cerebrospinal fluid (CSF) produced? What does it then do?

Answer 33

Constantly produced in the ventricular system by choroid plexus (mostly lateral ventricles) and then circulates around the CNS to protect, nourish and cushion the brain giving it buoyancy

Question 34

What route does cerebrospinal fluid (CSF) take?

Answer 34

1. From lateral ventricle through IV foramen to 3rd ventricle 2. Goes through cerebral aqueduct to get into 4th ventricle 3. Goes through lateral (x2) and median (most) apertures to get into subarachnoid space 4. Can then circulate around brain or go down central canal of spinal cord

Question 35

Where is the cerebral aqueduct?

Answer 35

Between the cerebellum and brainstem to the 4th ventricle

Question 36

What will the choroid plexus look like?

Answer 36

Fluffy appearance

Question 37

4th ventricle is continuous with _______.

Answer 37

Central canal of spinal cord

Question 38

Where is cerebrospinal fluid (CSF) reabsorbed?

Answer 38

Into dural venous sinuses and then into venous blood through superior sagittal sinus arachnoid villi/granulations

Question 39

What problems can go wrong with the ventricular system?

Answer 39

Blockage can cause a CSF build-up resulting in enlargement of the ventricles causing hydrocephalus - raised ICP, squashing structures and potentially causing herniation

Question 40

What are the common places for the ventricular system to get blocked?

Answer 40

Cerebral aqueduct will disrupt flow Arachnoid space will disrupt reabsorption

Question 41

What effect of hydrocephalus would you see in an infant but not in an adult?

Answer 41

Hydrocephaly where the head is enlarged as there bones and sutures are not fused together properly

Question 42

How do you fix a ventricular system blockage?

Answer 42

Drain the built up CSF by putting a shunt in