Skull & meninges

Question 1

How many bones make up the skull?

Answer 1

22

Question 2

What are the divisions of the skull?

Answer 2

1. Cranial vault: Space in which brain is located
2. Facial skeleton: Anterior part of skull making up face
3. Base: Contains the floor of the cranial cavity

Question 3

What are the bones making up the cranial vault?

Answer 3

Unpaired:

1. Ethmoid
2. Frontal
3. Sphenoid
4. Occipital

Paired:

1. Temporal
2. Parietal

Question 4

What are the features of the ethmoid bone?

Answer 4

• Cribriform plate
• Crista galli
• Perpendicular plate
• Superior/middle conchae
• Ethmoid air cells

Question 5

What are the features of the frontal bone?

Answer 5

• Air sinuses
• Superciliary arch
• Supra-orbital notch

Question 6

What are the features of the sphenoid bone?

Answer 6

• Greater/lesser wings
• Medial/lateral pterygoid plates
• Sella turcica
• Optic canal
• Superior orbital fissure
• Foramen rotundum
• Foramen ovale
• Foramen spinosum

Question 7

What are the features of the occipital bone?

Answer 7

• Squamous part
• Basal part
• Hypoglossal canals
• Foramen magnum
• Occipital condyles
• Internal/external occipital protuberances
• Superior nuchal line

Question 8

What are the features of the temporal bones?

Answer 8

• Squamous part (zygomatic process, mandibular fossa)
• Petromastoid part (middle/inner ear, internal auditory meatus, facial canal, air cells)
• Tympanic part (External auditory meatus, attachment of tympanic membrane)
• Styloid part (attachment of muscles and ligaments)

Question 9

What are the features of the parietal bones?

Answer 9

• Contains foramina for emmisary veins connecting scalp veins to dural venous sinuses

Question 10

What is the pterion?

Answer 10

Point on lateral aspects of the skull where several bones meet, including:

1. Parietal
2. Temporal
3. Frontal
4. Sphenoid (greater wings)

Question 11

What are the 3 divisions of the cranial cavity?

Answer 11

1. Anterior cranial fossa
2. Middle cranial fossa
3. Posterior cranial fossa

Question 12

What are the prominent features of the anterior cranial fossa?

Answer 12

1. Cribriform plate (of ethmoid)
2. Crista galli

Question 13

Which part of the brain lies within the ACF?

Answer 13

Frontal lobe

Question 14

What are the prominent features of the middle cranial fossa?

Answer 14

1. Sella turcica (clinoid processes + pituitary fossa)
2. Foramina

Question 15

What are the foramina in the middle cranial fossa?

Answer 15

1. Superior orbital fissure
2. Foramen rotundum
3. Foramen ovale
4. Foramen spinosum
5. Foramen lacerum

(Ant. → Post.)

Question 16

Which part of the brain lies within the middle cranial fossa?

Answer 16

Temporal lobe

Question 17

What are the prominent features of the posterior cranial fossa?

Answer 17

1. Clivus
2. Internal occipital protuberance

Question 18

What are the foramina in the posterior cranial fossa?

Answer 18

1. Interal acoustic meatus
2. Juglar foramen
3. Foramen magnum
4. Hypoglossal canal

Question 19

Which part of the brain lies within the posterior cranial fossa?

Answer 19

• Cerebellum
• Brainstem

Question 20

What are the layers of meninges?

Answer 20

1. Pia mater
2. Arachnoid mater

3 Dura mater

Question 21

What are the 2 layers of dura mater?

Answer 21

• Endosteal layer: Intimitely associated with with the periosteum of the skull.
• Meningeal layer: Intimitely associated with the arachnoid mater.

Question 22

What are the differences between cranial and spinal cord pia?

Answer 22

• Cranial pia is thinner than its spinal cord counterpart.
• Cranial pia is only loosely attached to surface of brain instead of tightly.

Question 23

What are the differences between cranial and spinal cord arachnoid mater?

Answer 23

Cranial arachnoid is thicker than its spinal cord equivalent.

Question 24

What are the different dural folds?

Answer 24

1. Falx cerebri: Between 2 cerebral hemispheres
2. Tentorium cerebelli: Between cerebellum and cerebral hemispheres
3. Falx cerebelli: Between 2 lobes of cerebellum
4. Diaphragma sella: Covers sella turcica and pituitary fossa

Question 25

What are the different meningeal spaces in the cranial vault?

Answer 25

- Real spaces: 1. Subarachnid space: Contains CSF and arteries 2. Spinal epidural space: Contains loose connective tissue, venous plexuses and lymphatics - Potential spaces: 1. Cranial epidural space 2. Subdural space

Question 26

How is the subarachnoid space formed?

Answer 26

- The pia mater is intimitely associated with the surface of the brain and follows into every sulcus. The arachnoid mater on the other hand, is not. - Spaces form between 2 layers when pia follows brain into sulcus. - Large CSF-filled spaces between 2 layers over large sulci are called cisterns.

Question 27

Where does the subarachnoid space end?

Answer 27

Second sacral vertebrae (termination of lumbar cistern)

Question 28

What are the differences between cranial dura and spinal cord dura?

Answer 28

Cranial dura consists of 2 layers while spinal cord dura contains only 1 (contination of meningeal layer)

Question 29

Where does the dural sac and filum terminale terminate?

Answer 29

S2