Session 1: Cranium, Meninges and Brain

Question 1

How many bones are there in the skull?

Answer 1

22 (excl. ossicles of the ear)

Question 2

What are the components of the skull?

Answer 2

• Mandible
• (Neuro)Cranium: made up of vault and base
• Viscerocranium

Question 3

What are the bones of the cranium?

Answer 3

• frontal
• parietal (2x)
• temporal(2x)
• occipital (2x)
• ethmoid
• sphenoid

Question 4

What are the facial bones of the skull?

Answer 4

• maxilla (2x)
• zygoma (2x)
• nasal (2x)
• lacrimal (2x)
• vomer
• inferior conchae (2x)
• palatine (2x)
• mandible

Question 5

What are sutures in the skull?

Answer 5

fibrous joints permitting little or no movement.

Question 6

What are the 2 openings in the skulls of newborns called? When do they close?

Answer 6

• anterior fontanelle (closes between 18-24 months of age)

- posterior fontanelle (closes during the first 2-3 months)

Question 7

What are the skull sutures called?

Answer 7

• coronal suture
• sagittal suture
• lambdoid suture

Question 8

Are the fontanelles easy to damage?

Answer 8

• no, contrary to popular belief

- there is tough fibrous tissue

Question 9

What is one of the “functions” of the fontanelles?

Answer 9

• the skull bones have to move as the baby passes through the birth canal
• this is aided by the fact that the bones are not fused.

Question 10

What are the intersections of the coronal sutures called?

Answer 10

• bregma (coronal and sagittal)

- lambda (sagittal and lambdoid)

Question 11

Which bone is the external acoustic meatus located in?

Answer 11

Temporal bone

Question 12

What is the inion?

Answer 12

• It is a protrusion on the posterior part of the skull.

- It is bigger in males than it is in females

Question 13

What are the occipital condyles?

Answer 13

• They sit on the C1 vertebra

- allow nodding of head

Question 14

What are the parts of the base of the skull?

Answer 14

• anterior cranial fossa
• middel cranial fossa
• posterior cranial fossa

Question 15

what sits in the posterior cranial fossa?

Answer 15

Cerebellum

Question 16

What is ‘ventral’ in neuroanatomy?

Answer 16

inferior

Question 17

What are the main parts of the anterior cranial fossa?

Answer 17

• orbital part of the frontal bone
• spehnoid
• cribriform plate containing foramina

note: there are 2 depressions in the frontal lobe because it sits in the orbital part of the frontal bone where the eyes are, bone is curved because eyes are underneath.

Question 18

What bones make up the middle cranial fossa?

Answer 18

• sphenoid bone
• temporal bone
• parietal bone
• foramina

Question 19

Where is the foramen magnum located?

Answer 19

in the posterior cranial fossa

Question 20

What bones make up the posterior cranial fossa?

Answer 20

• occipital bone
• temporal bone
• pariteal bone
• foramen magnum
• other foramina

Question 21

Approximately, in what order are the cranial nerves positioned?

Answer 21

From 1 to 12 from rostral to caudal

Question 22

What passes through the cribriform plate?

Answer 22

• olfactory nerve fibres

- ‘‘cribriform’’ = lat. ‘‘perforated’’ (cribrum = sieve)

Question 23

What passes through the optic canal?

Answer 23

• Optic nerve (including central artery of retina)

- ophthalmic artery

Question 24

What passes through the superior orbital fissure?

Answer 24

• Oculomotor (III)
• trochlear (IV)
• ophthalmic div. of V (V1)
• abducent (VI)
• sup ophthalmic vein

Question 25

What passes through the foramen rotundum?

Answer 25

- maxillary division of V (V2)

Question 26

What passes through the foramen ovale?

Answer 26

- mandibular division of V (V3)

Question 27

What passes through the foramen lacerum; spehnopetrosal fissure?

Answer 27

- internal carotid artery

Question 28

What passes through the foramen spinosum?

Answer 28

- Middle meningeal artery & vein

Question 29

What passes through the carotid canal, internal aperture?

Answer 29

- internal carotid artery

Question 30

What passes through the internal acoustic meatus?

Answer 30

- facial (VII) - vestibulocochlear (VIII) - labyrinthine artery

Question 31

What passes through the jugular foramen?

Answer 31

- Glossopharyngeal (IX) - Vagus (X) - Accessory n (XI) - sigmoid sinus → int jugular v

Question 32

What passes through the hypoglossal canal?

Answer 32

- Hypoglossal nerve (XII)

Question 33

What passes through the foramen magnum?

Answer 33

- Vertebral arteries - medulla of brain - spinal roots of accessory nerve

Question 34

What are the layers of meninges?

Answer 34

- dura mater - arachnoid mater - pia mater

Question 35

What are the qualities of the dura mater?

Answer 35

- thick - inelastic - 2 layers (meningeal and periosteal)

Question 36

What are the qualities of the arachnoid mater?

Answer 36

- elastic | - spider like projections

Question 37

What are the qualities of Pia mater?

Answer 37

- innermost - thin - delicate layer

Question 38

What space is filled with CSF?

Answer 38

the subarachnoid space

Question 39

What are the differences regarding epidural space in the brain and in the vertebral column?

Answer 39

- lack of epidural space in the brain - large epidural space in the vertebral column -> correct?

Question 40

What happens as the meninges exit through the foramen magnum?

Answer 40

- the outermost layer is lost, it fuses with the skull | - inner layer (meningeal) of dura continues down the vertebral column

Question 41

What is the purpose of dural folds?

Answer 41

- prevent movement of the brain | - provide spaces where blood can drain back into the venous system.

Question 42

Where does the inner layer of the dura mater peel away?

Answer 42

e. g. - down the longitudinal fissure - provide spaces where blood can drain back into the venous system

Question 43

What is the falx cerebra?

Answer 43

- main dural fold - sickle shaped double layer - at the top: superior sagittal sinus

Question 44

What is the superior sagittal sinus?

Answer 44

- runs along the midline on the superior part of the brain - where veins drain into the venous system to drain into the jugular veins - it is penetrated by the arachnoid mater so that the CSF can be reabsorbed into the venous system before the jugular

Question 45

What is the downside of the sheets?

Answer 45

- if there is a space occupying lesion (e.g. tumor, blood, oedema, cyst) in any compartment it can raise IC pressure and lead to herniation of part of the brain

Question 46

Subfalcine herniation

Answer 46

not usually clinically significant

Question 47

Uncal herniation

Answer 47

- affects midbrain | => unconsciousness

Question 48

Tonsillar herniation

Answer 48

- affects medulla | => cardiorespiratory failure

Question 49

Blood supply to the meninges

Answer 49

- rich blood supply | - Middle meningeal artery (MMA) inside the cranial cavity, supplies the meninges

Question 50

MMA

Answer 50

- middle meningeal artery - branches off of the maxillary artery which itself branches off of the external carotid - runs along the pterion -> if that is fractured a large epidural bleed could occur

Question 51

Pterion

Answer 51

- region where the frontal, parietal, temporal, and sphenoid bones join together - fragile, thin bone - if this area is fractured a large epidural bleed with disastrous consequences could occur

Question 52

Why can infections outside (e.g. scalp) sometimes get into the cranial cavity?

Answer 52

- there are veins that traverse to outside of the skull to the cranial cavity - some parts of skull and face drain not via the system external to the cranial cavity but internal to the cranial cavity => infections on the outside can sometimes get inside the cranial cavity

Question 53

Confluence of sinuses

Answer 53

- connecting point of the superior sagittal sinus, straight sinus, and occipital sinus -

Question 54

Cavernous sinus

Answer 54

- clinically relevant because bleeds in the cavernous sinus can affect many cranial nerves