Session 1: Cranium, Meninges and Brain

Question 1

What is another name for the facial skeleton?

Answer 1

Visceroskeleton

Question 2

What are the main components of the visceroskeleton? How many bones make it up?

Answer 2

Made of 22 bones (excluding ossicles of the ears)

Main components:

Cranium (Vault + Base)

Facial skeleton (Viscerocranium)

Mandible

Question 3

What are the two parts of the cranium?

Answer 3

Vault and Base

Question 4

Name all the cranial bones.

Answer 4

Frontal

Parietal x 2

Temporal x 2

Occipital

Sphenoid

Ethmoid

Question 5

Name all the facial bones.

Answer 5

Mandible

Maxillary

Zygomatic

Nasal

Lacrimal

Inferior Nasal Concha

Vomer

Palatine

Question 6

What are the gaps between the bones in the skull during development called? Identify between which bones they are and when they close.

What is the name of the suture that seperated the frontal bone present in babies?

Answer 6

Fontanelles

anterior fontanelle - frontal & parietal bones (18-24 months)

posterior fontanelle- parietal and occipital bones (2-3 months)

Frontal suture (Meitopic suture)

Question 7

What is the role of the nasal conchae? What cranial bone are the superior nasal concha and middle nasal concha derived from?

Answer 7

Increase the surface area of the upper respiratory tract

Derived from the ethmoid bone

N.B. Inferior nasal concha is a facial bone.

Question 8

Give an example of a synovial joint within the skull.

Answer 8

Temporo-mandibular Joint

Question 9

What are the tough fibrous joints between bones in the skull called?

Answer 9

Sutures

Question 10

Give the names of the sutures between:

a) frontal and parietal bones
b) parietal bones
c) parietal and occipital bone

Answer 10

Coronal Suture

Sagittal Suture

Lambdoid Suture

Question 11

What is the name given to the point at which the sagittal suture meets the coronal suture?

Answer 11

Bregma

Question 12

What is the name given to the point at which the sagittal suture meets the lambdoid suture?

Answer 12

Lambda

Question 13

List the three folds of dura mater in the cranium and describe their location.

Answer 13

Falx cerebri - along the fissure between the two cerebral hemispheres

Falx cerebelli - between the two cerebellar hemispheres (seperates them)

Tentorium cerebelli - between cerebellum (seperates them) & occipital lobes

Question 14

How can the cranial base be divided?

Name the relations to the brain regions and skull bones

Answer 14

Divided by Cranial Fossae:

Anterior Cranial Fossa - frontal lobes (frontal, ethmoid + sphenoid bones)

Middle Cranial Fossa - temporal lobes ( temporal + sphenoid bones)

Posterior Cranial Fossa - cerebellum (temporal + occipital bones)

Question 15

What are the three layers of the meninges?

Answer 15

Dura mater (Periosteal and meningeal)

Arachnoid mater

Pia mater

Question 16

What are the two layers of dura in the cranium?

Answer 16

Periosteal (outer layer) and Meningeal (inner layer)

Question 17

Which layer of the meninges goes in and out of the sulci?

Answer 17

Pia Mater

Question 18

What difference between the cranial dura and spinal dura allows for an epidural space?

Answer 18

At the foramen magnum the dura goes from having two layers (periosteal and meningeal) to just one layer (equivalent of the meningeal layer). This means that there is an epidural space sorrounding the spinal cord.

Question 19

How is CSF drained into circulation?

Answer 19

CSF drains into dural venous sinuses via the arachnoid granulation villi

Question 20

Describe the arrangement of dural venous sinuses and the direction of blood flow.

How many veinous sinuses and where are they located?

Answer 20

11 dural venous sinuses, located between the periosteal and meningeal layers of the dura mater.

Superior sagittal sinus - located along the top of falx cerebri

Inferior sagittal sinus - along bottom of falx cerebri

The inferior sagittal sinus and great cerebral vein of Galen drain into straight sinus.

The straight sinus + superior sagittal + occipital sinus all drain into the confluence

Confluence drain through right and left transverse sinuses into to right and left sigmoid sinuses which drain into right and left internal jugular veins

Cavernous sinuses (R&L) drain into superior petrosal sinuses (both right and left) which drain into the sigmoid sinuses.

Cavernous sinuses can also drain into inferior petrosal sinuses which drain directly into the internal jugular veins.

Cavernous sinuses drain from right and left pterygoid plexi, superior and inferior ophthalmic veins. Anterior and posterior intracavernous sinuses connect right and left cavernous sinuses

Question 21

What flat sheet of dura (with a small hole in it) keeps the pituitary gland in the sella turcica?

Answer 21

Diaphragma sellae

Question 22

List three different types of brain herniation and their consequences.

Answer 22

Subfalcine herniation – cingulate gyrus [The gyrus sorounding the corpus callosum (of frontal lobe) goes under falx cerebri

Uncal/transtentorial/uncinate – inner part of temporal lobe (uncus) goes under tentorium cerebelli. This affects the midbrain and can cause pupil/vision problems and unconsciousness

Tonsilar herniation – cerebellar tonsils go through foramen magnum. This can affect medulla and cause cardiorespiratory failure

Question 23

Which two main vessels supply the circle of Willis?

Answer 23

Vertebral arteries and internal carotid arteries

Question 24

There is a weak point in the skull behind which you find the largest artery entering the skull. Name the part of the skull in question and the artery. Explain the clinical significance of this

Answer 24

Pterion: Region where the frontal, parietal, sphenoid and temporal bones meet.

Behind this area of the skull you find the middle meningeal artery.

Therefore if there is trauma to the pterion, it may result in rupturing of the middle meningeal artery and cause an extradural haemorrhage.

Question 25

What are emissary veins and what is their clinical relevance?

Answer 25

Drain blood from scalp (outside of skull) into superior sagittal sinus via parietal foramina. Provide an entry route for infections to enter intracranial space

Question 26

Which veins drain into the cavernous sinus?

Answer 26

Superior and inferior ophthalmic veins There is also communication with the pterygoid plexus

Question 27

Which vein is joined to the end of the straight sinus at the pointwhere the inferior sagittal sinus joins the straight sinus?

Answer 27

Great cerebral vein

Question 28

What is the pterygoid plexus and where is it located?

Answer 28

A venous plexus of considerable size Is situated between the temporalis muscle and lateral pterygoid muscle, and partly between the two pterygoid muscles

Question 29

In between which dural layers do you find venous sinuses? Also where do you find diploic veins

Answer 29

Venous sinuses are found between periosteal and meningeal layers of dura mater Diploic veins are found between inner and outer parts of compact bone of the skull (within the skull bone) and drain into venous sinuses

Question 30

Name three structures found within the cavernous sinus.

Answer 30

Internal carotid artery Various cranial nerves (occulomotor, trochlear, trigeminal [ophthalmic and maxillary divisions] and abducens) Pituitary Gland

Question 31

What are the different tissue layers of the scalp? What is the clinical importance of a laceration there?

Answer 31

Skin Connective Tissue Aponeurosis Loose Areolar Tissue Periosteum (vascular connective tissue enveloping all bones) Laceration to the heavily perfused scalp (by external carotid + ophthalmic branches) will lead to profuse haemorrhage due to the dense connective tissue keeping the cut vessels open

Question 32

What is the tentorial notch and what is its clinical significance?

Answer 32

Triangular opening in the tentorium cerebelli through which the brainstem extends downwards Increased intracranial pressure can cause part of the temporal lobe to be pushed through this opening, this is known as a uncal/temporal herniation.

Question 33

Which major arteries pass through the foramen magnum?

Answer 33

Vertebral arteries

Question 34

List all the cranial foramina

Answer 34

Cribriform plate Optic canal Superior orbital fissure Foramen rotundum Foramen ovale Foramen spinosum Foramen lacerum Internal Acoustic Meatus Jugular Foramen Hypoglossal Canal

Question 35

List the three branches of the trigeminal nerve and the foramina through which they pass

Answer 35

Ophthalmic – Superior Orbital Fissure Maxillary – Foramen Rotundum Mandibular – Foramen Ovale

Question 36

Which artery passes through the optic canal?

Answer 36

Ophthalmic Artery

Question 37

Which vessels passes through the superior orbital fissure?

Answer 37

Superior Ophthalmic Vein Inferior Ophthalmic Vein

Question 38

Which vessels pass through the foramen spinosum?

Answer 38

Middle meningeal artery Middle meningeal vein

Question 39

Which foramen does the internal carotid artery pass through?

Answer 39

Carotid Canal

Question 40

Which vessel passes through the internal acoustic meatus?

Answer 40

Labyrinthine Artery

Question 41

Which vessel passes through the jugular foramen?

Answer 41

Sigmoid Sinus --\> Internal Jugular Vein

Question 42

Which foramen do the spinal roots of the accessory nerve pass through?

Answer 42

Foramen Magnum

Question 43

Besides the emissary veins, name another vein that can provide entry for infections from the outside into the cranium

Answer 43

Facial vein connects with the cavernous sinus

Question 44

Which cranial nerves pass through the cribriform plate?

Answer 44

Olfactory nerve CN 1

Question 45

Which cranial nerve passes through the optic canal?

Answer 45

Optic nerve CN II

Question 46

What cranial nerves pass through the superior orbital fissure?

Answer 46

Occulomotor Trochlear Opthalmic nerve (Trigeminal V₁)

Question 47

What cranial nerve passes through the foramen rotundum?

Answer 47

Maxillary nerve (Trigeminal V₂)

Question 48

What cranial nerve passes through the foramen ovale?

Answer 48

Mandibular nerve (Trigeminal V₃)

Question 49

What cranial nerves pass through the internal acoustic meatus?

Answer 49

Facial nerve VII Vestibulocochlear nerve VIII

Question 50

What cranial nerves pass through the jugular foramen?

Answer 50

Glossopharyngeal nerve CN IX Vagus nerve X Accessory nerve XI

Question 51

How does the hypoglossal nerve pass through the skull?

Answer 51

Passes through via the hypoglossal canal