P7: Cranial Cavity, dura and dural sinuses

Question 1

What is the calvaria?

Answer 1

Superior part of neurocranium

Question 2

Which bones comprise the calvaria?

Answer 2

Parts of the frontal, occipital and the two parietal bones.

Question 3

What runs in the groove on the midline of the inferior surface of the calvaria?

Answer 3

The superior sagittal sinus.

Question 4

What are the foveolae lateral to the midline groove in which the superior sagittal sinus runs, and what causes them (all of this is located on the inferior surface of the calvaria)

Answer 4

Pits caused by arachnoid granulations/villi lateral to the superior sagittal sinus.

Question 5

On the inferior surface of the calvaria, there are grooves which run laterally from the groove in which the superior sagittal sinus runs. What runs in these grooves?

Answer 5

Middle meningeal arteries and accompanying veins.

Question 6

Where are the parietal foramina located in the calvaria, and what runs through them? What is their clinical significance?

Answer 6

2-3cm anterior to the lambda. They transmit emissary veins from the scalp to the superior sagittal sinus. They can be a route for spread of infection.

Question 7

What are the three sections of the cranial floor?

Answer 7

Anterior, middle and posterior fossae.

Question 8

What separates the anterior and middle fossae of the cranial floor from each other?

Answer 8

Lesser wing of the sphenoid bone.

Question 9

What separates the middle and posterior fossae of the cranial floor from each other?

Answer 9

Petrous part of the temporal bone.

Question 10

Which bones contribute to the anterior cranial fossa?

Answer 10

Frontal, ethmoid and sphenoid bones. Most of it is formed by the orbital plates of the frontal bone. Ethmoid bone has the crista galli and posteriorly the cribriform plate.

Question 11

What acts as the room of the nasal cavity and orbit?

Answer 11

Anterior cranial fossa

Question 12

The crista galli projects superiorly from the cribriform plate of the ethmoid bone. What attaches do it?

Answer 12

Falx cerebri (midline projection of dura)

Question 13

Where does the flax cerebri attach to in the anterior cranial fossa?

Answer 13

Crista galli of ethmoid bone inferiorly, superiorly the frontal crest of the frontal bones

Question 14

Which foramen lies between the crista galli and frontal crest? To where does it lead?

Answer 14

The foramen caecum leads into the nasal cavity.

Question 15

What passes through the numerous small foramina of the cribriform plate of the ethmoid bone?

Answer 15

Sensory neurons from the olfactory mucosa to the olfactory bulb.

Question 16

What is contained within the middle cranial fossa?

Answer 16

Temporal lobes of the brain and the pituitary gland.

Question 17

Which bones contribute to the middle cranial fossa?

Answer 17

Sphenoid and temporal bones.

Question 18

Where is the anterior clinoid process?

Answer 18

It is a projection from the sphenoid bone. It projects posteriorly between the lesser wing of the sphenoid and the body of the sphenoid. Anteromedially to it is the optic canal.

Question 19

What passes through the optic canal into the orbit?

Answer 19

Opthalmic artery (from internal carotid) and optic nerve (CNII)

Question 20

What feature of the skull is located between the two optic canals?

Answer 20

Prechiasmatic groove - the anterior end of this groove is the boundary of the anterior and middle fossae medially.

Question 21

What is the sella turca?

Answer 21

This is the body of the sphenoid bone, and forms the medial part of the middle cranial fossa.

Question 22

What is the central depression in the sella turca called?

Answer 22

Hypophyseal fossa

Question 23

What is housed in the hypophyseal fossa?

Answer 23

The pituitary gland

Question 24

What is the diaphragm sellae?

Answer 24

It is a projection of the dura which stretches over the hypophyseal fossa except for a small gap through which the infundibular stalk of the pituitary gland passes through.

Question 25

Relative to the sella turca, where is the carotid sulcus located? What does it contain?

Answer 25

Inferolaterally. Internal carotid artery.

Question 26

How does the internal carotid artery enter the cranial cavity?

Answer 26

Through the carotid canal/foramen (NOT lacerum even though it looks very close to it)

Question 27

Which cranial nerves are closely associated with the cavernous sinus?

Answer 27

Oculomotor, trochlear, abducens, and V1, V2.

Question 28

Describe the course of the internal carotid artery relative do the cavernous sinus

Answer 28

It passes through it from posterior to anterior.