Cranial foramina and meninges

Question 1

Where are cranial foramina found?

Answer 1

At the base of the skull in cranial fossae which forms the floor of the cranial cavity

Question 2

What are the divisions of the cranial fossae, and what bones make up these fossae?

Answer 2

1.Ant. cranial fossa - frontal bone, sphenoid (lesser wing and body), and ethmoid bone.

2. Middle cranial fossa- Temporal bone and sphenoid bone (greater wing and sella turcica)
3. Posterior crania fossa -Temporal and occipital bones + small contributions frm the sphenoid and parietal bones

Question 3

List the cranial nerves

Answer 3

Olfactory I
Optic II
Oculomotor III
Trochlear IV
Trigeminal V
Abducens VI
Facial VII
Vestibulochochlear VIII
Glossopharyngeal IX
Vagus X
Accessory (XI)
Hypoglossal (XII)

Question 4

Name the foramina found in the ant. cranial fossa, their exact location and contents

Answer 4

Olfactory foramina - found in the cribriform plate of the ethmoid bone and contains CN-I

Question 5

List the cranial foramina found in the middle cranial fossa

Answer 5

Optic canal
Superior orbital fissure
Foramen rotundum
Foramen ovale
Foramen spinosum
Foramen lacerum

Question 6

Describe the optic canal in terms of its location and contents

Answer 6

Located in the sphenoid bone
Contains CN-II and ophthalmic artery

Question 7

Describe the sup. orbital fissure in terms of its location and contents

Answer 7

Located between the greater and lesser wings of the sphenoid bone.
Contents: CNIII, CNIV
CN V1 (Ophthalmic division),
CNVI

Question 8

Describe the foramen rotundum in terms of its location and contents

Answer 8

Located on the greater wings of the sphenoid bone
Contents: CN V2 (Maxillary division of trigeminal

Question 9

Describe the foramen ovale in terms of its location and contents

Answer 9

Located on the greater wings of the sphenoid bone
Contents: CN V3 (Mandibular division of the trigeminal nerve) and Accessory meningeal artery

Question 10

Describe the foramen spinosum in terms of its location and contents

Answer 10

Located on the greater wings of the sphenoid bone
Contents: Middle meningeal artery and vein

Question 11

Describe the foramen lacerum in terms of its location and contents

Answer 11

Located at the junction of temporal, sphenoid, and occipital bones
Contents: Deep petrosal nerve, internal carotid artery, and greater petrosal nerve.

Question 12

List the foramina found in the posterior cranial fossa

Answer 12

Internal accoustic meatus
Jugular foramen
Hypoglossal canal
Foramen magnum

Question 13

Describe the internal accoustic meatus in terms of its location and contents

Answer 13

Located on the greater wings of the sphenoid bone
Contents: CN VII ( Facial nerve) and CN VIII (Vestibulocochlear nerve)

Question 14

Describe the jugular foramen in terms of its location and contents

Answer 14

Located at the junction of temporal and occipital bones
Contents: CN IX (Glossopharyngeal nerve), CN X (Vagus nerve) and CN XI (Accessory nerve)

Question 15

Describe the Hypoglossal canal in terms of its location and contents

Answer 15

Located on the occipital bones
Contents: CN XII (Hypoglossal nerve)

Question 16

Describe the foramen magnum in terms of its location and contents

Answer 16

Located on the occipital bones
Contents: CN XI (Accessory nerve), meninges, vertebral and spinal arteries, and medulla oblongata

Question 17

What is the function of meninges?

Answer 17

Stabilize the shape and position of the central nervous system.

Question 18

Name the 3 layers of the meninges

Answer 18

Dura mater
Arachnoid mater
Pia mater

Question 19

Which layer is adherent to the brain?

Answer 19

Pia mater

Question 20

Which layer is made up of periosteal/endosteal and meningeal layer?

Answer 20

Dura mater

Question 21

Which layer is the intermediate layer?

Answer 21

Arachnoid mater

Question 22

What is another name of the dura mater?

Answer 22

Pachymeninx

Question 23

Describe the outer endosteal/periosteal layer of the dura mater

Answer 23

Serves as the periosteum on the cranial inner surface
It adheres tightly to the inner meningeal layer.
There is no clear boundary
Except at the sinuses

Question 24

Describe the two spaces that exist around the dura mater

Answer 24

Epidural (Extradural) space lies between the cranium and periosteal layer
Subdural space between inner meningeal layer and arachnoid mater

Question 25

Describe the inner meningeal layer

Answer 25

Separates from the periosteal layer and protrudes into the cranial cavity Separation creates double-layered dural folds

Question 26

What is another name for dural folds?

Answer 26

Dural reflections/septa

Question 27

List and describe the 4 types of dural folds

Answer 27

Falx cerebri - Sickle-shaped fold between cerebral hemispheres Falx cerebelli - Partially extends between cerebellar hemispheres Tentorium cerebelli - Horizontal fold between the cerebrum and cerebellum Diaphragma sellae - overlies pituitary fossa- Allows infundibulum of the pituitary gland through

Question 28

Explain what dural venous sinuses are and their location

Answer 28

They are spaces into which cerebral veins drain. Located where dural layers separate. Location of each sinus determined by dural fold attachment

Question 29

The ____________________sinus is located on the attached edge of the falx cerebri. It runs from ant. to post. along the____________________ plane.

Answer 29

Superior sagittal sinus Midsagittal plane

Question 30

Where does the sup. sag. sinus drain? and what does it drain?

Answer 30

Posteriorly drains into the confluence of sinuses Drains veins draining the brain and cerebrospinal fluid

Question 30

Ant. relation of the superior sagittal sinus

Answer 30

Foramen caecum

Question 31

Which dural venous sinus is found on the free edge of the falx cerebri?

Answer 31

Inf. Sag. sinus

Question 32

Where does it drain and what does it drain?

Answer 32

Posteriorly drains into the straight sinus Drains veins draining the brain and cerebrospinal fluid

Question 33

Where is the straight sinus found?

Answer 33

Located at the junction of the falx cerebri and tentorium cerebelli

Question 34

What does the straight drain and where does it drain?

Answer 34

Drains the cerebral, great cerebral, superior cerebellar veins and the inferior sagittal sinus Drains into the confluence of sinuses

Question 35

what is the connecting point of the superior sagittal sinus, straight sinus and occipital sinus called?

Answer 35

Confluence of sinuses

Question 36

Where is the confluence of sinuses located and what does it drain into?

Answer 36

Located near the internal occipital protuberance. Drains into the left and right transverse sinuses

Question 37

Describe the course of transverse sinuses briefly.

Answer 37

Extend horizontally along the attached edge of tentorium cerebelli From posterior to anterior

Question 38

What does the right transverse sinus drain? What does the left transverse sinus drain?

Answer 38

Right transverse sinus usually drains the superior sagittal sinus Left transverse sinus usually drains the straight sinus

Question 39

Sinuses also receive blood from the_______________.

Answer 39

Superior petrosal sinus

Question 40

The transverse sinuses leave the surfaces of the occipital bone to become the_____________________.

Answer 40

sigmoid sinuses

Question 41

Describe the course of sigmoid sinuses

Answer 41

Descends within the posterior cranial fossa - Towards the jugular foramen

Question 42

What do the sigmoid sinuses drain and where do they drain?

Answer 42

Sinus drains cerebral, cerebellar, diploic, and emissary veins Sinus drains into the internal jugular vein

Question 43

Location of cavernous sinuses

Answer 43

Lies against the lateral aspect of the body of the sphenoid On either side of the sella turcica

Question 44

The cavernous sinus receives blood from which structures?

Answer 44

Receives blood from cerebral ophthalmic and emissary veins

Question 45

Left and right cavernous sinuses are connected by __________________ (Anteriorly and posteriorly)

Answer 45

Intercavernous sinuses

Question 46

What structures pass through the cavernous sinuses?

Answer 46

Int. carotid a. Abducens n. (CNVI)

Question 47

What structures lie on the lateral wall of each sinus?

Answer 47

Oculomotor, trochlear nerve, ophthalmic nerve, and maxillary nerve

Question 48

Describe the arachnoid mater

Answer 48

Avascular membrane that lines the meningeal layer of the dura mater

Question 49

Thin process of the arachnoid mater extends into the______________

Answer 49

Subarachnoid space.

Question 50

The arachnoid mater is continuous with which layer?

Answer 50

Pia mater

Question 51

The arachnoid mater lies over sulci and gyri and within sulci (T/F)

Answer 51

F Does not lie within sulci

Question 52

Describe the pia mater

Answer 52

Thin delicate layer that closely adheres to the brain surface Enters grooves and fissures of the brain