Cranial Foramina

Question 1

cranial base is the ___ and has 2 surfaces which are ______ and _____

Answer 1

floor of cranial cavity
2 surfaces: endocranium and external cranial base

Question 2

external cranial base involves

Answer 2

viscerocranium and neurocranium

Question 3

endocranium

Answer 3

internal surface of cranial cavity base
3 cranial fossae: anterior, middle, & posterior (PAM)

Question 4

foramen

Answer 4

small opening in bone to allows passage of structure in/out of cranial cavity

Question 5

fissure

Answer 5

openings not entirely surrounded by bone structure

Question 6

canals

Answer 6

openings larger in length than diameter (long and skinny)

Question 7

anterior fossa

Answer 7

located superior to orbital and nasal fossa
contains frontal lobes and olfactory bulb

Question 8

what are the 2 foramina of the anterior fossa?

Answer 8

foramen caecum and cribiform plate

Question 9

foramen caecum

Answer 9

articulates with ethmoid bone
contains emissary vein from nose to superior sagittal sinus
clinical relevance: danger triangle of face –> nose infection can spread retrograde facilitated by emissary vein
risks: sinus thrombosis, abscesses, & meningitis

Question 10

cribiform plate

Answer 10

separates nasal and cranial cavities
supports olfactory bulb
contains crista galli (part of ethmoid bone)
olfactory foramina = passage for olfactory fibers

Question 11

middle cranial fossa contains

Answer 11

temporal lobes and pituitary gland (body sphenoid bone contains pituitary gland too)

Question 12

list foramina that the middle cranial fossa contains

Answer 12

1. optic canal
2. superioir orbital fissure
3. foramen ovale
4. foramen rotundum
5. foramen spinosum
6. foramen lacerum
7. foramen petrosum

Question 13

optical canal

Answer 13

location: sphenoid bone
connects orbital and cranial cavities
passage of: optic nerve & opthalmic artery
optic canals connect by chiasmatic sulcus on ea. side of skull

Question 14

superior orbital fissure

Answer 14

cleft between lesser and greater sphenoid bone
opens into orbital cavity
passage for:
1. Oculomotor nerve (CN3)
2. Trochlear nerve (CN4)
3. Trigeminal nerve (CN5) - (opthalmic branch)
4. Abducens nerve (CN6)
5. Opthalmic veins

Question 15

foramen rotundum

Answer 15

round opening
location: sphenoid bone
connects pterygopalatine with middle cranial fossa
passage for: maxillary branch of trigeminal nerve (CN5)

Question 16

foramen ovale

Answer 16

largest foramina in cranial base
location: greater wings of posterior sphenoid
opens into infratemporal fossa
passage for: mandibular brach of trigeminal nerve (CN5)

Question 17

foramen vesalii

Answer 17

sphenoidal emissary foramen
location: greater wing of sphenoid

Question 18

foramen spinosum

Answer 18

location: greater wing of sphenoid
passage for: middle meningeal artery, middle meningeal vein, meningeal branch of mandibular nerve (CN5)

Question 19

carotid canal

Answer 19

temporal bone passage
connects neck with middle cranial fossa
passage for: carotid artery and petrosal nerve

Question 20

foramen lacerum

Answer 20

triangular opening
filled with cartilaginous tissue after birth
houses petrosal nerve

Question 21

foramen petrosum

Answer 21

location: greater wing of sphenoid
found between foramen spinosum and ovale
passage for: petrosal nerve

Question 22

posterior cranial fossa

Answer 22

posterior and deepest depression of cranial cavity
supports brainstem and cerebellum
composed of: temporal bones, occipital bone, and small portion of parietal bones

Question 23

foramina of posterior cranial fossa

Answer 23

internal acoustic meatus
foramen magnum
jugular foramina
hypoglossal canal

Question 24

internal acoustic meatus

Answer 24

canal on petrous region of temporal bone
connects inner ear with posterior cranial fossa
passage for: facial nerve (CN7) , vestibulocochlear nerve (CN8), labyrinthe artery, & vestibular ganglion

Question 25

foramen magnum

Answer 25

location: occipital bone
passage for: medulla oblongata, meninges, spinal cord accessory nerve, anterior/posterior spinal carties, & vertebral arteries

Question 26

clinical relevance of conditions associated with foramen magnum

Answer 26

conditions like congenital structure defects or increased intracranial pressure from conditions like hydrocephalus can cause herniation of cerebellar tonsils through foramen magnum. this results in compression of vital structures like the pons and medulla oblongata

Question 27

jugular foramen

Answer 27

large foramen between temporal bone and occipital bone
passage for:
1. glossopharyngeal nerve (CN 9)
2. Vagus nerve (CN 10)
3. Spinal accessory nerve (CN 11)
4. Inferior jugular vein
5. inferior petrosal sinus
6. sigmoid sinus

Question 28

hypoglossal canal

Answer 28

location: occipital bone
passage for: hypoglossal nerve (CN 12)

Question 29

mastoid foramen

Answer 29

location: temporal bone
passage for:
1. mastoid emissary vein to sigmoid sinus
2. small branch of occipital artery to dura mater

Question 30

The vestibulocochlear nerve passes through the posterior cranial fossa. What provides passage of this structure?

Answer 30

internal acoustic meatus

Question 31

Olfactory axons of cranial nerve I pass through the anterior cranial fossa. What provides passage of this structure?

Answer 31

Cribiform plate

Question 32

A fissure exists between the anterior and middle cranial fossa. Which structure within this fissure is most inferior?

Answer 32

abducens nerve

Question 33

The greater petrosal nerve passes through the middle cranial fossa. What provides passage of this structure?

Answer 33

foramen lacerum