CRANIAL NERVE DISTRIBUTION

Question 1

Most cranial nerves pass through the ____ ____ fossa. This space in the skull communicates with the orbit, the infra-temporal fossa and the _____________ fossa.

Answer 1

Middle cranial fossa (MCF);

pterygopalatine fossa

Question 2

Define the pterygopalatine fossa.

Answer 2

This communicates between the infratemporal fossa and the pterygomaxillary fissure.

Question 3

Define the infratemporal fossa.

Answer 3

This is located below the zygomatic arch and serves as a passage between the middle cranial fossa and oral cavity.

Question 4

What is the pterygomaxillary fissure?

Answer 4

This is a slit between the maxilla and sphenoid bones.

Question 5

What are the exits for the 3 divisions of the trigeminal nerve (CN V) and what are the names of the nerve fibers?

Answer 5

V1 - ophthalmic division (sensory) exits @ supraorbital foramen;
V2 - maxillary division (sensory) exits @ infraorbital foramen;
V3 - mandibular division (sensory and motor) exits as the inferior alveolar nerve at the mental foramen alongside the mental artery.

Question 6

What nerve exits through the stylomastoid foramen and what nerve fibers do they carry?

Answer 6

Facial nerve carries general sensory and motor fibers once it exits this foramen. This innervates muscles of facial expression, posterior digastrics, stylohyoid and stapedius.

Question 7

Where is the jugular foramen located and what structures pass through it? What is found anterior to it?

Answer 7

The jugular foramen connects the posterior cranial fossa (PCF) and the neck. The cranial nerves 9, 10 and 11 pass through it. The carotid canal is anterior to the jugular foramen.

Question 8

Define the cribiform plate and what passes through it.

Answer 8

This connects the anterior cranial fossa (ACF) to the nasal cavity. The olfactory nerve (CN I) passes through it, pretty close to the amygdala and hippocampus of the brain.

Question 9

Define the optic canal and what structure(s) pass through it.

Answer 9

The optic canal is between the middle cranial fossa (MCF) and the orbit. The optic nerve (CN II) passes through it.

Question 10

Define the Superior Orbital Fissure and what structure(s) pass through it:

Answer 10

This fissure is between the MCF and orbit. The 4 nerves that pass through it are: occulomotor nerve (superior), trochlear nerve (lateral), abducens nerve (lateral to internal carotid artery) and ophthalmic division (CN V-1).

Question 11

Define the Foramen Rotundum and what structure(s) pass through it.

Answer 11

Found between the MCF and Pterygopalatine fossa. The maxillary division of the trigeminal nerve is found within it. This nerve turns into the inframandibular nerve closer to the mental foramen.

Question 12

Define the Foramen Ovale and what structure(s) pass through it.

Answer 12

Found between the MCF and infratemporal fossa. The otic ganglion, mandibular division of trigeminal (V-3), accessory meningeal artery, lesser petrosal nerve and emissary vein passes through it.

Question 13

Define the Foramen Lacerum and what structure(s) pass through it.

Answer 13

Found between the MCF and Carotid Canal. The internal carotid artery and Greater Petrosal Nerve pass through it.

Question 14

Define the Carotid canal and what structures pass through it.

Answer 14

This is a passage within the petrous temporal bone, anterior to the jugular fossa and superior to the Foramen lacerum. The internal carotid artery passes through this.

Question 15

Define the Foramen Spinosum and what structure(s) pass through it.

Answer 15

It is a small hole that is lateral and posterior to the foramen lacerum. The middle meningeal artery passes through this.

Question 16

Define the internal auditory meats and what structures pass through it.

Answer 16

This is between the PCF and inner ear. The nerves that pass through it are the vestibulocochlear (CN VIII) and the facial nerve (CN VII).

Question 17

Describe the location of the Jugular Foramen, it’s clinical significance and what structures pass through it.

Answer 17

This is found between the PCF and neck. The glossopharyngeal, vagus and spinal accessory nerves pass through this as well as the internal jugular vein. It’s important since a tumor or compression here can be life-threatening due to the function of the nearby nerves.

Question 18

Define the Hypoglossal canal and what structure passes through it.

Answer 18

This is found between the PCF and neck area. Cranial nerve XII Hypoglossal runs through it.

Question 19

Define the Foramen magnum and what structure passes through it

Answer 19

This is the largest foramen located at the base of the skull. It’s found between the PCF and Vertebral canal and is an entrance for the spinal cord.

Question 20

What cranial nerve aids the tongue in speaking and runs superior to the greater horn of the hyoid bone?
What phrase is good to remember this nerve?

Answer 20

Hypoglossal nerve (CN XII)
“The tongue licks the wound”

Question 21

What muscles does the Mandibular division (V-3) of the trigeminal nerve innervate in the face?

Answer 21

The mandibular division (V-3) innervates tensor tympani, temporalis, masseter, and the medial and lateral pterygoids.

Question 22

Injury to the Abducens nerve (CN VI) would lead to what defect?

Answer 22

Internal Strabismus which is the medial deviation of the eye, since the abducens normally helps abducts the eyeball.

Question 23

What is the significance of Sella Turcica?

Answer 23

This is known as the Turkish saddle and is located superior to the sphenoid sinus on the sphenoid bone. It can be found between the anterior cranial fossa and middle cranial fossa. In the human body, it would house the pituitary gland.

Question 24

Ocular lymphoma of the optic canal would damage what 2 structures that pass through it?

Answer 24

Ophthalmic artery and the Optic nerve (CN II).

Question 25

List the common muscles of the tongue and their actions.

Answer 25

Genioglossus muscle - protrudes (sticks out) the tongue;
Styloglossus - draws the tongue upward towards the palate
Hyoglossus - depresses the tongue towards the mouth floor

Question 26

If an oral surgeon wants to anesthetize a patient’s top right tooth before pulling it out, he would apply a nerve block in what part of the mouth?

Answer 26

In the alveolar process of the maxillary bone which contains the sockets that support the teeth.

Question 27

Define the tentorium cerebelli and the tentorial notch.

Answer 27

This is a meningeal layer that divides the cerebrum into the supratentorial and infratentorial parts. The tentorial notch is located anterior to this from which the brain stem passes through.

Question 28

The left and right vertebral arteries merge with one another to form what artery at the midline?

Answer 28

Basilar artery

Question 29

List 2 mnemonics for cranial nerves. One by name and the other by type of innervation.

Answer 29

Cranial names: “On Occasion, Our Trusty Truck Acts Funny. Very Good Vehicle Any How.”
Innervation type: “Some Say Marry Money But My Brother Says, Big Brains Matter More”.

Question 30

The Lingual nerve and Chorda tympani both travel to the _______ 2/3 of the tongue. The former relays ______ and the latter relays _______.

Answer 30

Anterior 2/3 of tongue;
General (somatic) sensation;
Special (taste) sensation

Question 31

What is the significance of stellate ganglia? What can occur if injured?

Answer 31

Stellate ganglia are cell bodies for sympathethic fibers in the head. A lesion here can lead to ptosis of the upper eyelids since the smooth muscle of the LPS is not tonically innervated or loss of sweating of the head.