CRANIAL NERVE TESTING

Question 1

Sniffing forces a lot of air into the nostrils at once, creating _______ in the nasal cavity. This allows the fragrance to get to the _________ mucosa in the superior nasal cavity.

Answer 1

Turbulence;

Olfactory epithelium/ mucosa

Question 2

A patient is told to powerfully sniff a vial of cinnamon from a foolish physician. What nerve was stimulated before she sneezed on his face?

Answer 2

Maxillary division of trigeminal nerve (V-2)

Question 3

When testing the extent of a patient’s visual field, the patient is asked to look _____ _____ while the physician assesses his or her _______ vision.

Answer 3

Straight ahead;

Peripheral vision assessed

Question 4

Temporal fibers detect light from the _______ field of view and (do/do not) cross the optic chiasm. This differs from nasal fibers that detect light from the ________ field of view and (do/ do not) cross the optic chiasm.

Answer 4

Temporal fibers = Nasal field = Do Not Cross chiasm;

Nasal fibers = Temporal field = Cross chiasm

Question 5

Describe the features of Bitemporal (heteronymous) hemianopsia and what causes it.

Answer 5

Aka “tunnel vision” is the loss of peripheral vision from a cut or compressed optic chiasm. This can be due to a pituitary adenoma that pushes up against the optic chiasm leading to a loss of detection of the temporal fields of view.

Question 6

A patient has his right optic nerve cut from a fracture in the optic canal. What visual defect may he experience?

Answer 6

Right Anopsia features the loss of both nasal and temporal fields, meaning blindness, in the right eye.

Question 7

A patient has been diagnosed by an ophthalmologist with Left Homonymous Hemianopsia. What structure in the cranium may have been affected?

Answer 7

The right optic tract posterior to the optic chiasm may be compressed or cut since the left field of view in both eyes is absent. The right optic tract contains temporal fibers of the right eye and the nasal fibers of the left eye are affected.

Question 8

Each optic tract contains fibers detecting the nasal visual field of the __________ eye and nerve fibers detecting the temporal visual field of the ___________ eye.

Answer 8

Ipsilateral eye - temporal fibers that pick up nasal field;

Contralateral eye - nasal fibers that pick up temporal field.

Question 9

A cut at the right optic tract would lead to ….

Answer 9

Left Homonymous Hemianopsia

Question 10

A lesion at the optic chiasm would present as…

Answer 10

Bitemporal heteronymous Hemianopsia (tunnel vision)

Question 11

A CT indicates an aneurysm of the right internal carotid artery near the optic chiasm. How would this present in a patient?

Answer 11

Right nasal hemianopsia that affects the nasal visual field of the ipsilateral eye. The aneurysm compressed the right temporal optic fibers that detect the nasal field of view in the right eye.

Question 12

Describe the cause of Papilledema.

Answer 12

Elevated CSF pressure can compromise the venous return from the retina through the Canal of Schlemm. This leads to visual obscurity in the affected eye since the retina is compressed.

Question 13

Define the Pupillary Light Reflex.

Answer 13

Light is shown in one eye to cause direct pupil constriction of that eye and consensual constriction of the contralateral eye. This tests both the optic nerve and motor branch of oculomotor nerve for the reflex.

Question 14

If light is shown in the right eye and ONLY the left pupil constricts, the right optic nerve _______ but the right CN III ______.

Answer 14

CN II works, but the CN III is out.

Question 15

Light is shown in the left eye and neither pupil constricts. This sign is ________. The left CN II is ______ OR both CN’s III are _______.

Answer 15

Inconclusive;

Left optic nerve is defective OR both CN III’s are not working.

Question 16

Define Uncal Herniation and why it can be lethal.

Answer 16

This is caused by increased intracranial pressure which pushes down the cortex. The uncus goes over the edge and the CN III can be compressed. This causes dilated pupils (lowered PSNS) and increased pressure on the brainstem which can lead to a coma or death.

Question 17

A common cause of Uncal Herniations can be _________ hematomas, which can be caused by a rip in the ___________ ________ artery, thus increasing ________ pressure.

Answer 17

Epidural hematomas;
Rip in Middle Meningeal Artery;
intracranial CSF pressure.

Question 18

The occulomotor nerve can be tested with the ________ for ocular movement and _______. Somatic innervation is tested by the ______ rectus and the PSNS autonomic is tested by the __________ ________.

Answer 18

H in Space, Convergence;

Medial Rectus, Constrictor Pupillae

Question 19

Define Oculomotor Palsy. What muscles still work?

Answer 19

The affected eye is abducted and depressed leading to Lateral Strabismus. The superior oblique and lateral rectus still work.

Question 20

Define Abducens Palsy. What muscle still works?

Answer 20

Adduction of the eye leads to Medial Strabismus. The medial rectus is normal.

Question 21

How can the trigeminal nerve (CN V) can be tested (along the sensory and the motor branches).

Answer 21

The physician can stimulate the senses of the face that were derived from the 1st pharyngeal arch. The motor branch can be tested by palpation of the mastication muscles and the anterior digastrics.

Question 22

List what features define Facial Palsy.

Answer 22

There is a loss of the nasolabial fold, drooping of the mouth, loss of wrinkles and no blink reflex on the affected side.

Question 23

How does a physician elicit the Corneal Blink Reflex and what does it mean?

Answer 23

Have the patient look away and gently stroke the cornea to elicit the reflex.

Question 24

If a physician touches the left eye cornea and neither eye blinks, then she touches the right eye cornea and ONLY the right eye blinks, this means…

Answer 24

The Left CN V and left CN VII are both not working.

Question 25

If a patient experiences a left vestibulocochlear nerve lesion, and a physician performs the Weber test on that patient, the noise will be heard at the _________ side or ______ ____ the lesion.

Answer 25

Sensorineural hearing loss: noise heard at opposite side, AWAY from the lesion

Question 26

A doctor asks a patient to protrude his tongue and say “Aah” while he checks the back of his throat with a light. The physician finds that the uvula has deviated to the LEFT side. Which cranial nerve is affected?

Answer 26

The RIGHT vagus nerve (CN X) was affected. The deviated uvula moves AWAY from the affected side.

Question 27

The Gag reflex evaluates what 2 nerves and how?

Answer 27

The Cranial nerve IX is tested by touching the wall of the pharynx (sensory limb). Meanwhile the cranial nerve X is tested as the soft palate and pharynx are elevated (motor limb) as a reflex.

Question 28

You touch the right side of the pharynx eliciting a gag reflex in a patient, but the uvula deviates to the right. You then touch the left side of the pharynx and the uvula still deviates to the right. What cranial nerves are indicated to be affected for the presentation of these signs?

Answer 28

Both left and right CN IX are good (for sensory), but the left vagus nerve (CN X) is out since the uvula deviates AWAY from affected side.

Question 29

In what 2 ways can the spinal accessory nerve be tested?

Answer 29

Have the patient shrug the shoulders against resistance to test the trapezius OR…
have the patient turn the head to one side to test the contralateral sternocleidomastoid.

Question 30

A young teen’s tongue protrudes and deviates left and the left side of his tongue seems to be smaller than the right side. What nerve is indicated to be affected?

Answer 30

The left Hypoglossal nerve (CN XII) is lesioned at the tongue moves TOWARD the side of the lesion. There is atrophy of the intrinsic tongue muscles on the left side.

Question 31

What are the somatic motor muscles for mastication and what is their innervation?

Answer 31

CN V-3 = Muscles of mastication + mylohyoid, anterior belly of digastrics, tensor tympani and tensor palatini (“MATT”)

Question 32

What are the somatic motor muscles innervated by cranial nerve VII (facial nerve)?

Answer 32

The muscles of facial expression, stapedius, posterior digastrics and stylohyoid (“SPS”) are innervated by CN VII.

Question 33

What muscles does the vagus nerve (CN X) provide somatic motor innervation to?

Answer 33

Pharyngeal muscles (except stylopharyngeus, CN IX) and the palate muscles (except tensor tympani, CN V-3) are innervated by the vagus nerve.

Question 34

The muscles of the intrinsic larynx are innervated by what nerve and what pharyngeal arch are these apart of?

Answer 34

Muscles from the 6th pharyngeal arch are innervated by the inferior laryngeal branch of the vagus nerve (CN X).

Question 35

The parasympathetic fibers along the face travel to their destinations along _______. The oculomotor nerve has PSNS fibers travel through the _______ ganglion to innervate the _________.

Answer 35

Cranial nerve V3;

Ciliary ganglion to sphincter pupillae and ciliary muscles.

Question 36

The facial nerve (CN VII) has PSNS fibers that synapse on the ________ ganglion to travel to ________ glands through the __________ nerve.

Answer 36

Submandibular ganglion;
submandibular/ sublingual glands;
Chorda tympani nerve

Question 37

CN VII has PSNS fibers synapse at the ________ ganglion to provide innervation to the _______ and _______ glands through the ______ and _______ nerves, respectively.

Answer 37

Pterygopalatine ganglion;
lacrimal and mucosal glands of the nasal cavity;
Lacrimal nerve, Palatine nerves

Question 38

CN IX has PSNS fibers synapse at the ______ ganglion to provide innervation to the __________ gland through the ________ nerve.

Answer 38

Otic ganglion in the infratemporal fossa;

Parotid gland via auriculotemporal nerve