Cranial Nerves + Dysfunctions & Testing

CN V name and function (3 subdivisions)

Trigeminal N V1 (ophthalmic n) = somatic sensory: sensation from cornea skin of forehead scalp, eyelids, nose and mucosa of nasal cavity and paranasal sinuses V2 (maxillary n) = Somatic sensory: Sensation from skin of face over maxilla including upper lip, maxillary teeth, mucosa of nose, maxillary sinuses, and palate V3 IS BOTH M and S!!! V3 (mandibular n) = Somatic sensory: Sensation from the skin over mandible, including lower lip, side of head mandibular teeth, TMJ, mucosa of mouth and anterior 2/3 of tounge V3 (mandibular n) = Somatic motor: motor to muscles of mastication

you are making out like an Eskimo, and rub the tip of your nose with your significant other. Which nerve senses this?

Trigeminal N - CN V1 (opthalmic n)

CN IV name and function

Trochlear N Somatic Motor (ANS): motor to superior oblique extraoccular mm that assists in moving eyeball inferolaterally

Trigeminal N exits (cranial exit, bone, fossa)

V1 (ophthalmic n): cranial exit = Superior orbital fissure bone = sphenoid bone fossa = middle cranial fossa V2 (maxillary n): cranial exit = Foramen rotundum bone = sphenoid bone fossa= middle cranial fossa V3 (mandibular n): cranial exit = foramen ovale bone = sphenoid bone fossa = middle cranial fossa

CN X name and function

Vagus nerve Somatic Sensory: Sensory from the inferior pharynx and larynx, cough reflex Visceral sensory from the thoracic and abdominal organs Test and somatic sensation form the root of tongue and taste buds on the epiglottis branches of the internal laryngeal nerve Somatic motor: soft palate, pharynx, and intrinsic laryngeal muscles, and a nominal extrinsic tongue muscle visceral motor to thoracic and abdominal viscera

Vestibulocochlear N Tests

Vestibular Nerve 1. Oculocephalic Test (tests for lesions of Vestibular Nerve): Procedure: In a seated position, manually move the patient's head in a "yes" and "no" head movement Negative (normal): Quick/smooth movement of eyeball in direction of head travel Positive (abnormal): Nystagmus (rapid involuntary movements of the eye), ataxia (uncoordinated movements), head tilt toward side of lesion Cochlear Nerve 1. Rinne Test (tests for unilateral conductive hearing loss): Procedure: In a seated position, place vibrating tuning fork behind the patient's ear (mastoid process). Then, move vibrating tuning fork over the patient's ipsilateral ear canal. Instruct patient to report when sound is no longer hear in both steps. 2. Weber Test (tests for unilateral conductive and sensorineural hearing loss): Procedure: In a seated position, place vibrating tuning fork on middle of patient's forehead and instruct patient to report where they hear the sounds most (right ear, left ear, or middle).

CN VIII name and function

Vestibulocochlear N Special sensory: Balance- vestibular sensation from semicircular ducts, utricle, and saccule related to position of movement of head Hearing- hearing from spiral organ

You are performing a neurologic examination on a 43-year-old patient that recently had a cranial mass resected near the internal opening of the right jugular foramen. Based on the location of the surgery near the jugular foramen, you plan to test the function of cranial nerve XI (CN XI). Identify the physical exam finding that would most likely be observed if there was damage to this nerve.

Weakness in shrugging the right shoulder against resistance

zygomaticus major and minor are innervated by

both zygomaticus and buccal branches of CN VII

levator labii superioris alaeque nasi, levator labii superioris, buccinator, and oribcularis oris are innervated by

buccal branch

platysma is innervated by

cervical branch of facial nerve (CN VII)

Trigeminal neuralgia what is it? what is its other name which branch is most commonly effected?

characterized by severe lightning-like pain due to an inflammation of the Trigeminal nerve that leads to its hyperactivation. Irritation is caused by light touch (like wind on the cheek). is also known as suicide disease bc its so painful people commit suicide to end the pain. V2 is most commonly affected. The pain most commonly radiates to the mandibular or maxillary regions.

Glossopharyngeal N (cranial exit, bone, fossa)

cranial exit = Jugular foramen bone = base of petrous ridge of temporal bone and occipital bone fossa = posterior cranial fossa

hypoglosseal N (cranial exit, bone, fossa)

cranial exit = hypoglossal canal bone = occipital bone fossa = posterior cranial fossa

vestibulocochlear N (cranial exit, bone)

cranial exit = internal acoustic meatus bone = temporal bone

spinal accessory n (cranial exit, bone, fossa)

cranial exit = jugular foramen base of petrous ridge of temporal bone and occipital bone fossa = posterior cranial fossa

Vagus nerve (cranial exit, bone, fossa)

cranial exit = jugular foramen bone = base of petrous ridge of temporal bone and occipital bone fossa = posterior cranial fossa

Optic nerve (CN II) (cranial exit, bone, fossa)

cranial exit = optic canal bone = the sphenoid bone fossa = middle cranial fossa (pink part of pic)

Oculomotor n exits (cranial exit, bone, fossa)

cranial exit = superior orbital fissure bone = sphenoid bone fossa = middle cranial fossa

Trochlear N (CN IV) dysfunction and test

dysfunction: Diplopia; weakness of downward movement of the eyeball causing double vision bc one set of extraoccular eye muscles isn't working to center the eye. Patient experiences 2 visual fields and will tilt their head sideways to compensate for this patient complaints may be: unable to look down for reading or descending stairs Test = Part of H test: instruct patient to follow object from eye level towards their nose (look down and in).

middle cranial fossa

formed by part of the sphenoid bone and the temporal bone includes: optic canal, Superior orbital fissure, Foramen rotundum, ovale, spinosum nerve: CN II - CN VI

anterior cranial fossa

formed by the frontal bone and part of the sphenoid bone, and ethmoid bone (cribiformplate) Nerve: CN I

Rinne test, which CN

hearing test using a tuning fork; checks for differences in bone conduction and air conduction; CN VIII

What muscle does Abducens innervate

lateral rectus muscle

Acromegaly is a hormonal condition in which the anterior pituitary gland produced too much growth hormone, causing some bones to increase in size, namely the bones of the face, hands, and feet. This gland can be found in which of the following cranial fossae?

middle cranial fossa; sphenoid bone -> sella turcica

CN IX Glossopharyngeal Test

normally tested with CN X, assess the uvula when patients says "ahhhh" and see if there is any deviations on one side Gag Test Asking patient to swallow or cough Evaluating for any speech impediments

You see Dr.S tell a patient to shut her eyes tightly and then he see if he can open her eyes with his fingers. Which muscle and nerve is he testing?

orbularis oris mm temporalis and zygomatic branch of CNVII

posterior portion of the occipitofrontalis muscle is innervated by the

posterior auricular branch of the CN VII

Patient has a right hypoglossal compression. PT instructs patient to protrude tongue out, where does it deviate

right side "lick your lesion"

pituitary gland sits on the

sella turcica of the sphenoid bone

What muscle does trochlear nerve innervate

superior oblique muscle

posterior cranial fossa

temporal and occipital includes: Internal auditory meatus, jugular foramen, hypoglossal canal, foramen magnum nerves: CN VII - CN XII

orbicularis oculist is innervated by the

temporal and zygomaticus

Snellen Chart, Which CN?

used to measure visual acuity; CN II

What muscles are innervated by the oculomotor

-Superior Rectus -Inferior Rectus -Medial Rectus -Inferior oblique -levator palpebrae superioris

What nerves go through the jugular foramen?

9 - 11

A 91-year-old woman suffers a stroke and is seen in the emergency department. An MRI shows damage to the right trigeminal motor nucleus. Which of the following muscles is most likely affected by the damage in this patient? A. Lateral Pterygoid B. Zygomaticus Major C. Rizzoti D. Mentalis

A. Lateral pterygoid

CN VI name and function

Abducens N Somatic motor: Motor to lateral rectus, which turns the eye laterally "abducens" = "Abduct", lateral muscle to turn eyeball away from midline (toward ipsilateral side)

A 10-year-old boy presents with a rare aggressive soft tissue tumor in the orbit of the eye that requires excision. During the procedure the surgeon unintentionally nicks the ophthalmic artery. She immediately clamps the ophthalmic artery to control the bleeding. Which of the following areas will temporarily lose blood supply as a result of this clamping? a. Upper lip b. Ear c. Forehead d. Cheeks

C. Forehead

CN exits (name all 10 with their corresponding holes)

CN I - Olfactory = Cribriform plate CN II - Optic = Optic Canal Superior Orbital Fissure - CN III - Oculomotor - CN IV - Trochlear - CN VI - Abducens - CN V1 - Ophthalmic (1st branch from CN V, Trigeminal) Foramen Rotundum = CN V2 - Maxillary N (2nd branch of CN V) Foramen Ovale = CN V3 - Mandibular N. (3rd branch of CN V) Internal Acoustic Meatus - CN VII - Facial - CN VIII - Vestibulocochlear Jugular Foramen - CN IX - Glossopharyngeal - CN X - Vagus - CN XI - Accessory CN XII - Hypoglossal = Hypoglossal Canal

Gag test/ evaluating speech impedence, which CN?

CN IX glossopharyngeal

A 45-year-old man presents with loss of sensation in his lower lip, chin, and jawline. A new resident ordered at CT scan, which revealed no cortical damage. Based on the symptoms, you suspect damage to one of the cranial nerves. Identify the cranial nerve that is most likely damaged in this patient.

CN V; mandibular branch of the Trigeminal N.

Say "Ah"; coughing/gag reflex test, Resting HR which CN?

CN X Vagus N. gag test is tested in conjunction with CN IX

Abducens N (cranial exit, bone, fossa)

Cranial exit = superior orbital fissure bone = sphenoid bone fossa = middle cranial fossa

Trochlear N (CN IV) cranial exit, bone, fossa

Cranial exit = superior orbital fissure bone = sphenoid bone fossa = middle cranial fossa

Oculomotor N. Dysfunction and tests (2)

Dysfunction = Occulomotor nerve palsy; impairment with eye movement, pupil dilation or both. Causes = compression of nerve, lack of bloody supply Signs = eyes only move outward, ptosis (drooping eyelid), pupils dilate in reponse to light (can't accomodate to light) Test for motor portion = Part of H test - have patient follow object with eyes. A positive test for n. damage would be demonstrated by eyes spazzing out/twitching laterally Test for sensory portion = check dilation by shining light; pupils dilate in reponse to light (can't accomodate to light)

Trigeminal N dysfunction + test:

Dysfunction = Trigeminal neuralgia; affects the sensory root of CN V, produces excruciating pain, episodic pain in the areas supplied by maxillary and/or mandibular divisions of the nerve. Palpate the masseter muscles while patient clenches, then ask patient to open dat mouf with applied resistance

Olfactory nerve (CN I) Dysfunction and Test

Dysfunction = anosmia (loss of smell) - COVID be effing our smell up Test = - Blindfold the person and have them occlude one nostril - Hold something with a strong or common oder 10cm away from nose - Ask them to identify the smell (i.e. coffee, vanilla, vinegar) Notes: Damage to all of the following can cause complete loss of smell or limitation or increased sensitivity to smell - trauma - rhino sinusitis - viral infections - CNS diseases

Vagus N dysfunction

Dysfunction: Elevated resting HR Loss of gag reflex Difficulty speaking or loss of voice A voice that is hoarse or wheezy Weight loss Abnormal pain

Hypglossal N dysfunction and test

Dysfunction: o Injury to the CN XII injures the ipsilateral half of the tongue o Tongue atrophies, looking shrunken and wrinkled o When the tongue is protruded, its apex deviates TOWARD the paralyzed side Test: o Have pt stick their tongue out and see if the tongue deviates toward the paralyzed side

Abducens N dysfunction and test

Dysfunction: Unalignment of the eyes/double vision. Patients usually present with diplopia (double vision), worse in the distance, an esotropia (eye misalignment) in primary gaze. Patients may compensate with a head-turn to minimize diplopia. Testing: Part of H test: move object laterally The abducens nerve is examined in conjunction with the oculomotor and trochlear nerves by testing the movements of the eye. The patient is asked to follow a point with their eyes (commonly the tip of a pen) without moving their head. The target is moved in an 'H-shape' and the patient is asked to report any blurring of vision or diplopia (double vision)

Facial N Dysfunctions

Dysfunctions = LOUDER NOISES; paralysis of facial muscles, loss of taste on ant. 2/3 of tongue Stapedius dims loud noises, if injured then noises will be LOUDER Bell's Palsy Paralysis of some or all facial muscles on the affected side Potential problems - Reduced tone of orbicularis oculi causing inferior eyelid eversion (fall away from the surface of the eyeball - Lacrimal fluid not spread over cornea- inadequate lubrication, hydration , and flushing of the cornea. This leaves cornea more vulnerable to ulceration and scarring that can impair vision - Weakness or paralysis of buccinator and orbicularis oris - Food accumulates in mouth during chewing Weakness of sphincters or dilators of mouth - Corners of mouth droop. Food and saliva can dribble out - Weakened lip muscles. Impaired ability to produce labial sounds (B,M, P ,W). Patient will frequently dab eyes and mouth with a handkerchief to wipe away tears and saliva-- may result in skin irritation - Loss of taste sensation on anterior ⅔ of tongue

CN VII name and function

Facial N somatic motor: Facial expression and scalp; also supplies stapedius of middle ear, stylohyoid and posterior belly of digastric belly Visceral motor: Parasympathetic innervation to submandibular and sublingual salivary glands, lacrimal glands, and glands of nose and palate Special sensory: anterior 2/3 of tongue, soft palate* Somatic sensory: sensory to small areas of skin on both aspects of auricle around the concha and external acoustic meatus

A 45-year-old man complains of facial paralysis. Physical examination shows a partial ptosis of the left eyelid, weeping from the left eye, drooping of the left corner of the mouth, and failure of that corner of the mouth to respond when the man smiles. Injury to which of the following cranial nerves would produce the symptoms in this patient?

Facial n. (CN VII)

a 43 year old patient's doctor put sour skittles on the patient's posterior 1/3 of his tongue. He didnt taste it, what nerve is compromised

Glossopharyngeal (CN IX)

CN IX name and function

Glossopharyngeal N somatic motor: Stylopharyngeus muscle to assist with swallowing visceral motor: Parasympathetic innervation to the parotid gland Special sensory (taste): Posterior 1/3 of tongue and pharnyx Somatic sensory: cutaneous sensation from external ear Visceral sensory: Carotid body (chemoreceptor) and Sinus (baroreceptor), pharynx, middle eat

Trochlear N (CN IV) test (elaborated version)

Have patient remove glasses if they use them Test can be done one eye at a time or bilaterally One eye at a time: Have finger lateral to ipsilateral eye about 8 inches from patients face and bring medially and straight down to patients mouth level Bilateral: start with finger in line with eyes ~8 inches from face, have patient follow with eyes while moving finger straight down to patients mouth level Normal is to have patient's pupil looking medial and downwards

Vestibulocochlear N dysfunction

Hearing loss Vertigo False sense of motion Motion sickness Nystagmus Tinnitus (ringing in the ear)

CNXII name and function

Hypoglosseal N. Somatic motor to the intrinsic and extrinsic muscles of the tongue styloglossus, hypoglossus, and genioglossus

Facial N (cranial exit (internal + external), bone)

Internal Cranial Exit = internal auditory meatus External Cranial Exit = stylomastoid foramen Bone = temporal bone

A 57-year-old man sees a neurologist for a 6-month history of significant weight loss and difficulty swallowing. On examination, he is noted to have an absent gag reflex and difficulty elevating his shoulders and turning his head against resistance. In light of the significant weight loss, the neurologist feels that this man may have a malignant brain tumor. A tumor at what cranial foramen would cause these findings?

Jugular foramen; mainly the CN IX and X are affected

If the orbicularis oris muscle is the muscle that closes the eye. What is its antagonist? What innervates the antagonist?

Levator palpebrae - a small muscle of the superior orbit that elevates and retracts the upper eyelid inn by CN III = occulomotor n.

Optic nerve (CN II) Tests (4)

Light reflex = looking at constriction of both pupils using light Accommodation reflex = test for eye's response to focusing on a near object, then looking at a distant object Visual acuity = tested using a Snellen chart from 20 feet away. to examine visual acuity color perception = tested using standard pseudoisochromatic Ishihara or Hardy-Rand-Ritter plates that have numbers or figures embedded in a field of specifically colored dots

Glossopharyngeal N Dysfunction

Loss of taste and sensation to the posterior 1/3 of the tongue and pharynx Impaired swallowing Absent gag reflex Parotid gland dysfunction Uvula points AWAY from dysfunctional side

A mucoepidermoid carcinoma of the parotid gland is found to have infiltrated the chorda tympani nerve, compromising its function. Which of the following deficits would likely result from the loss of function of this nerve?

Loss of taste in the anterior 2/3 of the tongue, loss of salivation from submandibular and sublingual glands

if the patient is asked to look the right, but their left eye has minimal adduction. which muscle and cranial nerve is affected

Medial Rectus, and oculomotor (CN III)

Nerve Name Mnemonic

O O O To Touch And Feel Very Good Vagina And Hiney

CN XI dysfunction

Observe for any wasting of muscles Look for any lateral winging of scapula Test both muscles against resistance - MMT SCM by pushing head against hand - MMT trapezius (upper, middle, lower) Observe: "atrophy, fasciculations, weakness, shoulder droops, inability to shrug ipsilateral shoulder or turn head to contralateral side"

CN III name and function

Oculomotor N. Somatic motor (MSK): motor to muscles that raise superior eyelids and direct gaze superiorly, inferiorly, and medially 4/6 extraocular muscles of eye and superior eyelid - Inferior Oblique (IO) - Superior Rectus (SR) - Inferior Rectus (IR) - Medial Rectus (MR) - Levator Palpebrae Superioris Visceral motor (ANS): Parasympathetic inn. to muscles that constrict pupil and accommodate-lens of eye

What nerves go through the superior orbital fissure

Oculomotor, Trochlear, Abducens way to remember: Muscles that move the eye

CN I name, function, type?

Olfactory nerve special sensory: smell from nasal mucosa of roof of each nasal cavity and superior sides of nasal septum and superior concha

CN I exits from (cranial exit + bone, fossa )

Olfactory nerve CN 1 cranial exit = cribriform plate of ethmoid bone fossa = anterior cranial fossa (bone colored yellow in pic)

Optic nerve (CN II) Dysfunction

Optic Neuritis = Lesion on the optic nerve, which results in changes in visual acuity (loss of vision) Using loss of vision to determine location of nerve lesion along the optic nerve - Monocular blindness: Complete loss of vision in 1 eye, vision completely intact in the other - Bitemporal hemianopsia: Loss of lateral vision in both eyes - Homonymous hemianopsia: Loss of medial vision in one eye, and lateral vision Demyelinating Diseases - Demyelination occurs when myelin or oligodendrocytes experience damage; Susceptible to damage via CNS demyelinating diseases (eg. MS)

CN II function and name

Optic nerve special sensory = vision from retina - brightness, color, contrast Assists in light reflex and accommodation reflex

Bell's Palsy

Paralysis of the facial muscles -Possible loss of taste on anterior 2/3 of tongue -Location of lesion will determine function loss

A 55-year-old man is the unrestrained driver of a motor vehicle involved in a crash at highway speeds. He is ejected from the vehicle and sustains multiple injuries including facial trauma, pelvic fracture, and ruptured spleen. Computed tomography of his brain and skull shows factures of the nasal bones including bilateral cribriform plate fractures. Which sense is likely to be diminished following this particular injury?

Smell

Type of nerve mnemonic

Some Say Marry Money But My Brother Says Big Brains Matter Motor

CN XI name and function

Spinal accessory N somatic motor to the striated SCM and TRAPS

anterior portion of the occipitofrontalis muscle is innervated by the

Temporal branch of the CN VII

Vagus N (CN X) Testing

Test: Say Ah Note, that the Vagus Nerve is usually accompanied by CN IX for the evaluating process. To begin the test, instruct the patient to open their mouth and say "Ahh" As the patient says "Ahh", note to see if the palate rises equally of if there is any deviation away from midline of the Uvula If the uvula deviates from midline, then a positive test for Vagus N disruption. Coughing/Hoarseness/Gag-Reflex With your patient sitting at the edge of the table, check the patient's voice to see if there's a decrease in volume of speech, hoarseness in voice, or a weak cough. You can also test the Vagus N by checking the "gag-reflex". To begin the test, have the patient open their mouth and perform the gag-rex Because the Vagus N helps with the process of speech/talking, if you notice any changes, then positive test for Vagus N defect. Resting HR Test the patient resting HR. Resting HR should be 60-100 bpm. If there's a dysfunction, then resting HR would be 120bpm.

Facial N test

Test: Observation of hemi-facial weakness/asymmetries of facial movements, loss of anterior tongue taste. - Have patient smile, noting any differences bilaterally - Have patient raise eyebrows, noting any differences bilaterally - Have patient shut eyes, examiner will try to open with fingertips (patient will try to resist) - Have patient puff cheeks out, examiner will push cheeks (patient will try to resist) - Test taste sensation on anterior 2/3rds of tongue (sweet, salty, sour)