Gross Anatomy:Cranial Nerve Review

Ref: Table 8.5 (pages 848-849) in Drake et al.

Cranial Nerves III, IV and VICN III innervates: MR, SR, IR, IO, levator palpebrae superioris, sphincter pupillae, cilliary mm.

CN IV innervates: Superior oblique

CN VI innervates: lateral rectus

Physiological “H”

Look straight ahead. Look right.

A 30-year-old male presents with the chief complaint of “double vision”. Physical exam reveals:

An 8-year-old girl presents as shown.

Cranial nerve testing reveals?Test CN XISCM may be paralyzed on left sideIf she holds head like this to see better, problem lies with CN IV - trochlear, which innervated Superior Oblique; her right eye is extortedIf it was torticullis, it would be on the left side, because it is shortening of the muscle

What is your DDx?

54-year-old male presents with the chief complaint of diplopia. Testing of extraocular movements reveals:

R L

Where is the lesion?

Where is the lesion?

Where is the lesion?

Compressive v. Ischemic

Where is the lesion?

A 37-year-old female presents with the chief complaint of difficulty walking. History reveals that she is a heavy crack user and supports her habit through prostitution. Physical exam reveals a gait ataxia; patellar reflex is 1 / 4 bilaterally. Examination of the eye provides the results to the right:

What are your observations?

What is the most likely diagnosis?

*

Cranial Nerve V – TrigeminalWhat nerve provides sensory

innervation at the:

• forehead: ophthalmic V1

• tip of nose: ophthalmic V1

• upper vs. lower eyelid: ophthalmic vs maxillary

• upper vs. lower lip: maxillary vs mandibular

• tip of chin:

What nerve innervates the skin here?

*

Cranial Nerve V – TrigeminalInnervates what muscles?

What is the circuit for the jaw jerk reflex?

What’s the diagnosis?What nerve/ganglion/branches are involved?

A. B.

C.

Cranial Nerve VII - Facial Nerve

How would you test the function of CN VII?

Sensory: Taste?

Motor: Smile, wrinkle forehead(mm. of facial expression)

Buccinator – keeps food from collecting between teeth and oral vestibule

Smile.Where is the lesion?

A 38-year-old female presents with

painful blisters as shown in the

figure.

What nerve/ganglion/branch

es are involved?

Compare and contrast the expected physical exam findings [related to CN VII] in following 4 patients:

Patient #1: A 23-year-old female with a vestibular schwannoma (a tumor of CN VIII). (at the internal auditory meatus; everything that nerve does) Difficulty with facial expression (Bell’s Palsy), loss of taste, dry eye, dry mouth,

Patient #2: A 10-year-old male with chronic otitis media that has eroded the facial canal. Lesion is after the greater petrosal nerve; innervation to lacrimal gland is intact as well as….

Patient #3: A 20-year-old male with a fractured mastoid.Greater petrosal nerve is intact, don’t have dry eyes. Chorda tympani is intact, don’t have loss of

taste

Patient #4: A 40-year-old female with a fractured mandibular ramus and a lacerated lingual nerve.

Cranial Nerve VII - Facial NerveFacial Nerve Lesions

A 59-year-old female presents with the chief complaints of hoarseness, difficulty swallowing and dry mouth. Physical examination reveals:

• Paralyzed vocal fold, on the right• Weak gag and cough reflexes• Weakness shrugging shoulder, on the right• Weakness turning head to left against resistance• Decreased taste sensation on the right

Where is the lesion?(i.e. identify one location where an injury/lesion could cause all of the above

findings)

Cranial Nerve IX - Glossopharyngeal Nerve

Cranial Nerve X – Vagus Nerve

Cranial Nerve XI – Spinal Accessory Nerve

Muscles:Testing:

Cranial Nerve XII – Hypoglossal Nerve

Muscles:

Testing:

Injury to the hypoglossal nerve as it crosses the internal carotid artery would result in paralysis of what other muscles?

Stick out your tongue. Where is the lesion?

Cranial Nerve Reflexes

• Jaw Jerk

• Corneal Reflex

• Tearing

• Gag

• Cough

In by: Out by: