Neuro - Anat & Phys (Cranial nerves applications) Flashcards

Pg. 474-475 in First Aid 2014 Sections include: -Cavernous sinus -Common cranial nerve lesions -Auditory physiology -Hearing loss -Facial lesions -Mastication muscles

1
Q

What is the Cavernous sinus, and where is it located?

A

A collection of venous sinuses on either side of the pituitary

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2
Q

From where does blood flow to the cavernous sinus, and to where does it from from there?

A

Blood from eye and superficial cortex –> Cavernous sinus –> Internal jugular vein

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3
Q

Which nerves pass through the cavernous sinus, and on their way to which structure? What vessel joins them?

A

CN III, IV, V1, V2, and VI (i.e., the nerves that control extraocular muscles plus V1 and V2) and postganglionic sympathetic fibers en route to the orbit all pass through the cavernous sinus; Carvenous portion of internal carotid artery is also here.

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4
Q

What are 3 causes of Cavernous sinus syndrome?

A

Cavernous sinus syndrome (e.g., due to mass effect, fistula, thrombosis)

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5
Q

What is the presentation of Cavernous sinus syndrome?

A

Cavernous sinus syndrome (e.g., due to mass effect, fistula, thrombosis) - ophthalmoplegia and decreased corneal and maxillary sensation with normal visual activity

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6
Q

Which CN is commonly affected by Cavernous sinus syndrome?

A

CN VI commonly affected

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7
Q

Draw the Cavernous sinus and its related structures, labeling the following: (1) Anterior cerebral artery (2) Anterior clinoid process (3) Arachnoid (4) Abducens (VI) nerve (5) Dura (6) Hypophysis (7) Internal carotid artery (8) Optic chiasm (9) Oculomotor (III) nerve (10) Ophthalmic (V1) nerve (11) Maxillary (V2) nerve (12) Pia (13) Sphenoid sinus (14) Subarachnoid space (15) Trochlear (IV) nerve.

A

See p. 474 in First Aid 2014 for visual

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8
Q

What sign/symptom occurs with a CN V motor lesion, and why?

A

Jaw deviates TOWARD side of lesion due to unopposed force from the opposite pterygoid muscle

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9
Q

What sign/symptom occurs with a CN X lesion, and why?

A

Uvula deviates AWAY from side of lesion. Weak side collapses and uvula points away

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10
Q

What signs/symptoms occur with a CN XI lesion, and why?

A

Weakness turning head to contralateral side of lesion (SCM). Shoulder droop on side of lesion (trapezius). The left SCM contracts to help turn the head to the right.

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11
Q

What sign/symptom occurs with a CN XII lesion, and why? What kind of motor neuron lesion is this?

A

Tongue deviates TOWARD side of lesion (Think: “lick your wounds”) due to weakened tongue muscles on the affected side; CN XII lesion (LMN)

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12
Q

What are the 3 major parts of the ear?

A

(1) Outer ear (2) Middle ear (3) Inner ear

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13
Q

What 3 structures are associated with the Outer ear?

A

Visible portion of ear (pinna), includes auditory canal and eardrum

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14
Q

What is the function of the Outer ear, and how does it work?

A

Transfers sound waves via vibration of eardrum

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15
Q

What is the Middle ear, and what does it contain?

A

Air-filled space with three bones called the ossicles (malleus, incus, stapes)

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16
Q

What are the names of the 3 ossicles? Where are they found, and what function do they serve?

A

Ossicles (Malleus, Incus, Stapes); Middle ear; Ossicles conduct and amplify sound from eardrum to inner ear

17
Q

Describe the contents of the inner ear. What major function does they serve?

A

Snail-shaped, fluid-filled cochlea. Contains basilar membrane that vibrates secondary to sound waves.

18
Q

What is the connection between the ear and the brain in terms of transmitting sound?

A

Inner ear: Vibration transduced via specialized hair cells –> auditory nerve signaling –> brainstem.

19
Q

Explain how different frequencies of sound are differentiated in the inner ear. Exactly where in the inner ear is low versus high frequency heard?

A

Each frequency leads to vibration at specific location on the basilar membrane (tonotopy): (1) Low frequency heard at apex near helicotrema (wide and flexible) (2) High frequency heard best at cochlea (thin and rigid)

20
Q

For a patient with conductive hearing loss, what would the Rinne versus Weber test results be?

A

Conductive hearing loss: Rinne test abnormal (bone > air) & Weber test localizes to affected ear

21
Q

For a patient with sensorineural hearing loss, what would the Rinne versus Weber test results be?

A

Sensorineural hearing loss: Rinne test Normal (air > bone) & Weber test localizes to unaffected ear

22
Q

What are 2 causes of noise-induced hearing loss?

A

Damage to stereociliated cells in organ of Corti; Sudden extremely loud noises can hearing loss due to tympanic membrane rupture

23
Q

What type of hearing is lost first in noise-induced hearing loss?

A

Loss of high-frequency hearing 1st

24
Q

What is a UMN (facial) lesion?

A

Upper Motor Neuron lesion = Lesion of motor cortex or connection between cortex and facial nucleus

25
Q

What symptom(s) is (are) seen with a UMN (facial) lesion?

A

Contralateral paralysis of lower space; Forehead spared due to bilateral UMN innervation

26
Q

What symptom(s) is (are) seen with a LMN (facial) lesion?

A

Ipsilateral paralysis of upper AND lower face

27
Q

What causes facial nerve palsy?

A

Complete destruction of the facial nucleus itself or its branchial efferent fibers (facial nerve proper)

28
Q

How does facial nerve palsy present?

A

Peripheral ipsilateral facial paralysis (drooping smile) with inability to close eye on involved side

29
Q

What is Bell’s palsy? Describe its recovery.

A

Facial nerve palsy that can occur idiopathically; Gradual recovery in most cases

30
Q

What are 6 disease/conditions with which Facial nerve palsy is associated?

A

Associated with (1) Lyme disease, (2) Herpes simplex and (less common) (3) Herpes zoster, (4) Sarcoidosis, (5) Tumors, and (6) Diabetes.

31
Q

What is the treatment for Facial nerve palsy?

A

Treatment includes corticosteroids

32
Q

Draw a visual depicting facial UMN lesion versus LMN lesion. Include and label the following in your visual: (1) Corticobular tract (2) CN VII (3) UMN lesion (4) LMN lesion (5) Central facial (6) Facial nerve palsy (7) Face area of motor cotex (8) Facial nucleus Upper division (9) Facial nucleus Lower division.

A

See p. 475 in First Aid 2014 for visual on right

33
Q

What are the 3 muscles that close the jaw?

A

3 muscles close jaw: (1) Masseter (2) teMporalis (3) Medial pterygoid; Think: “M’s Munch” & “It takes more muscle to keep your mouth shut”

34
Q

What muscle opens the jaw?

A

1 opens: Lateral pterygoid; Think: “Lateral Lowers (when speaking with respect to jaw motion)”

35
Q

What nerve innervates mastication muscles?

A

All are innervated by the trigeminal nerve (V3)