Nerves- FA Flashcards by Study Prep

Important nerves: T4

At the “teat pore”- nipple

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T10

At the belly but”ten”

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L1 is the 1nguinal Ligament (or Inguinal L1gament)

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Nerve root vs. spinal cord

Nerve roots are above vertebrae up to C7 and then C8 is below vertebrae

All other nerve roots are below the respective vertebrae

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Additional reflexes

S 1,2- Achilles
L 3,4- Patellar
C 5,6- Biceps
C 7,8- Triceps

PLUS
L 1,2- make the testicles move (cremaster reflex)
S 3,4- winks galore (anal wink)

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Primitive reflexes (when they disappear too)

Moro- startle (3mo)
Rooting- searching/ nipple seeking- when stroked (4mo)
Palmar- grasping (6mo)
Babinski/ plantar- extension of toes (12mo)
Galant- stroking spin when pronated/facing ventrally, leads to lateral flexion toward stimulated side

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Pineal gland

behind third ventricle

causes melatonin section and circadian rhythms

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Superior colliculi

conjugate vertical gaze

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Inferior colliculi

auditory

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Parinaud syndrome

paralysis of conjugate vertical gaze due to a lesion in the superior colliculi (e.g. stroke, hydrocephalus, and pinealoma)

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Superior vs. inferior colliculi

Eyes are above ears so superior colliculi (eyes) and inferior colliculi (ears)

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CN Nuclei locations

Essentially the same as the nerves themselves, except CN XI is located in the spinal cord

Lateral nuclei: sensory (aLar plate)
Medial nuclei: Motor (basal plate)

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COS(3)R(2)OSI(2)J(3)H

Cribriform plate- I
Optic canal- II
Superior orbital fissure- III, IV, VI
Rotundum- V1, V2
Ovale- V3
Spinosum- Middle meningeal
Internal auditory meatus- VII, VIII
Jugular foramen- IX, X, XI
Hypoglossal canal- XII

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CN nerve fibers (sensory vs. motor)

Some Say Money Matters But My Brother Says Big Brains Matter More

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CN I- role

Olfactory- smell (no thalamic relay)

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CN II- role

Sight

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CN III- role

Eye movement- SR (up and out), IR (down and out), MR (in), IO (up and in) and pupillary constriction

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CN IV- role

Eye movement: SO (down and in)

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CN VI- role

Eye movement: LR (out)

CN V- role & motor deficit

Mastication and facial sensation
V3: Somatosensation/ pain from anterior 2/3 of tongue

Deficit of motor component (master): deviation TOWARD side of lesion

CN VII- role

Muscles of facial expression
Taste from anterior 2/3 of tongue
Lacrimation
Salivation (submandibular and sublingual)
Eyelid closing (orbicularis oculi)
Auditory volume modulation (stapedius)

CN VIII- role

Hearing, balance

CN IX- role and deficit

Taste and sensation- posterior 1/3 of tongue
Swallowing
Salivation (parotid gland)
Baroreceptor monitoring (from carotids)
Elevation of pharynx and larynx

CN X- role and deficit

Taste from supraglottic region
Swallowing
Soft palate elevation
Uvula midline
Talking, coughing
Parasympathetics to thoracoabdominal aorta
Monitoring aortic arch baroreceptors

Deficit: Uvula shifts AWAY from side of lesion (U-A-X)

CN XI- role and deficit

``` Head turning Shoulder shrugging (SCM, trapezius) ``` Deficit: Trapezius muscle that is affected stays low (drooped); weakness turning head to the contralateral side of the lesion

CN XII- role and deficit

Tongue movement Deficit: LMN- tongue deviates TOWARD the side of the lesion (HTT)

Nucleus Solitarius

Sensory info (VII, IX, X)

Nucleus aMbiguus

Motor info (IX, X, and XI)

Dorsal motor nucleus

CN reflexes- corneal

Afferent: V1 (nasocilliary) Efferent: VII Similar to lacrimation reflex

CN reflexes- pupillary

Afferent: II Efferent: III

CN reflexes- jaw jerk

Afferent: V3- sensory Efferent: V3- motor (masseter)

CN reflexes- gag

Afferent: IX Efferent: X

CN reflexes- lacrimation

Afferent: V1 Efferent: VII Similar to corneal reflex

Muscles of mastication- innervated by V3

Closing (MMT) Masseter Medial Pterygoid teMporalis ``` Opening (L) Lateral Pterygoid (Lateral Lowers- bottom jaw) ```

Upper motor neuron lesions

CONTRALATERAL paralysis Forehead spared due to dual innervation

Lower motor neuron lesions

IPSILATERAL paralysis Forehead not spared because only one/ ipsilateral LMN

Facial nerve palsy- tx

Corticosteroids, acyclovir

Cavernous sinus

Collection of venous sinuses (on either side of pituitary)- blood from eye and superficial cortex

Cavernous sinus syndrome

Variable ophthalmoplegia, decreased corneal sensation, Horner syndrome, decreased maxillary sensation Cause: pituitary tumor (mass effect), carotid-cavernous fistula, cavernous sinus thrombosis (related to infection) CN VI (lateral movement)- generally most susceptible to injury- closest to the pituitary

Carotid sheath (contents and orientation)

``` Internal jugular (lateral and most superficial) Vagus nerve (posterior- and between IJ and CC) Common carotid (most medial) ```

Auditory physiology

Outer ear- pinna + auditory canal + eardrum; transfers sound waves Middle ear- three bones: malleus, incus, and stapes; conduct and amplify sound from eardrum to inner ear Inner ear- Fluid filled cochlea; contains basilar membrane (BASE: high-pitched frequencies, APEX: low-pitched frequencies)--> "every low has to be balanced with a high" (or just remember that they are opposites) Hair cells transduce vibration to the auditory nerve --> inferior colliculus of brain stem

Hearing loss- conductive

C-B-A Rinne test- Conductive: bone > air (abnormal) Weber test- sound travels to AFFECTED ear (makes sense, because sound resonates (gets louder) in the fluid that is built up in the ear- think about people talking when you are inside a swimming pool)

Hearing loss- sensorineural

Rinne test- Sensorineural: air > bone (normal) opposite of conductive) Weber test- sound travels to UNAFFECTED ear (makes sense because nerves to affected hear are damaged)

Noise-induced hearing loss

Damage to stereo ciliated cells in organ of Corti Loss of HIGH-frequency hearing 1st; sudden-loud noises can produce hearing loss due to tympanic membrane rupture

Cholesteatoma

Overgrowth of desquamated keratin debris within the middle ear space May erode ossicles, mastoid air cells --> causes CONDUCTIVE hearing loss