Lecture 41 - Cranial Nerves Flashcards by Brandon Craipley

Organization of the cranial nerves

forebrain: olfactory and optic
midbrain: oculomotor, trochlear
Pons: trigeminal
pontomedullary junction: abducens, facial, vestibulocochlear, glossopharyngeal
medulla: vagus, accessory, hypogossal

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Which cranial nerve is the only one to exit dorsally in the brain instead of ventrally

Trochlear nerve

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Mnemonics to memorize cranial nerves and if sensory, motor, or both

old Oliver ogg traveled to africa for very good vacation and holiday
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Olfactory tract sits in the

olfactory sulcus of the frontal lobe

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What is the function of the olfactory tract

Olfaction/Smell

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Is olfactory nerve sensory or motor

Special sensory

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What is the pathway of the olfactory nerve

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T or F: The olfactory nerve is the only nerve where sensory information is not first relayed through the thalamus

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What 4 structures does the primary olfactory cortex project to

Amygdala
Hippocampus
Piriform Cortex
Secondary olfactory cortex

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Anosmia

Lose sense of smell (injury, lesion, tumor)

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What are the 4 cranial nerves associated with the visual system and what do they control

Vision transmitted by: Cranial Nerve II (optic nerve)

Eye movements are controlled by:
- Oculomotor (CNIII)
-Trochlear (CNIV)
-Abducens (CNVI)

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Is the optic nerve sensory or motor

Special sensory

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T or F: The optic nerve is susceptible to diseases at numeral locations and the visual defect is associated with site of injury

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T or F: the optic nerve is capable of regeneration following a lesion

false, it is part of the CNS so it cannot regenerate

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What are the 6 extrinsic ocular muscles that control movement

-Four recti
-2 oblique

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Eyelid control is regulated by which muscle

Levator palpebrae superioris

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visual fields are controlled

Contralaterally, so some crossover at optic chiasm, some do not (right visual field coming in the left eye stays on left side)

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The pathway of the oculomotor nerve

midbrain -> superior colliculus -> superior orbital fissure -> divides to inferior and superior branches

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All cranial nerves that control eye movements pass through

the superior orbital fissure (III, IV, VI)

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What 5 muscles does the oculomotor nerve control through motor control and their function

Levator Palpebrae Superioris: Raise eyelids

4/6 muscles that move the eye:
2. Superior rectus: elevates eyeball
3. Inferior rectus: Depresses eyeball
4. Medial rectus: Adducts eyeball
5. Inferior oblique: Elevates, abducts, and laterally rotates eyeball

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What are the muscle functions of the 6 eye muscles (primary, secondary, and tertiary)

obliques abducted when they work together,
superior & inferior rectus adduct when they work together

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What 2 muscles does the oculomotor nerve control parasympathetically and their function

Sphincter pupillae: Constricts pupil and is responsible for pupillary light reflex
Ciliary Muscles: Contracts (affect lens shape) and focusses lens on short-range objects

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What 3 structures are affected by oculomotor nerve palsy and describe what occurs

Eyelid (Ptosis): dysfunction of levator palpebrae
Pupil (Mydriasis): Parasympathetic loss of ciliary function
Eyeball Position: Down and out, and unopposed action of lateral rectus and superior oblique

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Is the trochlear nerve motor or sensory

Motor

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Where does the trochlear nerve emerge from

At level of midbrain (decussates here) and emerges from dorsal surface

Where does the trochlear nerve exit

Superior orbital fissure

What does the trochlear nerve innervate and its functions

Contralateral superior oblique muscle: Intorsion, depression and abduction of the eye

What 3 characteristics define trochlear nerve palsy

1 Eye position moves up and out 2. Head position compensates causing to tilt head away from affected side 3. Vertical diplopia **Can affect reading, doing stairs, balance = risk of falls**

Is the abducens nerve motor or sensory

Motor

Where does the abducens nerve originate, exit and innervate

Originates: Pons (near pontomedullary junction Exits: Superior orbital fissure Innervates: Lateral rectus muscle

How can abducens nerve palsy occur

When any structure causes pressure on brainstem (space occupying lesion)

What are 2 effects caused by abducens nerve palsy

1. Eye resting in adduction 2. Diplopia (double vision)

What is the largest cranial nerve

Trigeminal nerve

Is the trigeminal nerve motor or sensory

Both

What 3 functions is the trigeminal nerve responsible for (are they motor or sensory)

1. Biting and chewing (motor) 2. Dampen tympanic membrane (motor) 3. Sensation in face (Sensory)

Where does the trigeminal nerve exit

Ventral surface of the pons

What does the trigeminal nerve control through motor movement

1. Muscles associated with mastication = chewing (temporalis, masseter, lateral and medial pterygoid, mylohyoid, and belly of digastric -> Dont memorize muscles) 2. Dampens tympanic membrane via tensor tympani for protective function

What are the 3 sensory branches of the trigeminal nerve

1. Ophthalmic 2. Maxillary 3. Mandibular

What are 4 sensory functions the trigeminal nerve is responsible for

1. Discriminative touch 2. Proprioception 3. nociception 4. Temperature ** all of the face

What is a disorder associated with damage to trigeminal nerve and what does it cause

Facial Hemianesthesia: Loss of sensation of face on one side (contralateral)

Where does the facial nerve emerge from

The pons (pontomedullary junction)

What 2 portions make up the facial nerve

Intracranial portion and extracranial portion

Is the facial nerve responsible for motor or sensory

Motor, sensory, special sensory, and parasympathetic

Where does the facial nerve exit

1. Internal acoustic meatus 2. Stylomastoid foramen

Stapedius of facial nerve function

dampens sound so if damaged = hypersensitivity to sound

Is the stapedius motor or sensory and is it intracranial or extracranial

Intracranial and motor

Hyperacusis

Hypersensitivity to sound

Chorda Tympani of facial nerve is

Responsible for taste

What are the 2 major landmarks of the facial nerve

What are the 4 muscles that make up the extracranial portion of the facial nerve

1. Posterior auricular nerve 2. Digastric muscle 3. Stylohyoid muscle 4. Motor root of facial nerve

The function of the posterior belly of digastric and stylohyoid and is it motor or sensory

Motor -> swallowing

Facial nerve is responsible for (4)

1) Facial expressions through facial muscles 2) ear dampening 3) swallowing 4) anterior 2/3 taste

What are the 5 branches of the facial muscles and function (don’t need to know -Mackeely confirm)

1. Temporal: Rase eye brows 2. Zygomatic: Close eye 3. Buccal: smiling and whistling 4. Mandibular: Pout 5. Cervical: frowning

The upper facial muscles are controlled

Bilaterally

The lower facial muscles are controllled

Contralaterally

Damage to UMN of facial nerve results in

Contralateral weakness to lower facial muscles

Damage to LMN of facial nerve results in

Bell's Palsy

What structure of the facial nerve is responsible for sensory and special sensory

Anterior 2/3 of tongue

What structure of the facial nerve is responsible for parasympathetic

Glands of the neck

Is the vestibulocochlear nerve sensory or motor

Sensory

What is the vestibular portion of the vestibulocochlear nerve responsible for

1. Balance 2. Vestibulo-Ocular Reflex

What is the cochlear portion of the vestibulocochlear nerve responsible for

Hearing

Where does the vestibular portion of the vestibulocochlear nerve arise from

Vestibular nuclei (pons/medulla)

Where does the cochlear portion of the vestibulocochlear nerve arise from

Ventral and dorsal cochlear nuclei (inferior cerebellar nuclei)

What can damage the vestibulocochlear nerve

Whiplash from MVA

The glossopharyngeal nerve originates in the

Medulla

The glossopharyngeal nerve exits the

cranium via jugular foramen

The glossopharyngeal nerve is responsible for sensory or motor

Sensory, Motor, special sensory, and parasympathetic

What is the motor muscle that the glossopharyngeal nerve controls

Stylopharyngeus muscle

What occurs if the glossopharyngeal nerve is damaged (in terms of the stylopharyngeus muscle)

Dysphagia (swallowing difficulties)

What sensory structures does the glossopharyngeal nerve control

1. Middle ear and eustachian tube 2. Tonsil and pharynx 3. Carotid body and sinus

What special sensory structures does the glossopharyngeal nerve control

Taste for posterior 1/3 of tongue

What special sensory structures does the glossopharyngeal nerve control

Parotid Salivary Gland

What nerve is responsible for the gag reflex

Glossopharyngeal nerve (sensory info)

What nerve control the gag reflex

Cranial Nerve 9 (glossopharyngeal) does sensory info and Cranial Nerve 10 does motor (Vagus)

The vagus nerve originates in the

Medulla

The longest cranial nerve is the

Vagus nerve

The vagus nerve exits the

Jugular foramen

Is the vagus nerve responsible for motor or sensory

Motor, Sensory, Special sensory, parasympathetic

What are the motor structures innervated by vagus nerve

1. Pharynx 2. Soft palate 3. Larynx

What are the sensory structures innervated by vagus nerve

1. External acoustic meatus 2. Larynx and laryngopharynx 3. Heart 4. Abdominal Viscera

What are the special sensory structures innervated by vagus nerve

Taste sensation to epiglottis and root of tongue

What are the parasympathetic structures innervated by vagus nerve

1. Trachea, Bronchi 2. GI Tract 3. Regulates heart rhythm

What are 6 affects of damage to vagus nerve

1. Gag reflex 2. Dysphonia and aphonia 3. Dysphagia 4. Deviation of uvula (damage to vagus nerve on right = deviate to left) 5. Loss of vagal tone of heart 6. Unusal heart rate