Lecture 1 - Cranial Nerves Flashcards Preview

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Flashcards in Lecture 1 - Cranial Nerves Deck (77):

List the 12 cranial nerves from rostral to caudal.

1. Olfactory
2. Optic
3. Oculomotor
4. Trochlear
5. Trigeminal
6. Abducens
7. Facial
8. Acoustic
9. Glossopharyngeal
10. Vagus
11. Accessory
12. Hypoglossal


How to remember the function of each cranial nerve?

Some say marry money but my brother says big brains matter more

S: sensory (olfactory nerve - CN I)
S: sensory (optic nerve - CN II)
M: motor (oculomotor nerve - CN III)
M: motor (trochlear nerve - CN IV)
B: both (trigeminal nerve - CN V)
M: motor (abducens nerve - CN VI)
B: both (facial nerve - CN VII)
S: sensory (vestibulocochlear nerve - CN VIII)
B: both (glossopharyngeal nerve CN IX)
B: both (vagus nerve - CN X)
M: motor (spinal accessory nerve - CN XI)
M: motor (hypoglossal nerve - CN XII)


Cranial nerve mnemonic?

Oh, Oh, Oh, To Touch And Feel A Girl's Vagina and Hymen


What cranial nerves are found in the forebrain?

1 and 2


What cranial nerves are found in the brainstem?

3 to 12


Do cranial nerves provide both somatic and visceral innervation?



Do cranial nerves provide both sympathetic and parasympathetic innervation?

NOPE, only parasympathetic


What 3 types of innervation do cranial nerves provide?

1. Somatic
2. Visceral
3. Special sensory


What are the 5 special senses that cranial nerves provide innervation for?

1. Vision
2. Smell
3. Taste
4. Hearing
5. Equilibrium


Function of olfactory nerve?



Function of optic nerve?



Function of trochlear nerve?

Serves the superior oblique eye muscle to facilitate intorsion, abduction, and depression of the eyeball = eye looking down and laterally


Functions of trigeminal nerve?

1. Sensory from face and mouth
2. Motor to muscles of mastication


Function of abducens nerve?

Serves the lateral rectus eye muscle to faciliate abduction of the eyeball


Functions of facial nerve?

1. Serves the muscles of facial expression
2. Serves parasympathetic innervation to all face glands except for the parotid gland
3. Special sensory from anterior 2/3 of tongue and palate


What are the lacrimal glands?

Paired, almond-shaped glands, one for each eye, that secrete the aqueous-layer of the tear film


Functions of the vestibulocochlear nerve? How many branches does it have?

1. Equilibrium
2. Hearing

2 branches (one for each sense)


Functions of the glossopharyngeal nerve? Most important one?

1. General/somatic sensory for posterior third of tongue, pharynx, back of palate, middle ear, and Eustachian tube
2. Visceral sensory from carotid baro/chemoreceptors
3. Special sensory from posterior third of tongue

1. Somatic innervation to 1 muscle of the pharynx for swallowing
2. Parasympathetic innervation of parotid gland


Functions of the vagus nerve?

1. General/somatic sensory innervation from structures in the lower pharynx and larynx and ear
2. Visceral sensory from visceral organs and chemo/baroreceptors in aorta (thorax)

1. Somatic innervation of 1 intrinsic tongue muscle (palatoglossus) and most muscles of the soft palate, pharynx, and larynx (phonation)
2. MAJOR Parasympathetic regulation of visceral organs and glands in thorax, abdomen (foregut and midgut), pharynx, and larynx


Function of accessory nerve?

Serves muscles that move head, neck, and shoulders: trapezius and sternocleidomastoid muscles


Function of hypoglossal nerve?

Somatic motor to all muscles of the tongue (except palatoglossus)


What is the pathway of smell?

Olfactory epithelium in upper nasal cavity with olfactory cilia and dendrites (these all constitute CN I) => ethmoid bone => synapse with olfactory bulb (termination of nerve) => olfactory tract => olfactory cortex of the cerebrum


What is the pathway of vision?

Photoreceptors (rods and cones) in retina => ganglion cell layer => converge to form CN II => optic chiasm => optic tracts => synapse at thalamus => synapse at visual cortex of cerebrum


What is the optic chiasm close to?

Pit gland


What do optic nerves connect?

Connect the retina to the optic chiasm


Which optic fibers decussate at the optic chiasm?

The fibers from the medial side of the retina (peripheral vision)


What are optic tracts?

Optic fibers starting at the optic chiasm


What do optic chiasm lesions (or pituitary tumors) cause?

Bi-temporal hemianopsia


What is hemianopsia?

Visual field loss on the left or right side of the midline


What is homonymous hemianopsia?

Visual field loss on the same side of both eyes


What visual field does the medial side of the retina sees?

Peripheral vision


What are the 3 extraocular cranial nerves?

What do they innervate? Which one innervates the most?

1. Oculomotor***
2. Trochlear
3. Abducens

Innervate extrinsic eye muscles


What are the 2 functions of the oculomotor nerve?

1. SOMATIC MOTOR: levator palpebrae superioris (ELEVATES eyelids) and 4/6 extraocular muscles to move the eyeball
2. VISCERAL MOTOR PARASYMPATHETIC: to intraocular/intrinsic muscles: sphincter pupillae muscle (pupil constriction) and ciliary muscles (lens accommodation)


When are ciliary muscles contracted?

Near vision


What are the 3 intrinsic eye muscles? What innervation does each receive?

1. Ciliary: CNIII parasympathetic
2. Sphincter pupillae: CNIII parasympathetic
3. Dilator pupillae: sympathetic


What is the function of extrinsic eye muscles?

Eyeball and eyelid movement


What are the 3 branches of the trigeminal nerve? What is the shorthand for each? What region does each innervate?

1. Ophtalmic (V1): top of face to bottom of nose (not including temples)
2. Maxillary (V2): temples, cheeks, and upper lip
3. Mandibular (V3): ears, bottom lip, jaw, chin


What is the only trigeminal nerve branch that has somatic motor innervation? For what? What are these called?


Mastication muscles for chewing (and some others in neck)


What are the 3 branches of the intracranial facial nerve? Function for each?

1. Greater petrosal nerve: parasympathetic innervation of lacrimal, palatine, and nasal glands AND taste from palate

2. Chorda tympani nerve: parasympathetic innervation of sublingual and submandibular glands AND taste from anterior 2/3rds of the tongue

3. Nerve to stapedius: muscle in the ear that reduces sound


What is a geniculate ganglion?

Sensory ganglion, mostly for taste


What are the 5 major extracranial branches of the facial nerve? List from superior to inferior.

1. Temporal
2. Zygomatic
3. Buccal
4. Marginal mandibular
5. Cervical


What do the extracranial branches of the facial nerve form and where? What do they supply?

Embedded in the parotid gland and form the parotid plexus

Supply muscles of facial expression


How does an UMN lesion (motor cortex) leading to the facial nerve affect the face?

- Upper face is spared because both primary motor cortex hemispheres contribute to movement of the upper face
- Lower face is affected on one side (contralateral)


How does a lesion of the facial nerve (LMN) affect the face?

The entire face will be affected on one side (ipsilateral)


What nerves provide the general sensory innervation to the tongue?

1. Lingual nerve from V3 of trigeminal nerve: anterior 2/3rds
2. Glossopharyngeal: posterior 1/3rd


What nerves provide the taste sensory innervation to the tongue?

1. Facial: anterior 2/3rds
2. Glossopharyngeal: posterior 1/3rd


What nerves provide the somatic motor innervation to the tongue?

1. Hypoglossal: most muscles
2. Vagus: palatoglossus


What is another way of saying peripheral vision?

Temporal vision


Why is loss of medial vision less common than loss of temporal vision?

Because you would need 2 separate lesions instead of just 1 at the optic chiasm for temporal vision


What are the 2 types of eye muscles? Describe each.

1. Intrinsic: inside eyeball
1. Extrinsic: outside and attached to the eyeball


What is the purpose of the pupil?

Regulates how much light passes through the eye


What is the ciliary muscle?

Muscle inside the eye that is attached to little chords attached to the lens


What is the function of the ciliary muscle?

Regulates near/far vision by focusing light on the retina


Which favors near vision: parasympathetic or sympathetic NS?



What happens if you lose CN III?

CN IV and VI will take over


What is the major sensory nerve of the face?

Trigeminal nerve (CN V)


Function of submandibular and sublingual glands?

Saliva production and secretion


What is the biggest gland of the face? Where is it located? Function?

Parotid gland

Back of the cheeks

Saliva production and secretion


What are the 3 salivary glands?

1. Submandibular
2. Sublingual
3. Parotid


How does the facial nerve go from intracranial to extracranial?

Hole in skull near mastoid process behind ear


Does the facial nerve innervate the parotid gland?



Why is resection of the parotid gland hard to perform?

Because the facial nerve plexus is embedded with it so it'll be hard to preserve it


What is the zygomatic process?

Cheekbone arch


What is the mnemonic to remember the 5 branches of the extracranial portion of the facial nerve?

To Zanzibar By Motor Car


What does the prefix/suffix
"-glossal-" mean?

Having to do with the tongue


Describe the pathway of the spinal accessory nerve?

Originates at the cervical spine, travels into the skull, meets with a little bundle of nerves from the brainstem and exits out with it


What 3 cranial nerves innervate the back of the mouth/throat/palate?

1. Glossopharyngeal: somatic sensory post 1/3rd of tongue, palate, top of pharynx
2. Vagus nerve: somatic sensory of bottom of pharynx and larynx, somatic motor of palate, palatoglossusus, pharynx and larynx for phonation
3. Facial: grater petrosal branch for special sensory of palate


Role of trapezius muscle?

Moving shoulders up and down and backwards


Role of sternocleidomastoid muscle?

Moving head site to side toward shoulders


What are the 2 types of tongue muscles? Describe each.

- Intrinsic muscles = that originate and insert inside the tongue
- Extrinsic muscles = that originate outside the tongue but insert inside it


Which 3 cranial nerves are tested together? How?

3, 4, and 6

Follow finger to test movement of eye in all directions and light test for pupillary reflex test


How to test the trigeminal nerve?

Touch 3 parts of the face in 3 areas innervated by the 3 branches


How to test facial nerve?

Smile, raise eye brows, frown, and puff up cheeks


How to test glossopharyngeal nerve?

Gag reflex


What is ptosis?

Drooping or falling of the upper eyelid


How can a lung tumor at the apex of the lungs affect the eyes?

Can stop sympathetic innervation of the eye causing the pupil to be constantly constricted


What is the Eustachian tube? What are the implications of this?

Connects the middle ear to the pharynx:

- Structure allows your ears to pop when pressure builds up.
- Common to get a middle ear infection/inflammation with/after an upper respiratory infection (URI) via the connection through the Eustachian tube.