Lab 4- Cranial Nerves & the Eye, pt. 1: Cranial Nerves

olfactory nerve foramina

Cribriform plate of ethmoid bone

what CN controls the special sense of smell?

CN I- Olfactory

What cranial nerve controls the special sense of vision?

CN II- Optic

Optic nerve foramina

optic foramina (optic canal)

Damage to what structure causes loss of temporal vision in both eyes, resulting in tunnel vision (loss of peripheral vision)?

loss of info from medial (nasal) retina of both eyes.

**medial (nasal) retina carries info from temporal (peripheral) visual field, therefore only nasal part of visual field of both eyes is retained.

optic chiasm

damage to what structure causes loss of vision in the eye on the same side that this is damaged? (ipsilateral)

This structure attached directly to the eye

optic nerve

damage to what structure causes loss of vision in the eye on the opposite side of the damage? (contralateral)

optic tract

1. optic nerve (CN II)

2. optic chiasm

3. optic tract

1. retina

2. optic nerve (CN II)

3. optic chiasm

4. right optic tract

5. diencephalon

6. midbrain

7. visual cortices of occipital lobes

what cranial nerve has motor function that moves the eye & eyelid by controlling 4/6 extraocular muscles,

has the parasympathetic function of accommodation & light reflex (constrict pupil by contracting sphincter pupillary muscles)

CN III- Oculomotor

what is the visual pathway?

1. light hits eye (retina)

2. CN II

3. optic foramina (optic canal)

4. optic chiasm

5. optic tract

6. thalamus

7. visual cortex in occipital lobe

what are the 4 extraocular muscles controlled by the oculomotor nerve?

superior rectus

medial rectus

inferior rectus

inferior oblique

What is the process whereby the ciliary muscles contract, causing the zonular fibers to slacken, then the lens becomes rounded/thickened?

Accommodation for near vision

What is the process whereby the ciliary muscles relax, causing the zonular fibers to stretch/lengthen, then the lens becomes flattened for near vision?

Accommodation for distant vision

what is the pathway of the light reflex & what CN controls this?

1. high amount of light enters eye

2. pupils constrict

3. sphincter pupillary muscles contract

4. squinting

controlled by CN III- oculomotor (parasympathetic)

foramina of oculomotor nerve

superior orbital fissure

what CN has motor function that moves the eye downward & laterally by controlling 1/6 extraocular muscles (superior oblique)?

CN IV- Trochlear “pulley”

what extraocular muscle does the trochlear nerve control and how does it move the eye?

superior oblique- downward & lateral eye movement

foramina of trochlear nerve

superior orbital fissure

what cranial nerve has motor function that abducts the eye (outward gaze)

CN VI- Abducens

foramina of abducens nerve

superior orbital fissure

what muscle does the abducens CN control?

lateral rectus muscle

What CN has sensory function of face, eyes, nasal cavity, & general sensation (NOT TASTE) of anterior 2/3 of tongue?

It also has motor function of mastication by controlling masseter muscle

CN V- Trigeminal

(think “tri” = 3 senses controlled)/3 branches

branch of trigeminal nerve that controls sensory info from forehead (superior orbital notch), eye, upper eyelid, & parts of the nose?

ex) pain sensation when cornea is poked → this branch of CN V

V1- Ophthalmic branch

foramina of ophthalmic branch (V1) of trigeminal nerve

superior orbital fissure

branch of trigeminal nerve that controls sensory info from upper jaw, cheek & face (infraorbital foramen), upper lip, nasal cavity, oral cavity, & upper teeth?

V2- Maxillary branch

foramina of maxillary (V2) branch of trigeminal nerve

foramen rotundum

branch of trigeminal nerve that controls sensory info from ear, lower jaw, lower face, lower lip, lower teeth, nasal cavity, oral cavity, & anterior 2/3 tongue general senses NOT taste?

Also has motor function of mastication 

V3- Mandibular branch

foramina of mandibular (V3) branch of trigeminal nerve

foramen ovale

what muscle elevates the mandible & closes the jaws and what CN controls it?

masseter

CN V- trigeminal (V3- Mandibular branch)

what CN has motor function of facial expression muscles, sensory function of taste of anterior 2/3 tongue, and parasympathetic function of gland secretions (tears & saliva)?

ex) eat spicy food = saliva, tears, & expressions

CN VII- Facial

foramina of facial nerve

internal acoustic meatus & stylomastoid foramen

what CN has sensory function of balance via semicircular canals & hearing via cochlea?

CN VIII- Vestibulocochlear

foramina of vestibulocochlear nerve

internal acoustic meatus

damage to what CN could cause vertigo?

vestibulocochlear

what CN has sensory function of posterior 1/3 tongue taste & general sensation, upper throat, carotid sinus (pressure) & body (oxygen levels), involved in gag reflex

motor function = stylopharyngeus muscle

parasympathetic function = innervates parotid gland for saliva production

CN IX- Glossopharyngeal

what muscle controls swallowing

stylopharyngeus (controlled by glossopharyngeal)

foramina of glossopharyngeal nerve

jugular foramen

What CN has sensory function of inferior pharynx & larynx (lower throat) and thoracic& abdominal organs,

motor function of soft palate (closes nasal opening while swallowing), pharynx, and larynx (speech aka voice box), and involved gag reflex).

parasympathetic function of digestion via thoracic & abdominal viscera → heart rate, breathing rate, bowel movements (secretes bile, prevents constipation, promotes proper digestion

CN X- Vagus

what is Vagus nerve also known as

wanderer

what two cranial nerves are involved in the gag reflex & what are their roles?

CN IX (glossopharyngeal)- sensation in upper throat

CN X (vagus)- gag via pharyngeal muscles motor function

foramen of vagus nerve

jugular foramen

what cranial nerve has motor function of sternocleidomastoid muscle (rotate head) & trapezius muscle (shrug shoulders)?

CN XI- Accessory

foramina of accessory nerve

foramen magnum & exits thru jugular foramen to muscle

what CN has motor function of extrinsic (shape for speech) & intrinsic (swallow) tongue muscles?

movement of tongue

CN XII- Hypoglossal

foramina of hypoglossal nerve

hypoglossal canal

what is the lower jaw bone called?

mandible

what nerve is responsible for sticking out your tongue?

hypoglossal

what type of damage would occur if the jugular foramen was injured?

glossopharyngeal, vagus, & accessory nerves all pass through

Injury results:

Glossopharyngeal → lose gag reflex(no upper throat sensation) & lose taste/general sensation of posterior 1/3 tongue

Vagus → lose gag reflex (no pharyngeal muscle movement), voice changes, difficulty swallowing

Accessory → unable/weak head turning & shoulder shrugging/droop

Cribriform Plate:

CN I- Olfactory

Optic Canal/Foramina:

CN II- Optic

Superior orbital Fissure:

CN III- Oculomotor

CN IV- Trochlear

V1- Ophthalmic branch of trigeminal

CN VI- Abducens

Foramen rotundum:

V2- Maxillary branch of trigeminal

Foramen ovale:

V3- Mandibular branch of trigeminal

Internal Acoustic Meatus:

CN VII- Facial

CN VIII- Vestibulocochlear

Jugular Foramen:

CN IX- Glossopharyngeal

CN X- Vagus

CN XI- Accessory

Hypoglossal Canal:

CN XII- Hypoglossal