N03: Neurological System II: Sensory - Cranial Nerves, Eyes, Ears

Extraocular muscles:

4 rectus + 2 oblique • Coordinated so eyes move together (conjugate movement) • Six muscles that attach the eyeball to its orbit and serve to direct the eye to points of the person's interest. Enable straight and rotary movements. • Rectus are straight. They are the superior, inferior, lateral and medial rectus muscles. • Oblique are slanting and are the superior and inferior oblique muscles.

Objective Data • Hearing Acuity:

Whispered voice test - place finger on tragus and rapidly push it in and out of the auditory meatus. Shield lips so pt cannot read them. 30-60 cm from pt, whisper two-syllable words Tuning fork tests - measuring hearing by air or bone conduction. Weber test - hearing better in one ear Fig. 15-20, Jarvis, 2009, p. 353 Rinne test - compares AC and BC sound

overall function of ears

"The ear is an engineering marvel because its sensory receptors can transduce sound vibrations... into electrical signals 1000 times faster than photoreceptors can respond to light." • The ear (specifically semicircular canals in the labyrinth) is also responsible for equilibrium and awareness of our orientation in space.

Overall function of the eyes

"The eyes are extremely sophisticated visual instruments - more versatile and adaptable than the most expensive cameras, yet light, compact, and durable." Martini, 2004, p. 571 • Light rays enter the cornea and are bent (refracted) onto the lens › Ciliary body controls thickness of the lens (will change shape based on distance of the object) › Iris serves as a diaphragm › Pupil controls amount of light entering retina (thus, aids in making vision clearer)

Ears, Structure (+ function) - Internal • Inner ear:

= labyrinth: bony labyrinth - contains vestibule; semicircular canals; cochlea • Labyrinth - holds sensory organs for equilibrium and hearing. Vestibule and semi-circular canals constitute the vestibular apparatus and cochlea contains the central hearing apparatus

Objective Data of the eyes, charts used

Central Visual Acuity: • Snellen eye chart • Near vision Visual Fields: • Confrontation test - gross measure of peripheral vision. Compared with person administering the test (if normal). Be eye level with pt. Direct pt to cover one eye with an opaque card and look straight at you with the other eye. Hold a pencil as a target midline between you and the pt, at the periphery vision and slowly advance it inward from the periphery in several directions. Tell pt to say now when they see the object (you should see it at the same time) 50° upwards, 60° nasally, 70° downwards and 90° temporally

Oculomotor Nerve (CN III), Trochlear (CN IV) Abducens (CN VI)

III - motor, most extraocular movements, i.e., opening of eyelid IV - motor, down and inward movement of eye VI - motor, lateral movement of eye • Check pupils for size, regularity, equality, direct (i.e., point light right on eye) and consensual (other eye will respond when light is shone on first eye) light reactions and accommodation (i.e., needs more light for far away, less for close) • Dim the room as much as possible • Bring penlight from periphery to center • Inspect the eyelids for ptosis • Measurements of pupils should be done in mm to avoid subjectivity • If normal use acronym PERRLA: Pupils, Equal, Round, Reactive to Light and Accommodate • All three control the movement • Muscles attached to sclera. • Left contains medial rectus. • Rectus means straight • Oblique means coming from another angle • light is brought to centre so that it is not shone right in there at first (also pupils would accommodate if penlight was right in front of the eye, even if it was off) • Can't accommodate on a comatose person or infant. (infant won't know to follow and comatose probably won't be able to) • Check 6 cardinal positions of gaze (CN III, IV, VI)

Objective Data of the eyes • Anterior Eyeball Structures

Inspect: cornea + lens Inspect: iris + pupil • Pupillary light reflex - normal constriction of the pupils when bright light shienes on the retina. Direct = constriction of pupil, consensual = simultaneous constriction of other pupil. • Accommodation - adaption of the eye for near vision. Accomplished by increasing the curvature of the lens through movement of the ciliary muscles. • PERRLA Cornea should be clear, smooth, curved Look at front, and side (brown on side) no bumps or scratches Cataracts are a clouding of the cornea (protein buildup on cornea over time) Iris - should be round and flat. Pupil is within the iris. Can be many different colors (someone could have a birth mark on eye and alter color or have a spot of a different color)

Structure (+ function) of the eye- External Lacrimal apparatus

Lacrimal apparatus - provides constant irrigation to keep conjunctiva and cornea moist and lubricated. Produces tears which drain into the puncta. Ask the patient to look down. With your thumbs, slide the outer part of the upper eyelid along the bony orbit to expose under the eyelid (inspect for any redness or swelling) Excessive tearing may indicate blockage of the nasolacrimal duct (check this by pressing your index finger against the sac, just inside the lower orbital rim, NOT against the side of the nose; pressure causes the lower eyelids to evert slightly but no other response to pressure should occur)

Structure - Visual pathways/fields

Light rays are refracted through the transparent media and strike the retina. Retina transforms the light stimulus into nerve impulses that are conducted through the optic nerve and the optic tract to the visual cortex of the occipital lobe. Image formed on retina is upside down and reversed from actual appearance.

Facial Nerve (CN VII)

Sensory and motor neuron sensory - taste (sweet, salty, sour, bitter) on anterior 2/3 of tongue motor - facial muscles, close eyes, labial speech, close mouth • Controls facial movements and expression • While noting mobility and facial symmetry ask patient to: • Smile • Frown • Close eyes tightly (attempt to open them) • Lift eyebrows • Show teeth • Puff cheeks (press in and note if air escapes equally) • Sensory function is not routinely tested unless facial nerve injury is suspected. • Use salt, sugar or lemon on anterior 2/3 of tongue.

Optic Nerve (CN II)

Sensory nerve • Controls central and peripheral vision Use the confrontation test: • Assumes you have normal vision • Hand needs to be kept in middle plane or equally in the vision field.

Olfactory Nerve (CN I)

Sensory nerve • Controls the sense of smell • Do not use a substance with a harsh odor (e.g. Bleach) • Assess for patency first - closing one nostril and asking pt to sniff, use aromatic substances with eyes closed. Nostrils may alter with one being able to smell better for example • Ask patient to close their eyes • Do both nostrils, one at a time • Use familiar scents eg. Coffee or mint

Objective Data • Inspect and palpate external ear:

Size and shape: Ears are of equal size bilaterally with no swelling or thickening; (ears of unusual size and shape may be normal familial trait with no clinical significance) Skin Condition Skin color is consistent with the patients facial skin color; skin is intact with no lumps or lesions; on some patients you may notice Darwin's tubercle, a small painless nodule at the helix (this is a congenital variation and in not significant) Tenderness: Move the pinna and push on the tragus; they should feel firm, and movement should not produce any pain; palpating the mastoid process should also produce no pain The External Auditory Meatus: - Note the size of the opening to direct your choice of speculum for the otoscope; no swelling, redness, or discharge should be present; some cerumen (ear wax) is usually present; color varies from grey-yellow to light brown and black, and texture varies from moist and waxy to dry and desiccated; a large amount of cerumen obscures visualization of the canal and eardrum

Objective Data • Inspect with otoscope

The External Canal: note any redness and swelling, lesions, foreign bodies, or discharge; if any discharge present, note color and odor; clean any discharge from speculum before examining the other ear to avoid contamination with possible infectious material); for a patient with a hearing aid, note any irritation on the canal wall from poorly fitting ear moulds Tympanic membrane = Color and Characteristics: systematically explore the eardrum's landmarks; normal eardrum is shiny and translucent, with pearly grey coloration; the cone-shaped light reflex is prominent at the 5:00 position in the right eardrum and 7:00 position in left eardrum; sections of the malleus are visible through the translucent eardrum—the umbo, manubrium, and short process Position: the eardrum is flat and slightly pulled in at the centre, and it flutters when the patient performs the Valsalva maneuver or holds the nose and swallows (insufflation) (you may ask the patient to perform these to test the eardrum's mobility); avoid these maneuvers in elderly patients as it may disrupt the equilibrium and also in patients with upper respiratory infections because it could propel infectious material into the middle ear Integrity of the Membrane: inspect the eardrum and the entire circumference of the annulus for perforations; the normal tympanic membrane is intact; some adults may show scarring, which is a dense white patch on the drum (this is a result of repeated ear infections)

Structure (+ function) of the eye - Internal • Middle layer:

choroid; iris; pupil; lens (ciliary body); anterior/posterior chambers (aqueous humor) Choroid - dark pigment to prevent light from reflecting internally and is heavily vascularized to deliver blood to retina • Iris - functions as a diaphragm to control amount of light admitted to the retina. • Lens - transparent biconvex disc located just behind the pupil. Serves as a refracting medium, keeping a viewed object in continual focus on the retina. Buldge for near, flatten for far. • Anterior chamber - posterior to cornea and anterior to iris and lens • Posterior - behind iris to sides of the lens. • These two chambers contain the clear, watery, aqueous humor, which is produced continually by the ciliary body.

Structure - Internal • Tympanic membrane:

cone of light • Aim a bit towards the nose • Cone of light: reflection of light on a healthy normal ear drum. Should reflect towards the nose or front. 5 o'clock in right, 7 in left

Structure (+ function) of the eyes - External Accessory structures:

eyelids; eye lashes; (palpebral fissure); canthus. • Inner to outer eye for drops, cream, ect. (start at clean and then go to dirty. Tear duct is "clean") • Palpebral - space between eye lids on opp side of tear duct. • Limbus - border between cornea and sclera • Canthus - corner of eye,angle where eyelids meet. • Caruncle - small, fleshy mass containing sebaceous glands General Note patient's facial expressions (a relaxed expressions accompanies adequate vision). Say patient's facial expression is relaxed State if the patient was walking into the room, you would note their visual functioning as they are able to avoid obstacles and respond to simple directions Eyebrows Normally, the eyebrows are present bilaterally, move symmetrically as the facial expressions change, and have no scaling or lesions Eyelids and lashes The upper eyelids normally overlap the superior part of the iris and approximate completely with the lower eyelids when closed The skin is intact, without redness, swelling, discharge, or lesions The palpebral fissures are horizontal or slightly upward in some people of Asian descent Note that the eyelashes are evenly distributed along the eyelid margins and curve outward Eyeball alignment The eyeballs are aligned normally in their sockets with no protrusion or sunken appearance (some people of African descent normally may have a slight protrusion of the eyeball beyond the supraorbital ridge) Conjunctiva and sclera Get the patient to look up. Use your thumbs, slide the patient's lower eyelids down along the bony orbital rim (make sure not to push against the eyeball) Inspect the exposed area. The eyeball looks moist and glossy. Numerous small blood vessels normally show through the transparent conjunctiva (Otherwise, the conjunctiva are clear and show the normal color of the structure below: pink over the lower eyelids and white over the sclera. Make sure to note any color change, swelling, or lesions) The sclera is china white, although in people with dark skin it is occasionally grey blue or muddy.

Ears, Structure (+ function) - Internal • Middle ear:

malleus; incus; stapes (oval window); Eustachian tube • Middle ear - backside of ear drum. Structures work together to create waves in inner ear and stabilize tympanic membrane. Doesn't do too much concerned with hearing, vibration and stabilization. Move it to the inner ear. • Inner ear - hearing and equilibrium. Cochlea and semi-circular?? • Malleus "hammer" • Eustachian tube - connects middle ear with the nasopharynx and allows passage of air. Opens with swallowing or yawning.

Hypoglossal (CN XII)

motor - movement of tongue • Innervates the tongue • Ask patient to stick out their tongue • Inspect for wasting or tremors • Thrust is midline • Ask patient to say "Light, tight, dynamite" • The sounds of the "l, t, d and n" should be clear and distinct

Spinal Accessory (CN XI)

motor - movement of trapezius and sternomastoid muscles. • Controls neck and shoulder movement • Examine: • Sternomastoid • Trapezius • Ask patient to rotate head each away against resistance applied to side of chin • Ask patient to shrug shoulders against resistance • Should be equal

cover/uncover test: normal/abnormal response

normal response is that the eye remains fixed on the object Abnormally: -Uncovered eye: if it jumps to fixate on designated point, it was out of alignment before (i.e., when you cover the stronger eye, the weaker eye now tried to fixate. Covered eye: If this is the weaker eye, once macular image is suppressed, the eye drifts to relaxed position. -As eye is uncovered: if it jumps to re-establish fixation, weakness exists.

Structure (+ function) of the eye- Internal • Inner layer:

retina; optic disc; vessels; macula; fovea centralis. • Retina - visual receptive layer of the eye in which light waves are changed into nerve impulses. • Optic disc - fibres from the retina converge to form the optic nerve. Nasal side of retina. Attachment spot • Retinal vessels - paired artery and vein extending to each quadrant, growing progressively smaller in calibre as they reach the periphery • Macula: exact centre of retina, temporal side of fundus. Receives and transduces light from the centre of the visual field. • Fovea centralis: highest visual acuity. (sharpest and keenest vision) Inspect the ocular fundus: - When using the ophthalmoscope make sure you darken the room to help dilate the pupils - Make sure to match sides with patient when using ophthalmoscope (ie. right to right, left to left) - Begin about 25 cm away from the patient at an angle of about 15 degrees lateral to the patient's line of vision - Note the red glow filling the patient's pupil (this is the red reflex, caused by the reflection of the light off the inner retina). Keep sight of the red reflex, and steadily move closer to the eye - Progress towards the patient until foreheads almost touch. By moving in at the 15 degree lateral line, you should bring your view only to the optic disc - Systematically, inspect the structures in the ocular fundus (optic disc, retinal vessels, general background and macula Optic Disc - The optic disc is located on the nasal side of the retina Size Note Margins of optic disc(s) are distinct/sharply demarcated although nasal edge may be slightly fuzzy Cup:Disc ratio (when visible, the physiological cup is a brighter yellow-white than the rest of the disc. Its width is not more than half the disc diameter; Macula is approximately 2- 3 Diameter of the disk (DD) from the optic disc. Optic disk is medial/nasally and macula is lateral. Shape Round/Oval Color Creamy yellow-orange to pink Retinal Vessels -Follow a paired artery and vein out to the periphery in the four quadrants, noting these points: 1) Number - a paired artery and vein pass through each quadrant (vessels look straighter at the nasal side 2) Color - arteries are brighter red than the veins. Also, they have the arterial light reflex, with a thin strip of light down the middle 3) Artery-Vein Ratio - the ratio of the artery width to vein width is 2:3 or 4:5 4) Caliber - arteries and veins show a regular decrease in caliber as they extend to the periphery 5) Arteriovenous Crossing - an artery and vein may cross paths. This is not significant if with in 2 DD of disc and if no sign of interruption in blood flow is seen. There should be no indenting or displacing of vessel 6) Tortuosity - mild vessel twisting when present in both eyes is usually congenital and not significant 7) Pulsations - pulsations are visible in veins near the disc as their drainage meets the intermittent pressure of the arterial systole (often hard to see) General Background of the Fundus - The color normally varies from light red to dark brown-red, generally corresponding to the patient's skin color. The fundus should be clear, and no lesions should obstruct the retinal structure Macula - The macula is 1 DD in size and located 2 DD temporal to the disc. Inspect last during your examination. The macula is somewhat darker than the rest of the fundus, but it is even and homogenous. Within the macula you may not the foveal light reflex (this is a tiny white glistening dot that represents a reflection of the ophthalmoscope light)

Structure (+ function) of the eye - Internal • Outer layer:

sclera; cornea • Sclera - tough, protective, white covering. • Cornea - sensitive to touch.

Acoustic Nerve(CN VIII) (Vestibulocochlear)

sensory - hearing and equilibrium • Controls hearing • Use whispered voice test • Mask 'good' ear by rapidly pushing on the tragus • Cover your mouth to avoid lip reading • 30-60 cm away from patient • State two-syllable words e.g. Frenchfry wheelchair jigsaw • Patient should normally repeat each word after you say it • Weber and Rinne tests are not routinely done because they do not yield precise or reliable data

Ears, Structure - External

• Auricle/pinna: external auditory meatus (ceruminous glands); tragus; helix; lobule {tympanic membrane} • External auditory meatus - opening that funnels sound waves • Tympanic membrane - separates the external ear and middle ear and is tilted obliquely to the ear canal, facing downward and somewhat forward.

Ears, pathways of hearing

• Bone conduction • Air conduction Pathways for hearing are of two ways - through the air and through the bone. Either way vibrations are move the bones of the middle ear to transmit them to the inner ear where they can be converted to nervous impulses... Air: vibrating tympanic Bone: vibrating bones Sound waves enter the ear... Waves strike the tympanic membrane, which causes the stapes to vibrate the oval window... Vibrations enter the cochlea - its basilar membrane now vibrates (hair cells of organ of Corti)... The vibrations converted to electrical impulses - travel to the brain (via cranial nerve VIII) to interpret sound.

types of hearing loss

• Conductive - mechanical dysfunction • Otosclerosis = 'hardening' around the oval window • Sensorineural - nervous system damage • {Mixed} • Conductive - of external or middle ear. Partial loss b/c person is able to hear if the sound amplitude is increased enough to reach normal nerve elemetns in inner ear. • Sensorineural - perceptive loss. Signifies disease of inner ear, cranial nerve VIII, or auditory areas of cerebral cortex. • Mixed - combination of conductive and sensorineural types in the same ear

Objective Data of the eyes • Extraocular Muscle Functioning

• Corneal light reflex • Cover test • Diagnostics positions test (6 fields of gaze) = should note parallel tracking of the eyes • 3,4, & 6 • Corneal reflex - get to the eye and pt wants to protect cornea. If a light is shone on eye, reflection off cornea should be the same. • Cover/uncover test - cover one eye, it disapears, remove cover and it reappears • Positions test - move eyes but keep head still. Reveals any muscle weakness during movement. Normal response is parallel tracking of object with both eyes. Not any nystagmus (fine oscillating movement best seen around the iris)

Trigeminal (CN V)

• Covers most of the face • Three areas need to be assessed: • Forehead (Opthalmic) • Cheek (Maxillary) • Jaw (Mandibular) • Motor: palpate temporal and masseter muscles as teeth are clenched and try to separate jaw with clenched teeth • Sensory: With eyes closed take a cotton ball and brush across each area bilaterally, patient should say 'now' when they feel the touch. Mix it up! • This is assessing light touch sensation sensory and motor neuron motor - muscles of mastication sensory - sensation of face and scalp, cornea, mucus membranes of the mouth and nose

Cranial Nerves

• Cranial nerves (LMN) • Exit brain • Supply head and neck • Vagus nerve extends to ht/lungs, gut • Face is supplied by cranial nerve • Vagus nerve has an autonomic function • Ordered in the way they enter and exit the brain stem Although they enter and exit the brain, they are lower motor neurons because they have direct innervation to end point (muscle, organ)

Developmental Considerations of the eye

• Infant and children o Eye function matures from birth onward o Eye movements may be poorly coordinated in infants o Infants do have peripheral vision. Macula absent at birth but developing by 4 months and mature by 8. • Older adults • Decrease in tear formation • Other physiologic changes

Ear, Developmental Considerations

• Infants and children • External auditory meatus and eustachian tube are shorter and horizontal • Adults • Otosclerosis • Older adults • Physiologic changes - impacted cerumen, sensorineural loss • Hearing loss - hearing aids

Glossopharyngeal (CN IX) and Vagus (CN X)

• Innervate the tongue and throat • Motor function: Midline rise of the uvula and soft palate, tonsillar pillars move medially in response to saying "ahh" or a yawn. Also touch the posterior pharyngeal wall with the tongue blade. MUST BE WATCHING BACK OF THROAT • Sensory: The glossopharyngeal nerve (IX) mediates taste on the posterior one third of the tongue but it is hard to get tastes that far back • Vagal response (heart rate slows, vessels dilate; could faint) IX: motor - pharynx (phonation and swallowing) sensory - taste on posterior 1/3 of tongue, pharynx (gag reflex) parasympathetic - parotid gland, carotid reflex X: motor - pharynx and larynx (talking and swallowing) sensory - general sensation from carotid body, carotid sinus, pharynx, viscera parasympathetic - carotid reflex

Objective Data of the eye • External Ocular Structures

• Inspect by working out to in • General' eyebrows; eyelids/lashes; eyeballs; conjunctiva + sclera; lacrimal apparatus • Eyebrows - present bilaterally, move symmetrically as facial expression changes and no scaling or lesions. • Eyelids and lashes - upper eyelids normally overlap superior part of the iris and approximate completely with the lower eyelids when close. Intact skin, without redness, swelling, discharge or lesions. • Eyeballs - aligned normally in their sockets with no protrusion or sunken appearence. • Conjuctiva and sclera - eyeball looks mosit and glossy. Should see small blood vessels or else eyes are clear and show the normal colour of the structure below (pink over lower eyelids and white over sclera) • Lacrimal apparatus - ask pt to look down. Slide outer part of upper eyelid and inspect for redness or swelling. • NO eversion of eyelid

Objective Data of the eye • Ocular Fundus - internal surface of retina

• Inspect using ophthalmoscope: › Red reflex › Optic disc - DD › Retinal vessels › Fundus background › Macula • Smallest light possible, not trying to dilate pupil. Small light to tuck in and get inside the eye. • Start at turning light on and pointing at person, a bit laterally. Should see a red light reflex (it is the retina which has many blood vessels) Use opposite eyes. (if looking at pt right eye, look with left eye) • Optic disc located nasally, is reference for disc diameter. Most prominent landmark. • Retinal vessels - number, colour, artery-vein ratio, calibre, arteriovenous crossing, tortuosity, pulsations. • Fundus background: varies from light red to dark brown-red, generally corresponding to pt skin color. Clear with no lesions • Macula - 1 DD in size. Darker than rest of fundus but even and homogeneous. Note foveal light reflex (glistening dot that represents a reflection of ophthalmoscope's light

eye, key terms

• Macular degeneration - disorder of retina, loss of central vision, peripheral stays largely intact • Cataracts -lens becomes cloudy. Clumping of proteins on lens • Glaucoma - increased pressures. Increased intraocular pressure, gradual loss of peripheral vision • Diabetic retinopathy - retinal changes/hemorrhages, "black spots" in vision • Presbyopia - 'old eye' • Myopia - nearsightedness • Hyperopia - farsightedness

Structure (+ function)of the eyes - External Tarsal plates; conjunctiva

• Outer layer: sclera; cornea • Middle layer: pupil; lens anterior/posterior chambers • Tarsal - thick fold of connective tissue. Give it shape. Contain Meibomian glands, modified sebaceous glands that Secrete lubricating substance to seal entire eyeball • Conjunctive - transparent protective covering (in exposed part of the eye) • Sclera - tough, protective white covering. • Cornea - sensitive to touch, bends incoming light rays so that they are focused on retina within. • Lens - refractive medium. Keeping a viewed object in continual focus on the retina Cornea and lens Shine a light from the side across the patient's cornea, and check for smoothness and clarity No opacities (cloudiness) should appear in the cornea, the anterior chamber, or the lens behind the pupil Iris and pupil Normally, the iris appears flat, with a round, regular shape and even coloration Normally, the pupils appear round, regular, and of equal size in both eyes (in adults, resting size is from 35 mm

Subjective Data of the eyes

• Questions regarding: • Difficulty seeing Blurring; blind spots • Pain • (Strabismus or diplopia) hx of crossed eyes or double vision • Redness or swelling • Excessive tearing • Injury or eye surgery • Testing for glaucoma • Glasses or contact lenses • Self-care behaviours; medications

Subjective Data of the ears

• Questions to ask: Earaches Infections Discharge Hearing loss Exposure to environmental noise Tinnitus (ringing/buzzing in ears) Vertigo (room spinning) Self-care behaviours

Posterior column tract

• Vibration - tuning fork over bony prominences. Ask when vibrations start and stop. • Position - ability to perceive movements of the extremities. Move a finger or big toe up and down and ask pt to tell you which way it moved while their eyes are closed. • Fine touch (tactile discrimination) • Stereognosis - close eyes, put something in pt hands (something familiar they can recognize with just touch) • Graphaesthesia - write a letter or number in pt hand and ask what it was • Two-point discrimination - two sharp objects, until pt can sense both at one time. Note distance at which the objects become separat • Extinction - knowing there is one or two. Touch body on both sides in same place and see how many stimulus' are felt. • Point location - touch skin, pull away quickly and ask pt to point where you touched them

Spinothalamic tract:

• pain - pt ability to perceive a pinprick • temp - hot and cold in various parts of body • light touch - wisp of cotton to skin. Brush at random intervals