Exam 1/Quiz 3- Physiology of the Eye/Physiology of the Ear Flashcards
What are the special senses?
- Vision
- Hearing
- Smell
- Taste
- Balance/Equilibrium
What are the names of the extrinsic muscles of the eye?
- Superior oblique
- Inferior oblique
- Superior rectus
- Inferior rectus
- Lateral rectus
- Medial rectus
Lateral Rectus:
- Innervation (number and name)
- Action
- CN VI: Abducens
2. Moves eye laterally
Medial Rectus:
- Innervation (number and name)
- Action
- CN III: Oculomotor
2. Moves eye medially
Superior Rectus:
- Innervation (number and name)
- Action
- CN III: Oculomotor
2. Elevates eye/Rolls eye superiorly
Inferior Rectus:
- Innervation (number and name)
- Action
- CN III: Oculomotor
2. Depresses eye/Rolls eye inferiorly
Inferior Oblique:
- Innervation (number and name)
- Action
- CN III: Oculomotor
2. Elevates eye/ Turns eye laterally
Superior Oblique:
- Innervation (number and name)
- Action
- CN IV: Trochlear
2. Depresses eye/Turns eye laterally
What extrinsic eye muscles does CN VI (abducens nerve) innervate?
Lateral Rectus
What extrinsic eye muscles does CN III (oculomotor ) innervate?
- Medial Rectus
- Superior Rectus
- Inferior Rectus
- Inferior Oblique
What extrinsic eye muscles does CN IV (trochlear) innervate?
Superior Oblique
The optic disc is also known as what?
Blind spot
What is different about the optic disc? (what is it missing)
Has no rod or cone cells
What part of the eye has the highest visual acuity?
Fovea centralis
The fovea centralis has a high concentration of what?
Cone cells
What is located within the anterior chamber of the eye?
Aqueous Humour
What is located within the posterior chamber of the eye?
Vitreous Humour
What does the optic nerve run through?
Optic disc
Define visual acuity.
Sharpness of vision
Normal vision (20/20) is known as __________.
Emmetropic Eye
Explain what it means to have 20/30 vision.
You can see at 20 feet what an emmetropic eye can see at 30 feet.
Myopia is also known as _______.
Nearsightedness
Hyperopia is also known as ______.
Farsightedness
What does it mean to have nearsightedness (myopia)?
Able to see close objects clearly but not distant ones
What does it mean to have farsightedness (hyperopia)?
Able to see distant objects clearly but not close ones
Define Astigmatism.
Blurred vision due to irregularities in the curvatures of the lens (or cornea-book)
Define Blind Spot.
An area of the retina lacking photoreceptors (rod and cone cells)
Define Accommodation.
The ability of the eye to focus specifically for close objects (eye lens changes shape to focus light on retina)
How many reflexes are involved in accommodation?
3
When the ciliary body muscles contract the lens becomes ______.
Round
When the ciliary body muscles are relaxed the lens is ______.
Flat
The ciliary body muscles contract (becomes round) to see closer or farther objects?
Closer
The ciliary body muscles relax (becomes flat) to see closer or farther objects?
Farther
Define Presbyopia.
Difficulty in focusing due to aging.
Why does presbyopia occur?
Elasticity of the lens decreases dramatically with age
What muscles are involved in the Eye Convergence Reflex? What muscle mainly?
- Extrinsic Eye Muscles
2. Medial rectus muscles
What does the Eye Convergence Reflex do?
Crosses both eyes to look straight at the object.
Describe what happens to these following structures when using close vision:
- Ciliary Body Muscles
- Suspensory Ligaments
- Lens
- Contracts the ciliary body
- Relaxes the suspensory ligaments holding the lens
- Lens more rounded in shape
Describe what happens to these following structures when using distant vision:
- Ciliary Body Muscles
- Suspensory Ligaments
- Lens
- Ciliary body relaxes
- Contracts the suspensory ligaments holding the lens
- Stretches the lens and flattens it
Define Saccades. Give examples.
Jumping eye motions that occur when a person is reading or looking out the window of a moving car
What is the point of saccades?
Involuntary larger movements to fix on a series of points in rapid succession
What does a Electrooculogram (EOG) do?
Measures neuromuscular signals by recording the voltage changes that occur as eye position changes
What can a Electrooculogram (EOG) be used for?
- Detect an eye movement impairment
- Measuring sleep patterns (This is a set up to record
Rapid Eye Movement [REM] during sleep) - Measuring retinal dysfunction
What is contained within the outer ear?
- Pinna
2. External Acoustic Meatus (Ear canal)
What is contained within the middle ear?
- Tympanic Membrane (ear drum)
- Auditory ossicles (malleus, incus, stapes)
- Eustachian Tube
What is contained within the inner ear?
- Cochlea
- Oval Window
- Round Window
- Vestibule
- 3 semicircular canals
What is the function of the vestibule?
Organ for sensing orientation of the head
The vestibule is involved with ____ ____.
Static Equilibrium
What are Maculae?
Receptors for static equilibrium
Where are maculae located? How are maculae structured? What is their function?
- Vestibule
- Have hair cells with stereocilia and weighted with otoliths
- Sense changes in the orientation of the head
What is the function of the Semicircular Canals?
Structures that detects rotation movement
The semicircular canals are involved with ____ ____.
Dynamic Equilibrium
Where are the receptors for dynamic equilibrium?
Crista in the ampulla of each semicircular duct
Define Nystagmus.
Is a reflex movement of the eyes in an attempt to maintain balance
Define Sound vibrations.
Waves of pressure changes
Define Frequency/Pitch. What is it measured in?
- Number of compressed regions that pass a given point in one second of the sound
- Hz
Define Amplitude/Intensity. What is it measured in?
- Measure of loudness of the sound
2. db
Frequency is the same as what?
Pitch
Amplitude is the same as what?
Intensity
When looking at a wavelength, amplitude/intensity is the what?
Height
When looking at a wavelength, frequency/pitch is the what?
Length of the waves
What are the two types of conduction of sound?
- Air conduction
2. Bone conduction
Describe the path air conduction of sound takes.
Ear canal -> Ear drum -> Auditory ossicles -> Oval window
Describe the path bone conduction of sound takes.
Through skull and soft tissues of the head -> Cochlea directly
Does air conduction or bone conduction have a higher amplification?
Air conduction
What are the two types of deafness?
- Conduction Deafness
2. Sensorineural Deafness
Describe Air conduction Deafness.
Caused by deficiencies in the air conduction route of hearing
Describe Sensorineural Deafness.
Caused by damage to the vestibulocochlear nerve or cochlea.
If air conduction deafness is the only problem then the ____ ___ should be able to detect ____ ___ ___ through ____ ____ route.
- inner
- ear
- normal
- sound
- levels
- bone
- conduction
What are the two types of test we use for hearing?
- Weber Test
2. Rinne Test
Where is the vibrating tuning fork placed in the Weber Test?
Medially on the head
Where is the vibrating tuning fork placed in the Rinne Test?
- Testing for conduction deafness: near ear
2. Mastoid process
What does the weber test tell us?
Can identify hearing loss in one ear, but it does not identify
the type of hearing loss
Conduction tests with tuning forks cause which ear to hear the sound louder?
The ear with the deafness to hear the sound louder than the normal ear
Why do conduction test with tuning forks cause the ear with the deafness to hear the sound louder than the normal ear?
Because of the increased sensitivity to sounds in the ear with conduction deafness
What does the iris regulate? How?
How much light can pass into the lens (by constricting the pupil)
What conditions does the Snellen eye chart test for?
- Myopic eye
2. Visual acuity
Which is sharper 20/20 or 20/30 vision?
20/20
Myopic eyes focus images where in relation to the retina?
Infront of the retina
Hyperopic eyes focus images where in relation to the retina?
Behind the retina
What is used to adjust vision of myopic/hyperopic eyes?
Corrective lenses
With astigmatism, the patient will have an irregularly shaped cornea or lens, what happens to light rays in this condition?
Bends/REFRACTS light rays incorrectly resulting in blurred vision
Objects 20ft or further (far) light rays enter the eye _____.
Parallel
Objects closer than 20ft (close) light rays enter the eye _____.
Divergent (spreading)
The rounder the lens the ______ the focal distance.
Shorter
What is presbyopia a form of?
Farsightedness
Near point
The closest distance from which one can see an object in sharp focus.
What are the names of the two primary mechanisms used to fixate on objects in the visual field?
- Voluntary Fixation
2. Involuntary Fixation
Voluntary fixation.
Allows you to direct your visual attention and lock onto the selected object.
Involuntary fixation.
Allows you to keep a selected object in your visual field once it has been found.
Define Tracking movements. Give an example.
Large slow movements (watching bird fly) that occur when YOU choose to look at a object
What two functions does the inner ear serve.
- Balance
2. Hearing
What is vertigo? How is vertigo caused?
Motion sickness (CNS receives conflicting information from inner ear, eyes, other receptors)
What are the receptors for hearing called? Where are they located?
- Auditory receptors
2. Cochlea of the inner ear
What does conduction deafness involve damage to?
Tympanic membrane or to one or more of the auditory ossicles.
What is used to correct conduction deafness?
Hearing aids
What is another name for sensorineural deafness?
Nerve deafness
What are the 6 steps in which hearing works?***
- Sound waves arrive at tympanic membrane
- Movement of the tympanic membrane causes displacement of the auditory ossicles
- Movement of the stapes at the oval window establishes pressure waves in the perilymph of the sacral vestibule
- The pressure waves distort the basilar membrane on their way to the round window of the scala tympani
- Vibration of the basilar membrane causes vibration of hair cells against the tectorial membrane
- Information about the region and the intensity of stimulation is relayed to the CNS over the cochlear branch of cranial nerve VIII (8)
Where are the hair cells of the cochlea located?
Cochlear duct of the cochlea
What are the 3 reflexes in accommodation?
- Accommodation of the lens
- Pupillary accommodation
- Convergence of the eyes
What is pupillary accommodation?
Iris contracts to constrict the pupil letting less divergent light in, thus making it easer to focus
Is a myopic eye usually caused by an elongated or shortened eye?
Elongated
Is a hyperopic eye usually caused by an elongated or shortened eye?
Shortened
What does the near-point accommodation test, test for?
- Hyperopic eyes
2. Presbyopic eyes
What can you test a astigmatism with?
Astigmatism chart
Nerve deafness affects which routes of conduction?
Air & Bone Conduction Routes
Conduction deadness affects which routes of conduction?
Only Air conduction routes
You preform a weber test on a patient, and the sound is heard equally in both ears. What can this mean?
- Equal normal hearing in both ears.
- -OR— - Equal hearing loss in both ears.
You preform a weber test on a patient, and the sound is louder in one ear. What can this mean?
- Air conduction deafness in the ‘good’ (ear that hears sound) ear
- OR— - Nerve deafness in the ‘bad’ ear.
What can the Rinne test tell us?
Which ear is deaf
In the Rinne test, are you supposed to hear the sound longer when the fork is on the mastoid process, or the near the ear?
Near the ear
When conducting the Rinne test, if after holding the tuning for to the ear, and then waiting for the sound to no longer be audible the patient hears the sound on the mastoid process this would indicate what?
Air conduction deafness
High Frequency/Pitch have long or short wavelengths?
Short
Low Frequency/Pitch have long or short wavelengths?
Long
