Sense Organs: The ye

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Sense Organs The ye the Ear
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THE EAR

• Combining Forms for the ear
• ot/o,
• aur/o,
• auricul/o
• Two functions of the ear
• Hearing
• Equilibrium (balance)
• Three separate regions of the ear
• Outer ear
• Middle ear
• Inner ear

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OUTER EAR

• Auricle (pinna) projecting flap where sound
  waves enter
• Auditory canal leads from pinna to middle ear
• Produces cerumen (ear wax) which lubricates and
  protects the ear

Auricle
Auditory canal
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MIDDLE EAR

• Sound waves travel through auditory canal and
  strike membrane
  between outer
  middle ear.
• This membrane is
  called the tympanic membrane or
  eardrum. The
  tympanic membrane vibrates
  with sound waves and moves 3
  small bones in the
  middle ear. These
  small bones are called ossicles.

Tympanic Membrane
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MIDDLE EAR

• The three small bones also have individual names
• Malleus the TM moves this
  bone first
• Incus vibration moves
  this bone next
• Stapes (staped/o)
  vibrates last and
  touches the next membrane
  called the oval window

Incus
Malleus
Tympanic Membrane
Stapes
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MIDDLE EAR

• Oval window separates the middle ear from the
  inner ear.
• Eustachian Tube (salping/o)
  leads from the middle ear
  to pharynx
• Is normally closed,
  except when swallowing.
• Aids in prevention of
  damage to eardrum and
  shock to middle and
  inner ear when air
  pressure is greater
  in the middle ear than in atmospheric air.

Incus
Malleus
Tympanic Membrane
Stapes
Eustachian Tube
Oval Window
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INNER EAR

• Also called the labyrinth because of its
  circular, maze-like structure.
• Cochlea (cochle/o) leads from the oval window
  small, snail shaped has two parts
• 1. Auditory Liquids
• a. Perilymph
• b. Endolymph
• c. Vibrations travel through
• these liquids
• 2. Organ of Corti sensitive auditory receptor
  are tiny hair like calls that
  receive vibrations from auditory liquids and
  relay sound waves to auditory nerve fibers.

Cochlea
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INNER EAR

• Auditory Nerve Fibers receive sound vibrations
  from the auditory liquids and end in the auditory
  center of the cerebral cortex of the brain where
  impulses are heard and interpreted.
• Vestibule connects the cochlea to 3
  semicircular canals for balance.
• Semicircular canals (Organ for
  Equilibrium) contain endolymph hair
  cells that fluctuate in response to movement of
  the head nerve fibers send message to brain
  brain sends message to muscles to maintain
  balance.
• -saccule utricle
  are membranous sacs

Auditory Nerve Fibers
Vestibule
Semicircular Canals
Cochlea
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SEQUENCE OF EVENTS IN STIMULATION OF SENSE ORGAN
Figure 17-1. Pattern of events in the stimulation
of a sense organ.
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PATHWAY OF SOUND VIBRATIONS
Figure 17-21. Pathway of sound vibrations from
the outer ear to the brain (cerebral cortex).
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TYPES OF DEAFNESS

1. Conduction caused by impairment of the middle
   ear ossicles and membranes that transmit sound
   waves into cochlea.
2. Nerve caused by impairment of the cochlea or
   auditory nerve

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AURAL TEMPERATURE
Figure 17-25. Ear thermometer using a tympanic
membrane thermometer.
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COMBINING FORMS ABBREVIATIONS

• acous/o HEARING acoustic
• audi/o SENSE OF HEARING audiometer
• audit/o HEARING auditory
• -cusis HEARING
  presbycusis
• -otia EAR CONDITION macrotia
  LARGE EARS
• microtia SMALL EARS
• ABBREVIATIONS
• AD RIGHT EAR
• AS LEFT EAR
• AU BOTH EARS
• ENT EAR, NOSE, THROAT
• EENT EYES, EARS, NOSE, THROAT

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PATHOLOGICAL CONDTIONS

• 1. Otitis Media inflammation of middle ear,
  caused by infection (staphylococcus or
  streptococcus bacteria)
• 2. Tinnitus tinkling sound in the ear can be
  ringing, buzzing, whistling, etc.
• 3. Vertigo sensation of irregular or whirling
  motion of oneself or external objects
  equilibrium and balance are affected.

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TYMPANIC MEMBRANE

1. Healthy tympanic membrane.
2. Tympanic membrane with cholesteatoma.
3. Tympanic membrane with acute otitis media.
4. Myringotomy with tympanostomy tube.

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PATHOLOGICAL CONDTIONS

• 4. Menieres Disease disorder of labyrinth
  marked by elevated endolymph pressure. Symptoms
  include tinnitus, vertigo, and loss of hearing.
  Cause is unknown. Bedrest, sedation and drugs
  for nausea and vertigo are commonly given.
• 5. Otosclerosis bone growth around oval window
  and stapes leading to fixation (stiffening)
  causing improper conduction of vibration.
  Corrected with stapedectomy and replacement by
  prosthesis.

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TREATMENT FOR A FORM OF CONDUCTION HEARING LOSS

1. Stapedectomy. Using microsurgical technique and a
   laser, the stapes bone is removed from the middle
   ear.
2. A prosthetic device (wire, Teflon, or metal) is
   placed into the incus and attached to a hole in
   the oval window.

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DEFINE THESE PATHOLOGICAL CONDITIONS

• Otomycosis -
• ot/o __ myc/ __ osis
• Myringotomy -
• myring/o ___ tomy
• Myringitis -
• myring/o __ itis __
• Otopyorrhea -
• ot/o __ py/o __ rrhea
• Ossiculoplasty -
• ossicul/o ___ plasty

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EAR PROCEDURES

• Audio / gram
• Audio / meter
• Audio / metry
• Oto / scopy

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AUDIOMETER
Figure 17-24. Pure-tone audiometer.
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OTOSCOPIC EXAM
Figure 17-26. Otoscopic examination. The auricle
is pulled up and back. The hand holding the
otoscope is braced against the face for
stabilization.
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Chapter 17 (Contd) The
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STRUCTURES OF THE EYE

• Cor/o and Pupil/o pupil
• Pupil - the dark center of the eye
• Conjunctiv/o conjunctiva
• Conjunctiva clear membrane that lines inner
  surface of eyelids over whites of eyes.
• Corne/o and kerat/o cornea
• Cornea a fibrous,
  transparent tissue that
  extends over
  the pupil
  of the eye and iris.
  Helps with
  refraction
  of light.

Conjunctiva
Cornea
Pupil
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STRUCTURES OF THE EYE

• Scler/o sclera
• Sclera white part of the eye. Avascular no
  blood vessels.
• Choroid dark brown membrane inside sclera.

Choroid
Sclera
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STRUCTURES OF THE EYE

• Ir/o iris
• Iris colored portion of the eye.
• Is also a muscle that surrounds pupil of the eye.
  
• If light is bright, the iris gets bigger
  (contracts) pupil gets smaller (constricts).
• If light is dim, the iris relaxes pupil dilates
  (gets larger).
• Mi/o smaller, less
• Miosis constriction of the pupil
• Mydr/o wider, enlarge
• Mydriasis enlargement of pupil

Iris
Ciliary Body
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STRUCTURES OF THE EYE

• Cycl/o ciliary body
• Ciliary body a muscle located next to the lens
  and that two functions
• 1. Thickens thins the lens for refraction
  (bending of light rays)
• 2. Secretes aqueous humor (AH)
• Aqueous Humor fluid that maintains shape of
  anterior portion of eye provides nourishment to
  structures in the same area.

Ciliary Body
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STRUCTURES OF THE EYE

• Phak/o and phac/o lens of the eye
• Lens flat for distant vision and rounded for
  close vision. Also helps with refraction of
  light.
• Refractive power of lens is ACCOMODATION

Lens
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STRUCTURES OF THE EYE

• Anterior Chamber of Eye
• Contains aqueous humor
• Secreted by ciliary body
• Maintains shape of anterior eye
• Constantly produced - leaves eye thru canal that
  carries it to bloodstream

Anterior Chamber
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STRUCTURES OF THE EYE

• Vitreous Chamber of Eye
• Contains vitreous humor
• Maintains shape of posterior eye
• Refracts light rays
• Is NOT constantly being produced
• Loss of VH may mean loss of eye

Vitreous Chamber
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STRUCTURES OF THE EYE

• Retin/o - retina
• Retina thin, nerve layer that contains rods
  and cones.
• Rods are for reduced lighting and peripheral
  vision.
• Cones are for color and central vision.

Retina
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STRUCTURES OF THE EYE

• When light energy hits rods cones (in retina)
  causes chemical changes, that initiate nerve
  impulse to travel to brain via the optic nerve
• Optic disc is area where optic nerve meets retina
  (it has no light receptors so called blind
  spot)

Optic Disc
Optic Nerve
Fovea Centralis
Macula
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STRUCTURES OF THE EYE

• Macula is small area to the side of the optic
  disc
• Macula contains the Fovea Centralis location of
  sharpest vision within eye (composed largely of
  cones)

Optic Disc
Optic Nerve
Fovea Centralis
Macula
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RETINA
Figure 17-3. The posterior, inner part (fundus)
of the eye, showing the retina as seen through an
ophthalmoscope.
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BINOCULAR VISION

• Optic Nerve Fiber carry light stimulus through
  nerve fibers to the brain.
• As fibers enter brain, travel more medially
  eventually cross.
• Optic Chiasm area where optic nerve fibers
  cross
• Nerve fibers from right 1/2 of each retina form
  an optic tract synapse in thalamus.
• Fibers end in the right visual field of the
  cerebral cortex.
• Same thing happens with the left half of each
  retina
• Images fuse, giving 3 dimensional image called
  Binocular Vision

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PATHWAY OF LIGHT
Figure 17-5. Pathway of light rays from the
cornea of the eye to the cerebral cortex of the
brain.
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AREAS OF BRAIN INVOLVED IN VISION

• Thalamus nerve fibers from right half of each
  retina form an optic tract and synapse in the
  thalamus. Fibers will end in the right visual
  field of the cerebral cortex. Same thing happens
  with nerve fibers on the left half of each
  retina.
• Cerebral Cortex surface of cerebrum where nerve
  cells lie in sheets. Receive visual stimulus
  from thalamus from both sides of the eye.
• Visual area of cerebral
  cortex is in occipital lobe
  of the brain.

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VISIONAL DISTURBANCES

• Accommodation normal adjustment of the eye for
  seeing objects at various distances eye has
  more problems with this as ages
• Astigmatism defective curvature of the cornea
  or lens of the eye.
• Presby/opia impaired vision of the cornea or
  lens of the eye, associated with aging.
• Hyper/opia farsightedness (cant see close
  objects), rays of light focus behind retina
• My/opia nearsightedness (cant see far away
  objects), rays of light focus in front of the
  retina

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ERRORS OF REFRACTION

• Astigmatism defective curvature of the cornea
  or lens of the eye.
• Presby/opia impaired vision of the cornea or
  lens of the eye, associated with aging.
• Hyper/opia farsightedness (cant see close
  objects), rays of light focus behind retina
• My/opia nearsightedness (cant see far away
  objects), rays of light focus in front of the
  retina

1. Astigmatism and its correction.
2. Hyperopia and its correction.
3. Myopia and its correction. Dashed lines in B and
   C indicate the contour and size of the normal
   eye.

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COMBINING FORMS

• Ambly/o DULL, DIM Amblyopia
• Dipl/o DOUBLE Diplopia
• Nyct/o NIGHT Nyctalopia
• Phot/o LIGHT Photophobia
• -opsia VISION Hemianopsia
• Blephar/o EYELID Blepharoptosis
• Dacry/o TEAR DUCTS
• Lacrim/o TEARS Lacrimal ducts

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LACRIMAL TEAR DUCTS
Lacrimal (tear) gland and ducts.
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ABBREVIATIONS

• OD RIGHT EYE
• OS LEFT EYE
• OU BOTH EYES
• VF VISUAL FIELD
• AH AQUEOUS HUMOR
• VH VITREOUS HUMOR
• IOP INTRAOCULAR PRESSURE

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DISORDERS OF THE EYE
Figure 17-6. (A) Acute bacterial conjunctivitis.
Notice the discharge of pus characteristic of
this highly contagious infection of the
conjunctiva. (B)
Anisocoria.
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DISORDERS OF THE EYE
Cataract. The lens appears cloudy.
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DISORDERS OF THE EYE
Figure 17-10. Chalazion.
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DISORDERS OF THE EYE
Figure 17-11. Glaucoma and circulation of aqueous
humor. Circulation is impaired in glaucoma,
so that aqueous fluid builds up in the anterior
chamber.
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DISORDERS OF THE EYE
Figure 17-12. (A) Picture as seen with normal
vision. (B) The same picture as it would appear
to someone with macular degeneration.
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PROCEDURES
A normal fluorescein angiogram.
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PROCEDURES
Figure 17-14. Ophthalmoscopy. In addition to
examining the cornea, lens, and vitreous humor
for opacities (cloudiness), the examiner can see
the blood vessels at the back of the eye (fundus)
and note degenerative changes in the retina.
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PROCEDURES
Figure 17-15. Slit lamp examination measuring
intraocular pressure by tonometry.
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PROCEDURES
(A) The Snellen chart assesses visual acuity.
(B) Visual fields are examined by comparing the
patient's field of vision with that of the
examiner's (assuming the examiner's is normal).
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SURGICAL TREATMENTS

• Keratoplasty surgical repair of the cornea
  (corneal transplant)
• Vitrectomy removal of vitreous humor

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Figure 17-17. Clinical appearance of the eye
after keratoplasty. (Courtesy of Ophthalmic
Photography at the University of Michigan, WK
Kellogg Eye Center, Ann Arbor, MI. From Black JM,
Hawks JH, Keene AM Medical-Surgical Nursing
Clinical Management for Positive Outcomes, 6th
ed. Philadelphia, WB Saunders, 2001, p. 1822.)
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Figure 17-18. Phacoemulsification of a
cataractous lens through a small, self-sealing,
scleral-tunnel incision. (From Lewis SM,
Heitkemper MM, Dirksen SR Medical-Surgical
Nursing Assessment and Management of Clinical
Problems, 5th ed. Mosby, St. Louis, 2000, p.
454.)
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Figure 17-19. (A) Detached retina. (B) Scleral
buckling procedure to repair retinal detachment.
(From Ignatavicius DD, Workman ML
Medical-Surgical Nursing Critical Thinking for
Collaborative Care, 4th ed. Philadelphia, WB
Saunders, 2002, p. 1041.)