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Eyes_and_Ears Powered By Docstoc
					Eyes & Ears
    • B&S
 • Chapter 11
               The Senses
• The sensory system serves to protect an
  individual by detecting changes in the

• An external environmental stimuli travels
  through the CNS into a sensory (afferent) nerve
  and leaves through an motor (efferent) nerve to
  the effector (muscle or gland or organ)
• The initiation of an impulse in a nerve

• An excitant or irritant
• The part of the nervous system that
  detects a stimulus is called a receptor
• The health and science dealing with the
  eye and its diseases
• A Physician who specializes in the
  treatment of disorders of the eye
           The Eye & Vision
• In the embryo, the
  eye is formed as an
  out - pocketing of
  the brain

• The eye is very
  delicate and is
  greatly protected
        Protection of the eye
• The skull bones help form the walls of the
  eye’s orbit or cavity
• The skull protects more than ½ of the
  dorsal part of the eye
• The eyelid protects the front of the eye.
  The eyelid can be closed and keeps the
  particles out of the eye. Blinking helps to
  keep the eye lubricated
• We have a muscle that when it contracts,
  keeps the eye open. In old age, this
  muscle weakens and the eye doesn’t stay
  open, this is called Ptosis

• Eyelashes and eyebrows keep foreign
  matter out of the eye
• A thin membrane that lines the eyelid and covers
  the anterior portion of the eyeball

• You can see the conjunctiva if you pull the lower
  eyelid down, it’s the pink part

• Cells within the conjunctiva produce mucus that
  aids in lubricating the eye
• As the conjunctiva extends from the eyelid to the
  front of the eye, a sac is formed where eye
  drops can be placed
       Conjunctivitis - Pinkeye
• The membrane that lines the eyelid becomes
  irritated or a pathogen enters

• The treatment is usually a general eye drop
  such as gentamycin opthalmic drops. Cortisone
  can be added to the drops if there is a great deal
  of itching and burning.
• Conjunctivitis can be contagious, good
  handwashing and non-sharing of pillow,
  washclothes is encouraged. Enc. Pt NOT to rub
  eyes, infection may spread
Pt looking up – conjunctiva is seen
                  • 1) “The Limbus’ is the junction
                    of the conjunctiva and cornea.
                  • 2) The conjunctiva
                  • 3) The tarsal conjunctiva
                  • 4) The tarsus (more
                  • 5) Punctum
                  • 6) The marginal conjunctiva is
                    at the eyelid margin where the
                    epithelium will begin to be
         Lacrimal Duct or gland
• Tears are produced by
  the lacrimal gland

• Tears are formed to
  lubricate the cornea
  and conjunctiva
• The actual lacrimal
  gland is near the outer
• Fluid produced by the lacrimal gland to moisten
  the cornea and conjunctiva contain the enzyme:

• This enzyme lysozyme, protects against
  bacterial invasion
• Tears drain into the inner canthus and drain into
  the punctum which is a hole in the inner eye, this
  drains into the nasolacrimal duct
        Where do tears go…
• If tears aren’t streaming down one’s
  cheeks, they are carried into ducts near
  the nasal corner of the eye where they
  drain into the nose by way of the
  nasolacrimal ducts

• Once the tears run through these ducts,
  they cause a runny nose. These ducts
  can be clogged at times
        Coats of the eyeball
• The eyeball has 3 coats or tunics:

• 1. Sclera
• 2. Choroid
• 3. Retina
• This is the white of the eye

• The sclera is made of tough connective

• The sclera circles all the way around the
  back of the eyeball and when it reaches
  the front of the eyeball, it becomes the
• This is the delicate network of connective
  middle layer

• This choroid layer is laced with blood
  vessels and brown pigment and prevents
  incoming light rays from scattering and
  reflecting off the inner surface of the eye
               Back of the eye
• The blood vessels in
  the back of the eye
  can reveal signs of
  disease (see picture on pg

• One can see these
  vessels by using an
• This complex structure has multiple layers and
  the retina is the actual receptor layer of the eye

• The multiple layers contains 10 layers of rods
  and cones which generate the nerve impulses
  associated with vision

• The rods and cones in the retina requires
  vitamin A. If Vit A is lacking, a person may have
  difficulty seeing in dim light to activate the rods.
  A deficiency in vit. A= night blindness
  Rods & Cones – the receptor
       cells of the eyes
• RODS – sensitive to light, rods function in dim
  light, images are not sharp, you see in gray.
  There are about 120 million rods in each retina.
  Rods are distributed more towards the front of
  the retina

• CONES – function in bright light, sensitive to
  color such as red, green, blue and give sharp
  images. There are about 6 million cones in each
  retina. Cones are located near the center of the
  retina in a pitted area known as the fovea
Rods & Cones in the Eye
       Entering a dark room
• When you enter a dark movie theatre, you
  cannot see for a moment. Your pupils
  enlarge so you can try and see more
• At this time, the rods are beginning to
  work, when you can see again, the images
  are blurred and you can only see objects
  in gray because the rods are not able to
  differentiate color
 Nerve impulses from rods and
• Nerve impulses from rods and cones flow into
  sensory neurons that eventually form the optic

• The optic nerve, which is the 2nd cranial nerve,
  connects to the retina at the back of the eye and
  is then connected to the occiptial lobe of the
• The impulses travel through the optic nerve to
  the visual center of the brain which is the
  occipital lobe
    Lights path through the eye
       (how does light travel)
• As light rays pass through the eye towards the
  retina, the rays travel through a series of
  transparent, colorless parts

• On the way, the light rays become bent
  (refracted). This refraction of the rays make it
  possible for light from a very large area, to be
  focused on a very small surface to the retina
  where the receptors are located. At this point,
  the rays also become overrefracted (turned
  upside down and backwards), The visual
  centers of the brain must reverse the images
 Light must pass through these
     parts in order to see…
• This is from the outside where we see the
  light on into the eye eventually to the
• Cornea
• Aqueous humor
• Lens
• Vitreous body
• Is a forward continuation of the sclera (see picture
  on pg 185)

• This part is transparent and colorless whereas
  the sclera we can see is white and opaque
• The cornea has no blood vessels and is well
  nourished by the fluids that constantly wash over
• The cornea can become scarred d/t injury=
  decreased vision. The cornea can be
           Aqueous Humor
• A watery fluid that fills much of the eyeball
  in front of the lens

• The aqueous humor helps maintain the
  slight forward curve of the cornea
• In the area where aqueous humor is found
  is where glaucoma is found
Aqueous Humor
• A clear, circular structure made of firm, elastic
  material. The lens has 2 bulging surfaces and is
  described as bi-convex

• The lens is important in light refraction because
  of the elasticity, the shape of the eye can
  change and it’s thickness can be adjusted to
  focus light for near or distant vision
              Vitreous Body
• Soft jelly-like substance that fills the entire
  space behind the lens. This jelly IS NOT

• The vitreous body helps maintain the
  shape of the eyeball as well in aiding in
  refraction of light
Eye Anatomy
Eye Anatomy
       • 1. Cornea in front,
         in back of eye is
       • 2. Aqueous humor
       • 3. Lens
       • 4. Retina
       • 5. Vitreous body
Anterior Parts of the Eye
             •   1. Conjunctiva
             •   2. Cornea
             •   3. Cilliary body
             •   4. Lens
        Muscles of the eye
• Intrinsic Muscles

• Extrinsic Muscles
           Intrinsic Muscles
• In general, these are the circular
  involuntary muscles of the eye.

• These include the muscles around the iris
  and the pupil and this includes the cilliary
   The ciliary body is a ring of tissue that encircles the lens. The ciliary body contains
  smooth muscle fibers called ciliary muscles that help to control the shape of the lens.
   Towards the posterior surface of the lens there are ciliary processes which contain
capillaries. The capillaries secrete the fluid (aqueous humor) into the anterior segment of
                                          the eyeball
• This is the colored part of the eye. Some colors
  include shades of blue, brown, green, hazel. In
  the center of the iris is the pupil.

• The purpose of the iris is to regulate the amount
  of light entering the eye. In the presence of
  bright light, the cilliary muscles of the iris
  contract, reducing the size of the pupil=
Cilliary Muscle – stretch the lens
• Is shaped like a flattened
  ring with a hole the size
  of the outer edge of the

• The cilliary muscle alters
  the shape of the lens
  during the process of
  accommodation –
  adjustment or adaption of
  the eye while it’s trying to
  focus on something,
  usually far away
           Draw a circle….
• Radial muscles are located around where
  the iris is (think of a radial tire and the
  treads or like the spokes of a bike)

• Circular muscles are around the pupil

• When circular contract, radial relax
• Adjustment or adaption.
• The adjustment of the eye for various distances
  where it is able to focus the image of an object
  on the retina by changing the curvature of the

• For near vision, the ciliary muscle contracts
  causing increased rounding of the lens and the
  pupils contract

• The ability to accommodate, decreases with
• The contractile opening at the center of
  the iris of the eye

• The pupil contracts when exposed to light
  and when the focus is on a near object

• The pupil dilates when in the dark and
  when focus is on a distant object
       Adjustment of the lens
• Ciliary muscles help the lens get fatter to
  see things up close
• Or
• Thin like a pancake in order to see things
  far away
           Extrinsic Muscles
• These are the 6 ribbon-like voluntary muscles
  attached to the outer surface of the eyeball.
  These muscles coordinate eye movement and
  the opening of the eyelid

• These muscles pull on the eyeball in a
  coordinated fashion so that both eyes center on
  one visual field at the same time (convergence).
  Convergence is necessary to the formation of a
  clear image on the retina
Extrinsic Muscles of the Eye
      Nerve supply to the eye
• 2 nerves supply the eye:

• We will discuss the optic nerve for this ch.
                Optic Nerve
• Carries visual impulses from the rods and cones
  to the brain

• Optic nerve starts from the retina toward the
  medial or nasal side of the eye

• There are no rods or cones in the area of the
  optic nerve but the optic nerve carries impulses
  only from the rods and cones to the brain
               Optic Disc
• Because there are no cones or rods near
  or around the optic nerve, no images can
  form on the retina around the optic nerve,
  at this point, this is known as the “blind
  spot” or optic disc
     Close to the optic disc…
• There is a tiny depressed or pitted area in
  the retina known as the fovea centralis
             Fovea Centralis
• The fovea is contained within a yellow spot
  called the macula, with age, this macula

• This yellowish fovea, contains the highest
  concentration of cones

• This portion of the area near the optic disc in the
  fovea centralis, is the point of sharpest vision
           Vision Problems

• Ptosis – drooping of the eyelid related to
  paralysis, can occur after a stroke
• Amblyopia – otherwise known as “lazy
  eye”. Can be treated with eyeglasses.
• The brain and eyes do not work together
  properly, the brain favors one eye.
• The brain may suppress the visual image
  from the deviating eye to prevent double
• This accounts for 50% of childhood
• A deviation of the eye that results from lack of
  coordination of the eyeball muscles. The 2 eyes do not
  work together.
• In children, when the eyes fail to focus on the same
  image, the brain may learn to ignore the input from one
• This loss of vision is called amblyopia, and it is
  frequently associated with strabismus

• Convergent strabismus is when the eye deviates toward
  the nasal side and gives the appearance of being cross-
              Google says…
• Strabismus, more commonly known as cross-
  eyed or wall-eyed, is a vision condition in which
  a person can not align both eyes simultaneously
  under normal conditions. One or both of the
  eyes may turn in, out, up or down. An eye turn
  may be constant (when the eye turns all of the
  time) or intermittent (turning only some of the
  time, such as, under stressful conditions or when
  ill). Whether constant or intermittent, strabismus
  always requires appropriate evaluation and
  treatment. Children do not outgrow
• If these disorders are not corrected early,
  the transmission and interpretation of
  visual impulses to the brain is decreased.
  Muscles become weakened in the eye and
  muscle restoration must be rebalanced,
  glasses, eye patch or surgery may be
Normal Vision

• Farsightedness caused by a short eyeball, the light seen
  hits the back of the eye (can only see far away)

• The focal point is behind the retina because light rays
  cannot bend sharply enough to focus on the retina.
  Objects must be moved far from the eye to be seen
• Farsightedness is common in infants but it corrects itself
  when the child uses the eyes more for near vision
• Treatment: glasses with convex lenses to increase the
  refraction of light rays corrects this visual disturbance
Hyperopia Far Sighted
• Nearsightedness caused by a long
  eyeball. The cornea bends the light rays
  too sharply so the focal point of the light is
  in front of the retina
• Distant objects appear blurred and may
  appear clear only if the object is brought
  near the eye (can only see things that are
  near to you)
• Treatment: a concave lens is used
Myopia-Near Sighted
• This is due to the irregularity in the curvature of
  the cornea or the lens therefore, light rays are
  incorrectly bent causing blurred vision. A person
  usually has myopia or hyperopia along with
• Treatment: corrective lenses are required.
  These people have difficulty wearing contacts at
  times. Today, surgical procedures such as
  refractive surgery can be used to correct near or
  farsightedness. The cornea is reshaped to
  change the refractive angle of light as it passes
• Constant, involuntary cyclical movement of
  the eye balls.

• Similar to spasms of the eyeball

• I’ll show you 
• Excess pressure of the aqueous humor. The
  blood constantly produces fluid that circulates in
  the eye and then gets reabsorbed into the
  bloodstream. Interference with the normal
  reentry of this fluid into the bloodstream leads to
  increased pressure inside the eyeball
• This condition occurs slowly, optic nerve
  damage occurs and poor vision is noticed

                    Mild Glaucoma

• Is an opacity of the lens or the outer covering of
  the lens
• Early cataracts causes a gradual loss of
  sharpness or (visual acuity). Untreated
  cataracts = complete loss of vision
• Surgical removal of the lens and placement of
  an artificial lens is successful.
• Age, diabetes and exposure to UV rays may
  cause cataracts

                    • Cataract
       Diabetic Retinopathy
• The retina is damaged by blood vessel
  hemorrhages and growth of new vessels.
  Blood vessels in the eye are tiny and get
  filled with plaque or too much sugar d/t
  uncontrolled diabetes and they tear away
  from the retina and eyeball. Blindness can
Diabetic Retinopathy
         Retinal Detachment
• The retina becomes separated from the
  underlying layer of the eye as a result of trauma
  or an accumulation of fluid or tissue between
  layers. Can occur slowly or suddenly. If left
  untreated, blindness will occur d/t total
  detachment of retina
• Surgery includes a “spot welding” with electric
  current or a weak laser beam. A series of
  pinpoint scars (connective tissue) develops to
  reattach the retina. Pt must lay face down for up
  to 48 hours after surgery to heal
Retinal Detachment
        Macular Degeneration
• The macula or yellow area of the retina that
  contains the fovea centralis, (the point of
  sharpest vision), changes or becomes distorted.
  Either material accumulates on the retina or
  abnormal blood vessels grow under the retina
  causing it to detach.
• Surgery may stop the growth of blood vessels
  and delay vision loss. Causes are smoking,
  exposure to sunlight, and high cholesterol diet,
  can be hereditary
Macular Degeneration
Severe Macular Degeneration
       Eye Drops used in the
       Ophthalmologist's office
• Class:
• Mydriatics – used to dilate the pupil for
  opthalmic exams

• Big word = Big pupil
• The “D” in this word = dilates

• Atropine eye drops
        Eye Drops used in the
        Ophthalmologist's office
• Miotics – used to constrict the pupil

• Little word, little pupil

• Pilocarpine constricts the ciliary muscles
  and pupil to increase the aqueous humor
  outflow so it won’t get stuck
• A lighted instrument, one of the
  most important tools of the
  physician, used to examine the
  interior of the eye, including
  the lens, retina and optic nerve
• The ophthalmoscope is
  equipped with a rotating disc of
  lenses to permit the eye be
  examined at different depths
  and magnifications. This may
  be enhanced by drugs that
  dilate the pupil and enlarge the
  opening into the structures
  within the eye.
          Infections of the eye
• Earlier, we discussed conjunctivitis,

• Stye – this is a localized purulent staphylococcal
  infection. Can occur at any age. Causes
  redness, swelling, pain and formation of an
• Treatment: warm compresses 4xs /day to help
  drain pus, topical ointment or antibiotic eye drop.
  Styes are contagious
        Infections of the eye
• Trachoma – caused by the STD
  chlamydia, forms granules on the eyelid
  and irritates the cornea, causing
  blindness. Proper hygiene and antibiotics
  are used to treat this
      Opthalmia Neonatorum
• Caused by gonococcus, Chlamydia or
  some other STD, seen at birth. Instilling
  erythromycin eye drops after delivery rids
             Injury to the eye
• The most common injury to the eye is related to
  a laceration or a scratching of the cornea
  caused by a foreign object

• Scar formation from the laceration or scratch
  causes an area of opacity through which light
  rays cannot pass. If the injury involves the
  central area in front of the pupil, blindness may
       Preventing lacerations
• It is important to prevent injury, scratching
  or trauma to the eye. Even a tiny scratch
  can become so seriously infected that
  blindness can result

• Protection by using goggles has
  decreased severe eye injuries
• An operation to remove the eyeball due to
  traumatic injury to the eye
The End of the Eye lecture
                 THE EAR
•   The ear is a sense organ for both:
•   Hearing
•   And
•   Equilibrium
    • A device for
      examination of the
      inner ear
  The ear is divided into 3 main
• 1. Outer ear

• 2. Middle ear

• 3. Inner ear
            The Outer Ear
• This includes the outer projection (pinna)
  or (auricle) of the actual ear and a canal

• The pinna collects and directs sound
  waves into the ear
      External auditory canal or

• Once you enter the hole to the ear, you enter this
  external auditory meatus.
• Here, the skin lining this tube extends approximately 2.5
  cm or more. There are many ceruminous glands here
  where cerumen is made
• This is where you stick a Q-tip to clean the ear
     At the end of this auditory
            meatus is…
• The tympanic membrane A.K.A. the ear drum

• The ear drum serves as a boundary between the
  external auditory canal and the middle ear cavity
  and pressure on either side of this tympanic
  membrane is usually =
• The tympanic membrane vibrates freely as
  sound waves enter the ear
• The tympanic membrane is usually pink or
  peach in color when not infected
             The Middle Ear
• This is the air space
  containing 3 small
  bones called ossicles

• These 3 ossicles are
  joined in such a way
  that they amplify the
  sound waves
  received by the
  tympanic membrane
  and then transmit the
  sounds to the fluid in
  the inner ear
     The 3 Ossicles are named
• 1. Malleus – has a handlelike part that is attached to the
  tympanic membrane. The headlike part of the malleus
  bone is attached to the incus

• 2. Incus – the middle of the 3 ossicles, attaches the
  malleus and the stapes. Sometimes called “anvil”

• 3. Stapes – the innermost of the ossicles that is shaped
  like a stirrup. The base of the stapes is in contact with a
  membrane called the oval window of the inner ear. This
  membrane vibrates and transmits the sound waves to
  the fluid of the inner ear
           The Eustachian Tube
• Is an auditory tube that
  connects the middle ear to the
  throat or pharynx
• This tube opens to allow
  pressure to equalize on the
  two sides of the tympanic
• The valve that closes the tube
  can be forced open by
  swallowing hard, yawning, or
  blowing with the mouth sealed
  as is done when one has
  pressure changes while being
  on an airplane
Infections in the eustachian tube
• The mucuous membrane of the pharynx is
  continuous through the eustachian tube
  into the middle ear cavity, and organisms
  may travel along the membrane causing
  infection of the middle ear known as otitis
             The inner ear
• This is the most complex of the 3 sections

• The inner ear contains the sensory
  receptors for hearing and equilibrium and
  contains fluid through which the vibratory
  sounds travel
      The Inner ear is complex
• The inner ear is complicated because it contains
  a mazelike area with 3 divisions:
• 1. vestibule
• 2. Semicircular canals
• 3. Cochlear

• All 3 divisions contain fluid that are important to
  the sensory functions of the inner ear

• The organ of hearing
  is called the organ of
  corti. It consists of
  ciliated receptor cells
  located inside the
  cochlear or cochlear
• Sound waves enter the external auditory canal and
  cause the tympanic membrane to vibrate
• These vibrations are amplified by the ossicles and
  transmitted to the fluid of the inner ear
• The sound waves enter the upper chamber of the
  cochlea called the vestibular duct, and travel to the top of
  the duct
• As the fluid moves through these chambers, they set up
  vibrations in the fluid of the cochlear duct
• These vibrations stimulate the tiny, hairlike cilia on the
  receptor cells setting up nerve impulses that travel to the
  brain in the cochlear nerve (a branch of the 8th cranial
• Takes place in the semicircular canals in the inner ear.
• The semicircular canal contains sensory cells
• Receptors for the sense of equilibrium are ciliated cells.
  As the head moves, the delicate hair like cells bend
  when the liquid is set in motion by the head and body
  movements and a nerve impulse is generated. The
  nerve impulses are sent to the brain to help maintain
  body balance or equilibrium.
• The semicircular canals have nothing to do with the
  sense of hearing
                 Ear Disorders
• Otitis Media

• Otitis Externa

• Otosclerosis

• Presbycusis

• Conduction deafness
              Otitis Media
• An infection of the middle ear cavity
  caused by a variety of bacteria or viruses

• Happens most often in children due to
  their ear canal being more horizontal, fluid
  sits there and causes bacteria to form
• Antibiotics are used to treat Otitis Media
             EAR DROPS
• In children <3 years old, pull auricle/pinna
  down and back and place drop in ear.
  Because their ear canal is more horizontal,
  you’ll be sure to get the drop into the canal

• In children 3+ years old/adults, pull
  auricle/pinna up and back d/t ear canal
  being sl. angled

• Pressure from pus or exudate in the
  middle ear can be relieved only by cutting
  the tympanic membrane (myringotomy)
  and then the placement of ear tubes to
  allow pressure to equalize and prevent
  further damage to the eardrum
            Otitis Media

• What treatments would be used for this
                Otitis Externa
              “Swimmer’s Ear”
• Inflammation of the skin of
  the external ear canal and

• May be acute or chronic

• Most common in the summer

• Treatment is over 7 days with antibiotic drops, no
  swimming and possibility of wearing ear plugs with
  further swimming
     Conductive Hearing Loss
• This is when there is interference with the
  passage of sound waves from the outside to the
  inner ear

• There may be an obstruction of the external
  canal caused by wax or a foreign object

• Blockage of the eustachian tube prevents the
  equalization of air pressure on both sides of the
  tympanic membrane thereby decreasing the
  ability of the membrane to vibrate
• A hereditary disease that
  causes bone changes in
  the stapes that prevents
  normal vibration

• Treatment: surgical removal of the diseased
  stapes and its replacement with an artificial
  device allows conduction of sound from the
  ossicles to the oval window and the cochlea
  Presbycusis (pres-be-KU-sis)
• A slowly progressive hearing loss that
  often accompanies aging

• The condition involves gradual atrophy of
  the sensory receptors and the nerve fibers
  in the cochlear nerves
                  Hearing Loss
• Affected person may feel
  isolated and depressed,
  psychological help may
  be needed

• The ability to hear high
  pitched sounds may be
  lost first

• It is therefore important to
  address elderly people in
  clear, low-pitched tones
        Hard of Hearing Sign
• H.O.H.

• Your hospital floor may have pre-made
  signs indicating that a pt has a hearing
           Nerve deafness
• Disorder of the cochlear nerve or auditory
  portion of the brain

• Nerve deafness may be caused by
  prolonged exposure to noise, drugs or
The End

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