Eye Anatomy

Aka: Eye Anatomy, Limbus Corneae, Iris, Uvea, Conjunctiva, Aqueous Humor, Aqueous Outflow Angle

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II. Images

  1. Globe
    1. eyeGlobeXsGrayBB869.gifLewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
    2. eyeCorneaLensGrayBB883.gifLewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
    3. eyeSagittalXsGrayBB888.gifLewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
    4. eyeSagittalXsGrayBB891.gifLewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
  2. Iris
    1. eyeIrisGrayBB875.gifLewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
  3. Nerves
    1. See Neurologic Anatomy of the Eye
  4. Extraocular Motor
    1. See Extraocular Movement
  5. Choroid
    1. See Choroid Anatomy
    2. See Vascular Anatomy of the Eye
  6. Vessels
    1. See Vascular Anatomy of the Eye
  7. Retina
    1. See Retinal Anatomy
  8. Lacrimal and lids
    1. See Lacrimal Anatomy
  9. Lids
    1. See Lid Anatomy
  10. Miscellaneous
    1. "Eye on You"
      1. eyeOnYou.jpg

III. Anatomy: General

  1. Eyelids
    1. Both lids contain a tarsal plate with Meibomian glands
    2. Lids join at medial and lateral canthi
  2. Sclera
    1. See Sclera
    2. Thick, protective outer coat of the eye underlying the Conjunctiva
    3. Normally white (with possible bluish discoloration) and opaque
    4. Scleral inflammation is very painful, and associated with Vision Loss
  3. Episclera
    1. Covers the anterior Sclera and lacks the Scleral bluish discoloration
    2. Continuous with the Cornea
    3. Episcleral inflammation is not typically painful, and does not cause Vision change
  4. Limbus
    1. Corneal-Scleral junction
  5. Iris
    1. Pigmented light filter
    2. Muscular aperture of the eye controlling the size of the pupil
      1. Iris dilator (Mydriasis) Muscles are radial and extend to iris periphery
      2. Iris constrictor (Miosis) Muscles are circular and are positioned centrally at pupil border
  6. Uvea
    1. Contains three pigmented and continuous structures: Choroid, Ciliary Body and Iris
    2. See Uveitis
  7. Pupil
    1. Central hole or shutter within the iris
    2. Size is controlled by iris constriction (Miosis) and relaxation (Mydriasis)
    3. Size of the pupil determines amount of light exposure on the Retina
  8. Lens
    1. Fine, variable focus of light directed at the Retina
    2. Cataracts clous the lens, resulting in Decreased Visual Acuity
  9. Conjunctiva: Thin, vascular tissue
    1. Covers inner lid lining (palpebral Conjunctiva)
    2. Covers Sclera (bulbar Conjunctiva)
  10. Cornea
    1. See Refractive Error
    2. See Cornea
    3. Transparent front refractive window of eye
  11. Macula and Fovea
    1. Macula is fine central Vision area at posterior pole
    2. Fovea is oval depression at center of Macula

IV. Anatomy: Extraocular Muscles: Innervated by CN 3 with 2 exceptions

  1. See Extraocular Movement
  2. Medial Range of Motion
    1. Medial Rectus (Cranial Nerve III)
  3. Lateral Range of Motion
    1. Lateral Rectus (Cranial Nerve VI)
  4. Upward Range of Motion
    1. Superior Rectus (Cranial Nerve III)
    2. Inferior Oblique (Cranial Nerve III)
  5. Downward Range of Motion
    1. Inferior Rectus (Cranial Nerve III)
    2. Superior Oblique (Cranial Nerve IV)

V. Anatomy: Chambers

  1. Anterior Chamber
    1. Between Cornea and iris
    2. Contains Aqueous Humor
  2. Posterior Chamber
    1. Between iris and lens zonulae (very small space)
    2. Also contains Aqueous Humor
  3. Ciliary body
    1. Produces Aqueous Humor
    2. Contains ciliary Muscle ring
      1. Suspends lens by fine ligamentous zonule fibers (zonulae)
      2. Ciliary Muscle Contraction narrows ring diameter, relaxing tension on lens
        1. Lens assumes and thicker, rounder shape, resulting in Visual Accommodation (near focus)
      3. Contrast with iris dilator (Mydriasis) and iris constrictor (Miosis) Muscles
  4. Aqueous Humor
    1. Aqueous Humor
      1. Clear fluid that fills anterior and posterior chamber
      2. Produced by ciliary body
      3. Passes through pupil
      4. Drains via trabecular meshwork (at outflow angle)
    2. Aqueous Outflow Angle
      1. Intersection of Cornea, iris, and ciliary body
      2. Circular Canal of Schlemm drains the Aqueous Humor into the venous circulation
      3. Blockage results in Glaucoma
  5. Vitreous Cavity
    1. Large space (4.5 cc) between lens and Retina
    2. Contains transparent thick gel (vitreous humor)
    3. Additional vitreous humor is not produced after the eye develops
      1. Contrast with Aqueous Humor that is produced throughout the eye's lifetime

VI. Anatomy: Vascular

  1. Central Retinal Artery
    1. Vascular supply of Retina (except photoreceptor cells which are supplied by Choroid)
  2. Choroid
    1. Vascular pigmented tissue between Sclera and Retina
    2. Vascular supply for outer Retina photoreceptor cells
  3. Avascular structures of the eye
    1. Lens
    2. Anterior vitreous
    3. Corneal Endothelium

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