-- card: 8692 from stack: in
-- bmap block id: 9307
-- flags: 0000
-- background id: 2278
-- name: EOM


-- part 1 (button)
-- low flags: 00
-- high flags: 2000
-- rect: left=305 top=326 right=338 bottom=317
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: 1
----- HyperTalk script -----
on mouseUp
  visual iris close
  go to card id 22458
end mouseUp




-- part 2 (button)
-- low flags: 00
-- high flags: 2000
-- rect: left=321 top=326 right=338 bottom=333
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: 1
----- HyperTalk script -----
on mouseUp
  visual iris close
  go to card id 22710
end mouseUp




-- part 3 (button)
-- low flags: 00
-- high flags: 2000
-- rect: left=335 top=326 right=338 bottom=347
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: 1
----- HyperTalk script -----
on mouseUp
  visual iris close
  go to card id 22864
end mouseUp




-- part 4 (button)
-- low flags: 00
-- high flags: 2000
-- rect: left=350 top=326 right=338 bottom=362
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: 1
----- HyperTalk script -----
on mouseUp
  visual iris close
  go to card id 23289
end mouseUp




-- part contents for background part 1
----- text -----

XI. Extraocular muscles: (EOM)

     A. General description:
          1. Feedback loop: Light falls on retina, blurry, correct gaze with  EOM, vision clears.
          2. Directions of gaze:
               a. Primary position: Head held normally, eyes focused at infinity, cornea centered in palpebral 
                   fissure.
               b. Duction: Movements of one eye:
                    1. Adduction: Nasally.
                    2. Abduction: Temporally.
                    3. Elevation: Sursumduction, upward.
                    4. Depression: Deorsumduction, downward.
                    5. Intorsion: Rotation around visual axis, top of eye rotates nasally.
                    6. Extorsion: Rotation around visual axis, top of eye rotates temporally.
               c. Version: Movements of two eyes:
                    1. Convergence: Both adduct.
                    2. Divergence: Both abduct.
                         a. Above two are vergences, eyes move opposite directions.
                    3. Levoversion: Both to left gaze.
                    4. Dextroversion: Both to right gaze.
                    5. Sursumversion: Both elevated.
                    6. Deorsumversion: Both depressed.
                         a. Above four are versions, both eyes move in same direction.
     B. Characteristics of EOM: Motor unit muscles.
          1. Striated.
          2. Rich nerve supply, 7 muscle fibers per neuron  (skeletal muscles have 10-100 fibers per 
              neuron), fine, fast, precise.
     C. Rectus muscles: Four of them.
          1. Characteristics:
               a. Lie in the four quadrants of the eyeball.
               b. Origin is annulus of Zinn.
               c. Insertion into sclera 5 to 8 mm. from limbus.
                   (See diagram 1)
          2. Medial rectus:
               a. Adduction: Lies in same plane as optic axis.
               b. Thickest and most powerful.
               c. Innervation by oculomotor (III) nerve, inferior division.
               d. Convergence of eye for nearpoint focus.
               e. Best developed check ligament.
          3. Lateral rectus:
               a. Abduction: Lies in same plane as optic axis.
               b. innervation by abducens (VI) nerve.
          4. Superior rectus:
               a. Lies above superior oblique.
               b. Insertion oblique to optic axis by 23 degrees.
               c. Elevation, adduction, intorsion.
               d. Innervation by oculomotor (III) nerve, superior division.
          5. Inferior rectus:
               a. Lies below inferior oblique.
               b. Insertion oblique to optic axis by 23 degrees.
               c. Depression, adduction, extorsion.
               d. Innervation by oculomotor (III) nerve, inferior division.
               e. Muscle sheath contributes to ligament of Lockwood.
     D. Oblique muscles: Two of them.
          1. Superior oblique:
               a. Origin: Lesser wing of the sphenoid above and medial to the optic foramen.
               b. Tendon passes through trochlea and turns posterior.
               c. Insertion into sclera under superior rectus.
               d. Trochlea: In superior nasal corner of orbit on frontal bone.
               e. Angle of action is 51 to 53 degrees from visual axis.
               f. Depression, intorsion, abduction.
               g. Insertion is primarily in posterior, superior, temporal quadrant.
               h. Innervation by trochlear (IV) nerve.
          2. Inferior oblique:
               a. Origin at anterior medial floor of orbit on maxillary bone.
               b. Runs posterior and lateral under LR.
               c. Insertion posterior, inferior, temporal quadrant, under macula.
               d. Angle of action is 51 to 53 degrees from visual axis.
               e. Elevation, extorsion, abduction.
               f. Muscle sheath contributes to ligament of Lockwood.
               g. Innervation by oculomotor (III) nerve, inferior division.
                   (See diagram 2)
     E. Motion:
          1. All muscles have constant tone, to move causes tone to increase or decrease.
                (See diagram 3)
                (See diagram 4)