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Extra Ocular Movements

Extra Ocular Movements. (aka) …and you thought hyperopia was bad…. WHAT ARE WE GOING TO DO T’DAY?. Some ( very, very little ) Basics Extra Ocular Muscles Innervation Control of movements Movements Terminology Actions Testing. BASICS. The Extra Ocular Muscles.

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Extra Ocular Movements

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  1. Extra Ocular Movements (aka) …and you thought hyperopia was bad…

  2. WHAT ARE WE GOING TO DO T’DAY? • Some (very, very little) Basics • Extra Ocular Muscles • Innervation • Control of movements • Movements • Terminology • Actions • Testing

  3. BASICS

  4. The Extra Ocular Muscles

  5. The Extra Ocular Muscles -Origin

  6. The Extra Ocular Muscles -Origin TROCHLEA SR SO Annulus LR MR IR IO

  7. The Extra Ocular Muscles -Origin TROCHLEA SR SO LR MR IR IO

  8. The Extra Ocular Muscles -Origin SR SO LR IO IR

  9. The Extra Ocular Muscles -Origin SR TROCHLEA SO MR IO IR

  10. The Extra Ocular Muscles SR SO MR LR IR IO

  11. The Extra Ocular Muscles IO SO MR LR SR

  12. The Extra Ocular Muscles SR SO LR MR IO IR

  13. The Extra Ocular Muscles MR SR LR

  14. The Extra Ocular Muscles SO IO 51° 23° SR IR OPTICAL AXIS

  15. THE EXTRA OCULAR MUSCLES • Superior & Inferior Recti make an angle of 23° with the eye ball • Superior & Inferior Obliques make an angle of 51° with the eye ball • Angular attachment allows for actions in multiple directions

  16. INNVERVATION LR6 SO4 O3

  17. SOME RULES

  18. RULES #1 • BOTH EYES MUST MOVE TOGETHER • MUSCLES IN BOTH EYES ARE THUS PAIRED • PARIED MUSCLES (YOKE MUSCLES) HELP MOVE THE EYE IN A GIVEN DIRECTION. • THEY BOTH THUS GET SIMILAR STIMULATORY SIGNALS FROM THE BRAIN (HERRINGS LAW)

  19. RULES #2 • MUSCLES IN ONE EYE HAVE AN AGONIST- ANTAGONIST RELATIONSHIP • THE HORIZONTAL RECTII FORM ONE SET • THE VERTICAL RECTII/ OBLIQUES FOR THE OTHER SET • WHEN ONE MUSCLE IN THE SET CONTRACT THE OTHER MUST RELAX (SHERRINGTON’S LAW)

  20. RULES #3 • MUSCLE ACTIONS & TESTINGARE DIFFERENT!

  21. CONTROL OF MOVEMENTS

  22. WHY? • Eyes; you have to see • Eyes must ‘fix’ on an object for you to see clearly • Two Step process • Find what you want to see (Voluntary fixation) • Keep your eyes ‘glued’ to it (Involuntary fixation)

  23. STEP 1: Find what you want to see STEP 2: Keep your eyes fixed on it

  24. SUPRA NUCLEAR: CONTROL MEHANISM

  25. CONTROL MECHANISMS • INVOLUNTARY • Tremors (Help keep image refreshed) • Drifts (Help keep image refreshed) • Flicks (Help eyes move so that image fall on fovea again) • VOLUNTARY • Pursuits (Slow movements to ‘track’ objects) • Saccades (Fast movements to ‘jump’ to objects)

  26. INVOLUNTARY MOVEMENTS DASHED = TREMORS/ DRIFTS SOLID = FLICKS

  27. VOLUNTARY MOVEMENTS • PURSUITS • To ‘follow’ objects • What we usually test • SACCADES • To ‘rapidly’ shift gaze to an object of interest

  28. THE SUPERIOR COLLICULI • Jack of all trades • Help in involuntary tracking • Help in voluntary tracking • Even if the visual cortex is kaput, these help turn the head in direction of ‘interest’

  29. NUCLEAR LEVEL CONTROL Co-ordinate eye movements -Between eyes* -Eyes and ears -Eyes and neck Mostly via Superior colliculus*

  30. VOLUNTARY MOVEMENTSPursuitsSaccades

  31. EXTRAOCULAR MOVEMENTS ROTATIONAL MOVEMENTS X Y Z

  32. PURSUITS(also applies to saccades, but we’ll deal with those a little later)

  33. TERMINOLOGY • DUCTIONS • Examining movement of one eye • Remember it is not possible to move one eye alone! • VERSIONS • Movements of both eyes in the same direction • VERGENCE • Movements of both eyes in opposite direction

  34. PURSUITS: DUCTIONS

  35. TERMINOLOGY: DUCTIONS

  36. TORSIONAL MOVEMENTS INTORSION Inward rotation Superior Rectus & Oblique EXTORSION Outward rotation Inferior Rectus & Oblique Rotation around ‘Y” axis HELP KEEP YOUR WORLD STRAIGHT!

  37. PRACTICE!

  38. PURSUITS: VERSIONS

  39. TERMINOLOGY: VERSIONS HERING’S LAW SUPRA VERSION Agonist Pairs in both eyes One eye follows the other LEVO VERSION DEXTRO VERSION These are called ‘Yoke’ muscles Both get equal impulses INFRA VERSION

  40. TERMINOLOGY: VERSIONS SHERRINGTON’S LAW SUPRA VERSION … are inhibited… The antagonist muscles to yokes… LEVO VERSION DEXTRO VERSION …to allow for optimal actions… …of yoke muscles INFRA VERSION

  41. TORSIONAL MOVEMENTS • TORSIONAL MOVEMENTS CAN ALSO BE DEFINED FOR BOTH EYES • INWARD ROTAION: INCYCLOVERSION • OUTWAR ROTATION: EXCYCLOVERSION

  42. PURSUITS: VERGENCE

  43. TERMINOLOGY: VERGENCE

  44. THE NUT CRACKER • Its all good knowing Versions & Ductions • But they DO NOT tell us anything about integrity of muscle function • As clinicians it is more important to know about muscle functions

  45. http://forums.studentdoctor.net/archive/index.php/t-109725.htmlhttp://forums.studentdoctor.net/archive/index.php/t-109725.html

  46. MUSCLE ACTIONS • ACTIONS ARE DETERMINED BY POSITION OF EYE BALL • Primary Position: Straight ahead • Secondary Positions: Left, Right, Up, Down • Tertiary positions: Oblique • MUSCLES, THUS, HAVE COMPLEX ACTIONS

  47. MUSCLE ACTIONS EYES STRAIGHT EYES U/D/L/R EYES OBLIQUE

  48. MUSCLE ACTIONS • MUSCLES, THUS, HAVE COMPLEX ACTIONS 

  49. MUSCLE ACTIONS • THANK FULLY WE OPHTHALMOLOGISTS ARE MASTERS OF SIMPLFICATIONS  →

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