EXTRA OCULAR MUSCLES

EXTRA OCULAR MUSCLES
Positions of eye
laws of movement

1. Extra- Ocular Muscles By/Mohamed Ahmed El – Shafie Assistant Lecturer in ophthalmology department KafrELShiekh University 1

2. ORBITAL MUSCLES Extrinsic muscles of eyeball. Involved in movement of eyeball. Intrinsic muscles Controls shape of lens and size of pupil. 2

3. Intrinsic Muscles iris sphincter, radial pupilodilator muscles ciliary muscle Controlled by autonomic nervous system, work in response to amount of light, closeness of an object (for focusing), etc serve to focus the eye and control the amount of light entering it 3

4. vedio 4

5. Extrinsic Muscles 5

6. Embryology mesodermal origin, Perimuscular Connective tissues from neural crest development beginning at 3– weeks of gestation.   6

7. Extra ocular Muscles: Origin Superior Oblique Levator palpebrae superioris Medial Rectus Lateral Rectus Superior Rectus Inferior Rectus Inferior Oblique 7

8. Oval, fibrous ring at the orbital apex. Structures passing through the annulus: 1. Occulomotor nerve (superior and inferior divisions) 2. Abducens Nerve 3. Optic Nerve 4. Nasociliary Nerve 5. Ophthalmic Artery Annulus of Zinn 8

9. 23rd July '15 9 Clinical Significance Retrobulbar neuritis Origin of SUPERIOR AND MEDIAL RECTUS are closely attached to the dural sheath of the optic nerve, which leads to pain during upward & inward movements of the globe. Thyroid orbitopathy Medial & Inf.rectus thicken. especially near the orbital apex - compression of the optic nerve as it enters the optic canal adjacent to the body of the sphenoid bone.

10. SPIRAL OF TILLAUX 5.5 mm 6.5 mm 6.9 mm 7.7 mm 10

11. 23rd July '15 11 23rd July '15 Dept. of Ophthalmology, JNMC, Belagavi Medial rectus inserts closest to the limbus and is therefore susceptible to injury during ant. segment surgery. Inadvertent removal of the MR is a well known complication of Pterygium removal The Scleral thickness behind the rectus insertion is the thinnest, being only 0.3 mm thick -> chances of scleral perforation while suturing Clinical Significance

12. 23rd July '15 12 LEVATOR PALPEBRAE SUPERIORIS Origin: Orbital surface of lesser wing of sphenoid bone, anterosuperior to optic canal. Insertion: Splits in two lamina Superior lamina (voluntary) to Skin of upper eyelid & anterior surface of superior tarsal plate Inferior lamina (Muller’s muscle) (involuntary) to upper margin of superior tarsus (superior tarsal or muller’s muscle) & superior conjunctival fornix

13. 23rd July '15 13 NERVE SUPPLY- Upper division of occulomotor nerve. ACTION- Elevation of upper eyelid. Ptosis Drooping of upper eyelid.

14. VEDIO 23rd July '15 Dept. of Ophthalmology, JNMC, Belagavi 14

15. 23rd July '15 15 Dept. of Ophthalmology, JNMC, Belagavi

16. SUPERIOR RECTUS MUSCLE Origin-Superior part of common tendon of zinn. Insertion-inserted into sclera by flat tendinous insertion about 7.7 mm behind sclero-corneal junction. Nerve supply-superior division of occulomotor nerve. 16

17. Action of Superior Rectus Primary action is elevation . . Secondary action is adduction Intorsion . 17

18. INFERIOR RECTUS Origin-inferior part of common tendon of zinn Insertion-in the sclera 6.5 mm behind sclero corneal junction. Nerve supply-inferior division occulomotor nerve. 18

19. ACTIONS- Primary depressor. Subsidiary actions are adduction and extorsion . 19

20. MEDIAL RECTUS Origin-annulus of zinn and from optic nerve sheath. Insertion-in sclera 5.5mm behind sclero -corneal junction. Nerve supply-lower division of occulomotor nerve. ACTION- Primary adductor of the eye. 20

21. LATERAL RECTUS Origin-annulus of zinn . Insertion-in the sclera 6.9mm behind sclerocorneal junction. Nerve supply- abducens nerve which enters the muscle on the medial surface. ACTION - Primary abductor of eye. 21

22. SUPERIOR OBLIQUE Longest and thinnest intraorbital muscle, the muscle ends before t he trochlea, tendon is 2.5 cm, smooth movement through trochlea. Origin-body of sphenoid above and medial to optic canal. Passes along superomedial part of orbit and ends in a tendon. Insertion- Posterosuperior quadrant of sclera behind equator of eyeball. Nerve supply-trochlear nerve entering it approximately one third of the distance from the origin to the trochlea. 22

23. ACTIONS Primary action- intorsion . Subsidiary actions-abduction and depression. Adducted position-depression. 23rd July '15 23

24. INFERIOR OBLIQUE Origin- Anteromedial part of orbital floor lateral to nasolacrimal groove. Insertion- posteroinferior surface of globe near the macula. Nerve supply-inferior division of occulomotor nerve enters the muscle laterally at the junction of the inferior oblique and inferior rectus muscles. 23rd July '15 24

25. ACTIONS Primary action- extorsion . Subsidiary actions-elevations and abduction. Causes elevation only in adducted position of eyeball. 23rd July '15 25

26. 26 Blood supply EOM are supplied by the branches of ophthalmic artery. Muscular branches Lacrimal braches As the ophthalmic artery enter the muscle cone through the optic canal it braches to Lateral and Medial muscular branches Medial muscular branch Lateral muscular branch

27. Dept. of Ophthalmology, JNMC, Belagavi 27 23rd July '15 Muscular artery course along with CN 3 to enter rectus muscle at the junction of posterior and middle one third. Lateral muscular branches- lateral rectus sup rectus LPS SO Medial muscular branches- medial rectus inferior rectus IO Lacrimal branch-LR and SR

28. Dept. of Ophthalmology, JNMC, Belagavi 28 Venous drainage of EOM The venous drainage of the extraocular muscles is via the superior and inferior orbital veins to ophthalmic veins Anterior ciliary vein Cavernous sinus Inferior ophthalmic vein Superior ophthalmic vein Superior orbital vein inferior orbital vein Clinical correlates: Secondary Perimuscular infection following EOM trauma can spread infection to cavernous sinus . Cavernous vascular disease can present as opthalmoplegia and proptosis

29. 23rd July '15 Dept. of Ophthalmology, JNMC, Belagavi Nerve Supply of Extraocular Muscles Superior division of oculomotor :- levator palpebrae superioris , superior rectus Inferior division of oculomotor :- medial rectus, inferior oblique, inferior rectus Trochlear nerve - superior oblique Abducent nerve - lateral rectus 23rd July '15 29 AL 3 SO 4 LR 6

30. VEDIO 30

31. 23rd July '15 31 Primary position of gaze Defined by Scobee Position of the eyes in binocular vision when, with the head erect, the object of regard is at infinity and lies at the intersection of the sagittal plane of the head and a horizontal plane passing through the centres of rotation of the two eyeballs

32. 23rd July '15 32 Secondary position of gaze Positions assumed by the eyes while looking straight up, ( supraversion ) straight down, ( infraversion ) to the right, ( dextroversion ) and to the left ( levoversion )

33. 23rd July '15 33 Tertiary position of gaze Positions assumed by the eyes when combination of vertical and horizontal movements occur. Dextroelevation Dextrodepression Levoelevation levodepression

34. 34 Motion of an Eye To describe eye motions we need a set of defined axes (Fick’s Axes -) X axis : nasal -> temporal Y axis: anterior -> posterior Z axis: superior -> inferior These axes intersect at the center of rotation - a fixed point, defined as 13.5 mm behind cornea.

35. 35 Ocular movements Ocular movement occurs around the axis of Fick 3 basic ocular movements 1.Ductions – 2.Version- monocular movement around the axis of Fick Binocular, simultaneous, conjugate movements-(in same direction) Binocular, simultaneous, disjugate /disjunctive movement-in opposite direction 3.Vergences- 1.Convergence 2.divergence

36. 36 Ductions Are tested by occluding one eye and asking the patient to follow target in each direction of gaze Ductions consist of following- 1.adduction-MR 4.depression- 2.abduction-LR 6.Extorsion (IO) 3.Elevation (SR) 5.Intorsion (SO) OD

37. Dept. of Ophthalmology, JNMC, Belagavi 37 Version Tested with both eye open and asking patient to follow a target in each direction of gaze . Following are the various gaze of versions-9 cardinal gaze 3.Dextroelevation (ODSR+OSIO) 2 .Destroversion ODLR+OSMR) 5.Laevoversion (OSLR+ODMR ) 6.Laevoelevation (OSSR+ODIO) 7.Laevodrepression (OSIR+ODSO) 9.drepression 8.elevation 1.Primary position 4.Dextrodrepression (ODIR+OSSO)

38. VEDIO 38

39. 39 23rd July '15 39 MUSCLE PRIMARY ACTION SECONDARY ACTION TERTIARY ACTION MR ADDUCTION __________ ____________ LR ABDUCTION __________ ____________ SR ELEVATION INTORSION ADDUCTION IR DEPRESSION EXTORSION ADDUCTION SO INTORSION DEPRESSION ABDUCTION IO EXTORSION ELEVATION ABDUCTION

40. 23rd July '15 40 Superior Oblique Inferior Oblique Superior rectus Inferior rectus Medial rectus Lateral rectus

41. 23rd July '15 41 Laws of ocular motility Agonist Any particular EOM producing specific ocular movement Synergists Muscles of the same eye that move the eye in the same direction

42. 23rd July '15 42 Antagonists A pair of muscles in the same eye that move the eye in opposite directions Yoke muscles ( contralateral synergists) Pair of muscles, one in each eye , that produce conjugate ocular movements

43. 43 An equal and simultaneous innervation flows from the brain to a pair of yoke muscles which contracts simultaneously in different binocular movements Ex. Right LR and Left MR during dextroversion Applies to all normal eye movements HERING’S LAW OF EQUAL INNERVATION

44. 23rd July '15 44 States that increased innervation to a contracting agonist muscle is accompanied by reciprocal inhibition of its antagonist Ex. During detroversion there is increased innervation to right LR and left MR accompanied by decreased flow to right MR and left LR SHERRINGTON’S LAW OF RECIPROCAL INNERVATION

45. 23rd July '15 Dept. of Ophthalmology, JNMC, Belagavi 45 Applied Anatomy Abnormal deviation of eyeball is known as Squint ( Strabismus ). Paralysis of Lateral rectus due to damage to Abducent nerve leads to Medial Squint. Damage to Occulomotor nerve leads to paralysis of all muscles of eye except Superior oblique and lateral rectus leading to Lateral Squint and Ptosis-Dropping of Eyelid. Damage to Trochlear nerve cause paralysis of superior oblique muscle causing diplopia while looking downwards. Medial Squint Lateral Squint and Ptosis -Dropping of Eyelid. Dept. of Ophthalmology, JNMC, Belagavi 45

46. Thankyou  46