Extraocular muscles.pptx

you can get information about the extraocular muscles which are responsible for the movement of the eyes in different direction, near and distance.
you will know how many extraocular muscles and how they work....
you will get information about the different position of gazes....

1. The eyeballs are moved by 6 extrinsic muscles, attached at one end to the eyeball and at the other to the walls of the orbital cavity. There are 4 straight and 2 oblique muscles. Movement of the eyes to look in a particular direction is under voluntary control but co-ordination of movement needed for convergence and accommodation to near or distant vision, is under autonomic control. Purpose: To control the movement of the globe

2. All of the extraocular muscles form a “cone within the bony orbit with the exception of the inferior oblique. This conic structure is known as the “ annulus of Zinn .”

3. The eye's major blood supply comes from the ophthalmic artery. The lateral muscular branch of ophthalmic artery supplies the lateral rectus, superior rectus, and superior oblique muscles. The medial muscular branch supplies the inferior rectus, medial rectus, and inferior oblique muscles.

4. Each EOM is innervated by a specific cranial nerve (CN) : Medial rectus (MR): CN III Lateral rectus (ER): CN VI Superior rectus (SR): CN III Inferior rectus (IR): CN III Superior oblique (SO): CN IV Inferior oblique (IO): CN III SO4 (LR6) 3

5. Origin Course Insertion Action

6. Muscle Length of active muscle (mm) Origin Anatomic insertion Direction of pull Innervation Medial Rectus 40 Annulus of Zinn 5.5 mm from Medical limbus 90 o Lower CN III Lateral Rectus 40 Annulus of Zinn 6.9 mm from Lateral limbus 90 o CN VI Superior Rectus 40 Annulus of Zinn 7.7 mm from Superior limbus 23 o Upper CN III Inferior Rectus 40 Annulus of Zinn 6.5 mm from Inferior limbus 23 o Lower CN III Superior Oblique 32 Orbital apex above annulus of Zinn Posterior to Equator in Supero -temporal Quadrant 51 o CN IV Inferior Oblique 37 Behind lacrimal fossa Muscular area 51 o Lower CN III

7. Main Action: Adduction Innervation: Inferior Division of Oculomotor Nerve C Temporal Nasal C

8. Main Action: Abduction Innervation: Abducens C Temporal Nasal C

9. Temporal Nasal C 23 ° Main Action: Supraduction Secondary Action: Incycloduction adduction Innervation: Sup. Division of Oculomotor Nerve (i.e. III Cranial Nerve)

10. Main Action: Infraduction Secondary Action: Excycloduction Adduction Innervation: Inferior Division of Oculomotor Nerve Temporal Nasal C 23 °

11. Main Action: Incycloduction Secondary Action: Infraduction abduction Innervation: Trochlear Nerve C Temporal Nasal C 51 °

12. Main Action: Excycloduction Secondary Action: Supraduction Abduction Innervation: Inferior Division of Oculomotor Nerve C Temporal Nasal C 51 °

13. All obliques Abduct All Recti Adduct except LR All superior muscles  Intort   All inferior muscles Extort

14. As the eye turns around the vertical axis,(Z) the visual axis sweeps along the horizontal plane. 

15. As the eye turns around the horizontal axis, (X) the visual axis sweeps along the vertical plane .  

16. Intortion and extortion refer to rotation around the visual axis, Y-axis Intortion refers to a nasal rotation from the 12 o'clock position.  Extortion refers to a temporal rotation from the 12 o'clock position.

17. R L RLR LMR RMR LLR RSR LIO RIO LSR RIR LSO RSO LIR

18. Agonist-Antagonist: Muscles of the same eye that move the eye in opposite directions. The Agonist is the primary muscle moving the eye in a given direction. The Antagonist acts in the opposite direction to the agonist. e.g. Rt- LR and Rt- MR

19. 3. Synergist: Muscles of the same eye that move the eye in the same direction. e.g. Rt-SR and Rt-IO acts synergistically in elevation. 4. Yoke Muscles: Pairs of muscles, one in each eye, that produce conjugate ocular movements. Ocular movements

20. RSR LIO RIO LSR RIR LSO RSO LIR RLR LMR RMR LLR Yoke Muscles R L Medial Rectus Lateral Rectus Lateral Rectus Medial Rectus Superior Rectus Inferior Oblique Superior Oblique Inferior Rectus Inferior Oblique Superior Rectus

21. Ductions Versions Vergences Ocular movements

22. Definition : monocular eye movements around the axis of Fick, consisting: Adduction Abduction Elevation Depression Torsion Ductions

23. Versions Definition:  These are binocular, simultaneous, conjugate movements. e.g. Positions of gaze Vergences Definition: These are binocular, simultaneous, disjugate movements. e.g. Convergence Divergence Versions and Vergences

24. Clinical orthoptics( Fiona J. Rowe) Diagnosis and management of ocular motility ( Alec M. Ansons and Helen Davis) References

25. All EOMS form a cone within the bony orbit except: Inferior oblique Superior oblique Superior rectus inferior rectus Secondary angle of deviation will be: Smaller than primary angle of deviation Greater than primary angle of deviation Equal to primary angle of deviation None of the above MCQs

26. 3. Versions are: Binocular, simultaneous, disjugate eye movements Uniocular, simultaneous, disjugate eye movements Binocular, simultaneous, conjugate eye movements 4. Superior oblique is supplied by: Third nerve Fourth nerve Sixth nerve 5. Length of superior oblique muscle: 42 mm 40mm 32mm