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Ophthalmology
Applied Anatomy and Physiology of Extraocular Muscles
Built from Strabismus Simplified, Second Edition
What’s inside
8 sections · 103 slides
Overview
- Scope of this topic
Anatomy of the extraocular muscles
- The six extraocular muscles
- Naming and arrangement of the extraocular muscles
- Extraocular muscles of the orbit
- Inter-rectus distance and limits on transposition
- Rectus insertions in relation to the limbus
- Anatomic features of the four recti
- Origin and course of the recti
- Rectus insertions and the spiral of Tillaux
- Functional origin and course of the obliques
- Forced duction testing of the oblique muscles
- Course of the superior oblique and the trochlea
- Brown's superior oblique sheath syndrome
- Insertion of the superior oblique
- Insertion of the superior oblique in detail
- Segmental function of the superior oblique fan
- Dimensions of the superior oblique
- The inferior oblique: origin and course
- Insertion of the inferior oblique
- Relations of the inferior oblique insertion
- Segmental function of the inferior oblique fan
Fascial connections and Tenon's capsule
- Suspensory ligament of Lockwood
- Fascial connections of the globe in longitudinal section
- Lid position after vertical rectus surgery
- Tenon's capsule: orifices and attachments
- Anterior and posterior orifice of Tenon's capsule
- Muscle sheaths and the intermuscular septum
Blood supply and innervation
- Neurovascular entry into the extraocular muscles
- Anterior ciliary circulation of the globe
- Anterior segment circulation and its iris sectors
- Risk of anterior segment ischaemia
- Cranial nerve supply of the extraocular muscles
- Nerve supply of the extraocular muscles
Physiology of eye movements
- Actions of the horizontal recti
- Vertical vector of the horizontal recti in elevation
- Anatomical and functional equators
- Anatomical and functional equators of the globe
- Arc of contact in adduction and abduction
- The cyclovertical muscles
- Actions of the superior rectus
- Superior rectus action in three eye positions
- Actions of the inferior rectus
- Actions of the superior oblique
- Superior oblique action in three eye positions
- Actions of the inferior oblique
- Actions of the cyclovertical muscles in each eye position
- Contributions to elevation and depression in the primary position
- Horizontal actions of the vertical recti and obliques
Laws of ocular motility
- Yoke muscles
- Synergists and antagonists for each version
- Hering's law of motor correspondence
- Symmetric convergence
- Innervation pattern in symmetric convergence
- Asymmetric convergence
- Innervation pattern in asymmetric convergence
- Hering's law in concomitant and incomitant squint
- Sherrington's law of reciprocal inhibition
- Failure of reciprocal inhibition
- Donder's law
- Listing's law and pseudotorsion
- Pseudotorsion in tertiary gaze positions
Neurophysiology of eye movements
- Mechanical analysis of eye movements
- Pulse-step innervation of a saccade
- Innervation during a 30 degree abduction
- Innervation profile of a refixation saccade
- Ramp innervation for smooth pursuit
- Innervation profile of following pursuit
- Boeder's contributions to elevation and depression
- Percentage contribution of each muscle to elevation
- Muscle contributions beyond 10 degrees of adduction
- The obliques as primary torsional muscles
- Horizontal rectus contribution and muscle slippage
- Torsional eye movements and Fick's Y axis
- Axis of intorsion at the lateral limbus
- Detecting intorsion in oculomotor nerve palsy
- Compensatory torsion on head tilt
- Vertical shoots on head tilt in oblique palsies
Physiological basis of strabismus surgery
- Determinants of the torque generated by a muscle
- Arc of contact and the efficiency of the Faden operation
- Lever arms in recession and Faden operation
- Strengthening procedures
- Weakening procedures
- Strengthening compared with weakening
- Safe limits for muscle surgery
- Safe limits for recession and resection
- Retroequatorial myopexy
- Length-tension curves of the extraocular muscles
- Family of length-tension curves for the medial rectus
- Minimum resting tension at 15 degrees temporal
- Tension changes during an adducting saccade
- Dynamic equilibrium in the new eye position
- Key anatomical numbers
- Key physiological and surgical principles
- Suggested reading
- Suggested reading (continued)
- Strabismus Simplified