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Ophthalmology
Extraocular Muscle Structure, Embryology and Ocular Motor Control
Built from Strabismus Simplified, Second Edition
What’s inside
6 sections · 79 slides
Overview
- Scope of this topic
Histopathology of extraocular muscles
- Extraocular muscle as striated muscle
- Connective tissue sheaths of the muscle
- Structure of the muscle fibre
- The sarcomere
- Sarcomere structure and changes after contraction
- Sliding filament mechanism of contraction
- Excitation-contraction coupling
- Energy supply for contraction
- Singly versus multiply innervated fibres
- Classification of skeletal muscle fibres
- Functional demands on the extraocular muscles
- Basis of extraocular muscle fibre classification
- Orbital and global layers of extraocular muscle
- Orbital singly innervated fibre
- Orbital multiply innervated fibre
- Global red singly innervated fibre
- Global intermediate singly innervated fibre
- Global white singly innervated fibre
- Global multiply innervated fibre
- Functional properties of extraocular muscle fibre types
- Fibre type properties at a glance
- The older Fibrillenstruktur and Felderstruktur classification
- Fine structure of the levator palpebrae superioris
Embryological development
- Origin of the extraocular muscles
- Timing of extraocular muscle differentiation
- Waves of myogenesis
- Critical period and anomalous innervation
- Postnatal maturation and botulinum toxin
- Extraocular muscle pulleys
Accommodation and convergence
- The near vision complex
- Accommodative convergence and the AC/A ratio
- Convergence demand at one metre
- The metre angle
- Amplitude of accommodation and the near point
- Near point of convergence
- Types of convergence
- Tonic convergence
- Proximal convergence
- Fusional convergence
- Accommodative convergence
- Relative convergence and relative accommodation
- Stimulus versus response AC/A ratio
- Agents that change the AC/A ratio
- Accommodative esotropia with a normal AC/A ratio
- Accommodative esotropia with a high AC/A ratio
- Miotics, glasses, prisms and surgery compared
- Methods of estimating the AC/A ratio
- Heterophoria method
- Gradient method at 6 metres with concave lenses
- Gradient method at 33 cm with convex lenses
- Graphic method
- Fixation disparity method
- Clinical uses of the AC/A ratio
Types of eye movements
- The six classes of eye movement
- Purposes of the eye movement systems
- Comparison of saccades, pursuit, vergence and reflex movements
- Eye movement characteristics
- Neural pathways of horizontal and vertical gaze
Relevant neuroanatomy
- Scope of the neuroanatomy covered
- Cortical control of eye movements
- Brainstem pathways for horizontal and vertical gaze
- Monocular elevator paresis and vertical gaze centres
- Reflex and vergence centres
- Organisation of the oculomotor nucleus
- Clinical rules for nuclear oculomotor lesions
- Trochlear nucleus and nerve
- Abducens nucleus and its position
- Cell populations of the abducens nucleus
- Internuclear ophthalmoplegia
- Summary of key points
- Suggested reading
- Suggested reading (continued)
- Strabismus Simplified