Extraocular muscles have fundamentally distinct properties that make them selectively vulnerable to certain disorders.
While skeletal muscles generally perform specific limited roles, extraocular muscles (EOMs) have to be responsive over a wider dynamic range. As a result, EOMs have fundamentally distinct structural, functional, biochemical and immunological properties compared to other skeletal muscles. While these properties enable high fatigue resistance and the rapid and precise control of extraocular motility, they might also explain why EOMs are selectively involved in certain disorders, such as chronic progressive external ophthalmoplegia (CPEO), myasthenia gravis and Graves' ophthalmopathy. This review first gives an overview of the novel myofibre classification in EOMs and then focuses on those properties that might explain why ophthalmoplegia should be so prominent in these disorders.
Yu Wai Man
C Y
CY
Department of Neurology, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4HH, UK.
Chinnery
P F
PF
Griffiths
P G
PG
D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D006111:Graves Disease / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000145:classification; D009157:Myasthenia Gravis / Q000378:metabolism / Q000503:physiopathology; D009218:Myosins / Q000378:metabolism; D009801:Oculomotor Muscles / Q000294:innervation / Q000502:physiology*; D017246:Ophthalmoplegia, Chronic Progressive External / Q000378:metabolism / Q000503:physiopathology
D009218:Myosins