Biological organization of the extraocular muscles

Spencer, Robert F.; Porter, John D.

doi:10.1016/s0079-6123(05)51002-1

Cited by 230 publications

(337 citation statements)

References 200 publications

Supporting

Mentioning

320

Contrasting

Unclassified

Order By: Relevance

“…Although extraocular muscles are classified as skeletal muscle, they differ in many respects from skeletal (limb) muscle, including their diversity of myofiber types (Spencer and Porter, 1988;Baryshnikova et al, 2007, submitted), their functional properties (Nelson et al, 1986), their susceptibility to diseases (Ruff, 2002), and they have a particularly strong vascular supply (Wooten and Reis, 1972;Cheng et al, 2004). These substantial differences between limb skeletal and extraocular muscle may relate to the fact that extraocular muscle viability is not maintained as predicted for other skeletal muscle.…”

Section: Differences Between Skeletal (Limb) Muscle and Extraocular Mmentioning

confidence: 99%

Measurement of contractile force of skeletal and extraocular muscles: Effects of blood supply, muscle size and in situ or in vitro preparation

Croes

Bartheld

2007

Journal of Neuroscience Methods

View full text Add to dashboard Cite

Contractile forces can be measured in situ and in vitro. To maintain metabolic viability with sufficient diffusion of oxygen, established guidelines for in vitro skeletal muscle preparations recommend use of relatively thin muscles (≤1.25 mm thick). Nevertheless, forces of thin extraocular muscles vary substantially between studies. Here, we examined parameters that affect force measurements of in situ and in vitro preparations, including blood supply, nerve stimulation, direct muscle stimulation, muscle size, oxygenated or non-oxygenated buffer solutions, and the time after interruption of vascular circulation. We found that the absolute forces of extraocular muscle are substantially lower when examined in vitro. In vitro preparation of 0.58 mm thick extraocular muscle from 3-week old birds underestimated contractile function, but not of thinner (0.33 mm) muscle from 2-day old birds. Our study shows that the effective criteria for functional viability, tested in vitro, differ between extraocular and other skeletal muscle. We conclude that contractile force of extraocular muscles will be underestimated by between 10 and 80%, when measurements are made after cessation of blood supply (at 5 -40 min). The mechanisms responsible for the declining values for force measurements are discussed, and we make specific recommendations for obtaining valid measurements of contractile force.

show abstract

Section: Differences Between Skeletal (Limb) Muscle and Extraocular Mmentioning

confidence: 99%

Measurement of contractile force of skeletal and extraocular muscles: Effects of blood supply, muscle size and in situ or in vitro preparation

Croes

Bartheld

2007

Journal of Neuroscience Methods

View full text Add to dashboard Cite

show abstract

“…2,15 Extraocular muscle comprises a diverse range of fibre types that are dissimilar from skeletal muscle. 16 Each rectus muscle has a distinct outer orbital layer and inner global layer. In the outer orbital layer, the predominant fibre type contains a large number of mitochondria and it has been suggested that their large energy demands make them especially susceptible to the involvement in mitochondrial myopathy.…”

Section: Discussionmentioning

confidence: 99%

Dynamic properties of eye movements in mitochondrial chronic progressive external ophthalmoplegia

DeBrosse

Ubogu

Yaniglos

et al. 2007

Eye

View full text Add to dashboard Cite

Aims To relate dynamic properties of eye movements to visual disability in a patient with chronic progressive external ophthalmoplegia (CPEO) due to mitochondrial DNA deletion. Methods Visual function was evaluated by neuro-ophthalmological examination and visual function index (VF-14). Eye movements were measured using the magnetic search coil technique. Results The patient denied diplopia or oscillopsia at rest or during locomotion. His range of eye movements was limited to o121 horizontally, and o191 vertically with smaller movements of the left eye. All classes of movements were impaired, but the eyes accelerated to over 10001/s/s at the onset of saccades and in response to brisk head rotations. Conclusions Diplopia and oscillopsia were suppressed, probably due to visual system adaptation during the slow disease progression. We postulate that relative sparing of pale global extraocular fibres accounted for preserved acceleration of saccades and vestibular eye movements.

show abstract

“…Motor nerves innervating horizontal rectus EOMs bifurcate into about equal regionally segregated intramuscular arborizations (Figure 1). 11 This was first suspected in LR because it has been thought to have a dual origin 13 arising from separate embryonic progenitors. 14 Longitudinal LR splitting can be observed by magnetic imaging resonance (MRI) in congenital cranial dysinnervation disorders, including congenital fibrosis, 15 Duane syndrome, 16 and congenital oculomotor palsy.…”

Section: Anatomic Evidence For Eom Compartmentalizationmentioning

confidence: 99%

Compartmentalization of extraocular muscle function

Demer

2014

Eye

View full text Add to dashboard Cite

Ocular motor diversity exceeds capabilities of only six extraocular muscles (EOMs), but this deficiency is overcome by the plethora of fibers within individual EOMs surpassing requirements of homogeneous actuators. This paper reviews emerging evidence that regions of individual EOMs can be differentially innervated to exert independent oculorotary torques, broadening the oculomotor repertoire, and potentially explaining diverse strabismus pathophysiology. Parallel structure characterizes EOM and tendon fibers, with little transverse coupling of experimentally imposed or actively generated tension. This arrangement enables arbitrary groupings of tendon and muscle fibers to act relatively independently. Coordinated force generation among EOM fibers occurs only upon potentially mutable coordination of innervational commands, whose central basis is suggested by preliminary findings of apparent compartmental segregation of abducens motor neuron pools. Humans, monkeys, and other mammals demonstrate separate, nonoverlapping intramuscular nerve arborizations in the superior vs inferior compartments of the medial rectus (MR) and lateral rectus (LR) EOMs that could apply force at the superior vs inferior portions of scleral insertions, and in the medial vs lateral compartments of the superior oblique that act at the equatorial vs posterior scleral insertions that might preferentially implement incycloduction vs infraduction. Magnetic resonance imaging of the MR during several physiological ocular motor behaviors indicates differential compartmental function. Differential compartmental pathology can influence clinical strabismus. Partial abducens palsy commonly affects the superior LR compartment more than the inferior, inducing vertical strabismus that might erroneously be attributed to cyclovertical EOM pathology. Surgery may selectively manipulate EOM compartments.

show abstract

Biological organization of the extraocular muscles

Cited by 230 publications

References 200 publications

Measurement of contractile force of skeletal and extraocular muscles: Effects of blood supply, muscle size and in situ or in vitro preparation

Measurement of contractile force of skeletal and extraocular muscles: Effects of blood supply, muscle size and in situ or in vitro preparation

Dynamic properties of eye movements in mitochondrial chronic progressive external ophthalmoplegia

Compartmentalization of extraocular muscle function

Contact Info

Product

Resources

About