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Accessory lateral rectus in a patient with normal ocular motor control
Yaping Joyce Liao1, Jaclyn J Hwang
1Department of Ophthalmology, Stanford University School of Medicine, Stanford, CA.
Summary
Supernumerary extraocular muscles are rare in humans. This case report details an incidentally discovered accessory lateral rectus muscle in an adult woman with normal eye movement and alignment.
Area of Science:
- Ophthalmology
- Human Anatomy
- Neuroscience
Background:
- Supernumerary extraocular muscles are frequently observed in non-human primates.
- In humans, these anatomical variations are uncommon and often associated with strabismus in childhood.
Observation:
- A case study of a 51-year-old woman with an incidentally identified unilateral accessory lateral rectus muscle.
- The accessory muscle was small, approximately 10% the size of the normal lateral rectus.
- It originated from the orbital apex, positioned between the optic nerve and the lateral rectus, inserting superolaterally on the globe.
Findings:
- The accessory lateral rectus muscle did not impede normal ocular motor control or alignment in the patient.
- This finding suggests that accessory extraocular muscles can exist asymptomatically in adults.
Implications:
- This case expands the understanding of human ocular anatomy variations.
- It highlights that accessory extraocular muscles may not always result in clinical dysfunction.
- Further research could explore the prevalence and functional significance of such anatomical variations in the human population.
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