The authors aimed to study and morphometrically define the surgical anatomy of the inferior oblique muscle and its variations, and to outline surgical coordinates to aid location of the inferior oblique origin and nerve supply to the inferior oblique muscle. This was a cross-sectional study on male cadavers aged 5-80 years (16 orbits). The origin and course of the inferior oblique to the insertion on the eyeball was identified. A single muscle belly was found in 68.8% with multiple bellies in the remainder. Some had multiple bellies in one eye and single in the fellow eye, but with single origins. Most were unified before insertion. Length from origin to insertion was mean 33.1 ±3.3mm – range 26.1-37.3mm. Width at origin was 3.1 ±0.6mm and width at insertion was 8.8 ±1.5mm. Maximum width was 9.2 ±1.3mm and minimum was 3.5 ±0.7mm. Length of the nerve was 27.6 ±5.8mm, distance from nerve to muscle origin was 15.5 ±2.3mm and distance from nerve to muscle insertion was 15.2 ±2.8mm. The nerve (branch of inferior division of III cranial nerve) enters through the orbital surface with the entry point almost midway between the origin and insertion. The authors report on the presence of a muscle bridge / connection between the inferior rectus and inferior oblique muscles which could influence surgical outcomes.
Inferior oblique muscle features
Reviewed by Fiona Rowe
Morphometry and anatomical variations of the inferior oblique muscle as relevant to the strabismus surgeries.
CONTRIBUTOR
Fiona Rowe (Prof)
Institute of Population Health, University of Liverpool, UK.
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