protractor operculi Muscle located in the lateral region of the cheek, linking the lateral surface of opercle with the posterolateral margin of the suspensorium (usually the preopercle). Occurs in most members of the Trichomycteridae, except in basal Copionodontinae and Trichogeninae (de Pinna, 1992). TAO:0001693 teleost_anatomy cranial muscle