Dictionary of Ichthyology  

rectus muscles = the muscles that move the eye up, down, backward and medially. They are the inferior, medial, lateral, and superior recti.

Eye muscles and nerves in a shark, a = abducens, om = oculomotor, t = trochlearis (nerves); oi = inferior oblique, os = superior oblique, re = external rectus, ri = internal rectus, rif = inferior rectus, rs = superior rectus (muscles), from Kingsley's "Textbook of Vertebrate Zoology, 1906. Photograph by Brian W. Coad.

Canadian Museum of Nature