Abnormal superior oblique muscle physiology 2018-01-13T20:12:43Z A neurological examination includes assessment of the trochlear nerve (CN IV) which innervates the superior oblique muscle. The test for CN IV function is for the patient to depress and adduct the eye (ie. to look down and in). This movement is impaired in the presence of a trochlear nerve palsy. A functional anomaly of the superior oblique muscle, a fusiform muscle that originates in the upper, medial side of the orbit. The superior oblique muscle abducts, depresses and internally rotates the eye, and is the only extraocular muscle innervated by the fourth cranial nerve. Abnormal oblique muscle physiology