Associated cranial nerves are the oculomotor, abducens, trochlear, and hypoglossal nerves. The orbital surface presents medially by trochlear fovea and laterally by lacrimal fossa. The oculomotor nerve (III), trochlear nerve (IV) and abducens nerve (VI) coordinate eye movement. It is the only extraocular muscle innervated by the trochlear nerve (the fourth cranial nerve). Cranial nerve 4 (trochlear nerve) wraps around the lowest part of the cerebral peduncle. Types of articular surfaces include trochlear surfaces. Abducens solely innervates the lateral rectus muscle of the eye, moving the eye with trochlear. It travels medial to the trochlear nerve. This ligament acts to keep the patella within the trochlear groove during flexion and extension. The trochlear nerve emerges from the back (dorsal) brainstem, just below the inferior colliculus. The human trochlear nerve is derived from the basal plate of the embryonic midbrain. On the lateral side is commonly a tubercle called the calcaneal tubercle (or trochlear process). The axial twist hypothesis also explains the chiasm of the trochlear nerve. Thus a lesion of the trochlear nucleus affects the "contralateral" eye. Imaging studies showed inflammation of superior oblique tendon/ trochlear pulley.