Trochlear nerve all true except-

Ans is 'c' i.e. Supplies ipsilateral superior oblique muscle Trochlear nerve is a crossed cranial nerve. The nucleus of the trochlear nerve supplies the contralateral superior oblique muscle. The trochlear nerve has certain unique features: It is the only cranial nerve whose fibers originate totally from the contralateral nucleus. It is the only cranial nerve to emerge from the dorsal surface of the brain stem. It is the smallest (thinnest) of the cranial nerves, (largest is trigeminal) It has the longest intracranial course and is thus highly susceptible to increased intracranial pressure, (shortest cranial nerve is olfactory) It supplies only one muscle- i.e. superior oblique (Abducent cranial nerve also supplies only one muscle i.e. Lateral rectus) Course: As the trochlear nerve emerges from the brainstem, it curves around the cerebral peduncle and proceeds anteriorly within the lateral wall of cavernous sinus to pass into the orbit via the lateral part of superior orbital fissure. Structures passing through the Superior orbital fissure Lateral part (lateral to the annulus of Zinn ) Middle part Medial part Lacrimal nerve Frontal nerve Trochlear nerve Superior ophthalmic vein Recurrent meningeal branch of Lacrimal artery Anastomotic branch of the middle meningeal artery {which anastomoses with the recurrent branch of the lacrimal artery) Oculomotor nerve (both upper and lower divisions) Nasociliary nerve (lies in between the two divisions of the oculomotor nerve) Abducent nerve Inferior ophthalmic vein Sympathetic nerves from the plexus around the internal carotid artery Structures passing through superior orbital fissure Also know Inferior orbital fissure transmits Zygomatic branch of maxillary nerve Rami of pterygopalatine ganglion Infraorbital nerve Infraorbital vessels Communicating vein b/w inferior phthalic vein & pterygoid plexus of veins