Editing Trochlear nerve (section)

=== Course ===
{{See also|Trochlear nucleus}}[[Image:Gray571.png|thumb|left|The Cavernous Sinus]]

Each trochlear nerve originates from a [[trochlear nucleus]] in the medial [[midbrain]]. From their respective nuclei, the two trochlear nerves then travel dorsal-ward through the substance of the midbrain surrounded by the [[periaqueductal gray]], [[Decussation|crossing over (decussating)]] within the midbrain before emerging from the dorsal midbrain<ref name=":0">{{Citation |last=Kim |first=Seung Y. |title=Neuroanatomy, Cranial Nerve 4 (Trochlear) |date=2022 |url=http://www.ncbi.nlm.nih.gov/books/NBK537244/ |work=StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30725929 |access-date=2023-01-03 |last2=Motlagh |first2=Mahsaw |last3=Naqvi |first3=Imama A.}}</ref><ref name=":2">{{Cite book |last=Patestas |first=Maria A. |title=A Textbook of Neuroanatomy |last2=Gartner |first2=Leslie P. |date= |publisher=Wiley-Blackwell |year=2016 |isbn=978-1-118-67746-9 |edition=2nd |location=Hoboken, New Jersey |pages=90}}</ref> just inferior to the [[inferior colliculus]].<ref name=":2" /> Each trochlear nerve thus comes to course on the contralateral side, first passing laterally (to the side) and then anteriorly around the [[pons]],<ref name=":0" /> then running forward toward the eye in the [[subarachnoid space]]. It passes between the [[posterior cerebral artery]] and the [[superior cerebellar artery]]. It then pierces the [[Dura mater|dura]] just under free margin of the [[tentorium cerebelli]], close to the crossing of the attached margin of the tentorium and within millimeters of the [[posterior clinoid process]].<ref name=":1">Bisaria KK.  "Cavernous portion of the trochlear nerve with special reference to its site of entrance".  ''J. Anat.'' 159:29–35, 1988</ref> It runs on the outer wall of the [[cavernous sinus]].<ref name=Grays2016/> Finally, it enters the orbit through the [[superior orbital fissure]] and to innervate the [[superior oblique muscle]].<ref name=Grays2016/>