Physiology
1. Innervates extraocular muscle: superior oblique muscle
2. Superior oblique muscle passes via pulley (trochlea)
Course
1. Trochlear nucleus at floor of cerebral aqueduct
2. Tracks around superior cerebellar, cerebral peduncles
3. Enters tentorium cerebelli at posterior clinoid process
4. Proceeds through lateral wall of Cavernous Sinus
5. Enters orbit via superior orbital fissure
Exam
1. Normal:
  1. Eye movement inferior laterally
2. Paralysis:
  1. Head Tilt toward the contralateral shoulder
  2. Affected eye slightly elevated in primary position
  3. Can only depress affected eye slightly

Trochlear nerve structure (C0041159)
Definition (MSH)	The 4th cranial nerve. The trochlear nerve carries the motor innervation of the superior oblique muscles of the eye.
Concepts	Body Part, Organ, or Organ Component (T023)
MSH	D014321
English	cranial nerve IV, Fourth Cranial Nerve, Fourth Cranial Nerves, pathetic nerve, Superior oblique nerve, Trochlear Nerve, Trochlear nerve structure, Trochlear nerve tree, Trochlear Nerves
Spanish	cuarto nervio craneal, cuarto par craneal, cuarto par craneano, estructura del nervio patetico, IV par craneal, nervio craneal IV, nervio oblicuo superior, nervio patetico, nervio troclear
Parent Concepts	Cranial Nerves (C0010268), Oculomotor system structure (C1298729), Peripheral Nervous System (C0206417)
Sources	AOD , MSH, MTH, NCI, SCTSPA, SNOMEDCT, UWDA Derived from the NIH UMLS (Unified Medical Language System)

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This page was written by Scott Moses, MD, last revised on 10/7/2011 and last published on 12/30/2011.

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Cranial Nerve 4