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1. Trochlear nerve

  1. Is the smallest cranial nerve in terms of the number of axons it contains. (T/F?)
  2. Has the shortest  intracranial length. (T/F?)
  3. Is the one of two cranial nerves that exit from the dorsal (rear) aspect of the brainstem. (T/F?)
  4. Innervates superior oblique muscle, on the opposite side (contralateral) from its origin. (T/F?)
  5. Emerges from the dorsal aspect of the brainstem at the level of the caudal mesencephalon, just below the inferior colliculus, (T/F?)
  6. Enters the orbit through the superior orbital fissure. (T/F?)

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  2. F
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  1. It is the smallest  in terms of the number of axons it contains.  The shortest is the olfactory nerve.
  2. Trochlear nerve has the longest intracranial length.
  3. Trochlear nerve is the only cranial nerve that exits from the dorsal aspect of the brainstem.

    Henry Vandyke Carter [Public domain], via Wikimedia Commons
  4. It is the only cranial nerve with contralateral innervation. It decussates within the mesencephalon before emerging on the opposite side of the brainstem. An injury to the trochlear nucleus in the brainstem will result in an contralateral superior oblique muscle palsy, whereas an injury to the trochlear nerve (after it has emerged from the brainstem) results in an ipsilateral superior oblique muscle palsy.