Trochlear nerve (Cranial Nerve IV)

[J. A. Kiernan]

In article <31FB0873.21F4 at clubi.ie> Trial Account <ph606267 at clubi.ie> writes:

>The trochlear nerve is the only cranial nerve to decussate in the brain-
>stem and emerge from its dorsal aspect.

  This isn't quite true. The innervation of the superior rectus muscle
  comes from the contralateral oculomotor nucleus, with the axons
  decussating before they enter the III nerve. The levator palpebrae
  superioris muscle is said to receive both ipsi- and contralaterally
  derived innervation. See A. Brodal's "Neurological Anatomy" for
  thorough discussion.
                                     John A. Kiernan
                                     Department of Anatomy
                                     Univ. of Western Ontario
                                     LONDON, Canada  N6A 5C1
                                     e-mail: kiernan at uwo.ca