Free Trial

Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.


  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint
Share this Page URL
Help

10. Ocular Reflexes > 10-2. The Vestibuloocular Reflex (VOR)

10-2. The Vestibuloocular Reflex (VOR)

The VOR is mediated by a tri-neuronal arc consisting of vestibular afferents, VOR relay neurons, and motoneurons supplying extraocular muscles. To control eye movement and eye position in three-dimensional space, the input VOR afferents are those that originate in the three semicircular canals (horizontal, anterior, posterior) and the two otolith organs (utricle, saccule) in each labyrinth (Uchino et al., 1996; Isu et al., 2000). The output of VOR motoneurons acts on six extraocular muscles (medial/lateral rectus, superior/inferior rectus, superior/inferior oblique) for each eye (Figure 27). Under experimental conditions, yaw, pitch, and roll of the head induce, respectively, the horizontal, vertical, and rotatory components of the VOR. Utriculo- and sacculo-ocular reflexes are evoked by linear motion and static tilt of the head. Under freely moving conditions, the VOR is mediated by the concerted operation of the parallel pathways that link the ten sensors in two labyrinths to the twelve muscles in the two eyes (Ezure and Graf, 1984b).


  

You are currently reading a PREVIEW of this book.

                                                                                                                    

Get instant access to over $1 million worth of books and videos.

  

Start a Free Trial


  
  • Safari Books Online
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint