April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Evidence for Compartmental Innervation of the Mammalian Superior Oblique (SO) Muscle By The Trochlear Nerve
Author Affiliations & Notes
  • Alan Le
    Ophthalmology, UCLA, los angeles, CA
  • Vadims Poukens
    Ophthalmology, UCLA, los angeles, CA
  • Joseph L Demer
    Ophthalmology, UCLA, los angeles, CA
  • Footnotes
    Commercial Relationships Alan Le, None; Vadims Poukens, None; Joseph Demer, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 2559. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Alan Le, Vadims Poukens, Joseph L Demer; Evidence for Compartmental Innervation of the Mammalian Superior Oblique (SO) Muscle By The Trochlear Nerve. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2559.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract
 
Purpose
 

Innervation of human, monkey, and non-primate mammalian horizontal rectus muscles is divided into superior and inferior zones innervating non-overlapping sets of muscle fibers. We sought evidence of anatomical potential for compartmental SO innervation in mammals.

 
Methods
 

Whole orbits were obtained from 4 humans: two adults, a 17 mos old toddler, and a 33 wk fetus; 2 rhesus monkeys; 1 rabbit, and 1 cow. Each orbit was formalin fixed , embedded in paraffin, coronally sectioned at 10 μm thickness, and stained with Masson trichrome. In digital micrographs, trochlear nerve (CN4) branches were traced in serial sections using Photoshop and reconstructed using ImageJ to create 3-D overlays of CN4 innervation and muscle fibers. Gross dissection of fresh bovine specimens was used to trace muscle fibers through the trochlear to the scleral insertion.

 
Results
 

In all four species, CN4 bifurccated prior to entering the SO muscle. In post-natal humans, CN4 arborized in non-overlapping superomedial and inferolateral muscle fibers zones. Fetal CN4 innervation showed more overlap with 4 major branches. Both monkey and the bovine orbits also displayed bifurcation of intramuscular CN4 with minimal overlap between resulting zones of innervated fibers. Gross dissection showed that the superior bovine SO compartment inserts posteriorly on the sclera for mainly vertical action, while the inferior portion inserts anteriorly for mainly torsional action. The rabbit SO had a double-headed origin unifying anteriorly but innervated by non-overlapping CN4 branches.

 
Conclusions
 

Compartmental innervation of the SO appears to be a general feature in mammals, perhaps refined during post-natal maturation in humans. Initial branching of CN4 external to the SO muscle would permit independent actions the two compartments, which at least in cow appears to be preferentially vertical vs. torsional. These neuroanatomical findings support MRI evidence of differential compartmental SO function in humans.

     
Keywords: 622 ocular motor control  
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×