The Collaborative International Dictionary of English v.0.48:

Orbitosphenoid \Or`bi*to*sphe"noid\, a. [Orbit + sphenoid.]
   (Anat.)
   Of or pertaining to the sphenoid bone and the orbit, or to
   the orbitosphenoid bone. -- n. The orbitosphenoid bone, which
   is situated in the orbit on either side of the presphenoid.
   It generally forms a part of the sphenoid in the adult.
   [1913 Webster]