The =pterygoid bones= (Ossa pterygoidea) are narrow, thin, bent plates,
situated on either side of the posterior nares. Each has two surfaces
and two extremities. The =internal surface= is smooth, and forms part of
the boundary of the posterior nares. The =external surface= articulates
with the palatine, vomer, and sphenoid, concurring with the last in the
formation of the =pterygoid= or =Vidian canal=. The =anterior extremity=
is free, turned slightly outward, and forms the =hamulus=, a pulley
around which the tendon of the tensor palati muscle is reflected.
=Development.=—The pterygoid ossifies in membrane from a single center.