A CASE OF CYCLOPIA 



205 



The sixth nerve comes to lie ventral to the oculomotor and in 

 the region of the central tendon turns laterad and passes to the 

 inferior surface of a muscular band which, from its nerve supply 

 and relations to the bulbus, represents the rectus lateralis muscle. 



Fig. 8 Diagram of structures exposed on removing the bony roof of orbit. 

 The metopic suture (M.S.) and an outline of the skull fossa are indicated, though 

 not in proportion to the dissection of the orbit. B.O., bulbus oculi; Md.V., 

 mandibular division of the fifth nerve; M.M., Miiller's muscle overlying the max- 

 illary division of the fifth nerve {Mx.V.); Oph.V., ophthalmic division of the 

 fifth nerve; P.F., squama frontalis; R.S., rectus superior muscle; T., central ten- 

 dinous mass; x., represents cut surface of bony ridge separating anterior and 

 middle skull fossae; ///, oculomotor nerve: VI., abducent nerve. 



Lateral to the nerves mentioned, the ophthalmic division of 

 the fifth nerve passes into the orbital fossa. Upon its dorso-medial 

 surface there lies a small nerve which has already been alluded 

 to as the possible representative of the trochlear. The relations 

 of this nerve could not be accurately followed after reaching the 

 region of the central tendon. Here it becomes lost in the median 

 mass of fibrous tissue. 



