362 Jacob Parsons Schaeffer. 
the maxillary nerve, in most of my cases were found to pass 
inferiorly and ventrally upon the infratemporal surface of the 
maxilla, through the alveolar foramina into the alveolar canals. 
They thus aided in the formation of the superior dental plexus of 
nerves. Occasionally some of the branches of these nerves 
instead of taking the above course, passed entirely through the 
infratemporal surface of the maxilla into the sinus maxillaris. 
They then passed under cover of the mucous membrane of the 
sinus inferiorly and ventrally to the sinus floor; thence to the 
superior dental plexus. 
Fia. 31 (X .633). Drawing from a disS8ection showing the anterior superior 
alveolar nerve (N.A.S.A.) passing diagonally from the roof or orbital wall of the 
sinus to the ventral or facial wall. The nerve in this position is suspended freely 
in the cavity of the sinus maxillaris merely covered with mucous membrane. 
N.A.S.A. = nervus alveolaris superior anterior; N. Info., = nervus infraor- 
bitalis; S. Max., = sinus maxillaris. 
The middle superior alveolar (dental) nerve, a branch of the 
infraorbital nerve, was as a rule given off in the proximal part of 
the infraorbital canal. It passed inferiorly and ventrally in a 
canal in the lateral wall of the sinus maxillaris and aided in 
establishing the superior dental plexus of nerves. The nerve I 
found in one case to arise from one of the anterior superior 
alveolar nerves. It also rarely passed under cover of the mucous 
membrane of the sinus to the superior dental plexus. 
