938 



THE NERVOUS SYSTEM 



The spheno -palatine nerve has two or three branches which descend in the pterygo- 

 palatine fossa and give a small part of their fibres to the spheno-palatine (Meckel's) gangUon 

 (fig. 735), the larger part of their fibres passing through the ganghon into its orbital, nasal, 

 and palatine branches. (See Spheno-palatine Ganglion, p. 962.) 



The zygomatic (orbital or temporo-malar) branch, given off from the upper surface of the 

 maxillary nerve, passes forward and lateralward, and, at the end of the inferior orbital (spheno- 

 maxillary) fissure, passes through it into the orbit and divides into two branches, facial and 

 temporal. 



;The zygomatico -facial (malar) branch runs forward, passes through a zygomatico-orbital 

 foramen, then through the zygomatico-facial (malar) foramen, pierces the orbicularis palpe- 

 brarum, communicates with the zygomatic (malar) branch of the facial nerve, and supplies 

 the skin of the prominence of the cheek. The zygomatico-temporal (temporal) branch runs 

 upward in a groove in the lateral wall of the orbit, passes through a zygomatico-orbital foramen, 

 then through the zygomatico-temporal (spheno-malar) foramen, and enters the temporal fossa. 

 It turns around the anterior border of the temporal muscle, pierces the deep layer of the temporal 

 fascia, and runs backward for a short distance in the fat between the superficial and deep lam- 

 ellae, then, turning lateralward, it pierces the superficial lamellae about an inch above the zygoma, 

 anastomoses with the temporal branch of the facial nerve, and supphes the skin of the anterior 

 part of the temporal region. 



The infra-orbital nerve, that part of the maxillary nerve lying distal to the spheno- 

 palatine gangUon, enters the orbit through the inferior orbital (spheno-maxillary) fissure, 

 accompanied bj^ the infra-orbital artery, and with it passes through the infra-orbital canal 

 (fig. 735) to the face, where it divides into four sets of terminal branches, some of which, by 

 anastomoses with the branches of the facial nerve, form the infra-orbital plexus. 



Three sets of superior alveolar nerves arise from the maxillary and the infra-orbital nerves, 

 namely, the posterior superior alveolar branches, the middle superior alveolar branch, and the 

 anterior superior alveolar branches. 



Fig. 735. — Lateral View of the Maxillary Nerve. 



Mandibular 



Ophthalmic Maxillary 



Zygomatic 



Vidian nerve 

 Spheno-palatine ganglion 



Spheno-palatine nerves 



Posterior inferior nasal 

 Posterior superior alveolar branches 



^Infraorbital 



Anterior 



superior 

 alveolar 

 branches 



Superior dental 

 plexus 



Superior dental 

 branches 



■~^^ Superior 

 gingival 

 branches 



Middle superior alveolar branch 



The posterior superior alveolar (dental) nerves are usually two in number, but sometimes 

 arise by a single trunk. They pass downward and lateralward through the pterygo-maxillary 

 fissure into the zygomatic fossa, where they give branches to the mucous membrane of the gums 

 and the posterior part of the mouth; then they enter the posterior alveolar (dental) canals and 

 unite with the other alveolar branches to form the superior dental plexus, through which they 

 give branches to the roots and pulp cavities of the molar teeth and to the mucous membrane 

 of the maxillary sinus (fig. 735). 



(c) The branches given off in the infra-orbital sulcus and canal are the middle 

 and anterior superior alveolar (dental) nerves. 



(i) The middle superior alveolar (dental) nerve loaves the infra-orbital nerve in the pos- 

 terior part of the infra-orbital sulcus, and, passing downward and forward in a canal in the max- 

 illa, it divides into terminal brandies th.'it anastomose with the other alveolar branches to form 

 the superior dental jdexus. Through the i)lcxus it supplies the bicuspid tooth and gives branches 

 to the mucous membrane of the maxillary sinus and also to the gums (fig. 735). 



