THE FIFTH, TRIGEMINAL, OR TRIFAC1AL NERVE 987 



The Posterior Superior Dental Branches (rami alveolares superiores posteriores) 

 (Fig. 734) arise from the trunk of the nerve just as it is about to enter the infra- 

 orbital canal; they are generally two in number, but sometimes arise by a single 

 trunk, and immediately divide and pass downward on the tuberosity of the 

 maxilla. They give off several twigs to the gums and neighboring parts of the 

 mucous membrane of the cheek, superior gingival branches (rami gingivales 

 superiores). They then enter the posterior dental canals on the zygomatic surface 

 of the maxilla, and, passing from behind forward in the substance of the bone, 

 communicate with the middle dental nerve by a plexus formation, and give off 

 branches to the lining membrane of the antrum and three twigs to each molar 

 tooth. These twigs enter the foramina at the apices of the fangs and supply 

 the pulp. 



The Middle Superior Dental Branch (ramus alveolaris superior medius) is given 

 off from the superior maxillary nerve in the back part of the infraorbital canal, 

 and runs downward and forward in a special canal in the outer wall of the antrum 

 to supply the two bicuspid teeth. It communicates with the posterior and anterior 

 dental branches by a plexus formation (plexus dentalis superior). 



At its point of communication with the posterior branch, above the root of the second bicuspid 

 tooth, is a slight thickening which is the so-called ganglion of Valentin; and at its point of 

 communication with the anterior branch is a second enlargement, which is called the ganglion 

 of Bochdalek. Neither of these is a true ganglion. 



The Anterior Superior Dental Branch (ramus alveolaris superior anteriores), of 

 large size, is given off from. the superior maxillary nerve just before its exit from 

 the infraorbital foramen; it enters a special canal in the anterior wall of the antrum, 

 and divides into a series of branches which supply the incisor and canine teeth. 

 It communicates with the middle dental nerve by a plexus, and gives off a nasal 

 branch, which passes through a minute canal into the nasal fossa, and supplies 

 the mucous membranes of the fore part of the inferior meatus and the floor of the 

 cavity, Communicating with the nasal branches from the sphenopalatine ganglion. 



The Palpebral Branches (ram* palpebrales inferiores) pass upward beneath the 

 Orbicularis palpebrarum muscle. They supply the integument and conjunctiva 

 of the lower eyelid, joining at the outer angle of the orbit with the facial nerve 

 and the malar branch of the orbital. 



The Nasal Branches (rami nasales interni) pass inward; they supply the integu- 

 ment of the side of the nose and join with the nasal branch of the ophthalmic. 



The Labial Branches (rami labiales superiores), the largest and most numerous, 

 descend beneath the Leva tor labii superioris muscle, and are distributed to the 

 integument of the upper lip, the mucous membrane of the mouth, and the labial 

 glands. 



$.11 these branches are joined, immediately beneath the orbit, by filaments 

 from the facial nerve, forming an intricate plexus, the infraorbital plexus. 



The Sphenopalatine or Meckel's Ganglion (ganglion sphenopalatinum) (Fig. 

 735), the largest of the ganglia associated with the branches of the trigeminal 

 nerve, is deeply-placed in the sphenomaxillary fossa, close to the sphenopalatine 

 foramen. It is triangular or heart-shaped, of a reddish-gray color, and is situated 

 just below the superior maxillary nerve as it crosses the fossa. 



Branches of Communication. Like the other ganglia of the trigeminal nerve, it 

 possesses a motor, a sensor, and a sympathetic root. Its sensor root is derived 

 from the superior maxillary nerve through its two sphenopalatine branches 

 (p. 986). These branches of the nerve, given off in the sphenomaxillary fossa, 

 descend to the ganglion. Their fibres, for the most part, pass in front of the 

 ganglion, as they proceed to their destination, in the palate and nasal fossa, and 

 are not incorporated in the ganglionic mass; some few of the fibres, however, 



