THE TRIGEMINAL NERVE. 



1239 



through the spheno-maxillary fissure. Either branch may be absent or smaller than normal, the 

 other branch supplying the deficiency. The malar may be replaced in its distribution by the 

 infraorbital and the temporal may be substituted or augmented by the lachrymal. 



5. The middle superior dental nerve (r. alveolaris superior medius) leaves 

 the maxillary in the posterior part of the infraorbital canal. It occasionally arises 

 from the anterior superior dental. It passes down in a canal in the outer wall of the 

 maxillary antrum and after forming a plexus with the other two dental nerves supplies 

 the premolar teeth. 



6. The anterior superior dental nerve (r. alveolaris superior anterior) is the 

 largest of the three superior dental nerves. It arises from the maxillary just before 

 the exit of the latter at the infraorbital foramen and descends in a canal in the 

 anterior wall of the antrum. It gives off a nasal bt'anch, which enters the nose 



Fig. 1060. 



Middle superior dental nerve 



, Maxillary nerve 

 Posterior superior dental nerve 

 Buccal nerve 

 Sensory division of mandibular nervi 

 Middle meningeal artery 

 Auriculo-teiuporal nerve 



Ext. pterygfoid muscle- 

 Lingual nerve 

 Inferior dental nerve 



Superficial temporal artery 



Internal maxillary artery 

 Int. pterygoid muscle 

 Part of mandible- 



Ext. carotid artery 



Parotid gland^ — "^ 



Mylo-hyoid branch of inferior dental 

 Submaxillary ganglion 



Submaxillary gland 



Inferior palpebral 



Lateral nasal and 

 superior la'oiai 

 brandies of 

 infraorbital nerve 

 Anterior superior 

 dental nerv 



N'asal branch of 

 anterior superior 

 dental 



ental nerve 



Sectional surface of 

 mandible 



Digastric muscle, anterior 



belly 



Myo-hyloid muscle, cut to show 

 lingual nerve 



Dissection showing maxillary and mandibular nerves and their branches; outer wall of orbit, part of facial wall of 



maxillary sinus and part of mandible have been removed. 



through a tiny canal in the outer wall of the inferior meatus of the nose and 

 supplies the mucous membrane of the anterior part of the inferior nasal meatus and 

 floor of the nose. After helping to form the superior dental plexus, the anterior 

 superior dental supplies the canine and incisor teeth. 



Two thickenings are sometimes found in the superior dental plexus. One of these, known 

 as the ganglion of Valentin, lies above the tip of the root of the second premolar tooth, at the 

 junction of the middle and posterior superior dental nerves; and the other, sometimes called 

 the ganglion of Bochdalek, is situated more anteriorly, at the junction of the middle and 

 anterior dental nerves. Neither of these enlargements is a true ganglion, being without nerve- 

 cells and consisting of interlacing bundles of nerve-fibres. 



