1580 A MANUAL OF ANATOMY 



the inferior dental foramen ; (6) the long buccal nerve emerging between the 

 two heads of the external pterygoid, and giving upwards the anterior deep 

 temporal nerve ; and (7) the middle deep temporal nerve and the masseteric 

 nerve, emerging from beneath the upper border of the external pterygoid, 

 the latter parting with the posterior deep temporal nerve. 



The first and second parts of the internal maxillary artery are to be dis- 

 sected, as are also the pterygoid muscles. In dissecting the artery the internal 

 maxillary lymphatic glands are to be borne in mind. The first part of the 

 artery will be found to give off (i ) the deep auricular, (2) the tympanic, (3) the 

 middle meningeal, furnishing the small meningeal, and (4) the inferior dental, 

 giving off its mylo-hyoid branch. The second part gives off masseteric, deep 

 temporal (anterior and posterior), pterygoid, and buccal branches. The 

 posterior dental artery will be found coming off from the vessel as it is about 

 to enter the spheno-maxillary fossa. The third part of the artery must be 

 deferred to the time when the spheno-maxillary fossa is being dissected. 



The inferior dental (with its mylo-hyoid branch) and lingual nerves having 

 been dissected in situ, the inferior dental canal is to be laid open, and the 

 inferior dental nerve fully dissected to its distribution. In opening the canal 

 the saw, chisel and mallet, and bone-pliers are to be used. This dissection 

 will show the dissector how the pulps of the lower teeth are supplied with 

 nerves, and it will also make evident the origin of the mental nerve at the 

 level of the mental foramen. 



Before reflecting the external pterygoid muscle certain details may be 

 looked to in connection with the temporo-mandibular joint. A complete 

 dissection, however, of this articulation can only be made at the sacrifice of 

 other structures. The dissector is therefore recommended to perform this 

 dissection upon a specially reserved part. He should have little difficult}' in 

 studying the external lateral ligament and the capsule. The capsule is to be 

 opened and the interarticular fibro-cartilage noted. This will at once make 

 evident the existence of two synovial membranes, upper and lower. Beyond 

 this the dissector can hardly go, but he should read the description which is 

 given of this joint in the text. 



The mandibular condyle is now to be disarticulated and turned forwards, 

 along with the interarticular fibro-cartilage. In this manner the external 

 pterygoid muscle will be reflected ; but, in disarticulating the condyle, the 

 dissector should keep a sharp look-out for the auriculo-temporal nerve, which 

 is in intimate contact with the back of the temporo-mandibular joint. The 

 reflection of the external pterygoid muscle will enable the dissector to expose 

 the following structures : (i) the inferior maxillary division of the fifth cranial 

 nerve and its branches ; (2) the otic (Arnold's) ganglion ; (3) the chorda 

 tympani nerve, passing forwards and downwards, and applying itself to the 

 lingual nerve at an acute angle ; (4) the middle meningeal artery, parting, as 

 a rule, with the small meningeal ; and (5) the upper part of the spheno- 

 mandibular ligament. 



The middle meningeal artery will be found to pass, as a rule, between the 

 two roots of origin of the auriculo-temporal nerve. The foregoing structures 

 are to be dissected, as nearly as possible, in agreement with the description 

 which has been given of them in the text. Admittedly the dissector >vilJ 

 find the otic ganglion extremely difficult of dissection, but he should not 

 refrain from attempting it. The ganglion lies behind the undivided trunk of 

 the inferior maxillary nerve close to the foramen ovale, and the best plan 

 is to trace upwards the internal pterygoid nerve, with which the ganglion is 

 closely connected. 



The pterygo-mandibular ligament is to be examined, which separates the 

 buccinator and superior constrictor muscles, giving origin to fibres of both 

 muscles. 



Sublingual Region. — The structures in the submaxillary region have been 

 previously dissected, e.g., the mylo-hyoid muscle, the structures covered by 

 it, the genio-hyoid, and the hyo-glossus. This being so, the dissector is 

 advised to saw through the inferior maxilla, say between the lateral incisor 

 and canine alveoli. This should also be done on the other side by his partner. 



