1248 HUMAN ANATOMY. 



the lingual nerve and, after accompanying it for a short distance, are distributed to 

 the sublingual gland. The sensory fibres, processes of the Gasserian neurones, tra- 

 verse the submaxillary ganglion without interruption ; the secretory fibres from the 

 facial end, at least in part, around the stellate sympathetic neurones of the ganglion, 

 from which cells axones pass to the alveoli of the submaxillary and sublingual 

 glands ; while other sympathetic filaments proceed, as the axones of stellate cells 

 either within the submaxillary or a more remote sympathetic ganglion, to supply the 

 glandular tissue and ducts, as well as to accompany the peripheral .branches of the 

 lingual nerve. 



Practical Considerations. — ^The fifth cranial nerve is the sensory nerve of 

 the face and the motor nerve to the muscles of mastication. It is more frequently 

 the seat of excessively painful neuralgia than any other nerve in the body. Extra- 

 cranial lesions are much more commonly the cause of such neuralgia than intracra- 

 nial. The neuralgia is rarely bilateral, and usually does not involve all three divisions 

 of the nerve. It rather attacks one or two divisions, or only a branch of one, the 

 first and second divisions being most frequently involved. Certain tender regions can 

 almost always be found, as over the points of emergence of the nerve on the face, at 

 the supraorbital, infraorbital and mental foramina, where in an interval from pain 

 pressure may produce a paroxysm. 



The supraorbital notch or foramen can usually be felt at the junction of the inner 

 and middle thirds of the supraorbital margin. The mental foramen is in the lower 

 jaw, below and between the two bicuspid teeth, while the infraorbital foramen lies 

 just below the lower margin of the orbit in a straight line between the supraorbital 

 and mental foramina. 



When the first division is the seat of neuralgia, the disease is almost always con- 

 fined to the supraorbital branch. Excision of this branch will usually give relief for 

 about two years, sometimes permanently. The same may be said of the infraorbital 

 nerve when the disease is confined to the second division. The infraorbital may be 

 excised at tlje foramen, through the mucous membrane of the mouth or by an in- 

 cision in the skin along the lower margin of the orbit. Through the latter the orbital 

 tissues may be raised and the nerve reached farther back in its canal, which in its 

 anterior part has a thin bony covering. By going through the antrum of Highmore 

 from the cheek, just below the infraorbital foramen, the second division, with 

 Meckel's ganglion attached to it may be excised at its emergence from the skull. 

 The anterior wall of the antrum is opened by a trephine or chisel and the floor of 

 the infraorbital canal in the roof of the antrum is gouged away so that the nerve is ex- 

 posed and followed to the posterior wall of the antrum. This wall is then opened, 

 the spheno-maxillary fossa exposed and the nerve is divided at the foramen 

 rotundum and removed with the ganglion. The bleeding will be severe, since 

 large and numerous branches of the internal maxillary artery surround the ganglion 

 and are divided. 



When the neuralgia is confined to the inferior dental nerve the mental branch 

 may be excised at its foramen through the mucous membrane of the mouth. The 

 inferior dental itself is more frequently attacked through a trephine opening in the 

 ascending ramus of the lower jaw. It may with greater difficulty be reached through 

 the mouth, the incision being made along the anterior margin of the descending 

 ramus, and the soft tissues separated from the inner surface of the ramus until the 

 dental spine marking the dental foramen is exposed; the inferior dental nerve and 

 artery will be found entering the canal. The nerve may then be exposed and ex- 

 cised with due regard for the accompanying vessels and the internal maxillary artery, 

 from which the inferior dental branch has just been given of?. 



The buccal nerve is sometimes the seat of neuralgia, and may be I'eached by an 

 incision through the cheek in front of the coronoid process and the insertion of the 

 tendon of the temporal muscle. The nerve can be reached from the mouth in the 

 same situation. 



When the peripheral operations for trigeminal neuralgia (tic douloureux) have 

 failed to effect a cure, or when the neuralgia piimarily shifts from one branch to an- 

 other, indicating an extensive central involvement, the Gasserian ganglion must be 



