MASDIBULAR DIVISIOX OF THE FIFTH NERVE 7oO 



maxillary _irlan(l and. after su))iilying the iniisc-lc with several twigs, it pierces the 

 anterior helly of the digastric, in the sul)stanee of wliieh it ends. 



(b) The alveolar branches are a series of twigs which are given off within the 

 mandihular canal to sui)]>ly the molar and bicuspid teeth. They connnunicate with 

 one another within the bone, forming a fine plexus. From this plexus twigs are 

 given off corresponding in numl)er to the fangs of the teeth; they enter the minute 

 apert\n-es at the ti]is of the fangs and end in the })ulp. Twigs are also given to the 

 adjacent part of the gums (nervi gingivales). 



(c) The incisive branch, the smaller of the two terminal divisions, is continued 

 forwards and inwards in tlie dental canal, and sup])lies the canine and incisor teeth 

 and the corresponding region of the gums. 



((/) The mental branch is a nerve of considerable size which emerges through 

 the mental foramen. It communicates, near its exit, with the supramandilndar 

 branch of the facial nerve, and then divides into three branches. The smallest 

 branch turns downwards to supply the chin. The other two pass upwards, diverg- 

 ing as they ascend, and divide into a number of twigs. The stoutest twigs ramify 

 upon the mucous membrane which lines the lower lip. Other twigs are distributed 

 to the integument and fascia of the li]i and chin. 



(8) Tlie lingual (formerly called gustatory) nerve is slightly smaller than the 

 mandibular nerve, and is placed at first in front of and close to the inner side of 

 the latter under cover of the external i)terygoid muscle. In this situation it is 

 joined by the chorda tympani nerve; the latter enters the lingual on its outer side, 

 the two nerves uniting at an acute angle. The lingual then escai^es from under 

 cover of the external pterygoid muscle, and is connected to the mandibular nerve 

 by a transverse communicating branch. It then passes between the ramus of the 

 mandible and the internal pterygoid muscle, and is continued forwards l)etween the 

 nuicous membrane of the mouth and the mylo-hyoid muscle, and lies on the origin 

 of this nuiscle close to the bone. In this )>art of its course it can be easily divided 

 by an incision through the mucous membrane at the level of the second lower 

 molar tooth. It then runs between the mylo-hyoid and hyo-glossus muscles, 

 crosses below Wharton's duet, and finally courses forwards by the side of the 

 tongue, so as to reach the tip of that organ. As it crosses the hyo-glossus muscle 

 it fonns a curve with the convexit}' directed downwards, and is connected at the 

 most dependent part of the curve to the submandibular (submaxillary) ganglion, to 

 which it furnishes sensory roots. Immediately l)eyond the ganglion it communi- 

 cates freely with the hypoglossal nerve, the communications forming several loops. 



Branches. — (a) Connnunicating branches are given to the mandiltular nerve, 

 to the submaxillary ganglion, and to the hypoglos.'^al nerve. These have already 

 been described. 



(b) Twigs are distributed to the interval between the tongue and gums, and 

 ramify in the mucous membrane of the floor of the mouth. 



(c) A twig enters the sublingual gland. This twig conveys secreto-motor fibres 

 from the chorda tympani to the gland. 



(d ) The lingual V)ranches are a series of twigs Avhich are given off by the lingual 

 nerve in the last stage of its course as it i« ])assing forwards towards the tip of the 

 tongue. They pierce the musculature at the side of the tongue, and jiroceed to the 

 dorsum of the nn'ddle and anterior ]>art of that organ. Avhere they end in the filifonn 

 and fungiform paiiilbe. 



SlBMANTHBlLAR (PuBMAXILLARV) GaNOLIOX 



The submandibular ganglion is a small reddish fusiform body which is placed 

 between the mylo-hyoid and hyo-glossus muscles above Wharton's duct. It is 

 connected with the lingual nerve by two communications, an anterior and a posterior. 

 The posterior communication contains the motor and sens(»rv roots of the ganglion. 

 The anterior communication represents a branch ]»assing from the ganglion to the 

 lingual nerve. The motor root is derived from the dutrda tympani. The ser.sorv 

 root is furnished by the lingual. The ganglion also receives a sympathetic root 

 from the ]>lexus of the sympathetic which accompanies the facial artery. 



Branches. — The ganglion furnishes live (jr six twigs to the submandibular 



