BKANCHES OF THE OTIC GANGLION. 681 



using much care in removing the latter. When some loose areolar 

 tissue has been cleared away, the internal pterygoid muscle (b) 

 comes into view, with the trunk ot the inferior maxillary nerve 

 above it ; and a branch descending from that nerve to the internal 

 pterygoid muscle. If the nerve to the pterygoid be taken as a 

 guide, it will lead to the ganglion. 



To complete the dissection, saw vertically through the petrous to define 

 part of the temporal bone near the inner wall of the tympanum, the fncnts" 

 bone being supported while it is divided. Taking off some mem- branches, 

 brane which covers the ganglion, the student may follow backwards 

 a small branch to the tensor tympani muscle ; but he should open 

 the small tube that contains the muscle, by entering it below 

 through the carotid canal. Above this small branch there is 

 another minute nerve (small superficial petrosal), which issues 

 from the skull, and joins the back of the ganglion. A small twig 

 is to be sought from the front of the ganglion to the tensor palati 

 muscle ; and other minute filaments to join the sympathetic nerve 

 on the large meningeal artery and the chorda tympani. 



The OTIC GANGLION (Arnold's ganglion ; fig. 241) is a small reddish otic gan- 

 glion is on 

 body, which is situate on the inner surface of the inferior maxillary inner side of 



nerve close to the skull, and surrounds the origin of the nerve to 



the internal pterygoid muscle. By its inner surface the ganglion is nerve. 



in contact with the Eustachian tube, and at a little distance behind 



lies the large middle meningeal artery. In this ganglion, as in the structure. 



others connected with the fifth nerve, filaments from motor, sensory, 



and sympathetic nerves are blended. Some twigs are furnished by 



it to muscles. 



Connecting branches roote. Through its connection with the Branches 



, . . , , . ,. PI r join it with 



nerve to the internal pterygoid, the otic ganglion receives fibres from fifth, 

 both the small and large roots of the inferior maxillary- nerve, so 

 that it may be said to derive its motor and sensory roots from the 

 fifth. Its sympathetic root comes from the plexus on the middle * n 'P a ' 

 meningeal artery. The ganglion is farther joined behind by the 

 small superficial petrosal nerve ( 2 ), through which fibres are conveyed seventh, 

 to it from the facial and glosso-pharyngeal nerves. One or two ninth, 

 short branches pass between the ganglion and the beginning of the auricuio- 

 auriculo-temporal nerve ; and a filament descends to the chorda and chorda 

 tympani. tympani - 



Branches to muscles. Two muscles receive their nerves through Branches to 

 the otic ganglion, viz., tensor tympani and tensor palati. The nerve tensor 

 to the tensor tympani ( 3 ) is directed backwards to gain the bony JS^m^ 

 canal lodging the muscle. The branch for the tensor palati ( 6 ) arises palati. 

 from the front of the ganglion, and enters the outer surface of its 

 muscle. The fibres of these branches are derived mainly from the 

 internal pterygoid nerve. 



The nerve of the internal pterygoid muscle ( 5 ) arises from the inner 1 ^ n e ia 1 f 

 side of the inferior maxillary nerve near the skull, and penetrates pterygoid. 

 the deep surface of the muscle. This nerve is formed almost entirely 

 by an offset from the motor root of the fifth. 



