THE HEAD AND NECK 1173 



The posterior auricular nerve arises from the facial close to 

 the stylo-mastoid foramen. It ascends between the auricle and 

 the mastoid process, where it lies deeply, and divides into two 

 branches, auricular and occipital. The auricular branch passes 

 upwards behind the auricle and beneath the retrahens auriculam, 

 to be distributed to that muscle, and it may be to the attollens 

 auriculam, as well as to the small intrinsic muscles on the inner 

 aspect of the auricle. The occipital branch passes backwards to 

 supply the occipitalis muscle. The posterior -auricular nerve com- 

 municates with the great auricular, the small occipital, and the 

 auricular branch (Arnold's nerve) of the pneumogastric. 



The digastric nerve is directed downwards, and breaks up into 

 branches which enter the posterior belly of the digastric muscle. 

 One of the digastric branches communicates with the glosso-pharyn- 

 geal nerve. 



The stylo-hyoid nerve usually arises in common with the preceding. 

 It is of some length, and, passing forwards, it enters the stylo-hyoid 

 muscle about its centre. 



The terminal divisions, as stated, are called temporo-facial and 

 cervico-facial. Both divisions continue to pass forwards in the 

 parotid gland, crossing superficially the temporo-maxillary vein 

 and the external carotid artery, the direction of these vessels being 

 vertical. In this part of their course these divisions receive the 

 following branches ; the temporo-facial division receives two 

 branches from the auriculo- temporal nerve, and the cervdco- facial 

 division receives branches from the great auricular nerve. The 

 temporo-facial division, which is the larger of the two, traverses the 

 upper part of the parotid gland, and the cervico-facial division 

 passes through the gland in a forward and downward direction. 

 Each division breaks up, within the gland, into three branches, 

 and, as these pass in various directions over the face and upper 

 portion of the neck, they ramify freely. The branches frequently 

 communicate with each other in a plexiform manner, both in the 

 parotid gland and on the face, the plexus thus formed being known 

 as the pes anserinus or goose's foot. The ramifications also com- 

 municate with the branches of the three divisions of the fifth nerve 

 which appear on the face, these being sensory nerves. 



The temporo-facial division furnishes three sets of branches, 

 namely, temporal, malar, and infra-orbital. The temporal branches 

 ascend over the zygomatic arch to the temporal region, and are 

 distributed to the following muscles : the attrahens and attollens 

 auriculam, the intrinsic muscles on the outer surface of the auricle, 

 the frontalis, the upper part of the orbicularis palpebrarum, and 

 the corrugator supercilii. The temporal branches communicate with 

 the supra-orbital and lachrymal branches of the ophthalmic, the 

 temporal branch of the orbital from the superior maxillary, and the 

 auriculo-temporal of the inferior maxiUary, all of these being sensory 

 nerves. 



The malar branches pass forwards over the malar bone towards 



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