398 CLINICAL APPLIED ANATOMY. 



in the parotid, entering the gland soon after its exit from the 

 stylo-mastoid foramen, is the facial nerve, which traverses the 

 parotid in a direction towards its anterior margin becoming 

 more and more superficial. It is this structure which is most com- 

 monly divided, resulting in partial, or possibly total, temporary 

 or permanent paralysis. In the uppermost part of the gland is 

 found the auriculo-temporal nerve, and incisions in this region 

 may damage it. 



A wound of the gland substance, but more especially of its 

 duct, is prone to be followed by a salivary fistula. Stenson's duct 

 emerges from the anterior border of the gland and runs across 

 the cheek, inclining slightly downwards. The middle third of a 

 line drawn from a point half-way between the bottom of the 

 concha and the lobule of the ear, to a point half-way between the 

 ala of the nose and the red margin of the upper lip, represents 

 very accurately the course of the duct. It is well to remember 

 that it first lies on the masseter, and at the anterior margin of 

 the muscle it makes a sharp bend inwards, perforates the 

 buccinator and opens on the mucous membrane of the cheek, 

 opposite to the second upper molar tooth, having a length in 

 the adult of about two inches. Thus any attempt to pass a probe 

 from the mucous opening should be preceded by eversion of the 

 cheek to straighten the duct. An incised wound across the line 

 of the duct may sever it, and thus establish a salivary fistula. 



Parotitis. The parotid gland is invested by a complete 

 capsule of deep cervical fascia, and is divided into lobes by 

 processes of the fascia passing into its interior. It is thus that 

 inflammatory products formed within are tightly bound down and 

 cause considerable suffering to the patient. The swelling of the 

 gland interferes with the proper movements of the mandible, and 

 the motion of this bone induces great pain by the pressure of the 

 condyle upon the inflamed gland tissue. Seeing that there is 

 very little tissue intervening between the parotid and the internal 

 jugular vein behind, it is possible that any cerebral symptoms 

 in the course of mumps may be due to cerebral hyperaemia 

 caused by pressure. 



