PAROTID GLAND 261 



the sterno-mastoid muscle. Above, it touches the posterior 

 part of the lower border of the zygoma and the lower surface 

 of the 'external meatus. 



From beneath the part in contact with the zygoma emerge 

 the auriculo-temporal nerve, the temporal branches of the 

 facial nerve, and the superficial temporal artery, on their way to 

 the scalp ; and the posterior facial vein disappears under cover 

 of it. Its lower extremity, which is wedged between the angle 

 of the mandible and the anterior border of the sterno-mastoid, 

 is usually in contact with one of the upper deep cervical 

 glands, whilst the posterior facial vein, the commencement of 

 the external jugular vein, and the cervical branch of the facial 

 nerve emerge from it ; the former passing downwards and 

 posteriorly, and the two latter downwards and anteriorly. 



From beneath the anterior border, which rests upon the 

 masseter, the duct of the gland (Stensen's), the transverse 

 facial artery, and the zygomatic, buccal, and mandibular 

 branches of the facial nerve pass forwards ; and the transverse 

 facial vein disappears under cover of it. 



The duct of the parotid gland (Stensen's), after appearing 

 from under cover of the anterior border of the gland, runs 

 anteriorly across the masseter, at the level of a line drawn 

 from the lobule of the auricle to a point situated midway 

 between the red margin of the upper lip and the ala of 

 the nose. At the anterior border of the masseter it turns 

 inwards, at right angles to its former course, and after piercing 

 the sucking pad of fat, the buccinator fascia, the buccinator 

 muscle and the mucous membrane of the vestibule of the 

 mouth, it opens into the vestibule, on the apex of a papilla, 

 opposite the second molar tooth of the maxilla. 



Immediately anterior to the anterior border of the gland, 

 below the zygoma and above the duct, lies a small separated 

 portion of the gland substance called the accessory parotid its 

 duct opens into the main duct. 



Dissection. The gland must be removed piecemeal as the structures 

 which pass through it are^issected out. The facial nerve and its branches 

 are the most superficial structures in the substance of the parotid ; therefore 

 they must be dissected first. Trace the terminal branches posteriorly into 

 the gland until they join the main divisions, which are the upper or temporo- 

 facial and the lower or cervico-facial. The temporal and zygomatic branches 

 spring from the temporo-facial division, the buccal, mandibular, and cervical 

 from the cervico-facial division. Follow the divisions posteriorly across 

 the posterior facial vein to their union with the trunk of the nerve, which 

 pierces the postero-medial surface of the gland ; then trace the trunk across 

 1117 b 



