FACE AND FRONTAL REGION OF HEAD 127 



lower and anterior angle of the masseter as they cross the lower border of 

 the mandible. Clean them at this point, but do not trace them towards 

 their terminations at present. 



At the posterior border of the mandible note the fascia over the super- 

 ficial surface of the parotid gland. It ascends from the fascia of the neck, 

 and is attached above to the zygomatic arch. Note also that at the anterior 

 border of the parotid this fascia blends with the fascia on the superficial 

 surface of the masseter muscle. Cut through the fascia covering the 

 parotid gland immediately anterior to the ear, extending the incision from 

 the zygoma above to the angle of the mandible below ; then raise the 

 fascia from the gland, dissecting carefully anteriorly, upwards, and down- 

 wards. As the extremities and the anterior border of the gland are 

 approached, look carefully for nerves and vessels which emerge from 

 beneath them, and also for the duct of the gland, which appears from 

 under cover of the anterior border about a finger's breadth below the 

 zygoma. The duct has thick walls, is of considerable size, and is easily re- 

 cognised. It runs anteriorly across the masseter and turns round the anterior 

 border of the muscle, bending at right angles to its original course. It 

 pierces, in turn, the fascia covering the buccinator muscle, the buccinator 

 muscle itself and the mucous membrane of the mouth ; and it opens into 

 the vestibule of the mouth, on a small papilla opposite the second molar 

 tooth of the maxilla. Above the duct and below the zygomatic arch find 

 (i) the accessory parotid, a small detached part of the parotid which 

 lies a short distance anterior to the anterior border of the main mass 

 of the gland ; (2) the transverse facial vessels ; and (3) the zygomatic 

 branches of the facial nerve. Below the duct find the buccal and the 

 mandibular branches of the facial nerve. At the upper end of the parotid 

 seek for the superficial temporal vessels. Posterior to them lies the auriculo- 

 tempoFal branch of the third division of the trigeminal nerve, and an- 

 terior to them, the temporal branches of the facial nerve. From, or from 

 beneath, the lower extremity of the gland emerge (i) the cervical branch of 

 the facial nerve, (2) the posterior facial vein (O.T. anterior division of the 

 temporo-maxillary vein), and (3) the external jugular vein. 



The Terminal Branches of the Facial Nerve. The dis- 

 sector should note that there are five terminal branches, or 

 groups of branches, of the facial nerve: (i) temporal; (2) 

 zygomatic; (3) buccal; (4) mandibular ; (5) cervical. They 

 all emerge from under cover of the parotid gland, the 

 temporal branches at its upper end, the cervical at its lower 

 end, and the remain-ing three groups of branches at its 

 anterior border. The temporal branches will be followed 

 when the temporal region and the scalp are being dissected, 

 and the cervical branch when the anterior triangle of the neck 

 is displayed; but the remaining three groups of branches 

 should now be followed to their terminations. 



The upper filaments of the zygomatic branch or branches run 

 anteriorly, across the zygomatic bone, and terminate, in both 

 the upper and the lower eyelid, in the fibres of the orbi- 

 cularis oculi. If the branches are carefully traced, one of 

 them will be found to communicate with the zygomatico- 



