FACE AND FRONTAL REGION OF HEAD 15 



the trigeminal nerve. It^communicates with one of the zygomatic 

 twigs of the lacial nerve. Next follow the lower zygomatic 

 bTanches of the facial nerve forwards to the zygomaticus muscle, 

 and note that one of the twigs supplies it ; then detach the 

 zygomaticus from its origin, turn it down to the angle of the 

 mouth. When that has been done detach the zygomatic and 

 infra-orbital parts of the quadratus labii superioris from their 

 origins and turn them downwards. Now follow the anterior facial 

 vein and the external maxillary artery forwards and upwards 

 to the nose, and secure the branches of the artery. Some of the 

 smaller branches pass backwards, but the main branches, the 

 inferior and superior labial, pass forwards into the lower and 

 upper lips respectively, where they lie deep to the orbicularis 

 oris against the mucous membrane. Beyond the angle of the 

 mouth the lateral nasal branch arises, and the continuation of 

 the external maxillary artery beyond that branch is called the 

 angular artery. 



After the external maxillary artery and its branches have 

 been cleaned follow the lower zygomatic branches of the facial 

 nerve forwards through the fat exposed by the reflection of the 

 zygomaticus and the quadratus labii superioris, and secure their 

 connections with the terminal branches of the infra-orbital 

 branch of the maxillary division of the trigeminal nerve, which 

 issues through the infra-orbital foramen accompanied by the 

 infra-orbital branch of the internal maxillary artery. The 

 interlacement of the zygomatic branches of the facial nerve 

 with the infra-orbital nerve constitutes the infra-orbital plexus. 

 From the infra-orbital plexus branches ascend to the lower 

 eyelid, other branches descend to the upper lip, and still others 

 pass medially to the nose. After the branches of the infra- 

 orbital plexus have been displayed clean the buccal branch of 

 the facial nerve. Follow it through the pad of fat called the 

 suctorial pad which lies on the buccinator muscle. Secure, 

 if possible, its junction with the buccinator branch of the 

 mandibular division of the trigeminal nerve, which issues from 

 under cover of the middle of the anterior border of the 

 masseter muscle, and follow its branches of supply to the 

 buccinator muscle. It may be necessary to cut through the 

 anterior border of the masseter to secure the buccinator branch 

 of the mandibular nerve. Next detach the triangularis from the 

 angle of the mouth and turn it downwards to its insertion, 

 secure the twig it receives from the mandibular branch of the 

 facial n prw j and display the union "of that branch with the 

 mental branch of the alveolar division of the trigeminal nerve, 

 which issues through tEe "mental foramen, under cover of the 

 triangularis and below the second lower premolar tooth. Secure 

 also a twig from the mandibular branch of the facial nerve which 

 supplies the quadratus labii inferioris. Accompanying the 

 mandibular nerve deep to the triangularis there is, usually, a 

 definite branch of the external maxillary artery which used to be 

 called the inferior labial. Finally, reflect the posterior part of 

 the platysma below the mandible to display the cervical branch 

 of the facial nerve, which issues from the lower part of the 

 parotid gland to supply the platysma and to communicate 

 with the upper branch of a cutaneous nerve called the nervus 

 cutaneus colli. Do not follow it to its termination at present 



