22 ANATOMY OF THE HEAD AND NECK. 



integument of the lower lip and anastomose with branches 

 of the facial nerve. The inferior dental branch of the 

 internal maxillary artery, accompanied by its vein, also 

 emerges at the mental foramen, and, communicating with 

 the facial artery, is distributed to the structures covering 

 the lower jaw. 



The LEVATOR LABII INFERIORIS is an extremely small 

 muscle, difficult to isolate; it is to be sought from the 

 inside of the under lip, which should be turned down and 

 the frenum divided. The muscle arises from the surface of 

 bone just below the incisor teeth, and is inserted into the 

 integument on the tip of the chin. 



The BUCCINATOR MUSCLE arises from the outer surface 

 of the alveolar borders of the upper and lower jaw, as far 

 forward as the first molar tooth ; also from a fibrous raphe 

 called the pterygo-maxillary ligament, which intervenes 

 between it and the superior constrictor of the pharynx ; 

 its fibres converge anteriorly and become continuous with 

 those of the orbicularis oris. The intersection of the 

 muscles anteriorly should be dissected with special care. 

 At about its centre, the buccinator is perforated by the 

 excretory duct (Steno's) of the parotid gland ; this lies 

 partly imbedded in a quantity of fat which occupies the 

 interval between this muscle and the masseter, and care 

 must therefore be taken not to divide it. 



The RISORIUS SANTORINI MUSCLE consists of a few fibres 

 of the platysma myoides, varying in their degree of dis- 

 tinctness, which pass transversely inward over part of the 

 buccinator and masseter muscle, to terminate near the 

 angle of the mouth. 



FACIAL ARTERIES. 



The facial arteries may be made the subject of a special dissection 

 upon one side of the face ; or, if the student has been careful to pre- 

 serve them in connection with the muscles, they may be studied on 

 the side already dissected. The arteries proper of the face are the 

 facial and transverse facial ; the former a branch of the external 

 carotid, the latter of the temporal artery. 



The FACIAL ARTERY emerges from the neck just anterior 

 to the masseter muscle y where it rests upon the lower jaw, 

 covered in by the platysma myoides ; it passes upward 

 obliquely and tortuously : near the angle of the mouth it 

 gives off an inferior labial branch, which passes beneath 

 the depressor anguli oris muscle, and is distributed to the 



