1 32 HEAD AND NECK 



Tributaries. In addition to the frontal and supra-orbital 

 veins, it receives external nasal, palpebral, superior labial, 

 inferior labial, masseteric and superficial parotid tributaries. 

 As it crosses the buccinator muscle it is joined by the deep 

 facial vein, which connects it with the pterygoid plexus of 

 veins in the infra-temporal region. 



Dissection. After the branches of the facial nerve, the external maxillary 

 artery and the anterior facial vein have been studied, the dissection of the 

 deeper muscles and the deeper vessels and nerves must be proceeded with ; 

 but the supra-orbital and supra-trochlear nerves, the supra-orbital vessels, 

 and the corrugator supercilii muscle may be left till the scalp is dissected 

 (p. 156). 



Musculus Caninus (O.T. Levator Anguli Oris). The 

 caninus is concealed by the lower part of the orbicularis 

 oculi, the quadratus labii superioris, and the zygomaticus, and 

 it is crossed superficially, near the angle of the mouth, by 

 the external maxillary artery. When the structures superficial 

 to it are turned aside, the muscle will be found springing from 

 the canine fossa below the infra-orbital foramen. It passes 

 downwards to the angle of the mouth, where it blends with the 

 orbicularis oris, some of its fibres passing into the lower lip 

 (Fig. 57). It is an elevator of the angle of the mouth. \j 



The Buccinator. This muscle occupies the interval 

 between the upper and the lower jaws and forms a most 

 important part of the substance of the cheek. Above, it 

 springs from the alveolar border of the maxilla, in the 

 region of the molar teeth. Below, it arises from the 

 alveolar border of the mandible, also in the region of the 

 molar teeth, and, posteriorly, it is attached to the pte_r^go- 

 mandibular raphe, which forms a bond of union between 

 tHe^uccmator-arid the superior constrictor of the pharynx. 

 This attachment will be seen to better advantage when the 

 wall of the pharynx is studied (p. 373). Anteriorly, its fibres 

 converge towards the angle of the mouth, where they blend 

 with the orbicularis oris, of which they form a large part. 

 The manner in which the fibres enter the orbicularis must be 

 carefully noted. The upper and lower fibres pass directly 

 to the corresponding lips ; the middle fibres, on the other 

 hand, decussate at the angle of the mouth, so that the lower 

 fibres of the series enter the upper lip, whilst the higher 

 fasciculi reach the lower lip (Fig. 61). 



The Molar Glands. The buccinator is covered posteriorly 



