104 



APPLIED ANATOMY. 



THE MOUTH AND THROAT. 



The lips are formed mainly by the orbicularis oris muscle with its subdivisions 

 and the accessory facial muscles (buccinator, levator and depressor anguli oris, 

 levator labii superioris, levator labii superioris alaeque nasi, the zygomaticus major 

 and minor, and the depressor labii inferioris). The orbicularis oris is attached to 

 the superior maxilla in the incisor fossa above the second incisor tooth and also 

 above to the septum. In the lower lip it is attached to the mandible beneath the 

 second incisor tooth. The lips contain, beside muscular tissue, some areolar tissue, 

 arteries, veins, and lymphatics. The muscular fibres are inserted into the skin. The 

 mucous membrane lining the lips has lying beneath it some mucous glands. They ' 

 sometimes become enlarged and form small, shot-like, cystic tumors containing mucus. 



Affections of the Lips. The lips are affected by wounds, angioma or blood 

 tumor, cancer (epithelioma), and clefts (harelip*). Wounds of the lip when properly 

 approximated heal readily on account of the free blood supply. The arteries sup- 



Auricularis superior 



Occipitalis 

 Auricularis anterior 



Auricularis posterior 



Zygomaticus major ^ 



Zygomaticus minor ' 



Levator anguli oris 



Levator labii superioris 



Buccinator 



Risorius 



Frontal is 



Corrugator supercilii 

 Orbicularis palpebrarum 

 Orbital part of same muscle 

 Pyramidalis nasi 



Lev. labii sup. alaeque nasi 

 Compressor tiariuin 



Dilatores naris 

 Depressor aloe nasi 

 Orbicularis oris 



'epressor anguli oris 

 Depressor labii inferioris 

 Levator menti 



Platysma 



FIG. 127. Superficial dissection, showing the muscles of the head and face. (Piersol.) 



plying the lips are the superior and inferior coronary branches of the facial. They 

 are given off about opposite the angle of the mouth and pierce the muscle to run 

 beneath the mucous membrane about midway betwen the edge of the lip and its 

 attachment to the gums or nearer the free border of the lip. Therefore, in' operating 

 on the lip, the artery should be looked for in this situation and not toward the skin 

 surface or in the substance of the lip. The superior coronary sends a branch to the 

 nasal septum, called the inferior artery of the septum. In the sulcus between the 

 lower lip and chin lies the inferior labial artery. The bleeding from this branch is 

 not so free as that from the coronary arteries, because the anastomosis across the 

 median line is not so marked. 



Angioma. The blood-vessels, mainly the veins, of the lips sometimes become 

 enlarged, forming a large protrusion. This may be noticed at or soon after birth 

 as a dusky blue, slightly swollen spot on the lip. As the child grows the swelling 

 enlarges. Sometimes it enlarges rapidly and operation is necessary to check its 

 growth; otherwise it may involve a large portion of the face and prove incurable. It 

 is composed of dilated veins with thin walls and large lumen. It does not pulsate 

 and disappears under pressure, only to return when this is removed. It is treated 

 by excision. The thin skin is dissected off and the growth cut away from the tissues 

 beneath, the bleeding being controlled by pressure, haemostats, and ligatures. In 



