34 DISSECTION OF THE FACE. 



SECTION III. 



DISSECTION OF THE FACE. 



Directions. The left side of the face may be used for learning the mus- 

 cles and vessels, and the right side is to be reserved for the nerves. 



Position. The previous position of the body for the examination of the 

 base of the skull will require to be changed : the head is to be lowered, 

 and the side of the face to be dissected is to be placed upwards. 



Dissection. As a preparatory step, the muscular fibres of th<> apertures 

 may be made slightly tense by inserting a small quantity of tow or cotton- 

 wool between the eyelids and the eyeball, and between the lips and the 

 teeth. 



First lay bare the sphincter muscle of the eyelids by a skin-deep circular 

 incision over the margin of the orbit, and by raising the skin of the lids 

 towards the aperture of the eye. Much care must be taken in detaching 

 the skin from the thin and oftentimes pale fibres of the orbicular muscle in 

 the lids, else they will be cut away in consequence of the little areolar 

 tissue between the two. 



Next the integument is to be removed from the side of the face by one 

 incision in front of the ear, from above the zygomatic arch to the angle of 

 the jaw, and then along the base of the jaw to the chin ; and by another 

 cut carried backwards horizontally from the corner of the mouth into the 

 first. The flaps of skin are to be raised from behind forwards, and left 

 adherent along the middle line. On the side of the nose the skin is closely 

 united to the subjacent parts, and must be detached with caution. Around 

 the mouth are many fleshy slips extending both upwards and downwards 

 from the orbicular muscle, but they are all marked so distinctly as to escape 

 injury, with the exception of the small risorius muscle which goes from 

 the corner of the mouth towards the ramus of the lower jaw. While 

 removing the fat from the muscles, each fleshy slip may be made tense 

 with hooks. 



The facial vessels and their branches will come into view as the muscles 

 are cleaned ; but the nerves may be disregarded on this side. 



In front of the ear is the parotid gland, whose duct is to be preserved ; 

 this is on a level with the meatus auditorius, and pierces the middle of the 

 cheek. 



MUSCLES OF THE FACE (fig. G). The superficial muscles of the face 

 are gathered around the apertures of the nose, eye, and mouth. An orbi- 

 cular or sphincter muscle encircles the apertures of the eye and mouth ; 

 and other muscles .are blended with each to enlarge the opening in the 

 centre of the fibres. There are three distinct groups of muscles : one of 

 the eyelids ; another of the nostril ; and a third of the aperture of the 

 rnouth. One of the muscles of mastication, viz., the masseter, is seen 

 between the jaws. 



MUSCLES OF THE NOSE. These muscles are the following : pyra- 

 midalis nasi, compressor naris, levator alas nasi, dilator naris, and depressor 

 alrc nasi. 



The PYRAMIDALIS NASI (fig. 5, *) is a small fleshy slip that covers the 

 nasal bone, and is continuous above with the occipito-frontalis muscle. 

 Over the cartilaginous part of the nose its fibres end in an aponeurosis, 



