DISSECTION OF THE HEAD AND NECK. 177 



sure, and terminates in the lower part of the outer ala. This alar car- 

 tilage, when dissected out, displays a close resemblance to a comma, the 

 broad part being placed in the upper part of the inner wing, and the 

 point in the lower part of the outer wing. The cartilages are movably 

 attached by fibrous tissue to the lower extremity of the septal cartilage 

 of the nose, and they give the necessary firmness to the edges of the 

 nostrils, preventing these from falling together in the act of inspiration. 

 The nostrils are covered outwardly by skin continuous with that of the 

 face. This skin, which is thin and adherent to the subjacent textures, is 

 carried roimd the margins of the alae, and for a short distance into the 

 nasal chamber. If the finger be introduced below the upper commis- 

 sure, it will be felt to enter a peculiar diverticuhun termed the false 

 nostril. This blind pouch extends upwards for about four inches, and 

 it is lined by a continuation of the skin. If the wings of the nostril be 

 separated as widely as possible, the opening of the lachrymal duct will 

 be seen a few inches within the lower commissure. The orifice is circu- 

 lar, appearing as if a small piece of skin had been punched out. Just 

 beyond the orifice the skin is continued by the mucous membrane of 

 the nasal chamber, which is distinguished from the common integument 

 by being non-pigmented, vascular-looking, and destitute of hairs. 



Directions. — The skin on the face should be entirely removed. Over 

 the lips and false nostril care is necessary to avoid going deeper than the 

 skin. One side should first be used for the muscles, and then the vessels 

 and nerves should be dissected on the opposite side. 



The muscles now to be dissected include a series of thin muscles 

 which terminate in and move the lips and nostrils ; the buccinator, 

 which forms the basis of the cheek ; and the masseter, a powerful 

 muscle of mastication, covering the vertical ramus of the lower jaw. 

 A reference to Plate 29 will enable the dissector to identify these 

 muscles. 



The Panniculus Carnosus does not form a continuous muscle on 

 the face. It consists of disconnected bundles developed in the sub- 

 cutaneous fascia. It is best developed over the masseter muscle, where 

 it is continuous over the edge of the inferior maxilla with the same 

 structure in the parotideal and intermaxillary regions. On the cheek a 

 few bundles reach the angle of the mouth, in whose retraction they 

 assist. 



Below the rim of the orbit there is found a thin layer of pale muscular 

 fibres and intermediate fascia, which may be viewed as a part of the 

 facial panniculus. It wrinkles the overlying skin. This is the lachry- 

 mal muscle of French authors, and the inferior palpebral muscle of Leyh. 



The Levator Labii Superioris Al^eque Nasi (Plate 29). This 

 muscle has a narrow, thin, and aponeurotic o^rigin from the frontal and 

 nasal bones, below and internal to the orbit. It passes over the levator 



N 



