195 



426. THE VISCERA, 



are very compound organs, consisting of various tissues, several 

 of which together form a system destined to the performance of 

 some particular function. Belonging to this division we have the 

 Organs of Digestion, Respiration, Generation, Micturition, and 

 the Senses. 



427. A. Organs of Digestion, Organa digestionis, 



consist of one canal, which extends from the opening of the 

 mouth to that of the anus, and several appendages (as: oral and 

 salivary glands, liver, ventral salivary glands, spleen). 



a. Parts above the Diaphragm. 



428. 1. Cavity of the Mouth, together with its appendages. 



Cavum om, mouth, is situated at the inferior part of the face 

 between the two jaws and the cheeks, behind the lips and before 

 the pharynx. Its roof forms in front the hard palate, behind the 

 soft; its floor the tongue and mm. genio-, hyo-glossi, genio- and 

 mylo-hyodei. Before, it opens externally between the lips ; be- 

 hind, through the fauces, isthmus faucium, into the pharynx. 

 The anterior, or buccal cavity, is the space between the cheeks 

 and the dental alveoli; the proper mouth, the space between the 

 dental alveoli and the fauces. 



The Lips, labia, form the moveable anterior wall of the cavity of the 

 mouth, separated by the transverse oral fissure, os, into the upper and under 

 lips, placed (in man) vertically over one another, before the alveoli and the 

 teeth. Their thick, everted, red edges, prolabia, are bounded laterally by the 

 angle of the mouth, angulus oris. On the anterior surface covered by the ex- 

 ternal skin, the upper lip is bounded by the skin of the cheek at the projecting 

 internal border of m. levator labii super, alaque nasi, the under lip at the inner 

 border of m. triangularis. The linea naso-labialis (s. abdominalis) thence arising 

 (the strongly-marked furrow of intestinal disorder), commences at the alee of 

 the nose, and terminates at the sides of the chin. On the upper lip we ob- 

 serve: the mustachios, mystax; in the centre a longitudinal furrow, philtrum ; 

 on the under lip : the beard, pappits; upon the transverse groove or the bound- 

 ary between the under lip and chin, sulcus mento-labialis. The posterior (in- 

 ternal) surface of the lips is covered with mucous membrane, which applied 

 to the gums, is beset with glands, glandules salivates labiates, and in the centre, 

 particularly of the upper lip, forms a fold, frenulum. Between the external 

 skin and the mucous membrane is placed the proper foundation of the lips, 

 namely, m. orbicularis oris (see before), together with fibres from the muscles 

 bordering it. 



Vessels of the lips. Arteries: 1. JLrtt. coronarue from art. facialis. 2. Artt. 

 buccales, infraorbitales, alveolares for the upper lip, from Art. maxillar. internet, 

 mentaks for the under lip from art. facialis. Veins : plexus labialis, opens 



