22 SURGICAL ANATOMY OF THE FACE. 



close vicinity of the carotid artery and lateral sinus 

 readily, accounts for the escape of blood from the ear in 

 fracture of the base of the cranium. 



The JEustachian tube is the means of communication 

 between the internal ear and the pharynx, and serves 

 to maintain the balance of air on either side of the mem- 

 bran a tympani. 



Its internal orifice is at the anterior internal aspect of 

 the tympanum. The tube is directed downwards and 

 forwards, and terminates in a flattened valve-like open- 

 ing in the pharynx, just behind and a little above and 

 external to the inferior meatus of the nose. Its mucous 

 membrane is continuous with that of the pharynx. The 

 pharyngeal extremity of the tube is in close relation with 

 the tonsil a fact which explains its temporary occlu- 

 sion in enlargement or inflammation of that gland. 



(The operation of introducing the Eustachian catheter 

 is explained at p. 31.) 



SURGICAL ANATOMY OF THE FACE. 



Dissection. Before commencing a dissection to dis- 

 play the various structures met with in the integument 

 of the face, a little tow should be inserted into the eye- 

 lids, buccal cavity, and nostrils, to make tense these 

 regions. An incision is then to be made from above the 

 zygoma to the angle of the jaw, and another meeting it 

 along the base of the jaw to the middle of the chin. The 

 skin-flap is then to be raised from behind forwards, and 

 left adherent along the middle line. Great care must 

 be taken in so doing, as the facial muscles, or " muscles 

 of expression/ 7 are inserted into the skin, and are easily 

 removed in dissection. 



