66 SURGICAL APPLIED ANATOMY. [Chap. v. 



The gap so formed is called the notch of Hivini, and is 

 occupied by loose connective tissue, covered by a con- 

 tinuation of the lining of the meatus, and through it pus 

 may escape from the middle ear into the auditory canal 

 without perforating the membrane. When the mem- 

 brane gives way owing to a violent concussion trans- 

 mitted through the air, it often gives way opposite the 

 notch, its attachments here being obviously less secure 

 than elsewhere. The membrane possesses but little 

 elasticity, as shown by the very slight gaping of the 

 part after it has been wounded. It is for this reason, 

 among others, that perforations made in the membrane 

 by the surgeon heal so very rapidly. The membrane 

 has been ruptured during fits of sneezing, coughing, 

 vomiting, etc. The same lesion has followed a box on 

 the ear, and even simple concussion such as that pro- 

 duced by a loud report. 



The umbilicus, or deepest point of the depression 

 in the diaphragm, is just below the centre of the entire 

 membrane, and corresponds to the attachment of the 

 end of the handle of the malleus. The rest of the 

 handle can be seen through the membrane during life. 

 The head of the malleus is in no connection with the 

 membrane, being above its highest limits. The seg- 

 ment of the membrane above the umbilicus is very 

 freely supplied by vessels and nerves ; it corresponds 

 to the handle of the malleus, and to the chain of 

 ossicles, and is opposite to the promontory and the 

 two fenestrse. The chorda tympani nerve also runs 

 across this supra-umbilical portion. The segment 

 below the umbilicus, on the other hand, corresponds 

 to no very important parts, and is less vascular and 

 less sensitive. Paracentesis of the tympanum through 

 the membrana tympani should therefore always be 

 performed in the sub-umbilical segment. 



The membrane is supplied by the stylo-mastoid 

 artery, and the tympanic branch of the internal max- 



