32 THE EXTERNAL AND MIDDLE EAR, BY J. KESSEL. 



groove the Bivinian hiatus. This notch is filled up by the 

 tissue of the cutis and the mucous membrane of the tympanic 

 membrane. The tendinous ring of the membrana tympani 

 curves away, with the greater part of its fibres, from its direction 

 at the two angles of the notch, and turns to the deeper-lying 

 apex of the processus brevis into which it is inserted, whilst the 

 remainder of the tendinous fibres of the ring extend upwards, and 

 are lost in the connective tissue of the periosteum. In this way 

 an irregular triangular space is formed, which is bounded above 

 by the Rivinian notch, and on the two sides by two ligaments, 

 by means of which the malleus, or rather the apex of its pro- 

 cessus brevis, is attached to the anterior and posterior angles of 

 the groove of attachment. The anterior ligament is 1'5 of a mil- 

 limeter, the posterior 2 millimeters in length. The three points of 

 insertion of these ligaments do not lie in a vertical plane, but 

 the inferior point, which is connected with both the others, pro- 

 jects as far laterally beyond them as the short process of the 

 malleus at this point pushes the membrana tympani towards 

 the auditory meatus, so that a perpendicular struck from the 

 Rivinian foramen downwards would cut off the malleus nearly 

 at its neck. The distance from the highest point of the notch to 

 the apex of the short process amounts to 2'5 3 millimeters. 



The tissue which fills the just-described foramen, and which 

 has been named the membrana flaccida by Odo Schrapnell (40), 

 is less tensely stretched than the rest of the membrana tym- 

 pani, and sometimes even projects like a pocket towards the 

 tympanic cavity (Henle, 12). It consists of two thin layers, 

 one of which is the continuation of the cutis, and the other of 

 the mucous membrane of the membrana tympani. The cutis 

 consists of an epidermis, beneath which are sinuous fasciculi of 

 connective tissue, which extend obliquely over the triangular 

 space from the posterior segment of the auditory meatus, to 

 become continuous with the circular fibres of the anterior and 

 superior segment, together with vessels and nerves. The layer 

 of mucous membrane extends as far as to the osseous margin 

 of the Rivinian perforation, and passes from this point to the 

 neck of the malleus opposite to it. 



The statement that the existence of a Rivinian foramen is quite 



