A STUDY ON THE ARCHITECTURE OF THE OSSICULAR CHAIN OF THE EAR

Y. SAKAI
1960 Nippon Jibiinkoka Gakkai Kaiho  
An attempt has been made to reveal the true architecture of the ossicular chain in the human ear by using newly devised method. The auditory ossicles were embedded with resin in their natural state in the tympanic cavity and then removed as a unit from the skull. Roentgenograms of the embedded ossicles were made in three directions. Projection figures were prepared from the X-ray pictures and the necessary distances and angles were calculated. The results obtained from the 57 cases examined
more » ... 1) The axis between the tip of the head and the tip of the handle of the malleus was almost parallel with the axis between the tip of the body and the tip of the long process of the incus. 2) The above-mentioned two axes were about rectangular with the usual axis of rotation but slightly inclined backwards. 3) The axis between the top of the body and the tip of the long process of the incus crossed roughly rectangular to the axes formed by the edge of the head of the stapes and the anterior and the tposterior edge of the base of the stapes, but slightly inclined to the former. 4) The tip of the handle of the malleus, the tip of the long process and the edge of the short process of the incus did not exist in a straight line. 5) The mean lever ratio of the malleus to the incus was 1.22, which was less than the data previously reported. In 8 cases out of 57, this ratio was less than 1. 6) This axis between the anterior process of the malleus and the tip of the long process of the incus was roughly rectangular to the anterior crus of the stapes. The axis between the edge of the short process and the tip of the long process of the incus was also roughly rectangular to the posterior crus of the stapes. From this fact, it was assumed that the low pitched sound might be more easily conducted by the anterior crus of the stapes, and on the other hand, the high frequency sound by the posterior crus of the stapes. However, this presumption will need further investigation.
doi:10.3950/jibiinkoka.63.2202 fatcat:quddnh4d7rfahce4efyndxacai