日本人耳小骨におけるキヌタ骨切痕incus notchおよびアブミ骨稜crista stapedisの観察

抄録

The incus notch and the crista stapedis in auditory ossicles were investigated morphologically. Of 47 incudes the notch was present in 22 (47%). It was located in the inferior border of the short process of the incus, near the apex. Its depth and extent were variable. The medium degree of notch was most frequently found in the present series of ossicles (77%). Scanning electron microscopy revealed that a part of the posterior incudal ligament was anchored deeply into the notch of the incus. This suggests that the notch may possibly function to tighten the posterior incudal ligament to the incus.
The crista stapedis was detectable in 9 of 32 stapeses (28%). It is an inconstant ridge passing between the crura on the tympanic surface of the stapedial base. Marked crest formation was extremely rare. In the mared degree of the notch, however, it was so large and high that the shape of the stapes resembed that of a fetus. This crest may be a remnant of a once-complete layer of the periosteal bone on the obturator surface of the base. Clinical and embryological significances of the incus notch and the crista stapedis are briefly discussed.