VARIATIONS AND MALFORMATIONS OF THE AUDITORY OSSICLE / 解剖学报

ABSTRACT

The morphological variations and congenital malformations of the auditoryossicles are not so rare as previously considered.The congenital anomalies of themhave sometimes been documented in the periodicals of the otorhinolaryngology,buttheir variations reported are scanty and incomplete.With dissecting microscope,weobserved 588 ossicles(200 mallei,224 incudis 164 stapes)from 120 full term foe-tuses without congenital defect except one case of anencephaly.We found that theauditory ossicles vary greatly in their form,length,size,angulation,curvature orthickness,etc.Those are variations of anterior fovea of caput mallei,anteriorcurvature of manubrium mallei,form of lateral margin of manubrium mallei,formof crus breve of incus,form of crus stapedis and patterns of basis stapedis.In 240 ears,five cases of congenital malformations of ossicular chain(2.1%)were discovered and listed as follows1.One case of congenital stapes footplate fixation,2.One case of ring form stapes detached from the basis stapedis,3.Two cases of columella stapes,4.One case of triple fusion of ossicles by osteoid tissue.Embryology of auditory ossicles available for understanding the variability anddeformity was briefly reviewed.According to our investigations we come to the conclusion that the stapesis probably the most frequently involved in the morphological variation andmalformation.