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 follows:1.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.

The arteries of auditory ossicles of 40 ears from 20 full term feotuses weredemonstrated by injection of liquid latex containing a small amount of Chinese inkthrough common carotid arteries.We found that the malleus and incus possess thenutrient arteries as well as the mucosal arteries,whereas the stapes gets its bloodsupply from the mucosal arteries only.The anterior tympanic artery is the principal source of blood supply of the mal-leus and the incus.It enters the middle ear through the petrotympanic fissure andramifies into five branches:malleolar artery,incudal artery,superior branch,posteriorbranch and chorda tympani branch.The malleolar and incudal arteries are nutrientarteries.The vascular network in mucosa over the manubrium mallei is supplied bythe branches of the deep auricular and stylomastoid arteries over the tympanic mem-brane.The mucosal arteries of the long crus of the incus is supplied by the smallvessels given off by incudal artery before entering the nutrient foramen,the finevessels from the arteries around the chorda tympani and the vessels passing to it fromstapes.The blood supply of the stapes is derived from the vessels located in two majorareas:one from the facial canal and the other from the promontory.The arteries tothe stapes from the promontory vascular plexus are the artery of the head of thestapes,the artery of the posterior crus and the artery of the anterior crus.The for-mer two vessels have not been reported previously.In the facial canal there are thestylomastoid artery and the superficial petrosal artery.The arterial supply of incudostapedial joint and the distal portion of the incuscomes from the vessels passing to them from the stapes rather than from the incudalsource.From above account,it would appear that the head of the malleus and thebody and short crus of the incus derived from first branchial cartilage are mainlysupplied by the anterior tympanic artery,and the remainder of the auditory ossiclesderived from second branchial cartilage are supplied by the stylomastoid artery.