morphometrical study of the temporal bone and auditory ossicles in guinea pig

in this research, anatomical descriptions of the structure of the temporal bone and auditory ossicles have been performed based on dissection of ten guinea pigs. the results showed that, in guinea pig temporal bone was similar to other animals and had three parts; squamous, tympanic and petrous .the tympanic part was much better developed and consisted of oval shaped tympanic bulla with many recesses in tympanic cavity. the auditory ossicles of guinea pig concluded of three small bones; malleus, incus and stapes but the head of the malleus and the body of incus were fused and forming a malleoincudal complex. the average of morphometric parameters showed that the malleus was 3.53 ± 0.22 mm in total length. in addition to head and handle, the malleus had two distinct process; lateral and muscular. the incus had a total length 1.23 ± 0.02mm. it had long and short crus although the long crus was developed better than short crus. the lenticular bone was a round bone that articulated with the long crus of incus. the stapes had a total length 1.38 ± 0.04mm. the anterior crus(0.86 ± 0.08mm) was larger than posterior crus (0.76 ± 0.08mm). it is concluded that, in the guinea pig, the malleus and the incus are fused, forming a junction called incus-malleus, while in the other animals these are separate bones. the stapes is larger and has a triangular shape and the anterior and posterior crus are thicker than other rodents. therefore, for otological studies, the guinea pig is a good lab animal.