Anatomical and morphometrical approaches on the auditory ossicles in European ground squirrel (Spermophilus citellus)

The malleus comprises the typical morphological elements, having a round, tuberous head and a very short neck with no bony processes. The manubrium is almost perpendicular to the rotational axis of the ossicle and presents, on its medial surface, the bony process for the insertion of the tensor tympani muscle. Incus is very short and has a deeply incised articular surface for malleus. The lenticular process was identified at the distal part of the long process. The stapes is the smallest ossicle, sheltered in a cavity of the mesotympanic area. It has a very short head, and the stapedial tendon marks its insertion on a visible bony process. An evident surrounding bony ridge marks the elliptic footplate. A comparison of the data related to lever ratio and stapedial surface is also provided based on the collected metrical data.