Anatomical Study on the Middle Ear of Donkey (Equus acinus)

Abstract

Studying the anatomical features of the middle ear of donkey was significant among scanty available literatures. The work was established on 14 formalized heads and dried skulls from both sexes of healthy donkeys of different ages. The samples were intended for the bony structural examination and dissection. Extraction of the auditory ossicles was difficult due to the rigidity of the temporal bone during sawing. The article discussed the anatomical features of the middle ear, bony boundary and ossicles. Examination of the latter detected four ossicles and described their posture and their relation to right or left for forensic purposes. Our study provided a good idea about donkey's middle ear for the comparative anatomy. Although intended donkeys as training model for otosurgeons due to the normal continuity to the Eustachian tube and guttural pouch.

Morphological and morphometrical study of the auditory ossicles in chinchilla

“…In case of the morphology of the malleus (head, neck, three processes), the general anatomy of the ossicle is somehow similar to the literature data presented in case of donkey (Nazih, ), goat and camel (Ayres Seibel et al, ). Unlike the situation in hamster or New Zeeland rabbit (Kurtul et al, ), where the rostral process is slightly developed, in chinchilla , this process is extended, being in fact the most developed part of the malleus.…”

“…For the two crura, there are significant differences in size, the anterior crus being almost 10% shorter as well as straighter than the caudal crus. The crura are almost equal in size in mule (Nazih, ), while in cat, rabbit and wolf (Gürbüz et al, ; Martin, ; Seifert et al, ), the anterior crus is described as being longer and slightly bent when compared to the posterior crus. The overall shape of the intercrusal foramen is elliptic, with a ratio of antero‐posterior axis versus dorso‐ventral axis of 1:0.91 to 1:0.96.…”

Morphological and morphometrical aspects of the auditory ossicles in goat (Capra hircus)

“…Similarly to some available literature data, in species like the wolf (Gürbüz et al., 2019), rabbits (Guan et al., 2019), non‐human primates (Borin et al., 2008), humans (Guan et al., 2019) and sheep (Simaei et al., 2017), in the goat one can describe, at the level of the tympanic cavity, an assembly of three auditory ossicles. This comes in contrast to some other species like the donkey, where consulted literature (Nazih, 2017) mentions the existence of the 4th auditory ossicle—the lenticular bone.…”

“…The anterior crus of the stapes for this species seems to be straighter and shorter than its fellow—the posterior crus in Capra (as in chinchilla, hamster and humans) (Martonos et al., 2019; Mohammadpour, 2011; Simaei et al., 2017; Wadhwa, Kaul, & Agarwal, 2005), unlike the situation described in donkey, camel and red deer (Nazih, 2017), bovine and swine fetuses (Simaei et al., 2017) and swine adults (Pracy et al., 1998) where the two crura are almost equal in size. In dog, as described by Berghes (Berghes et al., 2010), the almost even crura are also slightly curved, with an overall rounded trapezoid shape.…”

“…The same situation was reported for the rabbit (Guan et al., 2019; Kurtul et al., 2003), rat, pig and wolf (Gürbüz et al., 2019; Hoffstetter et al., 2011; Li et al., 2015). The existence of a separate piece—the lenticular bone—has been reported in literature for donkey (Nazih, 2017), mentioning the fact that only 7% of the investigated specimens were showing the lenticular piece as a fused structure to the distal part of the incus. For sheep fetuses, another interesting statement claims the non‐existence of the lenticular process (Ayres Seibel et al., 2006).…”