Article

A functional anatomy of the external and middle ear of the bactrian camel (Camelus bactrianus)

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Abstract

The special structure and function of the external and middle ears of the bactrian camel (Camelus bactrianus) were described and various anatomical and physiological parameters of the ear, such as the length of external acoustic meatus and ossicular chain lever, the areas of tympanic membrane and oval window were measured. Our data on the middle ear and transformer ratio on the bactrian camel were compared to those of other domestic animals, such as the horse, cattle, and the Indian elephant. The shapes of the external acoustic meatus, tympanic membrane and lever system of the ossicular chain of the bactrian camel all have its own properties. Based on functional parameters, it was calculated that the ear-canal resonance peak was at 1.3 kHz in bactrian camel. The transformer ratio of the middle ear was 49.6 times in bactrian camel. The data showed that the higher value in the bactrian camel may reduce the reflection of energy incurred as a result of the different acoustic impedences of air and inner ear fluid. All these special structures may increase the acoustical sensitivity by enhancing the transmission of sound in the bactrian camel, which lives in conditions of frequent sandstorms.

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... In the ox only the head of malleus and part of the incus [12] or the head of malleus and incus [4] are housed in the recess. In Bactrian camels, the malleus head and main part of incus are located in the recess [2]. ...
... The cellular divisions of the bullar cavity in water buffalos resemble what has been described in the ox [1,35]. This is not the case in other domestic ruminant species in veterinary anatomical textbooks [12,26] nor in Bactrian camels [2]. According to Fleischer [1978] and Plestilova et al. [2016], similar bony septa which divide the middle ear cavities of several types of mammals are expected to change the resonance properties of such cavities, but experimental data are lacking. ...
... In water buffalos, the lenticular process was located at the extremity of long crus of incus, as in goats [12], dromedary [22], and Bactrian camels [2]. However, in the sheep and ox the process was absent [2] or present [34,35] Stapes: Like in the ox [12], this ossicle was nearly rectangular in shape in water buffalos, whereas it is more trapezoidal in sheep [35]. ...
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Background: The purpose of this study was to provide a description of gross middle ear morphology in water buffalos, augmented with additional data on the osseous structures of middle ear derived from cone-beam computed tomography (CBCT). Materials and methods: Skulls of 10 young adult male water buffalos were used to examine their middle ear. Results: Anatomical features noted included the presence of tympanic cells in the tympanic bulla, the location of malleus head and neck, and all of incus in the dorsal epitympanic recess, the oval tympanic membrane (TM), absence of a prominent notch on the articular surface of malleus, positional variations of the lateral process of malleus relative to the muscular process and muscular process relative to the rostral process of malleus, absence of complete coverage of the articular facet of malleus head by incus body, and presence of the lenticular process of incus. In CBCT images, the osseous part of external acoustic meatus, the petrous part of temporal bone and the details of the ossicles were seen, except for stapes. Conclusions: Although TM, malleus and stapes of water buffalos are similar to those of ox, the incus of water buffalos is more similar to that of goats. The heaviest ossicles among the ruminants studied belonged to water buffalos; the mean length of malleus head and neck, total length and width of incus body as well as length of stapes head were greatest in water buffalos too. The auditory ossicles of water buffalos show ‘transitional type’ morphological characteristics. These features suggest a relatively wide frequency range of hearing, but not one biased towards especially low or especially high frequencies.
... In the ox only the head of malleus and part of the incus [12] or the head of malleus and incus [4] are housed in the recess. In Bactrian camels, the malleus head and main part of incus are located in the recess [2]. ...
... The cellular divisions of the bullar cavity in water buffalos resemble what has been described in the ox [1,35]. This is not the case in other domestic ruminant species in veterinary anatomical textbooks [12,26] nor in Bactrian camels [2]. According to Fleischer [1978] and Plestilova et al. [2016], similar bony septa which divide the middle ear cavities of several types of mammals are expected to change the resonance properties of such cavities, but experimental data are lacking. ...
... In water buffalos, the lenticular process was located at the extremity of long crus of incus, as in goats [12], dromedary [22], and Bactrian camels [2]. However, in the sheep and ox the process was absent [2] or present [34,35] Stapes: Like in the ox [12], this ossicle was nearly rectangular in shape in water buffalos, whereas it is more trapezoidal in sheep [35]. ...
Article
Abstract Background: The purpose of this study was to provide a description of gross middle ear morphology in water buffalos, augmented with additional data on the osseous structures of middle ear derived from cone-beam computed tomography (CBCT). Materials and methods: Skulls of 10 young adult male water buffalos were used to examine their middle ear. Results: Anatomical features noted included the presence of tympanic cells in the tympanic bulla, the location of malleus head and neck, and all of incus in the dorsal epitympanic recess, the oval tympanic membrane (TM), absence of a prominent notch on the articular surface of malleus, positional variations of the lateral process of malleus relative to the muscular process and muscular process relative to the rostral process of malleus, absence of complete coverage of the articular facet2 of malleus head by incus body, and presence of the lenticular process of incus. In CBCT images, the osseous part of external acoustic meatus, the petrous part of temporal bone and the details of the ossicles were seen, except for stapes. Conclusions: Although TM, malleus and stapes of water buffalos are similar to those of ox, the incus of water buffalos is more similar to that of goats. The heaviest ossicles among the ruminants studied belonged to water buffalos; the mean length of malleus head and neck, total length and width of incus body as well as length of stapes head were greatest in water buffalos too. The auditory ossicles of water buffalos show ‘transitional type’ morphological characteristics. These features suggest a relatively wide frequency range of hearing, but not one biased towards especially low or especially high frequencies. Key words: anatomy, auditory ossicles, cone beam computed tomography, middle ear, morphometry, water buffalo
... In the ox only the head of malleus and part of the incus [11] or the head of malleus and incus [4] are housed in the recess. In Bactrian camels, the malleus head and main part of incus are located in the recess [2]. ...
... The cellular divisions of the bullar cavity in water buffaloes resemble what has been described in the ox [1,35]. This is not the case in other domestic ruminant species in veterinary anatomical textbooks [11,25] nor in Bactrian camels [2]. According to Fleischer [10] and Plestilova et al. [29], similar bony septa which divide the middle ear cavities of several types of mammals are expected to change the resonance properties of such cavities, but experimental data are lacking. ...
... Mohammadpour [21] reported masses and other measurements of the different parts and process of the ossicles in the ox, sheep, goat, and dromedary camel. Bai et al. [2] weighed all ossicles and measured malleus head and length of stapes in Bactrian camels. Nummela [27] reported average masses of ossicles in various mammals including Bactrian camels, cattle and sheep. ...
Article
Abstract Background: The purpose of this study was to provide a description of gross middle ear morphology in water buffalos, augmented with additional data on the osseous structures of middle ear derived from cone-beam computed tomography (CBCT). Materials and methods: Skulls of 10 young adult male water buffalos were used to examine their middle ear. Results: Anatomical features noted included the presence of tympanic cells in the tympanic bulla, the location of malleus head and neck, and all of incus in the dorsal epitympanic recess, the oval tympanic membrane (TM), absence of a prominent notch on the articular surface of malleus, positional variations of the lateral process of malleus relative to the muscular process and muscularprocess relative to the rostral process of malleus, absence of complete coverage of the articular facet2 of malleus head by incus body, and presence of the lenticular process of incus. In CBCT images, the osseous part of external acoustic meatus, the petrous part of temporal bone and the details of the ossicles were seen, except for stapes. Conclusions: Although TM, malleus and stapes of water buffalos are similar to those of ox, the incus of water buffalos is more similar to that of goats. The heaviest ossicles among the ruminants studied belonged to water buffalos; the mean length of malleus head and neck, total length and width of incus body as well as length of stapes head were greatest in water buffalos too. The auditory ossicles of water buffalos show ‘transitional type’ morphological characteristics. These features suggest a relatively wide frequency range of hearing, but not one biased towards especially low or especially high frequencies. Key words: anatomy, auditory ossicles, cone beam computed tomography, middle ear, morphometr
... The footplate of the stapes varies much as far as its shape is concerned from species to species. For the roe-deer, we have observed an elliptic shape, somehow similar to the bactrian camel (Bai et al. 2009;Nourinezhad et al. 2021), goat (Martonos et al. 2021), and chinchilla (Martonos et al. 2019). In sheep, this segment is described as almost squared (Nourinezhad et al. 2021). ...
Article
Full-text available
The study provides a series of distinctive morphological features of the auditory ossicles alongside comparative morphometric data, bringing facts in respect to morphology and some morpho-functional elements of the auditory ossicles in this little-studied species. The most relevant features noted are evident conical shape of muscular process of malleus and triangular aspect of the handle of malleus. For the incus, a short body of the bone and the direct continuation is mentioned, with no clear distinction as an individualized piece for the lenticular process. As for the stapes, the clear profiling of the muscular tubercle for the stapedial muscle and elliptic shape of the foot of the stapes is noted. A series of comparative measurements and indices are also calculated in the attempt of profiling differences from the domestic couterspecies- sheep and goat.
... 2c,d). Asymmetrical crura as observed in cainotheriids are also observed in camelids (Camelus bactrianus; Bai et al., 2009), suoids (Tayassu tajacu and Microstonyx erymanthius; Orliac and Billet, 2016) and ruminants (e.g. Giraffa camelopardalis; Doran, 1878). ...
Article
This work describes an unparalleled sample of isolated fossil auditory ossicles of cainotheriid artiodactyls from the Paleogene karstic infillings of Dams (Tarn-et-Garonne, Quercy, France). This collection comprises a total of 18 mallei, 28 incudes and three stapedes. It allows the documentation of both intra- and interspecific variability of ossicular morphology within Cainotheriidae. We show that despite considerable intraspecific variability, the malleus, the incus and the stapes appear to be taxonomically informative at the Cainotheriidae scale. This work further provides the first description of a reconstructed ossicular chain of a terrestrial Paleogene artiodactyl species, found in a basicranium of the late Oligocene cainotheriine Caenomeryx filholi (Pech Desse locality).
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The study provides a series of distinctive aspects of the auditory ossicles alongside comparative morphometric data, bringing facts in respect to morphology and morphofunctionality of the auditory ossicles in this little-studied species. The most important features noted are evident conical shape of muscular process of malleus and triangular aspect of the handle of malleus. For the incus, a short body of the bone and the direct continuation, with no clear distinction as an individualized piece, for the lenticular process. As for the stapes, the clear profiling of the muscular tubercle for the stapedial muscle and elliptic shape of the foot of the stapes is noted. A series of comparative measurements and indices are also calculated in the attempt of profiling differences from the domestic counter species- sheep and goat.
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