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Background: The ossicula auditus is the structure that transmits vibrations from the tympanic cavity to the auris interna. This assembly is formed by three ossicles: the malleus, incus and stapes. In addition, the bone that exists as os lenticulare in humans exists as processus lenticulare in most mammals., Objective: To our knowledge, no in-depth study has been published on the ossicula auditus of gazelles. This study aims to provide a comparative study of the morphology of the auditory ossicles in sheep, goats and gazelles., Methods: Ossicula auditus from six adult Awassi sheep, six hair goats and six gazelles was examined and photographed under a stereomicroscope., Results and Conclusion: It was determined that the ossicula auditus of gazelle, hair goat and Awassi sheep consisted of malleus, incus and stapes. In the species examined, it was observed that the articular surface on the caput mallei, the malleus protrusions and the distal part of the manubrium mallei differed between species. It was determined that the incus bone consists of a body and two crus. As an important morphological difference, the proc. lenticulare was found to be on the crus breve in all three species. It was determined that the stapes bone was quadrangular in the species examined, especially in goats, but this quadrangular shape, which is specific to ruminants, was not fully formed in other species. As a result, it was determined that the ossicula auditus of gazelle, hair goat and Awassi sheep showed morphologically different characteristics., (© 2024 The Author(s). Veterinary Medicine and Science published by John Wiley & Sons Ltd.)

The auditory ossicles amplify and transmit sound from the environment to the inner ear. The distribution of bone mineral density is crucial for the proper functioning of sound transmission as the ossicles are suspended in an air-filled chamber. However, little is known about the distribution of bone mineral density along the human ossicular chain and within individual ossicles. To investigate this, we analyzed fresh-frozen human specimens using synchrotron-based phase-contrast microtomography. In addition, we analyzed the volume and porosity of the ossicles. The porosity for the auditory ossicles lies, on average, between 1.92% and 9.85%. The average volume for the mallei is 13.85 ± 2.15 mm 3 , for the incudes 17.62 ± 4.05 mm 3 and 1.24 ± 0.29 mm 3 for the stapedes. The bone density distribution showed a similar pattern through all samples. In particular, we found high bone mineralization spots on the anterior crus of the stapes, its footplate, and along areas that are crucial for the transmission of sound. We could also see a correlation between low bone mineral density and holey areas where the bone is only very thin or missing. Our study identified a similar pattern of bone density distribution within all samples: regions exposed to lower forces generally show higher bone density. Further, we observed that the stapes shows high bone mineral density along the anterior crus and its footplate, which may indicate its importance in transmitting sound waves to the inner ear., (© 2024. The Author(s).)

Background: Although stapedotomy is effective for patients with clinical otosclerosis, the time of hearing stabilization has not yet been consistent., Objective: To investigate the relationships between post-operative follow-up times, hearing outcomes, and threshold shift after stapedotomy., Materials and Methods: Fifty-five patients with clinical otosclerosis that underwent stapedotomy were retrospectively studied. Pure tone audiometry tests were conducted within the first month (short-term) and within 1 year (mid-term) postoperatively. Data were analyzed for two rounds of audiometry tests at different postoperative follow-up times., Results: Air conduction (AC) and bone conduction (BC) were significantly correlated with preoperative hearing levels ( p <.01). AC, BC, and air bone gap (ABG) significantly improved at the short-term ( p <.001) and continued to improve at the mid-term ( p <.01). The success rate of surgery increased from 87% at short-term to 98% at mid-term. Less than 1/3 of cases encountered BC deterioration at short-term, whereas most improved at mid-term., Conclusions: Hearing results showed a trend of improvement between short-term and mid-term follow-ups after stapedotomy. AC, ABG, and success rate displayed significant improvement several months postoperatively. BC deterioration occurred in less than 30% of patients at short-term. The recovery of BC at 4 kHz was later than that of low frequencies.

Among extant vertebrates, mammals are distinguished by having a chain of three auditory ossicles (the malleus, incus and stapes) that transduce sound waves and promote an increased range of audible-especially high-frequencies 1 . By contrast, the homologous bones in early fossil mammals and relatives also functioned in chewing through their bony attachments to the lower jaw 2 . Recent discoveries of well-preserved Mesozoic mammals have provided glimpses into the transition from the dual (masticatory and auditory) to the single auditory function for the ossicles, which is now widely accepted to have occurred at least three times in mammal evolution 3-6 . Here we report a skull and postcranium that we refer to the haramiyidan Vilevolodon diplomylos (dating to the Middle Jurassic epoch (160 million years ago)) and that shows excellent preservation of the malleus, incus and ectotympanic (which supports the tympanic membrane). After comparing this fossil with other Mesozoic and extant mammals, we propose that the overlapping incudomallear articulation found in this and other Mesozoic fossils, in extant monotremes and in early ontogeny in extant marsupials and placentals is a morphology that evolved in several groups of mammals in the transition from the dual to the single function for the ossicles.

The present paper deals with a detailed description of the auditory ossicles in Capra hircus. The paper focuses on the morphological and morphometrical description of the ossicular assembly, formed by malleus, incus and stapes. The malleus (overall length, as average- 8.16 mm) comprises the head of malleus (Caput mallei), a slightly strictured part-neck (Collum mallei) with 3 distinctive processes (lateral, rostral and muscular) (Processus lateralis, Processus rostralis and Processus muscularis) and a handle (Manubrium mallei). The head of malleus has an oval aspect with an obtuse articular surface on its medial surface (Facies articularis). The neck is evident with three bony processes described-the anterior, almost triangular, the muscular one quite reduced and the lateral one which is the most developed one. The manubrium is the longest sector-4.4 mm and appears as a slightly curved piece. The incus presents a body of 1.3 mm and two processes-the short and long crus (Crus breve and Crus longum). The overall shape of the ossicle resembles a biradicular molar. The lenticular process is a continuation of the distal part of the long crus. The stapes-the smallest in size of the three ossicles (2.7 mm), has a head (Caput stapedis), an anterior (Crus rostrale) and a caudal (Crus caudale) arm and a footplate (Basis stapedis). The two processes are slightly different in size and morphology, delimiting the intercrural space that shows the presence of a bony spicule. The footplate (1.6 mm 2 area) is ellipsoidal, with an anterior narrower extremity., (© 2020 Wiley-VCH GmbH.)

The sheep middle ear has been used in training to prepare physicians to perform surgeries and to test new ways of surgical access. This study aimed to (1) collect anatomical data and inertial properties of the sheep middle-ear ossicles and (2) explore effects of these features on sound transmission, in comparison to those of the human. Characteristic dimensions and inertial properties of the middle-ear ossicles of White-Alpine sheep (n = 11) were measured from high-resolution micro-CT data, and were assessed in comparison with the corresponding values of the human middle ear. The sheep middle-ear ossicles differed from those of human in several ways: anteroinferior orientation of the malleus handle, relatively small size of the incus with a relatively short distance to the lenticular process, a large area of the articular surfaces at the incudostapedial joint, and a relatively small moment of inertia along the anterior-posterior axis. Analysis in this study suggests that structure and orientation of the middle-ear ossicles in the sheep are conducive to an increase in the hinge-like ossicular-lever-action around the anterior-posterior axis. Considering the substantial anatomical differences, outcomes of middle-ear surgeries would presumably be difficult to assess from experiments using the sheep middle ear.

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)., (© 2020 Anatomical Society.)

Background: The Weberian apparatus enhances hearing in otophysan fishes, including Zebrafish (Danio rerio). Several studies have examined aspects of morphological development of the Weberian apparatus and hearing ability in Zebrafish. A comprehensive developmental description including both hard and soft tissues is lacking. This information is critical for both interpretation of genetic developmental analyses and to better understand the role of morphogenesis and integration on changes in hearing ability., Results: Histological development of hard and soft tissues of the Weberian apparatus, including ossicles, ear, swim bladder, and ligaments are described from early larval stages (3.8 mm notochord length) through adult. Results show a strong relationship in developmental timing and maturation across all regions. All required auditory elements are present and morphologically integrated early, by 6.5 mm SL. Dynamic ossification patterns and changes in shape continue throughout the examined developmental period., Conclusions: This study provides the first comprehensive histological description of Weberian apparatus development in Zebrafish. Morphological integration was found early, before increases in hearing ability were detected in functional studies (>10 mm total length), suggesting morphological integration precedes functional integration. Further research is needed to examine the nature of the functional delay, and how maturation of the Weberian apparatus influences functionality., (© 2020 Wiley Periodicals, Inc.)

The pink fairy armadillo Chlamyphorus truncatus is the smallest extant armadillo and one of the least-known fossorial mammals. The aim of this study was to establish if its middle ear is specially adapted to the subterranean environment, through comparison with more epigeic relatives of the groups Euphractinae (Chaetophractus villosus, Chaetophractus vellerosus, Zaedyus pichiy) and Dasypodinae (Dasypus hybridus). We examined the middle ears using micro-computed tomography and subsequent three-dimensional reconstructions. D. hybridus has a relatively small middle ear cavity, an incomplete bulla and 'ancestral' ossicular morphology. The other species, including Chlamyphorus, have fully ossified bullae and middle ear ossicles, with a morphology between 'transitional' and 'freely mobile', but in all armadillos the malleus retains a long anterior process. Unusual features of armadillo ears include the lack of a pedicellate lenticular apophysis and the presence, in some species, of an element of Paaw within the stapedius muscle. In common with many subterranean mammals, Chlamyphorus has a relatively flattened malleo-incudal articulation and appears to lack a functional tensor tympani muscle. Its middle ear cavity is not unusually enlarged, and its middle ear ossicles seem less robust than those of the other armadillos studied. In comparison with the euphractines, there is no reason to believe that the middle ear of this species is specially adapted to the subterranean environment; some aspects may even be indicative of degeneration. The screaming hairy armadillo, Chaetophractus vellerosus, has the most voluminous middle ear in both relative and absolute terms. Its hypertrophied middle ear cavity likely represents an adaptation to low-frequency hearing in arid rather than subterranean conditions., (© 2019 Anatomical Society.)

DNA recovery from ancient human remains has revolutionized our ability to reconstruct the genetic landscape of the past. Ancient DNA research has benefited from the identification of skeletal elements, such as the cochlear part of the osseous inner ear, that provides optimal contexts for DNA preservation; however, the rich genetic information obtained from the cochlea must be counterbalanced against the loss of morphological information caused by its sampling. Motivated by similarities in developmental processes and histological properties between the cochlea and auditory ossicles, we evaluate the ossicles as an alternative source of ancient DNA. We show that ossicles perform comparably to the cochlea in terms of DNA recovery, finding no substantial reduction in data quantity and minimal differences in data quality across preservation conditions. Ossicles can be sampled from intact skulls or disarticulated petrous bones without damage to surrounding bone, and we argue that they should be used when available to reduce damage to human remains. Our results identify another optimal skeletal element for ancient DNA analysis and add to a growing toolkit of sampling methods that help to better preserve skeletal remains for future research while maximizing the likelihood that ancient DNA analysis will produce useable results., (© 2020 Sirak et al.; Published by Cold Spring Harbor Laboratory Press.)

Textbooks frequently report that there are 206 human bones, or 200 bones and 6 auditory ossicles. The human bone counts in history and within adulthood were reviewed. Tallies of 197 to 307 bones have been reported over the past several centuries. The relatively low modern reckoning of 206 was due to exclusion of teeth and sesamoid ossicles, and to reassessments of the hyoid, sacrum, coccyx, and sternum as unitary bones. An audit of bone counts during adulthood failed to confirm a rational justification for the total of 206. The number is higher in young adults and lower in the elderly. Difficulties in establishing a definitive bone count include individual differences and the inconsistency of viewing the adult cranium as a collection of 21 bones. Clin. Anat. 33:187-191, 2020. © 2019 Wiley Periodicals, Inc., (© 2019 Wiley Periodicals, Inc.)

It is believed that non-mammals have poor hearing at high frequencies because the sound-conduction performance of their single-ossicle middle ears declines above a certain frequency. To better understand this behavior, a dynamic three-dimensional finite-element model of the chicken middle ear was constructed. The effect of changing the flexibility of the cartilaginous extracolumella on middle-ear sound conduction was simulated from 0.125 to 8 kHz, and the influence of the outward-bulging cone shape of the eardrum was studied by altering the depth and orientation of the eardrum cone in the model. It was found that extracolumella flexibility increases the middle-ear pressure gain at low frequencies due to an enhancement of eardrum motion, but it decreases the pressure gain at high frequencies as the bony columella becomes more resistant to extracolumella movement. Similar to the inward-pointing cone shape of the mammalian eardrum, it was shown that the outward-pointing cone shape of the chicken eardrum enhances the middle-ear pressure gain compared to a flat eardrum shape. When the outward-pointing eardrum was replaced by an inward-pointing eardrum, the pressure gain decreased slightly over the entire frequency range. This decrease was assigned to an increase in bending behavior of the extracolumella and a reduction in piston-like columella motion in the model with an inward-pointing eardrum. Possibly, the single-ossicle middle ear of birds favors an outward-pointing eardrum over an inward-pointing one as it preserves a straight angle between the columella and extrastapedius and a right angle between the columella and suprastapedius, which provides the optimal transmission.

In modern Cetacea, the ear bone complex comprises the tympanic and periotic bones forming the tympano-periotic complex (TPC), differing from temporal bone complexes of other mammals in form, construction, position, and possibly function. To elucidate its functioning in sound transmission, we studied the vibration response of 32 pairs of formaldehyde-glutaraldehyde-fixed TPCs of Globicephala macrorhynchus, the short-finned pilot whale (legally obtained in Taiji, Japan). A piezoelectric-crystal-based vibrator was surgically attached to a location on the cochlea near the exit of the acoustic nerve. The crystal delivered vibrational pulses through continuous sweeps from 5 to 50 kHz. The vibration response was measured as a function of frequency by Laser Doppler Vibrometry at five points on the TPC. The aim of the experiment was to clarify how the vibration amplitudes produced by different frequencies are distributed on the TPC. At the lowest frequencies (<12 kHz), no clear differential pattern emerged. At higher frequencies the anterolateral lip of the TP responded most sensitively with the highest displacement amplitudes, and response amplitudes decreased in orderly fashion towards the posterior part of the TPC. We propose that this works as a lever: high-frequency sounds are most sensitively received and cause the largest vibration amplitudes at the anterior part of the TP, driving movements with lower amplitude but greater force near the posteriorly located contact to the ossicular chain, which transmits the movements into the inner ear. Although force (pressure) amplification is not needed for impedance matching in water, it may be useful for driving the stiffly connected ossicles at the high frequencies used in echolocation., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This study is meant to illustrate and describe the features of the auditory ossicles of the chinchilla (Chinchilla lanigera), one of the species used more and more frequently in otology and ear surgery as animal model. Cephalic extremities of 12 C. lanigera individuals obtained from a private farm, where this species was bred for fur, were used in this study. The ossicles were obtained either by direct surgical harvesting by mastoid approach or after a dermestid beetle exposure followed by anatomical dissection. The three ossicles that form the assembly are the malleus, incus and stapes. After the removal of these ossicles, a series of anatomical descriptions were made, followed by seriate sets of measurements. The malleus and incus form a joined-single unit called the maleo-incal complex, with an elongated straight appearance, also due to the development of the anterior process. The handle of the malleus and the long process of incus are almost perpendicular to the main axis of the maleo-incal complex. The presence of the muscular process on the handle of the malleus is recorded. The overall shape of the incus is given by the uneven development of the two processes and the reduced neck part. The stapes is the smallest of the components that maintains the well-known architecture in accordance with the general model. The morphology of all three ossicles is backed by a series of measurements, some standard, some adapted to the morphology of the ossicles. From the very reduced comparative metrical data at our disposal, our study presents an average of 10% lower values for the ones presented earlier by other researchers in the same species., (© 2019 Blackwell Verlag GmbH.)

In the single-ossicle ear of chickens, the quasi-static displacement of the umbo shows great asymmetry; umbo displacements are much larger for negative than for positive pressure in the middle ear, which is opposite to the typical asymmetry observed in mammal ears. To better understand this behavior, a finite-element model was created of the static response of the chicken middle ear. The role of flexibility of the extracolumella in the model was investigated, and the potential effect of the outward orientation of the tympanic-membrane cone was studied by building two adapted models with a flat membrane and an inverted conical membrane. It is found that the extracolumella must be made of flexible material to explain the large inward displacements of the umbo, and that displacements of the footplate are much smaller due to bending of the flexible extracolumella. However, increasing extracolumellar stiffness mostly reduces umbo displacement rather than increasing footplate displacement. The results suggest that the inverted orientation of the membrane cone is responsible for the change in asymmetry of the umbo displacement curve. The asymmetry of the footplate displacement curve in the normal model is smaller, but increases towards positive middle-ear pressure in the case of a flat or inverted membrane geometry., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Objectives: To evaluate and compare functional outcomes of tympanoplasty procedures with temporalis fascia and four different types of cartilage grafts in chronic otitis media (COM) cases with normal preoperative hearing levels., Methods: Records of patients who underwent type 1 tympanoplasty for non-complicated COM in a tertiary medical center between January 2010 and January 2017 were reviewed. Patients with central or marginal and dry perforations of the tympanic membrane, normal middle ear mucosa, intact ossicular chain and patients with a preoperative pure tone average (PTA) level of 25 dB or less and a word recognition score (WRS) of 88% or greater were included in the study. Graft success rates, preoperative and postoperative functional outcomes, and anatomical results were analyzed., Results: One hundred and forty-four patients who met the inclusion criteria were evaluated in the study. PTA and Air-bone gap (ABG) levels decreased significantly both in TF and CG groups after the surgery (p = 0.001). Similarly, WRS scores increased significantly in both groups (p = 0.001). There was not a significant difference in terms of PTA increase, WRS increase, and ABG closure levels between cartilage and TF groups. Increase in PTA, closure in ABG, and increase in WRS levels were compared among TF, WsCCG, MCG, PCG, and CPIG groups. The increase in PTA levels was also found to be significantly superior in the TF group (p = 0,023). However, the multivariate analysis showed no significant difference for increase in WRS, closure in ABG and increase in PTA levels according to graft type (p = 0.285; p = 0.461; p = 0.106, respectively) and gender (p = 0.487; p = 0.811; p = 0.756, respectively)., Conclusion: In COM cases with normal preoperative hearing, both TF and cartilage lead to superb functional and anatomical outcomes. There was not a significant difference in terms of PTA increase, WRS increase and ABG closure levels between cartilage and TF groups. The graft success rate of cartilage was found to be superior to TF, but there was not a statistically significant difference. Different types of cartilage grafts can be used in cases with normal preoperative hearing without the concern of hearing impairment.

Background: The aim of the study was to determine morphometric and macroanatomic features of auditory ossicles and the tympanic bulla in wolf., Materials and Methods: For this purpose, 7 skulls of adult male wolf were used in the study. Auditory ossicles was photographed on a dissection microscope after it was removed from the skull. A total of 14 morphometric measurements were taken among the different points of malleus, incus and stapes in Image J programme. Mean values of the measurements were obtained and statistically compared in terms of sides (right-left)., Results: In male wolves, the lengths of the right and left malleus were determined as mean 9.35 ± 0.14 and 9.57 ± 0.25 mm, the lengths of the incus as mean 3.01 ± 0.32 and 2.94 ± 0.16 mm, and the lengths of the stapes as mean 2.57 ± 0.12 and 2.59 ± 0.14 mm, respectively. The differences were not statistically significant when all the morphometric parameters were compared in terms of sides (p > 0.05)., Conclusions: It is considered that this study will contribute to the anatomical studies to be conducted in the Canidae family regarding auditory ossicles.

The Weberian apparatus of otophysan fishes confers acute hearing that is hypothesized to allow these fishes to assess the environment and to find food resources. The otophysan family Serrasalmidae (piranhas and pacus) includes species known to feed on falling fruits and seeds (frugivore/granivores) that splash in rivers, herbivorous species associated with torrents and rapids (rheophiles), and carnivores that feed aggressively within shoals. Relevant sound stimuli may vary among these ecological groups and hearing may be tuned to different cues among species. In this context, we examined size variation of the Weberian ossicles, swim bladder chambers, and otoliths of 20 serrasalmid species from three broad feeding ecologies: frugivore/granivores, rheophiles, and carnivores. We performed 3D-reconstructions of high resolution tomographic data (μCT) from 54 museum specimens to estimate the size of these elements. We then tested for an ecology effect on covariation of auditory structure size and body size and accounted for phylogeny with phylogenetic generalized least squares analyses. Among ecological groups, we observed differences in relative sizes of otoliths associated with sound pressure and particle motion detection, and variation in Weberian ossicle size that may impact sound transmission. Rheophiles, which live in noisy environments, possess the strongest modifications of these structures., (© 2018 Wiley Periodicals, Inc.)

Human ear ossicles are essential for normal sound conduction from the external environment to the inner ear. These bones are subjected to high biomechanical loads due to the sustained vibrations which occur with reception of sound. It is expected that the bones would undergo a significant amount of remodeling and change in bone mineral density during the lifespan of an individual. Therefore, the aim of the study was to evaluate the possible changes in bone mineral density of regions of the ossicular chain during postnatal life. Forty four left and 36 right sets of human ear ossicles, ranging from a sub-adult age group to a mature adult age group, were sourced from the School of Anatomical Sciences, University of Witwatersrand. The ear ossicles were scanned using a micro-focus CT X-ray. A three-dimensional reconstruction of each ossicle was created from the CT scan. Bone mineral density was then determined at specific sites on the ossicles. There was no statistically significant variation found in the bone mineral density in relation to the age of the specimens. However, the handle of the malleus, the incudo-stapedial joint and the insertion site for the tendon of stapedius had lower bone mineral densities when compared to adjacent articulation and nonattachment sites on the ossicular chain. This is possibly due to biomechanical stress in response to sound conduction rather than ageing. Lower bone mineral density may be indicative of regions that experience the highest biomechanical force, thus, resulting in increased remodeling. Clin. Anat. 31:1158-1166, 2018. © 2018 Wiley Periodicals, Inc., (© 2018 Wiley Periodicals, Inc.)

The role of the ossicular joints in the mammalian middle ear is still debated. This work tests the hypothesis that the two synovial joints filter potentially damaging impulsive stimuli by transforming both the peak amplitude and width of these impulses before they reach the cochlea. The three-dimensional (3D) velocity along the ossicular chain in unaltered cadaveric human temporal bones (N = 9), stimulated with acoustic impulses, is measured in the time domain using a Polytec (Waldbronn, Germany) CLV-3D laser Doppler vibrometer. The measurements are repeated after fusing one or both of the ossicular joints with dental cement. Sound transmission is characterized by measuring the amplitude, width, and delay of the impulsive velocity profile as it travels from the eardrum to the cochlea. On average, fusing both ossicular joints causes the stapes velocity amplitude and width to change by a factor of 1.77 (p = 0.0057) and 0.78 (p = 0.011), respectively. Fusing just the incudomalleolar joint has a larger effect on amplitude (a factor of 2.37), while fusing just the incudostapedial joint decreases the stapes velocity on average. The 3D motion of the ossicles is altered by fusing the joints. Finally, the ability of current computational models to predict this behavior is also evaluated.

The middle ear bones of Mesozoic mammals are rarely preserved as fossils and the morphology of these ossicles in the earliest mammals remains poorly known. Here, we report the stapes and incus of the euharamiyidan Arboroharamiya from the lower Upper Jurassic (∼160 Ma) of northern China, which represent the earliest known mammalian middle ear ossicles. Both bones are miniscule in relation to those in non-mammalian cynodonts. The skull length/stapedial footplate diameter ratio is estimated as 51.74 and the stapes length as the percentage of the skull length is 4%; both numbers fall into the stapes size ranges of mammals. The stapes is "rod-like" and has a large stapedial foramen. It is unique among mammaliaforms in having a distinct posterior process that is interpreted as for insertion of the stapedius muscle and homologized to the ossified proximal (stapedial) end of the interhyal, on which the stapedius muscle attached. The incus differs from the quadrate of non-mammalian cynodonts such as morganucodontids in having small size and a slim short process. Along with lack of the postdentary trough and Meckelian groove on the medial surface of the dentary, the ossicles suggest development of the definitive mammalian middle ear (DMME) in Arboroharamiya. Among various higher-level phylogenetic hypotheses of mammals, the one we preferred places "haramiyidans" within Mammalia. Given this phylogeny, development of the DMME took place once in the allotherian clade containing euharamiyidans and multituberculates, probably independent to those of monotremes and therians. Thus, the DMME has evolved at least three times independently in mammals. Alternative hypothesis that placed "haramiyidans" outside of Mammalia would require independent acquisition of the DMME in multituberculates and euharamiyidans as well as parallel evolution of numerous derived similarities in the dentition, occlusion pattern, mandibles, cranium, and postcranium between the two groups and between "haramiyidans" and other mammals. J. Morphol. 279:441-457, 2018. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

The anatomy of the vestibular organs together with considerations of the middle and inner ear anatomy relevant to stapes surgery is discussed. An archival collection of macerated and freshly frozen human temporal bones underwent micro-computed tomography (CT) with subsequent volume-rendering. Three-dimensional (3D) reconstructions and the topographic anatomy of the oval window were considered. Micro-CT and 3D rendering revealed the relationship between the otolith organs and the oval window. Anatomic variations were extensive and included the distance between the footplate and the reconstructed macula margins. A "no-go" zone is suggested for the surgeon to avoid injury during stapes surgery., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The La Ferrassie 1 (LF1) skeleton, discovered over a century ago, is one of the most important Neandertal individuals both for its completeness and due to the role it has played historically in the interpretation of Neandertal anatomy and lifeways. Here we present new skeletal remains from this individual, which include a complete right middle ear ossicular chain (malleus, incus, and stapes), three vertebral fragments, and two costal remains. Additionally, the study of the skeleton has allowed us to identify new pathological lesions, including a congenital variant in the atlas, a greenstick fracture of the left clavicle, and a lesion in a mid-thoracic rib of unknown etiology. In addition, we have quantified the amount of vertebral pathology, which is greater than previously appreciated. We have complemented the paleopathological analysis with a taphonomic analysis to identify any potential perimortem fractures. The taphonomic analysis indicates that no surface alteration is present in the LF1 skeleton and that the breakage pattern is that of bone that has lost collagen, which would be consistent with the intentional burial of this individual proposed by previous researchers. In this study, we used CT and microCT scans in order to discover new skeletal elements to better characterize the pathological lesions and to quantify the fracture orientation of those bones in which the current plaster reconstruction did not allow its direct visualization, which underlines the broad potential of imaging technologies in paleoanthropological research. A century after its discovery, LF1 is still providing new insights into Neandertal anatomy and behavior., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Gliding is a distinctive locomotion type that has been identified in only three mammal species from the Mesozoic era. Here we describe another Jurassic glider that belongs to the euharamiyidan mammals and shows hair details on its gliding membrane that are highly similar to those of extant gliding mammals. This species possesses a five-boned auditory apparatus consisting of the stapes, incus, malleus, ectotympanic and surangular, representing, to our knowledge, the earliest known definitive mammalian middle ear. The surangular has not been previously identified in any mammalian middle ear, and the morphology of each auditory bone differs from those of known mammals and their kin. We conclude that gliding locomotion was probably common in euharamiyidans, which lends support to idea that there was a major adaptive radiation of mammals in the mid-Jurassic period. The acquisition of the auditory bones in euharamiyidans was related to the formation of the dentary-squamosal jaw joint, which allows a posterior chewing movement, and must have evolved independently from the middle ear structures of monotremes and therian mammals.

High resolution images are used as a basis for finite-element modeling of the middle-ear structures to study their biomechanical function. Commonly used imaging techniques such as micro-computed tomography (CT) and optical microscopy require extensive sample preparation, processing or staining using contrast agents to achieve sufficient soft-tissue contrast. We compare imaging of middle-ear structures in unstained, non-decalcified human temporal bones using conventional absorption-contrast micro-CT and using synchrotron radiation phase-contrast imaging (SR-PCI). Four cadaveric temporal bones were imaged using SR-PCI and conventional micro-CT. Images were qualitatively compared in terms of visualization of structural details and soft-tissue contrast using intensity profiles and histograms. In order to quantitatively compare SR-PCI to micro-CT, three-dimensional (3D) models of the ossicles were constructed from both modalities using a semi-automatic segmentation method as these structures are clearly visible in both types of images. Volumes of the segmented ossicles were computed and compared between the two imaging modalities and to estimates from the literature. SR-PCI images provided superior visualization of soft-tissue microstructures over conventional micro-CT images. Intensity profiles emphasized the improved contrast and detectability of soft-tissue in SR-PCI in comparison to absorption-contrast micro-CT. In addition, the semi-automatic segmentations of SR-PCI images yielded accurate 3D reconstructions of the ossicles with mean volumes in accord with volume estimates from micro-CT images and literature. Sample segmentations of the ossicles and soft tissue structures were provided on an online data repository for benefit of the research community. The improved visualization, modeling accuracy and simple sample preparation make SR-PCI a promising tool for generating reliable FE models of the middle-ear structures, including both soft tissues and bone., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Genetic mouse models are widely used for understanding human diseases but we know much less about the anatomical structure of the auditory ossicles in the mouse than we do about human ossicles. Furthermore, current studies have mainly focused on disease conditions such as osteomalacia and rickets in patients with hypophosphatemia rickets, although the reason that these patients develop late-onset hearing loss is unknown. In this study, we first analyzed Dmp1 lac Z knock-in auditory ossicles (in which the blue reporter is used to trace DMP1 expression in osteocytes) using X-gal staining and discovered a novel bony membrane surrounding the mouse malleus. This finding was further confirmed by 3-D micro-CT, X-ray, and alizarin red stained images. We speculate that this unique structure amplifies and facilitates sound wave transmissions in two ways: increasing the contact surface between the eardrum and malleus and accelerating the sound transmission due to its mineral content. Next, we documented a progressive deterioration in the Dmp1-null auditory ossicle structures using multiple imaging techniques. The auditory brainstem response test demonstrated a conductive hearing loss in the adult Dmp1-null mice. This finding may help to explain in part why patients with DMP1 mutations develop late-onset hearing loss, and supports the critical role of DMP1 in maintaining the integrity of the auditory ossicles and its bony membrane., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective To systematically review the anatomy of the ossicular chain. Data Sources Google Scholar, PubMed, and otologic textbooks. Review Methods A systematic literature search was performed on January 26, 2015. Search terms used to discover articles consisted of combinations of 2 keywords. One keyword from both groups was used: [ ossicular, ossicle, malleus, incus, stapes] and [ morphology, morphometric, anatomy, variation, physiology], yielding more than 50,000 hits. Articles were then screened by title and abstract if they did not contain information relevant to human ossicular chain anatomy. In addition to this search, references of selected articles were studied as well as suggested relevant articles from publication databases. Standard otologic textbooks were screened using the search criteria. Results Thirty-three sources were selected for use in this review. From these studies, data on the composition, physiology, morphology, and morphometrics were acquired. In addition, any correlations or lack of correlations between features of the ossicular chain and other features of the ossicular chain or patient were noted, with bilateral symmetry between ossicles being the only important correlation reported. Conclusion There was significant variation in all dimensions of each ossicle between individuals, given that degree of variation, custom fitting, or custom manufacturing of prostheses for each patient could optimize prosthesis fit. From published data, an accurate 3-dimensional model of the malleus, incus, and stapes can be created, which can then be further modified for each patient's individual anatomy.

Animals are frequently used for the development and testing of new hearing devices. Dimensions of the middle ear and cochlea differ significantly between humans and commonly used animals, such as rodents or cats. The sheep cochlea is anatomically more like the human cochlea in size and number of turns. This study investigated the middle-ear ossicular velocities and intracochlear sound pressure (ICSP) in sheep temporal bones, with the aim of characterizing the sheep as an experimental model for implantable hearing devices. Measurements were made on fresh sheep temporal bones. Velocity responses of the middle ear ossicles at the umbo, long process of the incus and stapes footplate were measured in the frequency range of 0.25-8 kHz using a laser Doppler vibrometer system. Results were normalized by the corresponding sound pressure level in the external ear canal (P EC ). Sequentially, ICSPs at the scala vestibuli and tympani were then recorded with custom MEMS-based hydrophones, while presenting identical acoustic stimuli. The sheep middle ear transmitted most effectively around 4.8 kHz, with a maximum stapes velocity of 0.2 mm/s/Pa. At the same frequency, the ICSP measurements in the scala vestibuli and tympani showed the maximum gain relative to the P EC (24 dB and 5 dB, respectively). The greatest pressure difference across the cochlear partition occurred between 4 and 6 kHz. A comparison between the results of this study and human reference data showed middle-ear resonance and best cochlear sensitivity at higher frequencies in sheep. In summary, sheep can be an appropriate large animal model for research and development of implantable hearing devices., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Multiple mammalian lineages independently evolved a definitive mammalian middle ear (DMME) through breakdown of Meckel's cartilage (MC). However, the cellular and molecular drivers of this evolutionary transition remain unknown for most mammal groups. Here, we identify such drivers in the living marsupial opossum Monodelphis domestica , whose MC transformation during development anatomically mirrors the evolutionary transformation observed in fossils. Specifically, we link increases in cellular apoptosis and TGF-BR2 signalling to MC breakdown in opossums. We demonstrate that a simple change in TGF-β signalling is sufficient to inhibit MC breakdown during opossum development, indicating that changes in TGF-β signalling might be key during mammalian evolution. Furthermore, the apoptosis that we observe during opossum MC breakdown does not seemingly occur in mouse, consistent with homoplastic DMME evolution in the marsupial and placental lineages., (© 2017 The Author(s).)

Current clinical practice cannot distinguish, with any degree of certainty, the multiple pathologies that produce conductive hearing loss in patients with an intact tympanic membrane and a well-aerated middle ear without exploratory surgery. The lack of an effective non-surgical diagnostic procedure leads to unnecessary surgery and limits the accuracy of information available during pre-surgical consultations with the patient. A non-invasive measurement to determine the pathology responsible for a conductive hearing loss prior to surgery would be of great value. This work investigates the utility of wideband acoustic immittance (WAI), a non-invasive measure of middle-ear mobility, in the differential diagnosis of pathologies responsible for conductive hearing loss. We focus on determining whether power reflectance (PR), a derivative of WAI, is a possible solution to this problem. PR is a measure of the fraction of sound power reflected from the middle ear when a sound stimulus is presented to the ear canal. PR and other metrics of middle-ear performance (such as ossicular motion via laser Doppler vibrometry) were measured in well-controlled human temporal bone preparations with simulated pathologies. We report measurements before and after simulation of stapes fixation (n = 8), malleus fixation (n = 10), ossicular disarticulation (n = 10), and superior canal dehiscence (n = 8). Our results are consistent with the small set of previously published reflectance measurements made in temporal bones and patients. In this present study, these temporal bone experiments with different middle- and inner-ear pathologies were compared to the initial normal state by analyzing both WAI and ossicular motion, demonstrating that WAI can be a valuable tool in the diagnosis of conductive hearing loss., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The diminutive middle ear ossicles (malleus, incus, stapes) housed in the tympanic cavity of the temporal bone play an important role in audition. The few known ossicles of Neandertals are distinctly different from those of anatomically modern humans (AMHs), despite the close relationship between both human species. Although not mutually exclusive, these differences may affect hearing capacity or could reflect covariation with the surrounding temporal bone. Until now, detailed comparisons were hampered by the small sample of Neandertal ossicles and the unavailability of methods combining analyses of ossicles with surrounding structures. Here, we present an analysis of the largest sample of Neandertal ossicles to date, including many previously unknown specimens, covering a wide geographic and temporal range. Microcomputed tomography scans and 3D geometric morphometrics were used to quantify shape and functional properties of the ossicles and the tympanic cavity and make comparisons with recent and extinct AMHs as well as African apes. We find striking morphological differences between ossicles of AMHs and Neandertals. Ossicles of both Neandertals and AMHs appear derived compared with the inferred ancestral morphology, albeit in different ways. Brain size increase evolved separately in AMHs and Neandertals, leading to differences in the tympanic cavity and, consequently, the shape and spatial configuration of the ossicles. Despite these different evolutionary trajectories, functional properties of the middle ear of AMHs and Neandertals are largely similar. The relevance of these functionally equivalent solutions is likely to conserve a similar auditory sensitivity level inherited from their last common ancestor., Competing Interests: The authors declare no conflict of interest.

The presence of three interconnected auditory ossicles in the middle ear is a defining characteristic of mammals, and aspects of ossicle morphology are related to hearing sensitivity. However, analysis and comparison of ossicles are complicated by their minute size and complex three-dimensional shapes. Here we introduce a geometric morphometric measurement protocol for 3D shape analysis based on landmarks and semilandmarks obtained from μCT images and apply it to ossicles of extant hominids (great apes and humans). We show that the protocol is reliable and reproducible over a range of voxel resolutions, and captures even subtle shape differences. Using this approach it is possible to distinguish the hominid taxa by mean shapes of their malleus and incus (p < 0.01). The stapes appears less diagnostic, although this may in part be related to the small sample size available. Using ancestral state estimation, we show that, within hominids, Homo sapiens is derived with respect to its malleus (short manubrium, long corpus, head anterior-posterior flattened, articular facet shape), incus (wide intercrural curvature, long incudal processes, articular facet shape) and stapes (high stapes with kidney-shaped footplate). H. sapiens also shows a number of plesiomorphic shape traits whereas Gorilla and Pan possess a number of autapomorphic characteristics. The Pongo ossicles appear to be close to the plesiomorphic hominid condition. The malleus shows little difference in size among hominids, and allometry is thus of little importance. In contrast, the incus and stapes are more variable in size, and their shape is more strongly related to size differences. Although the form-function relationships in the middle ear are not fully understood, some aspects of ossicle morphology suggest that interspecific differences in hearing capacities are present among hominids. Finally, the results of this study provide a comparative framework for morphometric studies analyzing ossicles of extinct hominids, with a bearing on taxonomy, phylogeny and auditory function., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

William Cheselden's famous anatomical treatise spanned the entire 18th century period with its 15 editions. The aim of this study is to analyze the otological knowledge described in all these editions, to identify key 18th century otological advancements, and to study their concordance.In the first edition (1713), Cheselden notably mentioned four middle ear ossicles: malleus, incus, fourth ossicle, and stapes; four auditory muscles: "external tympani," "external oblique," tensor tympani, and stapedial; and a small opening in the tympanic membrane. In subsequent editions, minimal changes appeared, except for nomenclature changes and the proposal of an artificial opening of the tympanic membrane. Virtually no changes were performed up to the last edition (1806). All Cheselden's Editions confirm the uncertain presence of a fourth ossicle, the disputable presence of a tympanic membrane opening and the "usual" accepted presence of three muscles to the malleus. Key otologic advancements, not found in any of Cheselden's writings, were catherization of the Eustachian tube, presence of fluid in the inner ear, and the surgical opening of the mastoid.This study demonstrates that Cheselden, and his subsequent editors, were unaware of some important otologic developments that revolutionized the field of otology. Description of key advancements lacking in his treatise includes catherization of the Eustachian tube, the presence of fluid in the inner ear, and the surgical opening of the mastoid. Nevertheless, Cheselden is first in proposing to artificially open the tympanic membrane in humans.

The auditory ossicles in primates have proven to be a reliable source of phylogenetic information. Nevertheless, to date, very little data have been published on the metric dimensions of the ear ossicles in African apes and humans. The present study relies on the largest samples of African ape ear ossicles studied to date to address questions of taxonomic differences and the evolutionary transformation of the ossicles in gorillas, chimpanzees and humans. Both African ape taxa show a malleus that is characterized by a long and slender manubrium and relatively short corpus, whereas humans show the opposite constellation of a short and thick manubrium and relatively long corpus. These changes in the manubrium are plausibly linked with changes in the size of the tympanic membrane. The main difference between the incus in African apes and humans seems to be related to changes in the functional length. Compared with chimpanzees, human incudes are larger in nearly all dimensions, except articular facet height, and show a more open angle between the axes. The gorilla incus resembles humans more closely in its metric dimensions, including functional length, perhaps as a result of the dramatically larger body size compared with chimpanzees. The differences between the stapedes of humans and African apes are primarily size-related, with humans being larger in nearly all dimensions. Nevertheless, some distinctions between the African apes were found in the obturator foramen and head height. Although correlations between metric variables in different ossicles were generally lower than those between variables in the same bone, variables of the malleus/incus complex appear to be more strongly correlated than those of the incus/stapes complex, perhaps reflecting the different embryological and evolutionary origins of the ossicles. The middle ear lever ratio for the African apes is similar to other haplorhines, but humans show the lowest lever ratio within primates. Very low levels of sexual dimorphism were found in the ossicles within each taxon, but some relationship with body size and several dimensions of the ear bones was found. Several of the metric distinctions in the incus and stapes imply a slightly different articulation of the ossicular chain within the tympanic cavity in African apes compared with humans. The limited auditory implications of these metric differences in the ossicles are also discussed. Finally, the results of this study suggest that several plesiomorphic features for apes may be retained in the ear bones of the early hominin taxa Australopithecus and Paranthropus as well as in the Neandertals., (© 2014 Anatomical Society.)

Since there is a lack of information about the normal appearance or pathological findings of the equine external ear canal (EEEC) and tympanic membrane (TM), we aimed to find a practical way to perform the otoscopic examination in standing, sedated horses. Therefore, we worked with common veterinary video endoscopes, which are normally used for gastroscopy or bronchoscopy. Both ears each of 38 randomly selected, chemically restrained horses were otoscopically examined. 33 of those horses had no history or signs of potentially ear-associated diseases. However, two horses with vestibular disease and three horses with head shaking were included in the otoscopic examinations. We created references of the normal appearance of the EEEC and TM on the basis of the characteristic anatomical landmarks, degree of debris, amount of keratin scales, shape of the intersection between the cartilaginous (CEEC) and osseous (OEEC) portion of the external ear canal, shape of the OEEC, formation of the keratin layer and its integrity, epithelium colour of the OEEC, and complexion of the TM. With this information, we were able to visualise tympanosclerosis in two equine eardrums, as well as low-grade to severe external otitis in three horses. Severe bilateral external otitis combined with temporohyoid osteoarthropathy (THO) was found in one of those horses. A foreign body was found in one OEEC. This study shows that otoscopic examination is a basic, easy to perform and beneficial diagnostic procedure for a complete work-up of ear-related diseases, such as THO, facial nerve paralysis, vestibular disease, head-shaking or head trauma. Plus, regarding animal welfare, well being of horses is highly influenced by noise exposure. Therefore research on equine audiological aspects needs to be promoted. The standardized otoscopic examination provides an important basis for further research on aural diseases.

Traditionally, otologists have aimed to produce a clean, dry, safe ear with the best possible hearing result. More recently, "less invasively" has been added to this list of goals. The development of small-diameter, high-quality rigid endoscopes and high-definition video systems has made totally endoscopic, transcanal surgery a reality in adult otology and a possibility in pediatric otology. This article reviews the anatomy of the pediatric middle ear and its surrounding airspaces and structures based on the work of dozens of researchers over the past 50 years. It will focus on the developmental changes in ear anatomy from birth through the first decade, when structure and function change most rapidly. Understanding the limits and possibilities afforded by new endoscopic technologies, the pediatric otologist can strive for results matching or exceeding those achieved by more invasive surgical approaches.

This paper presents a design guideline for matching a fully implantable middle ear microphone with the physiology of human hearing. The guideline defines the first natural frequency of a seismic sensor placed at the tip of the manubrium mallei with respect to the frequency-dependence hearing of the human ear as well as the deflection of the ossicular chain. A transducer designed in compliance with the guideline presented reduces the range of the output signal while preserving all information obtained by the ossicular chain. On top of a output signal compression, static deflections, which can mask the tiny motions of the ossicles, are reduced. For guideline verification, a microelectromechanical system (MEMS) based on silicon on insulator technology was produced and tested. This prototype is capable of resolving 0.4 pm/Hz with a custom made read-out circuit. For a bandwidth of 0.1 kHz, this deflection is comparable with the lower threshold of speech (≈ 40 phon)., (Copyright © 2013. Published by Elsevier Ltd.)

Efficient transfer of sound by the middle ear ossicles is essential for hearing. Various pathologies can impede the transmission of sound and thereby cause conductive hearing loss. Differential diagnosis of ossicular disorders can be challenging since the ossicles are normally hidden behind the tympanic membrane (TM). Here we describe the use of a technique termed optical coherence tomography (OCT) vibrography to view the sound-induced motion of the TM and ossicles simultaneously. With this method, we were able to capture three-dimensional motion of the intact TM and ossicles of the chinchilla ear with nanometer-scale sensitivity at sound frequencies from 0.5 to 5 kHz. The vibration patterns of the TM were complex and highly frequency dependent with mean amplitudes of 70-120 nm at 100 dB sound pressure level. The TM motion was only marginally sensitive to stapes fixation and incus-stapes joint interruption; however, when additional information derived from the simultaneous measurement of ossicular motion was added, it was possible to clearly distinguish these different simulated pathologies. The technique may be applicable to clinical diagnosis in Otology and to basic research in audition and acoustics., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The middle ear apparatus varies considerably among living mammals. Body size, phylogeny and acoustic environment all play roles in shaping ear structure and function, but experimental studies aimed ultimately at improving our understanding of human hearing can sometimes overlook these important species differences. This review focuses on three groups of mammals, bringing together anatomical, zoological and physiological information in order to highlight unusual features of their middle ears and attempt to interpret their function. "Microtype" ears, found in species such as mice and bats, are associated with high-frequency hearing. The orbicular apophysis, the focus of some recent developmental studies on mouse ears, is characteristic of microtype mallei but is not found in humans or other "freely mobile" species. The apophysis increases ossicular inertia about the anatomical axis of rotation: its adaptive purpose in a high-frequency ear is still not clear. Subterranean mammals have convergently evolved a "freely mobile" ossicular morphology which appears to favour lower-frequency sound transmission. More unusual features found in some of these animals include acoustically coupled middle ear cavities, the loss of middle ear muscles and hypertrophied ossicles which are believed to subserve a form of inertial bone conduction. Middle ears of the rodent group Ctenohystrica (which includes guinea pigs and chinchillas, important models in hearing research) show some striking characteristics which together comprise a unique type of auditory apparatus requiring a classification of its own, referred to here as the "Ctenohystrica type". These characteristics include a distinctive malleus morphology, fusion of the malleus and incus, reduction or loss of the stapedius muscle, a synovial stapedio-vestibular articulation and, in chinchillas, enormously expanded middle ear cavities. These characteristics may be functionally linked and associated with the excellent low-frequency hearing found in these animals. The application of new experimental and imaging data into increasingly sophisticated models continues to improve our understanding of middle ear function. However, a more rigorous comparative approach and a better appreciation of the complex patterns of convergent and divergent evolution reflected in the middle ear structures of living mammals are also needed, in order to put findings from different species into the appropriate context. This article is part of a special issue entitled "MEMRO 2012"., (Copyright © 2012 Elsevier B.V. All rights reserved.)

We investigated the contribution of the middle ear to the physiological response to bone conduction stimuli in chinchilla. We measured intracochlear sound pressure in response to air conduction (AC) and bone conduction (BC) stimuli before and after interruption of the ossicular chain at the incudo-stapedial joint. Interruption of the chain effectively decouples the external and middle ear from the inner ear and significantly reduces the contributions of the outer ear and middle ear to the bone conduction response. With AC stimulation, both the scala vestibuli Psv and scala tympani Pst sound pressures drop by 30-40 dB after the interruption. In BC stimulation, Psv decreases after interruption by about 10-20 dB, but Pst is little affected. This difference in the sensitivity of the BC induced Psv and Pst to ossicular interruption is not consistent with a BC response to ossicular motion, but instead suggests a significant contribution of an inner-ear drive (e.g., cochlear fluid inertia or compressibility) to the BC response. This article is part of a special issue entitled "MEMRO 2012"., (Copyright © 2012 Elsevier B.V. All rights reserved.)

There is a great demand for implantable microphones for future generations of implantable hearing aids, especially Cochlea Implants. An implantable middle ear microphone based on a piezoelectric membrane sensor for insertion into the incudostapedial gap is investigated. The sensor is designed to measure the sound-induced forces acting on the center of the membrane. The sensor mechanically couples to the adjacent ossicles via two contact areas, the sensor membrane and the sensor housing. The sensing element is a piezoelectric single crystal bonded on a titanium membrane. The sensor allows a minimally invasive and reversible implantation without removal of ossicles and without additional sensor fixation in the tympanic cavity. This study investigates the implantable microphone sensor and its implantation concept. It intends to quantify the influence of the sensor's insertion position on the achievable microphone sensitivity. The investigation considers anatomical and pathological variations of the middle ear geometry and its space limitations. Temporal bone experiments on a laboratory model show that anatomical and pathological variations of the middle ear geometry can prevent the sensor from being placed optimally within the incudostapedial joint. Beyond scattering of transfer functions due to anatomic variations of individual middle ears there is the impact of variations in the sensor position within the ossicular chain that has a considerable effect on the transfer characteristics of the middle ear microphone. The centering of the sensor between incus and stapes, the direction of insertion (membrane to stapes or to incus) and the effect of additional contact points with surrounding anatomic structures affect the signal yield of the implanted sensor. The presence of additional contact points has a considerably impact on the sensitivity, yet the microphone sensitivity is quite robust against small changes in the positioning of the incus on the sensor. Signal losses can be avoided by adjusting the position of the sensor within the joint. The findings allow the development of an improved surgical insertion technique to ensure maximally achievable signal yield of the membrane sensor in the ISJ and provides valuable knowledge for a future design considerations including sensor miniaturization and geometry. Measurements of the implanted sensor in temporal bone specimens showed a microphone sensitivity in the order of 1 mV/Pa. This article is part of a special issue entitled "MEMRO 2012"., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The middle ear ossicles are only rarely preserved in fossil hominins. Here, we report the discovery of a complete ossicular chain (malleus, incus, and stapes) of Paranthropus robustus as well as additional ear ossicles from Australopithecus africanus. The malleus in both early hominin taxa is clearly human-like in the proportions of the manubrium and corpus, whereas the incus and stapes resemble African and Asian great apes more closely. A deep phylogenetic origin is proposed for the derived malleus morphology, and this may represent one of the earliest human-like features to appear in the fossil record. The anatomical differences found in the early hominin incus and stapes, along with other aspects of the outer, middle, and inner ear, are consistent with the suggestion of different auditory capacities in these early hominin taxa compared with modern humans.

The ossicular chain in La Ferrassie 3 was briefly described in the monograph on the La Ferrassie Neandertal children, but to date has not been the subject of detailed study. We provide new data on these important fossils and re-examine some previous suggestions of derived Neandertal features in the middle ear ossicles based on more limited evidence. The malleus shows a curved lateral margin of the manubrium and a relatively large head. The incus shows a tall articular facet, a depressed area on the medial surface of the body, a straight anterior border of the long process and a more closed angle between the processes. The stapes shows an asymmetrical configuration of the crura, with an anteriorly skewed head, and generally small dimensions, including a smaller and relatively wider stapedial footplate. These same features can also be seen in the few other Neandertal ear ossicles known, suggesting that a consistent anatomical pattern characterizes the Neandertal ossicular chain. While the phylogenetic polarity of many of these features remains to be clarified, the asymmetrical stapes and anteriorly skewed stapedial head appear to be derived Neandertal features. In addition, while the larger malleus head and incus articular facet in La Ferrassie 3 might reflect larger body mass in Neandertals, the larger stapes footplates in Homo sapiens cannot be explained by changes in body mass. Indeed, H. sapiens seems to depart from the general mammalian pattern in combining an increase in stapes footplate size with a decrease in body mass. Although the malleus/incus lever ratio in La Ferrassie 3 is similar to that in H. sapiens, Neandertals appear to be characterized by a slightly different spatial relationship and articulation of the ossicular chain within the tympanic cavity. While only limited inferences can be drawn regarding hearing ability based on the ossicles, the few physiologically relevant dimensions in the La Ferrassie 3 ear bones are similar to H. sapiens., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The human ear is a complex biomechanical system and is divided into three parts: outer, middle and inner ear. The middle ear is formed by ossicles (malleus, incus and stapes), ligaments, muscles and tendons, which transfers sound vibrations from the eardrum to the inner ear, linking with mastoid and Eustachian tube. In this work, a finite element modelling of the tympano-ossicular system of the middle ear was developed. A dynamic study based on a structural response to harmonic vibrations, for a sound pressure level (SPL) of 110, 120 and 130 dB SPL applied in the eardrum, is presented. The connection between the ossicles is made using a contact formulation. The model includes the different ligaments considering its hyperelastic behaviour. The activation of the muscles is based on the constitutive model proposed by previous work. The harmonic responses of displacement and pressure obtained on the stapes footplate, for a frequency range between 100 Hz and 10 kHz, are obtained simulating the muscle activation. The results are compared considering the passive and active states. The results are discussed and they are in accordance with audiological data published with reference to the effects of the middle ear muscles contraction.

Having three ossicles in the middle ear is one of the defining features of mammals. All reptiles and birds have only one middle ear ossicle, the stapes or columella. How these two additional ossicles came to reside and function in the middle ear of mammals has been studied for the last 200 years and represents one of the classic example of how structures can change during evolution to function in new and novel ways. From fossil data, comparative anatomy and developmental biology it is now clear that the two new bones in the mammalian middle ear, the malleus and incus, are homologous to the quadrate and articular, which form the articulation for the upper and lower jaws in non-mammalian jawed vertebrates. The incorporation of the primary jaw joint into the mammalian middle ear was only possible due to the evolution of a new way to articulate the upper and lower jaws, with the formation of the dentary-squamosal joint, or TMJ in humans. The evolution of the three-ossicle ear in mammals is thus intricately connected with the evolution of a novel jaw joint, the two structures evolving together to create the distinctive mammalian skull., (© 2012 The Authors. Journal of Anatomy © 2012 Anatomical Society.)

The ossicular chain of the human middle ear has a key role in sound conduction since it transfers vibrations from the tympanic membrane to the cochlea, connecting the outer and the inner part of the hearing organ. This study reports firstly a description of the main anatomical features of the middle ear to introduce a detailed survey of its biomechanics, focused on model development, with a collection of geometric, inertial and mechanical/material parameters. The joint issues are particularly discussed from the perspective of developing a model of the middle ear both explanatory and predictive. Such a survey underlines the remarkable dispersion of data, due also to the lack of a standardization of the experimental techniques and conditions. Subsequently, a 3D multi-body model of the ossicular chain and other structures of the middle ear is described. Such an approach is justified as the ossicles were proven to behave as rigid bodies in the human hearing range and was preferred to the more widely used finite element one as it simplifies the model development and improves joint modeling. The displacement of the umbo (a reference point of the tympanic membrane) in the 0.3-6kHz frequency range was defined as input of the model, while the stapes footplate displacement as output. A parameter identification procedure was used to find parameter values for reproducing experimental and numerical reference curves taken from the literature. This simple model might represent a valid alternative to more complex models and might provide a useful tool to simulate pathological/post-surgical/post-traumatic conditions and evaluate ossicular replacement prostheses., (Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.)

Objective: The aim of this study was to assess the feasibility of ultrashort echo time (UTE) imaging in the visualization of middle ear ossicles in normal subjects., Methods: 12 young adult volunteers (males/females = 6/6, age 25-44 years, mean 30.3 years) with normal hearing levels underwent MRI studies using a 3.0 T clinical unit with an eight-channel SENSE head coil. For each subject, the whole head was imaged using a three-dimensional dual-echo UTE imaging sequence with radial trajectory and the following parameters: field of view, 240 × 240 × 240 mm; matrix, 320 × 320; flip angle, 7°; repetition time/echo time (TE)1/TE2, 8.0 ms/0.14 ms/1.8 ms; acquisition voxel size, 0.75 × 0.75 × 0.75 mm; number of signals averaged, 1; imaging time, 27 min 20 s. Subsequently, subtraction images were obtained by subtracting long TE (1.8 ms) images from short TE (0.14 ms) images. By using these three images, the visibility of the bilateral middle ear ossicles was evaluated. Moreover, as a reference for the UTE findings, CT images of the temporal bone were obtained in one volunteer., Results: In all subjects, the middle ear ossicles were clearly visualized as a high signal intensity spot surrounded by a signal void of air on short TE images bilaterally, while they were not visible in long TE images in any of the subjects. The subtraction images provided better contrast of the ossicles., Conclusion: We demonstrated the feasibility of UTE imaging of the middle ear ossicle in normal subjects.

Hypothesis: Precise knowledge of the expression and distribution of extracellular matrix (ECM) molecules and osteochondrogenic markers helps target the proper in vitro regeneration of novel ossicular chain (OC) replacements via tissue engineering (TE)., Background: We performed an extensive histologic analysis of human ear ossicles in healthy adults. A variety of OC prostheses are currently available, but extrusion of synthetic devices still represents an important clinical phenomenon. TE is a novel discipline combining stem cells, bioresorbable biomaterials, and stimulatory factors for the development of new living tissues in vitro, which might offer forefront opportunities to otologic surgery. However, to drive stem cell differentiation correctly, the final tissue target must be accurately known., Methods: Malleus, incus, and stapes were collected from cadaveric temporal bones. TE PORPs were obtained via osteodifferentiation of human mesenchymal stromal cells on polymeric scaffolds. Histochemical and immunohistochemical analyses were performed to detect ECM molecules and osteochondrogenic markers., Results: Malleus and incus showed the same histologic tissue type, with similar levels of expression and distributions for both ECM molecules and osteochondrogenic markers, whereas the stapes showed self-standing histologic patterns. In TE PORPs, mesenchymal ECM synthesis and early stage development of ossification sites could be observed, highlighting good cellular integration with the scaffold biomaterial., Conclusion: Detailed morphologic study of the ossicles provides data related to tissue dynamics involved in their development, defining features of tissue differentiation and maturation. Such findings underpin the future development of biomimetic ossicular replacement, data that can guide tissue-engineered ossiculoplasty.

High-resolution 3D morphology models of cat, gerbil, rabbit, rat and human ossicular chains are presented. The models are based on high-resolution CT measurements. The resolution of the CT images, from which the models are segmented, varies from 5.6 to 33.5 μm. Models are freely available in different formats at our website (http://www.ua.ac.be/bimef/models) for research and educational purposes., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The middle ears of seven species of rodents, including four hamster species, were examined under light microscopy and through micro-CT imaging. Hamsters were found to possess a spectrum of ossicular morphologies ranging from something approaching "freely mobile" (Mesocricetus) to something nearer the "microtype" (Cricetulus), although no hamster has an orbicular apophysis of the malleus. Rats, mice and Calomyscus were found to have typically microtype ossicles. To explore the functional effects of these morphological differences, CT scan data were used to calculate the magnitudes of the moments of inertia and positions of the centres of mass and principal rotational axes for the malleus-incus complexes. Microtype species were found to have much greater ossicular inertias, relative to size, about the "anatomical axis" extending between anterior process of the malleus and short process of the incus; ossicular centres of mass were displaced further from this axis. Calculated inertial values were then put into an existing model of middle ear function (Hemilä et al., 1995), in order to see whether the more accurate data would improve predictions of upper hearing limits. For the rat and mouse they did, but this was not so for the hamster Mesocricetus. This might indicate that the inner rather than the middle ear limits hearing in this species, or might simply reflect other shortcomings of the model. Functional differences appear to exist even among rodent ears of the same general type, but the adaptive significance of these differences remains enigmatic., (Copyright © 2011 Elsevier B.V. All rights reserved.)