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Purpose: The aims of the present study were to identify detailed positional relationship between the auditory ossicles and to provide theoretic navigational guidelines for optimal prosthesis adaptation and effective malleostapedotomy., Methods: Fifty sides of the temporal bone from donated cadavers were scanned by MicroCT and the malleus, incus, stapes and tympanic membrane were materialized three dimensionally using computer software. Dimensions between the auditory ossicles closely related to malleostapedotomy were measured twice., Results: The grip site of malleus handle was mean 1.8 mm superior and mean 1.3 mm anterior, and linear distance between the grip site of malleus handle and the footplate of the stapes was mean 6.5 mm. The stapes was not parallel to the tympanic membrane and rotated mean 10.7° posteriorly relative to the tympanic membrane., Conclusion: Surgeons should start with at least 8.75 mm prosthesis to cover the upper limits of potential anatomy and then trim down to the individualization to the case. The ideal loop morphology has to be oval shape more than 1.4 mm in the long diameter and 1.0 mm in the short diameter. The wire of the prosthesis has to be bended at the two points: about 10° anteriorly at the most proximal point of the wire and about 50° superiorly at the stapes head point.

A detailed anatomy of the braincase and stapes of the subadult specimen of Diadectes absitus from early Permian sediments of Germany are described for the first time based on the high-resolution X-ray microcomputed tomography. In contrast to previous studies of Diadectes, the bones of the braincase (opisthotic, prootic, supraoccipital, basioccipital, exoccipital, basisphenoid, and sphenethmoid), and parasphenoid of D. absitus are not co-ossified, but suturally defined. This has allowed for a reconstruction of a complete braincase with all sutures between the individual bones. The opisthotic, prootic, and supraocciptal contain a well-preserved endosseous labyrinth. The three-dimensional-reconstruction of its cavities shows a well-preserved vestibule, three semicircular canals, and well-developed cochlear recess. In addition, a shallow subarcuate fossa is present on the ventral surface of the supraoccipital, which lies medial to the anterior semicircular canal. A typical feature of the diadectid braincase is the presence of the otic tube leading from the fenestra vestibuli to the vestibule. A revision of the topology of this structure is presented here. Here, we describe new structures of the stapes, especially in its proximal portion, as well as its position to the fenestra vestibuli. These structures are described for the first time not only in D. absitus, but for the genus., (© 2020 American Association for Anatomy.)

Background: Ultra-high-resolution computed tomography (U-HRCT) utilizes a 1024 × 1024 matrix with 0.25-mm section thickness, offering better spatial resolution than conventional multi-detector row CT to detect anatomic data for otologic surgery., Aims: We examined stapes footplate thickness using U-HRCT in relation to stapedotomy to predict the difficulty of the surgical procedure., Materials and Methods: Subjects were 12 otosclerosis patients and 25 controls who underwent diagnostic U-HRCT. A profile curve (Hounsfield units) was used to measure stapes footplate thickness along a perpendicular line across the stapes footplate in a plane parallel to the lateral semicircular canal., Results: Footplate thickness was smaller at the midpoint than just before the anterior crus and just after the posterior crus. Interobserver variability was lowest at the midpoint, where foot plate thickness was significantly greater in the affected ear in otosclerosis patients compared with controls (0.60 ± 0.09 mm vs 0.46 ± 0.04 mm; p  < .001). Otosclerosis patients were detected using U-HRCT with a high area under the curve. Difficulty in the stapes opening procedure correlated with stapes footplate thickness., Conclusions: Footplate thickness on U-HRCT correlated with temporal bone anatomy and corresponded to surgical difficulty. Significance: U-HRCT-derived anatomic data is useful for evaluating the stapes.

Objectives: To compare the results of ossiculoplasty with two different partial ossicular replacement prostheses (PORP) to ossiculoplasty with a total ossicular replacement prosthesis (TORP) in patients with an intact stapes suprastructure., Methods: All patients required primary or revision surgery for chronic middle ear disease and ossicular reconstruction with either a PORP or a TORP, as well as a with an intact stapes suprastructure. In total, 141 patients receiving classic tympanoplasty with PORP (N = 92), ossiculoplasty with PORP with ball joint (N = 22), or TORP (N = 27) between January 2011 and March 2017 were included in this study. The inclusion criterion was an intact stapes suprastructure. The underlying indication for surgery was either middle ear disease, such as cholesteatoma, or revision surgery for audiological improvement. The main outcome measures were four-frequency pure tone average (0.5, 1, 2, 3 kHz) at early and late follow-up after ossiculoplasty, the effects of clinical factors including the underlying middle ear disease, and primary or revision surgery., Results: All patients showed a significantly reduced air-bone gap (ABG 0.5, 1, 2, 3 kHz) at late follow-up (mean: 18 dB) compared to preoperative measurements (mean: 25.5 dB). A significantly better outcome in ABG closure was shown among patients with a preoperatively intact tympanic membrane, with an intact stapes suprastructure or without preexisting cholesteatoma. Outcome was not significantly influenced by the prosthesis-type, the creation of an open mastoid cavity, the status of the mucosa, or the indication for surgery., Conclusion: TORP with an intact stapes suprastructure is a safe procedure and provides audiological outcomes similar to PORP., Level of Evidence: 2C Laryngoscope, 130:768-775, 2020., (© 2019 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives: Research using rat as an in-vivo model has played an important role in otological research. The rat ear anatomy has been described; however, detailed surgical procedures to access the temporal bone are limited. The authors present a technique to approach the inner ear of rat that was standardized by cadaveric dissections and later replicated in living animals., Methods: Adult Wistar albino rats were dissected via the post-auricular approach. The emphasis was on early identification of the facial nerve that formed a reliable landmark for the tympanic bulla, which in turn houses the round window and stapedial artery. The point of identification of facial nerve was postero-inferior to the external auditory meatus. The procedure was then repeated in living animals., Results: Seventeen cadaveric rats were dissected. Initially, the investigators attempted to identify the facial nerve at its crossing over the external auditory meatus. However, that method was found to be unsatisfactory. The facial nerve was then attempted to be identified in its course postero-inferior to the external auditory meatus. The technique improved drastically, and the facial nerve was identified promptly and reliably. The procedure was then repeated in seven living rats under general anaesthesia. The major issues encountered were bleeding from the stapedial artery, hematoma of the pinna in one rat., Conclusion: This study suggests that the post-auricular approach is a feasible and less time consuming route for round window drug delivery experiments in Wistar albino rats. Recognition of anatomical landmarks, particularly the facial nerve is the key to surgery., (Copyright © 2019 Elsevier B.V. All rights reserved.)

BACKGROUND Otosclerosis is a primary disease of the bony labyrinth. In the course of otosclerosis, abnormal resorption and recalcification of the endochondral layer of the temporal bone is observed. The otosclerotic process most commonly develops in the anterior part of the oval window. MATERIAL AND METHODS We analyzed stapes superstructures from 4 patients undergoing surgery for otosclerosis. The first step involved tissue assessment under a scanning electron microscope. The resulting images were analyzed in terms of morphological changes. The stapes superstructure was then divided into small "ossicles", including fragments from the closest vicinity of the stapes footplate and a fragment of the head of the stapes. This material was examined using a scanning electron microscope with a unit for chemical analysis in microareas. RESULTS Chemical analysis confirms the appearance of considerable quantities of the following elements: carbon, oxygen, potassium, and calcium, and the appearance of small quantities of sodium and magnesium. Based on a detailed analysis of the chemical composition, these fragments could represent a calcium phosphate compound from the following system: CaO-P₂O₅-H₂O. Fragments of the superstructure from the region closest to the base of the stapes demonstrated a considerably larger presence of carbon, oxygen, and nitrogen, which most likely suggests an increased metabolic process in this region. CONCLUSIONS Our analysis revealed an increased metabolic activity in the closest vicinity of the otosclerotic focus, the fissula ante fenestram. The increased metabolism correlated with the bone tissue changes seen on scanning electron microscopy.

Background: The anatomy of the membranous labyrinth within the vestibule has direct implications for surgical intervention. The anatomy of the otoliths has been studied, but there is limited information regarding their supporting connective tissue structures such as the membrana limitans in humans., Methods: One guinea pig and 17 cadaveric human temporal bones were scanned using micro computed tomography, after staining with 2 per cent osmium tetroxide and preservation with Karnovsky's solution, with a resolution from 1 µm to 55 µm. The data were analysed using VGStudio Max software, rendered in three-dimensions and published in augmented reality., Results: In 50 per cent of ears, the membrana limitans attached directly to the postero-superior part of the stapes footplate. If attachments were present in one ear, they were present bilaterally in 100 per cent of cases., Conclusion: Micro computed tomography imaging allowed three-dimensional assessment of the inner ear. Such assessments are important as they influence the surgical intervention and the evolution of future innovations.

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 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.)

Although human stapes are known to have varied dimensions and the footplate is considered to be oval (fitting as it does into the oval window), few studies of high-resolution imaging of these structures have been performed. No study appears to have addressed the bilateral symmetry of stapes dimensions or to have determined if an association exists between the size of the stapes and the size of mastoid pneumatization; a small mastoid pneumatization is an indicator of childhood otitis media. We obtained 41 ear-normal cadaver crania specimens for study in our temporal bone laboratory and isolated 10 for further analysis: the 5 with the largest areas of mastoid pneumatization and the 5 with the smallest. Microcomputed tomography of tissue blocks was performed on the in situ stapes. Using ImageJ software, we created a three-dimensional model of each stapes. The mean height of these stapes was 3.43 mm (range: 3.20 to 3.80), the mean length of the footplates was 2.71 mm (range: 2.52 to 2.97), and the mean width of the footplates was 1.23 mm (range: 1.12 to 1.46). Qualitatively, the footplate was shaped like a human footprint in moist sand, as Eysell described in 1870. The dimensions of the stapes were found to be bilaterally symmetrical in general, but there was no correlation between these dimensions and the size of mastoid pneumatization. The distribution of footplate widths may be bimodal, which is consistent with the observation of Sim et al that men have wider footplates than do women.

Middle ear ossicles (malleus, incus, stapes) are known for few multituberculate taxa, and three different stapedial morphotypes have been suggested: (i) slender, columelliform and microperforate, (ii) robust and rod-like, and (iii) bicrural. Reinvestigation of Upper Jurassic (Kimmeridgian) mammalian petrosals from the Guimarota coal mine in central Portugal (Western Europe) revealed an asymmetric bicrural stapes (ABS) in the paulchoffatiid Pseudobolodon oreas The middle ear ossicles displaced inside the osseous vestibule were detected by a µCT analysis. The Kimmeridgian age of the Guimarota stapes exceeds the stapes from the Early Cretaceous (Barremian) of Asia (about 122-124 Ma) by approximately 30 Myr, and is only slightly younger than the stapes of the recently described Oxfordian euharamiyidan Arboroharamiya allinhopsoni The Guimarota stapes indicates that the stapes of Lambdopsalis , described as columelliform and microperforate (small stapedial foramen), does not represent a general condition for multituberculates. The stapes of Pseudobolodon is bicrural, the anterior crus sits centrally on the oval footplate, and the stapedial head is simple and smaller than the footplate. We hypothesize that the ABS evolved from the symmetric bicrural stapes (SBS) of non-mammaliaform cynodonts. The ABS appears to be the ancestral morphotype of the mammalian SBS, and the mammalian columelliform imperforate stapes., (© 2018 The Author(s).)

Functional outcomes and complications in otosclerosis surgery are governed by the surgeon's experience. Thus, teaching the procedure to residents to guide them through the learning process as quickly as possible is challenging. Artificial 3D-printed temporal bones are replacing cadaver specimens in many institutions to learn mastoidectomy, but these are not suitable for middle ear surgery training. The goal of this work was to adapt such an artificial temporal bone to aid the teaching of otosclerosis surgery and to evaluate this tool. We have modified a commercially available 3D-printed temporal bone by replacing the incus and stapes of the model with in-house 3D-printed ossicles. The incus could be attached to a 6-axis force sensor. The stapes footplate was fenestrated and attached to a 1-axis force sensor. Six junior surgeons (residents) and seven senior surgeons (fellows or consultants) were enrolled to perform piston prosthesis placement and crimping as performed during otosclerosis surgery. The time required to perform the tasks and the forces applied to the incus and stapes were collected and analyzed. No statistically significant differences were observed between the junior and senior groups for time taken to perform the tasks and the forces applied to the incus during crimping and placement of the prosthesis. However, significantly lower forces were applied to the stapes by the senior surgeons in comparison with the junior surgeons during prosthesis placement (junior vs senior group, 328 ± 202.9 vs 80 ± 99.6 mN, p = 0.008) and during prosthesis crimping (junior vs senior group, 565 ± 233 vs 66 ± 48.6 mN, p = 0.02). We have described a new teaching tool for otosclerosis surgery based on the modification of a 3D-printed temporal bone to implement force sensors on the incus and stapes. This tool could be used as a training tool to help the residents to self-evaluate their progress with recording of objective measurements.

The stapes is held in the oval window by the stapedial annular ligament (SAL), which restricts total peak-to-peak displacement of the stapes. Previous studies have suggested that for moderate (<130 dB SPL) sound levels intracochlear pressure (P IC ), measured at the base of the cochlea far from the basilar membrane, increases directly proportionally with stapes displacement (D Stap ), thus a current model of impulse noise exposure (the Auditory Hazard Assessment Algorithm for Humans, or AHAAH) predicts that peak P IC will vary linearly with D Stap up to some saturation point. However, no direct tests of D Stap , or of the relationship with P IC during such motion, have been performed during acoustic stimulation of the human ear. In order to examine the relationship between D Stap and P IC to very high level sounds, measurements of D Stap and P IC were made in cadaveric human temporal bones. Specimens were prepared by mastoidectomy and extended facial recess to expose the ossicular chain. Measurements of P IC were made in scala vestibuli (P SV ) and scala tympani (P ST ), along with the SPL in the external auditory canal (P EAC ), concurrently with laser Doppler vibrometry (LDV) measurements of stapes velocity (V Stap ). Stimuli were moderate (∼100 dB SPL) to very high level (up to ∼170 dB SPL), low frequency tones (20-2560 Hz). Both D Stap and P SV increased proportionally with sound pressure level in the ear canal up to approximately ∼150 dB SPL, above which both D Stap and P SV showed a distinct deviation from proportionality with P EAC . Both D Stap and P SV approached saturation: D Stap at a value exceeding 150 μm, which is substantially higher than has been reported for small mammals, while P SV showed substantial frequency dependence in the saturation point. The relationship between P SV and D Stap remained constant, and cochlear input impedance did not vary across the levels tested, consistent with prior measurements at lower sound levels. These results suggest that P SV sound pressure holds constant relationship with D Stap , described by the cochlear input impedance, at these, but perhaps not higher, stimulation levels. Additionally, these results indicate that the AHAAH model, which was developed using results from small animals, underestimates the sound pressure levels in the cochlea in response to high level sound stimulation, and must be revised., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Determining the degree of ossicular fixation is a difficult task, with the final assessment often being made with manual palpation during exploratory tympanotomy. A more objective method to evaluate ossicular fixation would be valuable. In this paper we describe a new method which makes use of a magnet and coil to measure ossicular motion through the ear canal with an elevated tympanic membrane. We report measurements of the vibration response at the umbo, the tip of the incus long process and the lateral posterior crus of the stapes before and after artificially fixing the stapes footplate and anterior mallear ligament with luting cement. Results were obtained on temporal bones, but the practicality of the method allows easy clinical implementation. Velocity ratios between different measurement points along the ossicular chain may provide a quantitative indication of the degree of stapes fixation. Isolated anterior mallear ligament fixation was not distinguishable from the unfixed condition., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The Mongolian gerbil (Meriones unguiculatus) is commonly used in hearing research because the hearing frequency spectrum of the gerbil is rather similar to that of the human being. However, a precise description of the surgical post-auricular route has not been reported. The aim of this technical note is to provide details on the procedure and the surgical anatomy of the post-auricular route in the Mongolian gerbil. Surgery was performed under general anesthesia on eight (2 males and 6 females) adult Mongolian gerbils. All steps of the post-auricular route were detailed. This surgery provided an access to the following structures: the semi-circular posterior and lateral canals, the external auditory meatus, the tympanic membrane, the round window, the stapes, the stapedial artery and the reliefs of the cochlea. No anatomic variation was noticed among the 8 animals. This post-auricular route in the Mongolian gerbil defines a brief and simple surgery, overall standardized as a consequence of the absence of common anatomic variation, with painless and uncomplicated post-operative stage., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The stapes is known in several non-mammaliaform cynodonts, although it has only been cursorily studied. Here we thoroughly analyze the stapedial anatomy of several basal cynodonts in a phylogenetic framework. Our study shows that the stapedial anatomy is more variable than previously thought. The morphological variation of the stapes led to the recognition of 11 phylogenetic characters that were included in a total evidence data matrix centered in the analysis of gomphodont cynodonts. Stapes morphology does not provide evidence to suggest a direct connection between the stapes and a postquadrate tympanic membrane (if present) and the hypothesis of a dorsal process as the site of attachment of a small ligament or the stapedial muscle is supported. The re-evaluation of the theories concerning the position of the tympanic membrane in non-mammaliaform cynodonts allowed us to conclude that the hypothetical postquadrate tympanic membrane associated with the squamosal sulcus is at best relictual and most likely non-functional (not connected with the stapes). The sound waves were most likely transmitted to the stapes from a postdentary tympanic membrane through the quadrate. Our analysis results in a better understanding of the auditory system in basal cynodonts and its evolution, highlighting the variability of the stapedial anatomy.

The morphology of the vertebrate head skeleton is highly plastic, with the number, size, shape, and position of its components varying dramatically between groups. While this evolutionary flexibility has been key to vertebrate success, its developmental and genetic bases are poorly understood. The larval head skeleton of the frog Xenopus laevis possesses a unique combination of ancestral tetrapod features and anuran-specific novelties. We built a detailed gene expression map of the head mesenchyme in X. laevis during early larval development, focusing on transcription factor families with known functions in vertebrate head skeleton development. This map was then compared to homologous gene expression in zebrafish, mouse, and shark embryos to identify conserved and evolutionarily flexible aspects of vertebrate head skeleton development. While we observed broad conservation of gene expression between X. laevis and other gnathostomes, we also identified several divergent features that correlate to lineage-specific novelties. We noted a conspicuous change in dlx1/2 and emx2 expression in the second pharyngeal arch, presaging the differentiation of the reduced dorsal hyoid arch skeletal element typical of modern anamniote tetrapods. In the first pharyngeal arch we observed a shift in the expression of the joint inhibitor barx1, and new expression of the joint marker gdf5, shortly before skeletal differentiation. This suggests that the anuran-specific infrarostral cartilage evolved by partitioning of Meckel's cartilage with a new paired joint. Taken together, these comparisons support a model in which early patterning mechanisms divide the vertebrate head mesenchyme into a highly conserved set of skeletal precursor populations. While subtle changes in this early patterning system can affect skeletal element size, they do not appear to underlie the evolution of new joints or cartilages. In contrast, later expression of the genes that regulate skeletal element differentiation can be clearly linked to the evolution of novel skeletal elements. We posit that changes in the expression of downstream regulators of skeletal differentiation, like barx1 and gdf5, is one mechanism by which head skeletal element number and articulation are altered during evolution., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Objective: The stapes is difficult to analyse on computed tomography because of the small size of its components and its oblique orientation. The stapes axial plane, parallel to the superstructure, seems optimal for this purpose. The present study assessed the position of the stapes axial plane with respect to the usual axial plane including the lateral semicircular canal, and sought to measure the main dimensions of the stapes., Methods: This retrospective study comprised 208 computed tomography scans of normal ears. Stapes length and width, footplate thickness and incudostapedial joint width were measured., Results: The stapes axial plane was directed upward, outward (44°) and forward (12°) with respect to the lateral semicircular canal plane. Mean head-to-footplate distance was 3.7 mm and mean superstructure width was 2.7 mm. Mean footplate thickness was 0.27 mm on stapes axial plane versus 0.48 mm on lateral semicircular canal plane. Incudostapedial joint width was systematically less than 0.7 mm., Conclusion: Stapes dimensions on stapes axial plane were close to anatomical data, particularly for footplate thickness.

The effect of different stapes prostheses on the basilar membrane (BM) motion was determined. To that end, a three dimensional finite element (FE) model of the passive human cochlea was developed. Passive responses of the BM were found based on coupled fluid-structure interactions between the cochlear solid structures and the scala fluids. The passive BM vibrations in normal (healthy) cochlea were compared with vibrations in the cochlea in which a 0.4-mm piston or a proposed new type of prosthesis was implanted. The proposed chamber prosthesis was not experimentally implanted, but only numerically simulated. Design of the new chamber stapes prosthesis is presented for the first time in this paper. The simulation results showed 10-20 dB decrease in BM displacement amplitude in the case of the piston. In contrast, the BM responses in the cochlea with the new prosthesis are higher with respect to the healthy ear. The results obtained in this study are promising for further research to optimize the design of the new chamber stapes prosthesis., (Copyright © 2014 Elsevier B.V. All rights reserved.)

We report the discovery of three isolated primate petrosal fragments from the fossiliferous locality of Chambi (Tunisia), a primate-bearing locality dating from the late early to the early middle Eocene. These fossils display a suite of anatomical characteristics otherwise found only in strepsirhines, and as such might be attributed either to Djebelemur or/and cf. Algeripithecus, the two diminutive stem strepsirhine primates recorded from this locality. Although damaged, the petrosals provide substantial information regarding the ear anatomy of these advanced stem strepsirhines (or pre-tooth-combed primates), notably the patterns of the pathway of the arterial blood supply. Using μCT-scanning techniques and digital segmentation of the structures, we show that the transpromontorial and stapedial branches of the internal carotid artery (ICA) were present (presence of bony tubes), but seemingly too small to supply enough blood to the cranium alone. This suggests that the ICA was not the main cranial blood supply in stem strepsirhines, but that the pharyngeal or vertebral artery primitively ensured a great part of this role instead, an arterial pattern that is reminiscent of modern cheirogaleid, lepilemurid lemuriforms and lorisiforms. This could explain parallel loss of the ICA functionality among these families. Specific measurements made on the cochlea indicate that the small strepsirhine primate(s) from Chambi was (were) highly sensitive to high frequencies and poorly sensitive to low frequencies. Finally, variance from orthogonality of the plane of the semicircular canals (SCs) calculated on one petrosal (CBI-1-569) suggests that Djebelemur or cf. Algeripithecus likely moved (at least its head) in a way similar to that of modern mouse lemurs., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The transfer function H(V) between stapes velocity V(S) and sound pressure near the tympanic membrane P(TM) is a descriptor of sound transmission through the middle ear (ME). The ME power transmission efficiency (MEE), the ratio of sound power entering the cochlea to power entering the middle ear, was computed from H(V) measured in seven chinchilla ears and previously reported measurements of ME input admittance Y(TM) and ME pressure gain G(MEP) [Ravicz and Rosowski, J. Acoust. Soc. Am. 132, 2437-2454 (2012); J. Acoust. Soc. Am. 133, 2208-2223 (2013)] in the same ears. The ME was open, and a pressure sensor was inserted into the cochlear vestibule for most measurements. The cochlear input admittance Y(C) computed from H(V) and G(MEP) is controlled by a combination of mass and resistance and is consistent with a minimum-phase system up to 27 kHz. The real part Re{Y(C)}, which relates cochlear sound power to inner-ear sound pressure, decreased gradually with frequency up to 25 kHz and more rapidly above that. MEE was about 0.5 between 0.1 and 8 kHz, higher than previous estimates in this species, and decreased sharply at higher frequencies.

Objective: To provide the anatomic data for the correlated otologic microsurgery by the microdissection of temporal bone through facial recess approach., Method: Sixteen human temporal bones of eight adult cadaveric heads were dissected under surgical microscope through facial recess approach, and the relative anatomic structures were observed and measured, such as the bony entrance of facial recess approach, facial nerve, stapes, round window, round window niche, pyramidal eminence, cochleariform process, etc. The data were analyzed statistically., Result: The width of the bony entrance of facial recess approach was (2.94 +/- 0.32) mm, the height was (8.83 +/- 0.84) mm, the depth was (3.51 +/- 0.17) mm. The distances from stapes to tympanic segment of facial nerve, mastoid segment of facial nerve, round window, cochleariform process and anterior ligament of malleus were (1.38 +/- 0.21) mm, (6.94 +/- 0.47) mm, (3.60 +/- 0.55)mm, (2.23 +/- 0.33)mm, (4.93 +/- 0.61) mm, respectively. The distances from pyramidal eminence to tympanic segment of facial nerve, mastoid segment of facial nerve, round window, round window niche and cochleariform process were (1.05 +/- 0.09) mm, (5.63 +/- 0.41) mm, (3.01 +/- 0.34) mm, (3.29 +/- 0.44) mm, (4.13 +/- 0.51) mm, respectively. The distances from round window to cochleariform process and tympanic segment of facial nerve were (5.11 +/- 0.61) mm and (3.97 +/- 0.61) mm. The distances from round window niche to tympanic segment of facial nerve and mastoid segment of facial nerve were (4.13 +/- 0.38) mm and (7.28 +/- 0.29) mm., Conclusion: The facial recess approach played an important role in modern otologic microsurgery. The position of anatomical structure was constant relatively, including short crus of incus, stapes, pyramidal eminence and cochleariform process, etc. These could be used as reference marks for otologic microsurgery.

During reconstruction of the ossicular chain, there is a need to address the forces and loads caused by the ambient atmospheric pressure variations and the resulting tympanic membrane movements. It is understood that when a rigid middle ear prosthesis is inserted the malleoincudal joint, a keyfactor in controlling pressure variations in the middle ear space is bypassed. In this paper we describe a modified total titanium ossicular replacement prosthesis with an innovative micro ball joint in the headplate which is designed to compensate for tympanic membrane movements caused by atmospheric pressure variations. The characteristics of this modified prosthesis were examined in temporal bone experiments and compared to the standard titanium total ossicular reconstruction prosthesis. Sound-induced stapes footplate movements were investigated by means of a Laser vibrometer and revealed no significant differences between the two prostheses in vitro. Intraoperatively, the insertion of the modified prosthesis required more delicate handling. The angle between the shaft and the headplate was variable and ranged from 60 to 90° as estimated by the surgeon. Twelve consecutive patients were eligible for clinical evaluation. The pure tone average (PTA) air-bone gap after a mean follow up period of 32 months was 18.8 dB. Furthermore, no extrusion, dislocation or other adverse events were observed. We conclude that the modified total ossicular replacement prosthesis with integrated micro ball joint yields similar volume velocities of the stapes footplate in the laboratory experiments compared to the standard rigid prosthesis. The audiological and morphological results are encouraging and show that the mobile prosthesis headplate adjusting to the level of the tympanic membrane is a further step in the development of a physiological middle ear implant. 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 accuracy of any stapes model relies on the accuracy of the anatomical information upon which it is based. In many previous models and measurements of the stapes, the shape of the stapes has been considered as symmetric with respect to the long and short axes of the footplate. Therefore, the reference frame has been built based upon this assumption. This study aimed to provide detailed anatomical information on the dimensions of the stapes, including its asymmetries. High-resolution microcomputed tomography data from 53 human stapes and 11 guinea pig stapes were collected, and their anatomical features were analyzed. Global dimensions of the stapes, such as the size of the footplate, height, and volume, were compared between human and guinea pig specimens, and asymmetric features of the stapes were quantitatively examined. Further, dependence of the stapes dimensions on demographic characteristics of the subjects was explored. The height of the stapes relative to the footplate size in the human stapes was found to be larger than the corresponding value in guinea pig. The stapes showed asymmetry of the footplate with respect to the long axis and offset of the stapes head from the centroid of the medial surface of the footplate for both humans and guinea pigs. The medial surface of the footplate was curved, and the longitudinal arches of the medial surface along the long axis of the footplate were shaped differently between humans and guinea pigs. The dimension of the footplate was gender-dependent, with the size greater in men than in women.

Hypothesis: In the absence of patent cochlear windows, cochlear fluid inertia depends on the presence of a "third window" as a major component of the bone-conduction response., Background: Studies have shown conflicting results regarding changes in air and bone conduction whenever, the round window, oval window, or both windows were occluded., Method: The study was performed in a tertiary university-affiliated medical center. Auditory brain responses to clicks and 1-kHz tone bursts delivered by air and bone conduction were tested in 5 adult-size fat sand rats. The round window membrane (total, 7 ears) was sealed with Super Glue, and auditory brain response testing was repeated. Thereafter, the stapes footplate was firmly fixated, and auditory brain responses were recorded for a third time., Results: Round-window fixation induced a significant increase in air-conduction thresholds to clicks from 36.4 ± 0.9 to 69.3 ± 4.1 dB SPL, with no significant change in bone-conduction thresholds. When the stapes footplate was immobilized as well, air conduction increased by another 20 dB, on average, with no change in bone conduction. A similar deterioration was seen in response to 1 kHz stimulus., Conclusion: These findings support and complement earlier studies in the same animal model, suggesting that when the pressure outlet through the cochlear windows are abolished, still bone conduction displaces the cochlear partition probably because of a functioning "third window."

The piston-like (translation normal to the footplate) and rocking-like (rotation along the long and short axes of the footplate) are generally accepted as motion components of the human stapes. It has been of issue whether in-plane motions, i.e., transversal movements of the footplate in the oval window, are comparable to these motion components. In order to quantify the in-plane motions the motion at nine points on the medial footplate was measured in five temporal bones with the cochlea drained using a three-dimensional (3D) laser Doppler vibrometer. It was found that the stapes shows in-plane movements up to 19.1 ± 8.7% of the piston-like motion. By considering possible methodological errors, i.e., the effects of the applied reflective glass beads and of alignment of the 3D laser Doppler system, such value was reduced to be about 7.4 ± 3.1%. Further, the in-plane motions became minimal (≈ 4.2 ± 1.4% of the piston-like motion) in another plane, which was anatomically within the footplate. That plane was shifted to the lateral direction by 118 μm, which was near the middle of the footplate, and rotated by 4.7° with respect to the medial footplate plane.

Background: The stapes, an ossicle found within the middle ear, is involved in transmitting sound waves to the inner ear by means of the oval window. There are several developmental problems associated with this ossicle and the oval window, which cause hearing loss. The developmental origin of these tissues has not been fully elucidated., Results: Using transgenic reporter mice, we have shown that the stapes is of dual origin with the stapedial footplate being composed of cells of both neural crest and mesodermal origin. Wnt1cre/Dicer mice fail to develop neural crest-derived cartilages, therefore, have no middle ear ossicles. We have shown in these mice the mesodermal stapedial footplate fails to form and the oval window is induced but underdeveloped., Conclusions: If the neural crest part of the stapes fails to form the mesodermal part does not develop, indicating that the two parts are interdependent. The stapes develops tightly associated with the otic capsule, however, it is not essential for the positioning of the oval window, suggesting that other tissues, perhaps within the inner ear are needed for oval window placement., (Copyright © 2012 Wiley Periodicals, Inc.)

Objective: To investigate the related parameters of temporal bone structure in the surgery of cochlear implantation through facial recess approach so as to offer a theoretical reference for the avoidance of facial nerve injury and the accurate localization., Method: In a surgical simulation experiment, twenty human temporal bones were studied. The correlation parameters were measured under surgical microscope., Result: Distance between suprameatal spine and short process of incus was (12.44 +/- 0.51) mm. Width from crotch of chorda tympani nerve to stylomastoid foramen was (2.67 +/- 0.51) mm. Distance between short process of incus and crotch of chorda tympani nerve was (15.22 +/- 0.83) mm. The location of maximal width of the facial recess into short process of incus, crotch of chorda tympani nerve were (6.28 +/- 0.41) mm, (9.81 +/- 0.71) mm, respectively. The maximal width of the facial recess was (2.73 +/- 0.20) mm. The value at level of stapes and round window were (2.48 +/- 0.20 mm) and (2.24 +/- 0.18) mm, respectively. Distance between pyramidalis eminence and anterior round window was (2.22 +/- 0.21) mm. Width from stapes to underneath round window was (2.16 +/- 0.14) mm., Conclusion: These parameters provide a reference value to determine the position of cochlear inserting the electrode array into the scale tympani and opening facial recess firstly to avoid potential damage to facial nerve in surgery.

Although intratympanic (IT) administration of drugs has gained wide clinical acceptance, the distribution of drugs in the inner ear following IT administration is not well established. Gadolinium (Gd) has been previously used as a marker in conjunction with magnetic resonance imaging (MRI) to visualize distribution in inner ear fluids in a qualitative manner. In the present study, we applied gadolinium chelated with diethylenetriamine penta-acetic acid (Gd-DTPA) to the round window niche of 12 guinea pigs using Seprapack(TM) (carboxlmethylcellulose-hyaluronic acid) pledgets which stabilized the fluid volume in the round window niche. Gd-DTPA distribution was monitored sequentially with time following application. Distribution in normal, unperforated ears was compared with ears that had undergone a cochleostomy in the basal turn of scala tympani and implantation with a silastic electrode. Results were quantified using image analysis software. In all animals, Gd-DTPA was seen in the lower basal scala tympani (ST), scala vestibuli (SV), and throughout the vestibule and semi-circular canals by 1 h after application. Although Gd-DTPA levels in ST were higher than those in the vestibule in a few ears, the majority showed higher Gd-DTPA levels in the vestibule than ST at both early and later time points. Quantitative computer simulations of the experiment, taking into account the larger volume of the vestibule compared to scala tympani, suggest most Gd-DTPA (up to 90%) entered the vestibule directly in the vicinity of the stapes rather than indirectly through the round window membrane and ST. Gd-DTPA levels were minimally affected by the implantation procedure after 1 h. Gd-DTPA levels in the basal turn of scala tympani were lower in implanted animals, but the difference compared to non-implanted ears did not reach statistical significance.

Objective: Measurements of the proximity of the membranous labyrinth to the stapes footplate show considerable variation. Largely, such measurements have been from histologic sections of fixed temporal bones, which may be affected by shrinkage artifact and perspective distortion in the 2-dimensional plane. To overcome these problems, the present study undertook an analysis of the 3-dimensional (3D) architecture of the relationship of the stapes to the membranous labyrinth using high-resolution X-ray micro-computed tomography., Methods: Eleven temporal bones were fixed with Karnovsky's fixative (known to minimize shrinkage), soaked in 2% osmium tetroxide, and scanned in a micro-computed tomography scanner. The otic capsule was intact to exclude sectioning artifact, and no alcohol was used to avoid tissue shrinkage. Measurements were taken in a vertical plane to provide distances from the utricle and saccule to the footplate, and 3D reconstruction of the spatial relationship of these structures was carried out. The relationship of these structures to a stapes piston also was studied., Results: The safest area of piston placement was the central and inferior part of the footplate. This was safe up to 0.5 mm depth at all areas except posterosuperiorly where the utricular macula is, on average, only 0.61 mm away from the footplate. The angle of insertion of the piston also influences the end result., Conclusion: Two-dimensional information about vestibular end organ location should serve as a guideline only because the operative field is 3D, and the relationship of the piston to the vestibular labyrinth changes with the angle of placement., (© 2011, Otology & Neurotology, Inc.)

Cranial arterial patterns are commonly used for determining phylogenetic patterns in extant taxa and have often been used in studies investigating the relationships among fossil taxa. In primitive eutherians, the stapedial artery provided blood to the meninges, orbits, and certain regions of the face. In many modern mammals, however, blood supply to most of these areas has been taken over by branches of the external carotid, although some groups (e.g., treeshrews, some families of primates) still retain aspects of the ancestral pattern. Here, we show that the relative size of the obturator foramen of the stapes is a reliable indicator of the presence or absence of a "functional" stapedial artery in Euarchonta. We also describe newly discovered stapedes for extinct euarchontans, Ignacius graybullianus, and Plesiadapis tricuspidens, and use the approach described here to show that these taxa likely did not have a functional stapedial artery. The implications of these findings for auditory function and phylogenetic studies are discussed., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

CD46 (Membrane Cofactor Protein, MCP) is a transmembrane glycoprotein, which is expressed by all nucleated human cells whose purpose is to protect against autologous complement attack. In addition, CD46 can serve as a receptor for several viruses and bacteria and as a potent regulator of the inflammatory response by affecting T cell differentiation. Multiple isoforms of CD46 exist due to alternative splicing and are coexpressed in human cells in various patterns and expression levels. However, specific diseases have not been associated with isoform coexpression. We applied a nested RT-PCR method to investigate the coexpression pattern of CD46 splicing variants in otosclerotic and normal stapes footplate specimens. Using this method, we detected an altered isoform expression pattern and identified four novel CD46 splicing variants overexpressed in otosclerotic bone. This study is the first comprehensive report to provide evidence for disease associated alternative splicing of CD46.

Objective: SMart, a newly introduced piston prosthesis for stapedotomy, is a nitinol-based, heat-activated, self-crimping prosthesis. We review our hearing results and postoperative complications using this self-crimped piston prosthesis and compare them with those obtained using stainless steel or platinum piston prostheses., Hypothesis: Audiometric results using the SMart piston are identical to those obtained using a conventional piston prosthesis., Study Design: Retrospective chart review., Setting: Private neurotologic tertiary referral center., Patients: The 416 ears reviewed included 306 with a SMart prosthesis and 110 conventional prostheses. 61% were women. Mean follow-up time was 5.6 (standard deviation [SD], 6.3 mo) and 6.9 months (SD, 7.0 mo) for the 2 groups, respectively., Intervention: Stapedotomy using the SMart or a conventional (non-SMart) prosthesis., Main Outcome Measures: Audiometric hearing results, including pure-tone average (PTA) and air-bone gap (ABG), and prevalence of postoperative complications., Results: Mean postoperative PTA was 32.6 (SD, 16.8) dB for the SMart group and 29.4 (SD, 13.5) dB for the non-SMart group, with ABGs of 7.6 (SD, 8.9) and 6.0 (SD, 5.2) dB, respectively. Mean change (decrease) in ABG was 18.7 (SD, 13.1) dB for the SMart group and 19.9 (SD, 10.3) dB for the non-SMart group. High-frequency bone PTAs showed overclosure of 2.0 (SD, 7.9) dB for the SMart group and 3.6 (SD, 8.6) dB for the non-SMart group. Postoperative vertigo and tinnitus were infrequent. No significant differences in these audiometric outcomes or complication rates were noted between groups. There was no significant difference in rate of gap closure to within 10 dB (78.3 versus 84.2%, SMart and non-SMart, respectively) or 20 dB (94.2 and 98.0%)., Conclusion: Compared with conventional stapes prostheses, the nitinol-based SMart is a safe and reliable stapes prosthesis that eliminates manual crimping without significantly altering the audiometric outcome. Complications are rare, but longer follow-up is needed before establishing long-term stability.

Hypothesis: The aim of this study was to investigate the impact of cochlear implant electrode insertion on middle-ear low frequency function in humans., Background: Preservation of residual low frequency hearing with addition of electrical speech processing can improve the speech perception abilities and hearing in noise of cochlear implant users. Preservation of low frequency hearing requires an intact middle-ear conductive mechanism in addition to intact inner-ear mechanisms. Little is known about the effect of a cochlear implant electrode on middle-ear function., Methods: Stapes displacement was measured in seven patients undergoing cochlear implantation. Measurements were carried out intra-operatively before and after electrode insertion. Each patient acted as his or her own control. Sound was delivered into the external auditory canal via a speaker and calibrated via a probe microphone. The speaker and probe microphone were integrated into an individually custom-made ear mould. Ossicular displacement in response to a multisine stimulus at 80 dB SPL was measured at the incudostapedial joint via the posterior tympanotomy, using an operating microscope mounted laser Doppler vibrometry system., Results: Insertion of a cochlear implant electrode into the scala tympani had a variable effect on stapes displacement. In three patients, there was little change in stapes displacement following electrode insertion. In two patients, there was a significant increase, while in a further two there was a significant reduction in stapes displacement. This variability may reflect alteration of cochlear impedance, possibly due to differing loss of perilymph associated with the electrode insertion., Conclusion: Insertion of a cochlear implant electrode produces a change in stapes displacement at low frequencies, which may have an effect on residual low frequency hearing thresholds.

Sound-induced stapes velocity (Vs) was measured intraoperatively in 14 patients undergoing cochlear implantation. All 14 patients had no history of middle-ear pathology, and their ossicular chains appeared normal on intraoperative inspection and palpation. The magnitude of the mean Vs (normalized by simultaneously-measured ear-canal sound pressure) was stiffness-dominated at frequencies below 1 kHz, increased up to approximately 4 kHz, and then decreased at higher frequencies. The phase of the mean velocity was +0.2 periods at 0.3 kHz, and gradually became a phase lag at higher frequencies. The mean Vs measured in this study was similar to that of seven ears reported in the only other published study of live human measurements (Huber et al., 2001). We also made measurements of Vs in fresh cadaveric temporal bones using a technique identical to that used in live ears, including similar measurement angles and location. The mean Vs measured in the cadaveric ears under these conditions was similar to the mean Vs measurements in the 14 live ears. This indicates that middle-ear mechanics are similar in live and cadaveric ears. In addition, interspecies comparisons were made between our live human Vs and the Vs reported in different animal studies. There were some clear similarities in Vs across species, as well as differences. The primary interspecies differences were in the magnitude of the Vs as well as in the frequency of transitions in the magnitudes' frequency dependence from rising to flat or falling.

Objectives: To reveal microscopic surgical anatomy of the middle ear in guinea pigs (GPs)., Materials and Methods: Twenty ears of GPs were dissected under dissection microscopy via inferior approach. By using digital equipment, the most suitable photograph was taken for each step. Differences and similarities between the ears of GPs and those of human beings are discussed to show the advantages and disadvantages of the GP ear for experimental studies., Results: Tympanic membrane of the GP merely consists of pars tensa and above this there is a bony segment called as supratympanic crest. There were two spaces called bulla and hypotympanium in the GP,s middle ear. Cochlea, which is normally found in the inner ear in humans, separates these two spaces. Upper part of this space which is called epitympanium is a slit like cavity having a bony complex called malleoincudal complex. Bulla, the largest cavity in the middle ear, is a hemispherical cavity having a smooth surface. It corresponds to hypotympanum and mesotympanum of human middle ear. Cochlea has 3.5 turns from basal turn to apical turn. While the oval window is placed vertically, the round window is placed horizontally. While the stapes is almost identical to that of the humans, there is a bony bridge between the crura of the stapes called crista stapedius. Stapes can not removed unless this bony bridge is taken., Conclusion: The middle ear in GP differs from the human middle ear in many aspects. Researchers who are planning to the study with this animal model should be aware of all these differences.

We have performed a study on 11 human embryos regarding the development of the tympanic ossicles and their relationship with the first pharyngeal arch. After performing measurements to date the embryos and foetuses chronologically, we performed a meticulous dissection of the temporal bones. Subsequently, they were fixed in 10% formol, decalcified with 2% nitric acid, embedded in Paraplast, sectioned in 7-mm sequences and stained with Martin's trichrome technique. In the 21- and 24-mm cranium-raquis (CR) length human embryos, we have observed the head of the malleus and the body of the incus close to Meckel's cartilage, in addition to the handle of the malleus, the long limb of the incus and the stapes. Between them there was a mesenchymal band inside the primordium of the tympanic cavity. In the 27-mm CR embryo, the various components of the malleus and incus were fusing, and in the 30-mm CR embryo the union was complete. From our observations, we can conclude that the malleus and the incus are derived from the first and second pharyngeal arches.

Objective: To study the management of basic parameters related to individual piston shaping on malleostapedotomy by MDST 3D reconstruction and microanatomy and to assess the accuracy of MDST method., Method: Ten Chinese temporal bones without ear diseases were numbered randomly and scanned by GE Light Speed Ultra 64 rows of spiral CT. 3D structure of ossicular chain were reconstructed by MPR and VR methods in AW4. 1 workstation. Then measurements of distances between stapes head to stapes footplate (A line), and manubrium to stapes head (B line), and manubrium to stapes footplate (C line), angle between line A and line B (angle AB) are completed. After that, all samples of temporal bone were undergone canal wall down mastoidectomy under microscope and the relevant measurements were completed., Result: The MPR and VR technique of MDCT reconstructed ossicular chain clearly, and revealed the spatial relationship between every structure stereoscopically. Respectively, lengths of A, B, C line by MDST and microanatomy are (3.42 +/- 0.86) mm and (3.60 +/- 0.94) mm, (3.42 +/- 0.80) mm and (2.96 +/- 0.42) mm, (5.86 +/- 0.60) mm and (6.22 +/- 1.10) mm, while angle AB (141.05 +/- 30.07) degrees and (144.57 +/- 41.86) degrees. There are no statistically significant differences between two groups (P>0.05)., Conclusion: The MPR and VR technique of MDCT can clearly reconstructed the 3D shapes of the temporal bone and finish the exactly managements on A, B, C lines and AB angel which is crucial for shaping a individual piston on malleus-to-oval window surgery.

A detailed description of the skull and jaw of the gecko Sphaerodactylus roosevelti is presented. The bones are described articulated and isolated with special consideration given to the type of suture among joining elements. S. roosevelti was compared with 109 gekkotan species to evaluate the osteological variation and to find characters for cladistic analysis. Changes in the skull associated with the miniaturization process are discussed within the sphaerodactylid geckos. A noticeable increase of overlapping sutures was observed in the snout of the smallest sphaerodactylids compared to other gekkotans. This pattern is convergent with that in miniaturized pygopodids and may be attributed to adaptations for decreasing mechanical resistance of the cranium during feeding or burrowing. New cranial characters support Sphaerodactylinae as a monophyletic group and should be useful for resolving questions such as their relationship with other gekkotans.

Middle-ear sound transmission was evaluated as the middle-ear transfer admittance H(MY) (the ratio of stapes velocity to ear-canal sound pressure near the umbo) in gerbils during closed-field sound stimulation at frequencies from 0.1 to 60 kHz, a range that spans the gerbil's audiometric range. Similar measurements were performed in two laboratories. The H(MY) magnitude (a) increased with frequency below 1 kHz, (b) remained approximately constant with frequency from 5 to 35 kHz, and (c) decreased substantially from 35 to 50 kHz. The H(MY) phase increased linearly with frequency from 5 to 35 kHz, consistent with a 20-29 micros delay, and flattened at higher frequencies. Measurements from different directions showed that stapes motion is predominantly pistonlike except in a narrow frequency band around 10 kHz. Cochlear input impedance was estimated from H(MY) and previously-measured cochlear sound pressure. Results do not support the idea that the middle ear is a lossless matched transmission line. Results support the ideas that (1) middle-ear transmission is consistent with a mechanical transmission line or multiresonant network between 5 and 35 kHz and decreases at higher frequencies, (2) stapes motion is pistonlike over most of the gerbil auditory range, and (3) middle-ear transmission properties are a determinant of the audiogram.

Despite its important role in the study of the evolution of tetrapods, the hyomandibular bone (the homologue of the stapes in crown-group tetrapods) is known for only a few of the fish-like members of the tetrapod stem-group. The best-known example, that of the tristichopterid Eusthenopteron, has been used as an exemplar of fish-like stem-tetrapod hyomandibula morphology, but in truth the conditions at the base of the tetrapod radiation remain obscure. We report, here, four hyomandibulae, from three separate localities, which are referable to the Rhizodontida, the most basal clade of stem-tetrapods. These specimens share a number of characteristics, and are appreciably different from the small number of hyomandibulae reported for other fish-like stem-tetrapods. While it is unclear if these characteristics represent synapomorphies or symplesiomorphies, they highlight the morphological diversity of hyomandibulae within the early evolution of the tetrapod total-group. Well-preserved muscle scarring on some of these hyomandibulae permit more robust inferences of hyoid arch musculature in stem-tetrapods., (2008 Wiley-Liss, Inc)

Recent measurements of three-dimensional stapes motion in gerbil indicated that the piston component of stapes motion was the primary contributor to intracochlear pressure. In order to make a detailed correlation between stapes piston motion and intracochlear pressure behind the stapes, simultaneous pressure and motion measurements were undertaken. We found that the scala vestibuli pressure followed the piston component of the stapes velocity with high fidelity, reinforcing our previous finding that the piston motion of the stapes was the main stimulus to the cochlea. The present data allowed us to calculate cochlear input impedance and power flow into the cochlea. Both the amplitude and phase of the impedance were quite flat with frequency from 3 kHz to at least 30 kHz, with a phase that was primarily resistive. With constant stimulus pressure in the ear canal the intracochlear pressure at the stapes has been previously shown to be approximately flat with frequency through a wide range, and coupling that result with the present findings indicates that the power that flows into the cochlea is quite flat from about 3 to 30 kHz. The observed wide-band intracochlear pressure and power flow are consistent with the wide-band audiogram of the gerbil.

Objective: To analyze if titanium material and a clip attachment to the incus offer a hearing result advantage over the traditional Teflon piston in stapes surgery., Study Design: Retrospective chart review., Setting: Subspecialty private practice., Patients: One hundred seven ears in 97 consecutive patients who had primary stapes surgery during 2003 to 2005., Intervention: The first 74 ears received either a Teflon 0.5- or 0.6-mm piston, and the last 33 received a titanium 0.6-mm piston., Main Outcome Measures: American Academy of Otolaryngology-Head and Neck Surgery guidelines, including 4-frequency pure-tone average air-bone gap and success rate (gap, 10 dB)., Results: Mean pure-tone average air-bone gap for the Teflon 0.6-mm piston (5.1 dB) was significantly smaller than for the titanium 0.6-mm piston (8.1 dB) and the Teflon 0.5-mm piston (7.5 dB). Success rate did not differ. Although labeled as 0.6-mm pistons, the Teflon piston diameter was 10% greater than the titanium piston. Results were comparable among devices when adjusted for true piston diameter. Results for the titanium piston were significantly better when the fenestra was no more than 0.05 mm larger than the piston diameter., Conclusion: Comparing 2 pistons designated 0.6 mm in diameter, the Teflon piston produced better hearing results than the titanium device. However, actual piston diameter differed between devices that contributed to the superior results with the larger Teflon piston. In addition, the titanium piston performed better with a small stapes fenestra diameter that suggests an advantage for titanium over Teflon in certain conditions. The clip design was problematic for a few patients.

Twelve human stapes from temporal bones fixed by formalin were extracted. Different dimensions were measured by an electronic microscope with an accuracy of microm. These dimensions were as follows: (1) maximum diameter of stapes head parallel to the axis of footplate, 1088 microm (range, 857-1277 microm); (2) distance of main nutritional foramen to head surface, 398 microm (range, 250-833 microm); (3) stapes head to shoulders, 757 microm (range, 571-1000 microm), head to foramen, 1047 microm (range, 785-1500 microm), and head to lateral surface of footplate, 2612 microm (range, 1892-3400 microm); (4) anterior crus width at shoulder, 398 microm (range, 333-500 microm); minimum width of anterior crus, 251 microm (range, 214-350 microm); (5) posterior crus width at shoulders, 386 microm (range, 285-600 microm); minimum width of posterior crus, 191 microm (range, 142-300 microm); (6) maximum width of footplate near anterior crus, 371 microm (range, 321-500 microm), maximum width of footplate near the posterior crus, 411 microm (range, 357-611 microm), minimum width of footplate, 228 microm (range, 178-388 microm); (7) maximum width of ossicle, 2298 microm (range, 1928-3050 microm); (8) angle between crura, 19.5 degrees (range, 15-24 degrees ); and (9) diameter of foramen at the end of curve, 1343 microm (range, 1071-1888 microm).

Background: The malleus-stapes offset create challenges during ossiculoplasty, specifically the positioning of an interposed incus or replacement prosthesis relative to the manubrium., Objectives: To depict the malleus-stapes offset, its relationship to the orientation of the manubrium as viewed through the external ear canal relative to a horizontal plane, and mastoid pneumatization size., Study Design: Postmortem anatomic dissection of 41 bequeathed adult crania (82 temporal bones) without clinical otitis., Methods: The malleus-stapes offset was analyzed both as a surgeon does intraoperatively and from above through the tegmen tympani. Mastoid sizes were determined radiographically., Results: : From the surgeon's perspective, for the right ear, the "height" (manubrium to caput stapedis) ranged from 0 to 1.5 (mean, 0.5) mm; the "horizontal" offset ranged from 1.0 to 4.0 (mean, 2.2) mm. Differences in angular offset, as viewed transcanally versus trans-tegmenally, averaged 8.5 degrees (range to 53 degrees). Both height and horizontal offset exhibited wide intersubject variability, quite weak bilateral symmetry, and no relationship with either manubrium orientation or mastoid size., Conclusion: Reliable determination of the malleus-stapes offset is difficult. Because the error of visual offset assessment exceeds the generally accepted 45 degrees alignment allowance for an ossicular prosthesis, visualized ossiculoplasty alignment should be perfect. The ranges of manubrium-stapes offset do not correlate with either manubrium orientation or the extent of mastoid pneumatization.

Objective: Physicians and patients alike have concerns regarding exposing in vivo implanted metal stapes prostheses to magnetic resonance imaging (MRI) scanners. As MRI scanners become more powerful, the possibility for stapes prosthesis displacement due to ferromagnetic forces increases. It is hypothesized that some metal stapes prostheses may be exposed to powerful MRI scanners without leading to potential adversities for patients., Study Design: Literature review, retrospective case review, and physician survey., Settings: Tertiary care, University Medical Center., Materials and Methods: A review of the medical literature,a retrospective case review, and a clinical survey were performed., Results: In the history of stapes prostheses, 1 adverse patient outcome was causally substantiated when a defective stapes prosthesis was exposed to an MRI field. Otherwise, a review of the literature on experiments investigating stapes prostheses and MRI fields revealed a lack of any adverse clinical reports. In addition, 2 physician's surveys revealed no other cases of symptoms or damage to the ears of patients with stapes prostheses that had been exposed to an MRI scanner., Conclusion: All patients with a metallic stapes prosthesis may be sent to the MRI scanner, with the exception of 1 specific defective prosthesis type. The exception is a 1987 accidental mismanufacture of several lots of McGee pistons with a magnetic alloy. Patients with these specifically identified lots of McGee pistons should go to a computed tomographic scanner or be reimplanted with another prosthesis if MRI scans are mandatory. It would be advisable for manufacturers to use nonferromagnetic metals such as titanium for production of future stapes prostheses.

The auditory anatomy of the Florida manatee (Trichechus manatus latirostris) was investigated using computerized tomography (CT), three-dimensional reconstructions, and traditional dissection of heads removed during necropsy. The densities (kg/m3) of the soft tissues of the head were measured directly using the displacement method and those of the soft tissues and bone were calculated from CT measurements (Hounsfield units). The manatee's fatty tissue was significantly less dense than the other soft tissues within the head (p<0.05). The squamosal bone was significantly less dense than the other bones of the head (p<0.05). Measurements of the ear bones (tympanic, periotic, malleus, incus, and stapes) collected during dissection revealed that the ossicular chain was overly massive for the mass of the tympanoperiotic complex.

Objective: To determine the optimal drill area on the footplate with the 3D measurements of the stapes and the vestibular end organs., Methods: Four temporal bones were extracted from the fresh cadavers and undecalcified polymer-embedded. After serially sectioning, image processing and the 3D precisely reconstruction, a local Cartesian coordinates was established in which the tympanic surface of the footplate was supposed to be XY plane and the Z coordinate axis passed through the central point of the footplate and was vertical to the XY plane. The configurations of the utricle and saccule were delineated quantitatively, and then any distance between one point on the surface of the footplate and another point on the surface of the utricle or saccule and its orientation can be measured., Results: There was a "V" shaped cleft between the utricle and the saccule. The angle of the" V" shaped cleft was 50.31 +/- 19.90 (17.00 - 68.00) degrees. The apex of the cleft directed anterosuperiorly and approached the footplate center, while beneath the posteroinferior part of the footplate was an open and deep area. The vertical distance from the center point of the footplate to the vestibular end organs was (2.20 +/- 0.548) mm, the maximum of 3.0 mm and the minimum of 1.6 mm., Conclusions: The posterior and inferior quadrant of the footplate may be the optimal drill area for the fenestra.

Background: Anatomical variants such as an overhanging facial nerve or promontory can impede access to the footplate during stapedectomy. Drilling away bone from the cochlear promontory may be required. In the case of a floating or depressed footplate, it has been recommended that a "pothole" be drilled in the inferior margin of the oval window. There is little published information on the anatomy of the promontory with respect to these maneuvers., Materials and Methods: Twenty temporal bones were studied. A series of measurements was made to assess how much bone may safely be removed without risking damage to the underlying cochlear endosteum and, hence, spiral ligament and stria vascularis., Results: The bony promontory is thickest posteriorly, and here, the endosteum has least lateral projection. The promontory becomes thinner closer to the oval window. Moving anteriorly, the bone becomes thinner and the underlying endo steum more closely follows the bony contour. The stria vascularis and spiral ligament may be less than 0.2 mm inferior to the inferior margin of the oval window posteriorly. This distance is at least 0.3 mm at the midpoint of the footplate (range, 0.3-0.5 mm)., Conclusion: Bone may be removed inferiorly to the posterior one-third of the footplate from lateral to a line that makes an angle of 35 degrees with the superoinferior axis of the footplate. In creating a "pothole" in the case of a floating or depressed footplate, the authors recommend that it be created at the midpoint of the inferior margin of the oval window and should not exceed 0.3 mm in diameter.