Anatomy Of Ear Research Articles

Active middle ear implantation: imaging in the pre-operative planning and post-operative assessment of the Vibrant SoundbridgeTM.

Active middle ear implants augment sound waves and directly stimulate the middle ear structures. The most frequently utilised active middle ear implant is the Vibrant Soundbridge TM (VSB).CT plays a vital role in appropriate patient selection and surgical planning of active middle ear implant surgery. The VSB TM offers a number of options for implant placement. The ideal location is influenced by the patient's middle ear and mastoid anatomy as well as the type and severity of the hearing loss. CT provides important information on the surgical access to the middle ear and helps determine the most appropriate implant site by assessing the adjacent middle ear anatomy and the continuity of the ossicular chain. Post-operative active middle ear implant imaging may be indicated in the setting of poor auditory outcomes and when revision surgery is being considered so as to assess for suboptimal implant placement or migration.This pictorial review will describe the VSB TM middle ear device and explain the role of imaging in both the pre-operative and post-operative settings.

Evaluating the effectiveness of learning ear anatomy using holographic models

BackgroundComputer-assisted learning has been shown to be an effective means of teaching anatomy, with 3-D visualization technology more successfully improving participants’ factual and spatial knowledge in comparison to traditional methods. To date, however, the effectiveness of teaching ear anatomy using 3-D holographic technology has not been studied. The present study aimed to evaluate the feasibility and effectiveness of learning ear anatomy using a holographic (HG) anatomic model in comparison to didactic lecture (DL) and a computer module (CM).MethodsA 3-D anatomic model of the middle and inner ear was created and displayed using presentation slides in a lecture, computer module, or via the Microsoft HoloLens. Twenty-nine medical students were randomized to one of the three interventions. All participants underwent assessment of baseline knowledge of ear anatomy. Immediately following each intervention, testing was repeated along with completion of a satisfaction survey.ResultsBaseline test scores did not differ across intervention groups. All groups showed an improvement in anatomic knowledge post-intervention (p < 0.001); the improvement was equal across all interventions (p = 0.06). Participants rated the interventions equally for delivery of factual content (p = 0.96), but rated the HG higher than the DL and CM for overall effectiveness, ability to convey spatial relationships, and for learner engagement and motivation (p < 0.001).ConclusionsThese results suggest that 3-D holographic technology is an effective method of teaching ear anatomy as compared to DLs and CMs. Furthermore, it is better at engaging and motivating learners compared to traditional methods, meriting its inclusion as a tool in undergraduate medical education curriculum.

A Ten-Year Review of Audiological Performance in Children with Inner Ear Abnormalities after Cochlear Implantation in Singapore.

Objectives To evaluate children with inner ear malformations following cochlear implantation (CI) in a tertiary pediatric hospital in Singapore to identify factors influencing outcomes after CI. Methods This is a retrospective cohort study of children aged 0 to 18 years, who had CI between 2000 and 2013. Demographic information, data on risk factors, type of inner ear malformation (IEM), age at implantation, speech pre- and postimplantation, and duration of follow-up were collected from clinical records. Operative details and audiological outcomes were also analyzed. Results A total of 70 children underwent 83 CI surgeries. The mean age of the patients was 4.05 ± 3.17 years (range 1–18 years). Twenty patients (28.57%) had abnormal CT scan findings. CSF gusher occurred in 15 out of 26 CI (57.69%) in the group with IEM. Nine out of twenty patients (45.00%) had poor IT-MAIS scores prior to implantation. The average preoperative IT-MAIS score for children with anomalous inner ear anatomy was 14.1. The older CI patients, 3/20 (15.00%), mean age 8.33 years (range 7–10 years), were mostly referred for persistently unclear speech following hearing aids. Eleven patients (55.00%) had good speech and aided hearing threshold within speech limits after CI and were eligible for reintegration into mainstream schools. Five patients (25.00%) had improvement in speech but continued to receive education in special schools. Four patients (20.00%) had poor progress after surgery. Conclusion The presence of absent cochlear nerve, electrode folding, and underlying neurological disorders seemed to be associated with poorer outcomes.

Supratubal recess and sinus tympani: CT analysis of middle ear hidden areas

BackgroundHigh-resolution computed tomography (HRCT) magnifies the role of preoperative imaging for detailed middle ear anatomy particularly its hidden area. The purpose of the current study was to assess the sinus tympani (ST) and supratubal recess (STR) by HRCT, to create CT classification of the STR depth, and to study the relationship between ST types and the new STR grades.ResultsIn HRCT of non-pathological temporal bones of 100 subjects (200 ears), measurements of the STR and ST were calculated, registered, and analyzed. The depth of the STR was classified into grade 1 with depth less than 3 mm, grade 2 with depth ranged between 3 and 5 mm, and grade 3 with depth more than 5 mm. The mean STR length, width, and height were 4.17 ± 0.86, 3.55 ± 0.65, and 3.64 ± 0.7 mm, respectively, while the ST mean length and width of were 2.52 ± 0.5 and 1.82 ± 0.78 mm, respectively, without significant differences between either sexes or sided. The ST types were found to be type A in 56 ears (28%), type B in 142 ears (71%), and type C in 2 ears (1%). The STR grading was grade 1 in 12 ears (6%), grade 2 in 160 ears (80%), and grade 3 in 28 ears (14%) without significant relationship between ST types and STR grading (P = 0.3).ConclusionThe current study provided reliable and applicable methods of CT assessment of STR and ST that can help to predict the degree of surgical visibility of the ST and STR during ear surgery.

Systematic Method for Morphological Reconstruction of the Semicircular Canals Using a Fully Automatic Skeletonization Process

We present a novel method to characterize the morphology of semicircular canals of the inner ear. Previous experimental works have a common nexus, the human-operator subjectivity. Although these methods are mostly automatic, they rely on a human decision to determine some particular anatomical positions. We implement a systematic analysis where there is no human subjectivity. Our approach is based on a specific magnetic resonance study done in a group of 20 volunteers. From the raw data, the proposed method defines the centerline of all three semicircular canals through a skeletonization process and computes the angle of the functional pair and other geometrical parameters. This approach allows us to assess the inter-operator effect on other methods. From our results, we conclude that, although an average geometry can be defined, the inner ear anatomy cannot be reduced to a single geometry as seen in previous experimental works. We observed a relevant variability of the geometrical parameters in our cohort of volunteers that hinders this usual simplification.

Improved postauricular surgical approach to the round window of rats

ObjectivesResearch 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. MethodsAdult 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. ResultsSeventeen 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. ConclusionThis 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.

Endoscopic exploratory tympanotomy in cases of conductive hearing loss with intact tympanic membrane: our experience

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Determining the cause of conductive hearing loss with an intact tympanic membrane has been a challenge for the otologists for over decades&lt;strong&gt;. &lt;/strong&gt;The aim of this study is to ascertain the usefulness of endoscopes to study the various middle ear pathologies on performing endoscopic exploratory tympanotomy.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; A retrospective analysis of various pathologies encountered in the middle ear in 88 patients who underwent endoscopic exploratory tympanotomy done over a study period of 3.5 years (January 2015 to June 2018). &lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; In our study, age of the patients ranged from 14 to 50 years with a mean age of 32 years. Most common finding on exploration was otosclerosis in 59 patients followed by revision stapedotomy in 12 patients. 5 patients had normal middle ear findings with all ossicles intact and mobile while other pathologies encountered were tympanosclerosis (4.6%), biscuit foot plate (2.3%), mucosal bands (3.4%) and middle ear developmental anomalies (3.4%).&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; On exploring the middle ear&lt;strong&gt; &lt;/strong&gt;knowing the various aetiologies helps in better preoperative counseling of the patients for the outcome of surgery. Endoscopic approach for exploratory tympanotomy has the benefit of excellent resolution with higher magnification and wider panoramic view of middle ear anatomy.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;

Is CT necessary for imaging paediatric congenital sensorineural hearing loss?

Objectives: To determine if MRI alone is adequate for pre-operative assessment of paediatric congenital sensorineural hearing loss (SNHL). While aberrant intratemporal facial nerve anatomy is usually occult on MRI, we postulate that the majority of cases have no adverse bearing on surgical outcomes.Methods: MRI and CT of the temporal bones were analysed in 240 children who underwent both on the same day for SNHL. Only children under the age of 5 years with no reported clinical syndrome or dysmorphic external ear anatomy were included.Results and discussion: 169 patients satisfied the inclusion criteria. MRI detected 32/54 cases of cochleovestibular dysplasia, with the majority of the additional CT findings comprising subtle incomplete partition type 2 (IP2) anomalies. Of the 22 cases not evident on MRI, 13 patients also had large vestibular aqueduct syndromoe (LVAS), which would have prompted evaluation with CT due to the near universal co-existence of these entities. Only one patient exhibited aberrant intratemporal facial nerve anatomy that may have conferred surgical risk and was occult on MRI.Conclusion: In a defined paediatric SNHL cohort, the addition of routine temporal bone CT to MRI offers limited additional yield but confers a significant radiation burden on a young population.

Acquisition of basic ear surgery skills: a randomized comparison between endoscopic and microscopic techniques

BackgroundEndoscopic ear surgery is gaining increasing popularity and has an important impact on teaching middle ear anatomy and basic surgical skills among residents and fellows. Due to the wide-angled views offered, the approach significantly differs from the established microscopic technique. This randomized study compares the acquisition of basic ear-surgery skills using the endoscopic and microscopic technique under standardized conditions. We aim to investigate the required surgical times, attempts and accidental damages to surrounding structures (errors) in surgeons with different training levels.MethodsFinal-year medical students (n = 9), residents (n = 14) and consultants (n = 10) from the Department of Otorhinolaryngology, Head and Neck Surgery at the University Hospital of Bern, Switzerland were enrolled in the present study. After randomization every participant had to complete a standard set of grasping and dissecting surgical tasks in a temporal bone model. After the first session the participants were crossed over to the other technique.ResultsTime required for completion of the surgical tasks was similar for both techniques, but highly dependent on the training status. A significant increase in the number of damages to the ossicular chain was observed with the microscopic as compared to the endoscopic technique (p < 0.001). Moreover, students beginning with the endoscopic technique showed an overall significantly lower amount of time to complete the tasks (p = 0.04). From the subjective feedback a preference towards the endoscopic technique mainly in medical students was observed.ConclusionsThe endoscopic approach is useful and beneficial for teaching basic surgical skills, mainly by providing a reduction of damage to surrounding tissues with similar operating times for both techniques. Moreover, medical students performed significantly faster, when first taught in the endoscopic technique. Especially for young surgeons without previous training in ear surgery, the endoscope should be considered to improve surgical skills in the middle ear.

Ear-EEG Forward Models: Improved Head-Models for Ear-EEG.

Computational models for mapping electrical sources in the brain to potentials on the scalp have been widely explored. However, current models do not describe the external ear anatomy well, and is therefore not suitable for ear-EEG recordings. Here we present an extension to existing computational models, by incorporating an improved description of the external ear anatomy based on 3D scanned impressions of the ears. The result is a method to compute an ear-EEG forward model, which enables mapping of sources in the brain to potentials in the ear. To validate the method, individualized ear-EEG forward models were computed for four subjects, and ear-EEG and scalp EEG were recorded concurrently from the subjects in a study comprising both auditory and visual stimuli. The EEG recordings were analyzed with independent component analysis (ICA) and using the individualized ear-EEG forward models, single dipole fitting was performed for each independent component (IC). A subset of ICs were selected, based on how well they were modeled by a single dipole in the brain volume. The correlation between the topographic IC map and the topographic map predicted by the forward model, was computed for each IC. Generally, the correlation was high in the ear closest to the dipole location, showing that the ear-EEG forward models provided a good model to predict ear potentials. In addition, we demonstrated that the developed forward models can be used to explore the sensitivity to brain sources for different ear-EEG electrode configurations. We consider the proposed method to be an important step forward in the characterization and utilization of ear-EEG.

Histopathology of Inner Ear Malformations: Potential Pitfalls for Cochlear Implantation.

The presence of bony inner ear malformations may associate with a number of anatomical abnormalities affecting the middle ear structures. Those malformations may create pitfalls and complications for cochlear implantation. Inner ear malformations associate with varying degrees of hearing loss, and frequently require cochlear implantation for hearing rehabilitation. Therefore, the abnormalities affecting the middle- and inner-ear structures may increase the risk of surgical complications. We examined 38 human temporal bones from donors with bony inner ear malformations. Using light microscopy, we analyzed the presence of abnormalities in the structures of the middle- and inner-ear. Our collection comprises of 38 specimens with inner-ear malformations (cochlear aplasia, n = 3; cochlear hypoplasia, n = 30; incomplete partition, n = 3; isolated vestibular malformation, n = 2). The anatomy of the middle ear was abnormal in most temporal bones with cochlear aplasia, cochlear hypoplasia, and incomplete partition type I (40%-100%). Some of those abnormalities (hypoplastic or obliterated mastoid, 55.2%; aplastic or obliterated round window, 71.0%; aberrant course of the facial nerve, 36.8%) may hinder the access to the round window using the conventional facial recess approach for cochlear implantation. The cochlear nerve and associated bony structures (internal auditory canal and bony canal for cochlear nerve) were normal in 71.0% of all temporal bones with inner ear malformations. Each different type of malformation may create specific surgical challenges to surgeons. Comprehensive preoperative imaging is fundamental toward the surgical success of cochlear implants in patients with malformations. Alternatives to circumvent those middle- and inner-ear abnormalities and potential complications are further discussed.

Petrosal morphology and cochlear function in Mesozoic stem therians.

Here we describe the bony anatomy of the inner ear and surrounding structures seen in three plesiomorphic crown mammalian petrosal specimens. Our study sample includes the triconodont Priacodon fruitaensis from the Upper Jurassic of North America, and two isolated stem therian petrosal specimens colloquially known as the Höövör petrosals, recovered from Aptian-Albian sediments in Mongolia. The second Höövör petrosal is here described at length for the first time. All three of these petrosals and a comparative sample of extant mammalian taxa have been imaged using micro-CT, allowing for detailed anatomical descriptions of the osteological correlates of functionally significant neurovascular features, especially along the abneural wall of the cochlear canal. The high resolution imaging provided here clarifies several hypotheses regarding the mosaic evolution of features of the cochlear endocast in early mammals. In particular, these images demonstrate that the membranous cochlear duct adhered to the bony cochlear canal abneurally to a secondary bony lamina before the appearance of an opposing primary bony lamina or tractus foraminosus. Additionally, while corroborating the general trend of reduction of venous sinuses and plexuses within the pars cochlearis seen in crownward mammaliaforms generally, the Höövör petrosals show the localized enlargement of a portion of the intrapetrosal venous plexus. This new vascular feature is here interpreted as the bony accommodation for the vein of cochlear aqueduct, a structure that is solely, or predominantly, responsible for the venous drainage of the cochlear apparatus in extant therians. Given that our fossil stem therian inner ear specimens appear to have very limited high-frequency capabilities, the development of these modern vascular features of the cochlear endocast suggest that neither the initiation or enlargement of the stria vascularis (a unique mammalian organ) was originally associated with the capacity for high-frequency hearing or precise sound-source localization.

Effect of Torsional Beam Length on Acoustic Functionalities of Bio-Inspired Piezoelectric MEMS Directional Microphone

In MEMS, the vibrations of torsionally supported diaphragms largely depend on the torsional beam specifications. An amiss selection of the beam parameters can lead to significant imperfection in the microphone functionalities, such as modal frequency, sensitivity, directionality, signal-to-noise ratio (SNR), and input-referred noise floor. Here, we present two piezoelectric MEMS directional microphones inspired by the ear anatomy of fly Ormia ochracea, with a prime focus to identify the effect of torsional beam dimensions on their acoustic functionalities. The dimensions of both diaphragms and the width & thickness of the torsional beams are identical for both microphones, the only difference between these two microphones lies in the torsional beam length. The microphones are fabricated by a commercially available micromachining process; PiezoMUMPs. To convert the mechanical vibrations into the electronic signal, a unique piezoelectric sensing scheme is developed comprising of aluminium nitride (AlN) and D33 transducer mode. The performances of both microphones are carried out by the theoretical analysis and simulation and further verified with the experimental measurements. It is found from all analyses that the microphone having a shorter length of the torsional beam is better in terms of sensitivity, noise floor, and SNR regarding its low propagation delay.

Utility of a smartphone-enabled otoscope in the instruction of otoscopy and middle ear anatomy

To present the utility of a smartphone-enabled otoscope as a teaching adjunct in pre-clinical otoscopy training. 60 pre-clinical medical students were randomized into either a control group using a conventional otoscope or an experimental group using a smartphone-enabled otoscope. Participants in each group were trained to use their assigned device and were given time to practice on a colleague's ear. Participants then completed a questionnaire indicating their ability to visualize anatomical landmarks of the middle ear as well as their confidence in performing a middle ear examination using their device. Compared to participants using the conventional otoscope, significantly more students using the smartphone-enabled otoscope identified the umbo (93% versus 63%, P = 0.005), the short process of the malleus (67% versus 33%, P = 0.008), the cone of light (100% versus 70%, P = 0.001), and the pars flaccida (60% versus 33%, P = 0.03). Furthermore, participants who used the smartphone-enabled otoscope reported significantly increased confidence in performing otoscopy compared to those who used a conventional otoscope (4.1 ± 0.7 versus 2.8 ± 0.9, P < 0.001). Finally, participants rated the smartphone-enabled otoscope as an excellent teaching aid for otoscopy training. The smartphone-enabled otoscope serves as a valuable teaching tool for pre-clinical otoscopy education. After using the device, pre-clinical students were more confident in performing a middle ear examination and in identifying important anatomical landmarks of the middle ear.

The History of Ear Acupuncture and Ear Cartography: Why Precise Mapping of Auricular Points Is Important.

The current author had the opportunity to present a study on the history of ear acupuncture at the International Summit Forum on Clinical Application of Acupoints in August 2018 (from August 25 to August 27), in Beijing, China, and to introduce the latest ear chart by Frank R. Bahr, MD, there. This article is based on that presentation and includes more historical facts. Although the relationship between the ear and meridians was discussed previously in the famous book, The Internal Classic of the Yellow Emperor (Huang Di Neijing), the first auricular map was published in 1888 by Zhenjun Zhang in his book Essential Techniques for Massage (Lizheng Anmo Yaosu). This map was a drawing of the posterior aspect of the ear showing areas of the five Zang organs: Heart; Liver; Spleen; Kidney; and Lung. Paul Nogier, MD, discovered ear somatotopy, a representation of the whole person on the ear in the shape of a homunculus, or inverted fetus, on the ear. Dr. Paul Nogier's ear map was first published in 1957. A more-detailed presentation, the Loci Auriculomedicinae, elaborated by Drs. Paul Nogier and Bahr as well as René J. Bourdiol, MD, appeared in 1974. A new edition will soon appear in French. Auricular medicine is an excellent method, but only if the ear points are located precisely. Preconditions for this ability are excellent knowledge of the ear's anatomy, documented on a very detailed modern ear chart, such as the one recently created by Dr. Bahr, and constant practice of pulse palpation according to Dr. Paul Nogier with the vascular autonomous signal.

New information on the braincase and endocranial morphology of the Late Triassic neotheropod Zupaysaurus rougieri using computed tomography data

ABSTRACTZupaysaurus rougieri is an early neotheropod from the middle Norian Los Colorados Formation of northwestern Argentina represented by an almost complete skull and several postcranial bones. Most of its braincase morphology has remained obscured by other skull bones and sediment. Additional mechanical preparation and X-ray computed tomography on the single known specimen of Zupaysaurus has allowed a detailed description of the braincase, the cranial endocast, and the inner ear of this Triassic dinosaur. Basal theropod braincases are poorly sampled and there is little information on this region, and even poorer knowledge on the brain and inner ear anatomy of Triassic forms. The virtual reconstruction of the braincase of Zupaysaurus shows anteroventrally oriented, finger-like basipterygoid processes, an elongate and horizontally projected cultriform process, and well-developed preotic pendant, basisphenoid recess, and subsellar recess. The endocranial morphology is partially reconstructed, showing an anteroposteriorly short but dorsoventrally tall cranial endocast, with well-marked demarcations between the forebrain, midbrain, and hindbrain. The inner ear preserves the three semicircular canals, but not the lagena. The posterior semicircular canal is proportionally large when compared with that of other theropods. The new information presented here on Zupaysaurus rougieri contributes to the knowledge of the neuroanatomy of basal theropods and sheds light on the evolutionary patterns of the braincase morphology in nonavian Theropoda.

Pars tensa and tympanicomalleal joint: proposal for a new anatomic classification.

The tympanic membrane (TM) belongs to the ear. Despite its place in the ear anatomy, can we give it also a different anatomic classification? The main objective is to clarify the nature of TM, tympanic bone and malleus to propose a new anatomic classification. This cadaveric study was performed in two human heads and six fresh temporal bones. A study of the temporomandibular joint, external acoustic meatus (EAM), TM and middle ear structures was conducted. A medical literature review englobing anatomy, embryology, histology and phylogeny of the ear was performed and the results were compared with the results of the dissection. The external ear is constituted by the auricle and the EAM. This last segment is made by a cartilaginous and an osseous portion. The osseous portion of the EAM is constituted mainly by tympanic bone. The external ear is separated from the middle ear by the TM. Inside the middle ear, there are three ossicles: malleus, incus and stapes, which allow the conduction of sound to the cochlea. Based on the anatomic dissection and medical literature review of the tympanic bone, malleus and TM, we propose that these structures are interconnected like a joint, and named it "Tympanicomalleal joint". It seems that the TM can be part of a joint that evolved to improve sound transmission and middle ear protection. Thinking TM has part of a joint may help in the development of more efficient reconstructive surgical techniques.

Percutaneous Threshold of Facial Nerve Stimulation Predicts Facial Canal Dehiscence

ABSTRACTIatrogenic facial nerve (FN) injury is one of the most feared complications of otologic surgery. Dehiscence of the bony covering of the FN within the temporal bone increases FN vulnerability to accidental injury. High-resolution computed tomography (HRCT) of the temporal bone is used preoperatively to assess middle ear and mastoid anatomy; however, it is unreliable for detecting facial canal dehiscence. In this study, our aim was to determine if preoperative percutaneous FN stimulation could predict middle ear facial canal dehiscence. Between January 2015 and February 2017, we performed preoperative HRCT and percutaneous FN stimulation on adult patients who underwent otologic surgery at our institution. Stimulation was performed with a monopolar probe placed on the skin over the stylomastoid foramen. Electrical stimuli ranged from 0 to 40 milliamperes (mA). Recordings were made from ipsilateral facial muscles. Dependent variables included threshold to compound muscle action potential (CMAP), threshold to maximum amplitude of CMAP, and maximum amplitude of CMAP for each muscle. A retrospective chart review was performed. Seventy patients met inclusion criteria. Of the 24 with an intraoperatively confirmed dehiscence, 10 were identified preoperatively by the attending surgeon on HRCT. Averages of the lowest recorded threshold to CMAP (5.1mA v. 9.1mA), and an average of the threshold to CMAP (8.9 mA. 11.8 mA) of dehiscent versus non-dehiscent nerves were significantly different (p < .05). In conclusion, percutaneous FN stimulation is a simple and cost-effective tool that can give the surgeon important preoperative information about FN anatomy.

The Effect of Virtual Three‐Dimensional Stereoscopic Middle and Inner Ear Models on First‐Year Dental Students' Short‐Term Retention

Several studies in virtual three‐dimensional (3D) anatomy have shown either no difference in traditional and 3D learning among dental students or disadvantages in 3D learning over traditional learning. There are few studies in the literature that explore the effectiveness of virtual stereoscopic 3D anatomy models on dental students' learning. This study aimed to determine if virtual 3D stereoscopic anatomical models of the middle and inner ear could improve first‐year dental students' short‐term retention. This study also aimed to determine if there was a correlation between first‐year dental students' spatial abilities and their learning gains from virtual 3D anatomy exposure. During the fall 2018 semester, the first‐year dental students were invited to participate in 3D learning sessions pertaining to the middle and inner ear. Students (n=18) attended to a 3D learning session featuring virtual stereoscopic middle and inner ear models. During the learning session, the student participants completed a pre‐test before and a post‐test after the virtual 3D learning experience. At the end of the 3D learning sessions, students completed a mental rotation test (MRT) for measuring their spatial abilities and a survey for assessing their perceptions of 3D learning. The average scores on all of the students' performance measures, pre‐tests, post‐tests, and MRT's, will be analyzed using a repeated measures ANOVA. In addition, the pre‐ and post‐ knowledge test performances, respectively, of the students with high and low spatial ability will be compared using a one‐way ANOVA. The results of the statistical analyses will determine whether there is a significant difference between the pre‐ and post‐3D test scores of the first‐year dental students and whether there is a significant relationship between first‐year dental students' spatial abilities and learning. Overall, the first‐year dental students perceived the 3D learning sessions of middle and inner ear anatomy to be a positive learning experience. The use of virtual stereoscopic 3D anatomy has the potential to improve first‐year dental students' learning of the anatomy of regions as complex as the middle and inner ear when used as a supplement to traditional instruction.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Displacement of the stapes differs across species—Implications for studies of auditory function

Sound is transferred to the cochlea via the middle ear. The anatomy and physiology of the middle ear varies significantly across species, and these differences impact both the stimulation provided to the inner ear, and the suitability of different animal models for use in various types of research. Studies of auditory trauma from blast, for example, require generation of intracochlear pressures with sufficiently high intensities to cause damage. In some species, e.g., mice and rats, it may not be possible to generate sufficiently high pressures through air conducted sound alone, whereas in humans sufficiently high pressures can readily be generated through air conduction. We hypothesize that this is due to limits on the displacement of the stapes by the stapedial annular ligament, which thereby constrains the energy transferred to the cochlea through the middle ear. To test this hypothesis, we made measurements of the motion of the middle ear bones in response to tones of varying intensities and frequencies in several different species commonly used in laboratory research. Our results reveal peak stapes displacements from ~150 um in humans to 10-20 um in mice and rats. We will discuss the implications of these findings for basic studies of auditory function.