Fossils document evolutionary changes of jaw joint to mammalian middle ear.

The dual jaw joint of Morganucodon1,2 consists of the dentary-squamosal joint laterally and the articular-quadrate one medially. The articular-quadrate joint and its associated post-dentary bones constitute the precursor of the mammalian middle ear. Fossils documenting the transition from such a precursor to the mammalian middle ear are poor, resulting in inconsistent interpretations of this hallmark apparatus in the earliest stage of mammaliaform evolution1-5. Here we report mandibular middle ears from two Jurassic mammaliaforms: a new morganucodontan-like species and a pseudotribosphenic shuotheriid species6. The morganucodontan-like species shows many previously unknown post-dentary bone morphologies1,2 and exhibits features that suggest a loss of load-bearing function in its articular-quadrate joint. The middle ear of the shuotheriid approaches the mammalian condition in that it has features that are suitable for an exclusively auditory function, although the post-dentary bones are still attached to the dentary. With size reduction of the jaw-joint bones, the quadrate shifts medially at different degrees in relation to the articular in the two mammaliaforms. These changes provide evidence of a gradual loss of load-bearing function in the articular-quadrate jaw joint-a prerequisite for the detachment of the post-dentary bones from the dentary7-12 and the eventual breakdown of the Meckel's cartilage13-15 during the evolution of mammaliaforms.

Structure and scaling of the middle ear in domestic dog breeds.

Although domestic dogs vary considerably in both body size and skull morphology, behavioural audiograms have previously been found to be similar in breeds as distinct as a Chihuahua and a St Bernard. In this study, we created micro-CT reconstructions of the middle ears and bony labyrinths from the skulls of 17 dog breeds, including both Chihuahua and St Bernard, plus a mongrel and a wolf. From these reconstructions, we measured middle ear cavity and ossicular volumes, eardrum and stapes footplate areas and bony labyrinth volumes. All of these ear structures scaled with skull size with negative allometry and generally correlated better with condylobasal length than with maximum or interaural skull widths. Larger dogs have larger ear structures in absolute terms: the volume of the St Bernard's middle ear cavity was 14 times that of the Chihuahua. The middle and inner ears are otherwise very similar in morphology, the ossicular structure being particularly well-conserved across breeds. The expectation that larger ear structures in larger dogs would translate into hearing ranges shifted towards lower frequencies is not consistent with the existing audiogram data. Assuming that the audiograms accurately reflect the hearing of the breeds in question, oversimplifications in existing models of middle ear function or limitations imposed by other parts of the auditory system may be responsible for this paradox.

Differential effects of mass-loading the eardrum and stiffening the middle ear on wideband absorbance.

The current work investigated the effects of mass-loading the eardrum on wideband absorbance in humans. A non-invasive approach to mass-loading the eardrum was utilized in which water was placed on the eardrum via ear canal access. The mass-loaded absorbance was compared to absorbance measured for two alternative middle ear states: normal and stiffened. To stiffen the ear, subjects pressurized the middle ear through either exsufflation or insufflation concurrent with Eustachian tube opening. Mass-loading the eardrum was hypothesized to reduce high-frequency absorbance, whereas pressurizing the middle ear was hypothesized to reduce low- to mid-frequency absorbance. Discriminant linear analysis classification was performed to evaluate the utility of absorbance in differentiating between conditions. Water on the eardrum reduced absorbance over the 0.7- to 6-kHz frequency range and increased absorbance at frequencies below approximately 0.5 kHz; these changes approximated the pattern of changes reported in both hearing thresholds and stapes motion upon mass-loading the eardrum. Pressurizing the middle ear reduced the absorbance over the 0.125- to 4-kHz frequency range. Several classification models based on the absorbance in two- or three-frequency bands had accuracy exceeding 88%.

Interpretation of the nine-step test for Eustachian tube function should consider mastoid cavity volume.

INTRODUCTION: The modified nine-step test is a classical method for evaluating Eustachian tube function. However, clinical interpretation of the increased maximal difference in middle ear pressure (mdMEP) in the modified nine-step test is unknown. We hypothesised that the different reservoir effects of the mastoid cavity can bias the results of the modified nine-step test. METHODS: A total of 108 consecutive participants (216 ears) were retrospectively screened. Of these, 55 participants (82 ears) who met the inclusion/exclusion criteria were enrolled. The volumetric results of the mastoid cavity, parameters of the modified nine-step test (mdMEP, middle ear pressure, tympanic membrane compliance), and demographic data were analysed. RESULTS: A significant negative correlation was found between mdMEP and mastoid cavity volume (R = .467, p < .001). Ears with mdMEP >70 daPa showed poor pneumatization in the mastoid cavity, with volumes less than 3000 mm3 (10th percentile of all ears analysed). Ears with mastoid cavity volumes lower than the 25th percentile showed a significantly higher mdMEP (p < .001). Patients with mastoid cavity volumes higher than the 75th percentile were significantly younger (p < .001). Multivariate regression analysis for mdMEP showed a good fit (R = .854) using factors including middle ear pressure, admittance and, most importantly, the reciprocal of mastoid volume (Beta = 0.752, p < .001). CONCLUSIONS: The mdMEP, the main parameter of the modified nine-step test, was negatively correlated with the mastoid cavity volume. Therefore, the results of the modified nine-step test should be interpreted with consideration of mastoid cavity volume.

The tympanic region of the skull in extant pinnipeds: A pilot study of auditory morphological disparity using linear morphometric principal component analysis.

Pinnipeds are unique semiaquatic taxa possessing adaptations to hear efficiently both in water and on land. Research over the past century is extremely limited on the auditory apparatus morphology of pinnipeds, which include the Families Phocidae (true seals), Otariidae (sea lions/fur seals), and Odobenidae (walruses). Our extensive literature review revealed inaccurate terminology of this region, with details corresponding only to terrestrial taxa, and a severe lack of information due to very few current studies. This demonstrates the need for evaluation and comparison of the auditory morphologies of modern terrestrial and semiaquatic carnivorans in relation to hearing. This initial study compares tympanic bullar morphologies of Phocidae to other pinnipeds and representatives of terrestrial carnivoran families. Morphological correlations of the basicranial auditory region were also compared within phocid subfamilies. Eleven skull measurements and about eleven calculated ratios were included in multiple principal component analyses to determine what areas of the auditory apparatus had the most significant morphological variation. This is the first study using this methodology, especially in reference to the hearing adaptations of pinnipeds, specifically in phocids. Results demonstrate distinct trends in phocid bullar morphology relative to other pinnipeds. Analyses reveal that: (1) phocids generally have different bullar morphology than otariids and odobenids; (2) Neomonachus schauinslandi (Hawaiian monk seal) and Neomonachus tropicalis (Caribbean monk seal) have unique morphology compared to phocids and other pinnipeds. Future work with increased number of specimens will further substantiate these findings and both ontogenetic and sexual variations will be examined.

Morphological variations of auditory bullae in otomyine rodents (Rodentia: Otomyini) in southern African biomes.

Mammalian middle ear cavities differ from those of other taxa as they comprise three ossicles and in rodents, can be encapsulated by an auditory bulla. In small mammals, the middle ear cavity (bulla) was found to be enlarged in the desert-dwelling species; however, differences in bullar size could have been due to ancestry. In this study, we sampled seven species from three genera (Myotomys, Otomys, and Parotomys) of the African murid tribe Otomyini (laminated-toothed rats), and compared the bullar volumes and shapes between the otomyine species and within the species Myotomys unisulcatus. Photographs of museum skull specimens were taken from ventral and lateral views, and the volumes of the bullae were estimated digitally from the photographs. No sexual dimorphism in bullar volumes was found in any of the species. Corrected bullar volumes were significantly different between species and larger bullae were seen in individuals inhabiting regions with lower annual rainfall. Bullar shape (estimated using geometric morphometrics) was significantly different between the genera and the species. Parotomys have tympanic meatuses that face more anteriorly compared to both, Otomys and Myotomys. When comparing bullae within M. unisulcatus, those inhabiting regions with lower annual rainfall had significantly larger bullar volumes, but no significant difference was found in bullar shape between the regions. This study shows that otomyine rodents in more xeric habitats have different auditory structures to those inhabiting wetter habitats.

The tympanoperiotic complex of the blue whale, Balaenoptera musculus.

The tympanoperiotic complex of a blue whale Balaenoptera musculus is described and compared to the homologous structures in the other extant and fossil baleen whale species. The periotic and the tympanic bulla represent informative anatomical regions in both functional and phylogenetic studies and for this reason a micro-CT scan of the bones was performed in order to better characterize their external aspect and to reconstruct the inner structures. In particular, the cochlea, the semicircular canals and associated portions of the periotic are reconstructed so that these structures may be used in phylogenetic analyses. We observed that the blue whale periotic is characterized by the presence of a strong dorsal protrusion which is posteriorly bordered by a previously undescribed morphological character that we name the posterotransverse fossa. The peculiar shape of the anterior process and the en echelon organization of the posterior foramina of the pars cochlearis are also described and compared. From a phylogenetic perspective, the blue whale is confirmed to be closely related to the fin whale, Balaenoptera physalus, but it is suggested, based on ear bone characters only, that it diverged before the other balaenopterid species in the phylogeny of Balaenopteridae. This placement supports a series of morphological observations suggesting that the extant blue whale was an early-diverging member of Balaenoptera. Our results help to decipher the evolutionary origin of the blue whale, the largest living animal, by allowing new and more detailed morphological analyses of the balaenopterid fossil record.

Revisión Exploratoria: Comunicación de la Articulación Temporomandibular y del Oído Medio en Fetos y Niños / Exploratory Review: Temporomandibular Joint and Middle Ear Communication in Fetuses and Infants

La Articulación temporomandibular (ATM) cumple funciones importantes para la vida; su adecuado funcionamiento se puede alterar por trastornos temporomandibulares (TTM). La sintomatología de los TTM es variada, entre ellos se encuentra dolor en los músculos masticatorios, ruidos articulares y con menos frecuencia algunos pacientes refieren síntomas auditivos, lo que sugiere la existencia de una relación entre la ATM y el oído medio; sin embargo, esta relación no es clara. En consecuencia, el presente estudio tiene como propósito realizar una revisión de literatura para identificar los aspectos conocidos, desconocidos y controvertidos sobre la relación entre la ATM y el oído medio en niños y fetos. Se efectuó una búsqueda de la literatura en bases de datos utilizando los operadores booleanos (AND/OR) y los términos clave en inglés y en español. Se identificaron inicialmente 1080 artículos, se eliminaron los artículos duplicados y se aplicaron los criterios de inclusión y exclusión. Finalmente, se seleccionaron un total de 14 artículos que se revisaron a texto completo. Los estudios encontrados se enfocan en el desarrollo histoembriológico de la ATM y cómo ese desarrollo se da en conjunto con los componentes del oído medio. Adicionalmente, se identificaron investigaciones sobre el origen, la morfología y función del ligamento discomaleolar, el ligamento esfenomandibular y la fisura petrotimpánica como estructuras que conectan la ATM y el oído medio, pero los resultados han sido controvertidos. Se concluye que son necesarios más estudios para determinar cualquier relación anatómica y fisiológica que pueda existir entre la ATM y el sistema auditivo en fetos y niños.

SUMMARY: The temporomandibular joint (TMJ) has important functions for life; its proper functioning can be altered by temporomandibular disorders (TMD). The symptomatology of TMD is varied, including pain in the masticatory muscles, joint noises and less frequently some patients report auditory symptoms, suggesting the existence of a relationship between the TMJ and the middle ear; however, this relationship is not clear. Consequently, the present study aims to conduct a literature review to identify the known, unknown and controversial aspects of the relationship between TMJ and the middle ear in children and fetuses. A literature search was performed in databases using Boolean operators (AND/ OR) and key terms in English and Spanish. A total of 1080 articles were initially identified; duplicate articles were eliminated and inclusion and exclusion criteria were applied. Finally, a total of 14 articles were selected and reviewed in full text. The studies found focus on the histoembryological development of the TMJ and how that development occurs in conjunction with the middle ear components. Additionally, research on the origin, morphology, and function of the discomalleolar ligament, sphenomandibular ligament, and petrotympanic fissure as structures connecting the TMJ and middle ear was identified, but the results have been controversial. It is concluded that further studies are necessary to determine any anatomical and physiological relationship that may exist between the TMJ and the auditory system in fetuses and children.

The development of a didactic model to facilitate the understanding of the components and anatomical relations of the middle ear / O desenvolvimento de um modelo didático para facilitar a compreensão dos componentes e das relações anatômicas da orelha média

The middle ear is important from an anatomical and clinical point of view, seeing that it contains and allows the passages of structures, in addition to establishing relations with other regions of the head. However, the middle ear is small and difficult to dissect, making difficult the study in cadavers and understanding. In this context, professors and students from Universidade Estadual do Oeste do Paraná developed an anatomical model of the middle ear, showing its main bones, membranes, muscles and nerves. The model was developed with acrylic plates joined to form a cube, each side representing one of the middle ear's walls. The tympanic membrane and the secondary tympanic membrane were represented by an elastic fabric, which covered openings on the membranous wall and the labyrinthic wall, respectively. The auditory ossicles, the muscles and the nerves were made from polymer clay and positioned inside the cube, according to their characteristics and anatomical position in the middle ear. Furthermore, the auditory tube was represented by a plastic cone projecting from the carotid wall. The use of these low-cost anatomical models is an alternative to enable and improve learning. These initiatives favor the teaching of Human Anatomy, increasing understanding, the establishment of clinical correlations, and improving the academic education of health professionals (AU)

A orelha média é importante do ponto de vista anatômico e clínico, pois contém e permite a passagem de estruturas, além de estabelecer relações com outras regiões da cabeça. Porém, a orelha média é pequena e dissecação, o que dificulta seu estudo em cadáveres e a compreensão por parte dos alunos. Nesse contexto, docentes e discentes da Universidade Estadual do Oeste do Paraná desenvolveram um modelo anatômico da cavidade timpânica, apresentando seus principais componentes membranáceos, ósseos, musculares e nervosos. Para a confecção da maquete, placas de acrílico transparente foram unidas formando um cubo, com cada placa representando uma das paredes da cavidade timpânica (exceto a parede tegmental). Tecidos elásticos foram colocados em orifícios feitos nas paredes membranácea e labiríntica para representação da membrana timpânica e da membrana timpânica secundária, respectivamente. Os ossículos da audição, músculos e nervos foram confeccionados em biscuit e posicionados no espaço interno do cubo, observando-se as características e a posição anatômica dessas estruturas na orelha média. A tuba auditiva foi representada pela colocação de um cone plástico projetando-se a partir da parede carótica. A confecção de modelos didáticos é uma alternativa de baixo custo para facilitar o ensino e a compreensão da Anatomia Humana. O aprendizado de conceitos básicos favorece o entendimento das correlações anatomoclínicas, melhorando a formação acadêmica dos profissionais de saúde (AU)

Dehiscencia timpánica (foramen de Huschke): a más de 300 años de su primera descripción / Tympanic dehiscence (Huschke's foramen): more than 300 years after its first description

RESUMEN: La dehiscencia timpánica o Foramen de Huschke se considera un rasgo craneal morfológico menor, hipostósico, no estocástico, transitorio, ubicado en la placa timpánica del hueso temporal, cuya expresión se considera fisiológica hasta los 5 años de edad. La mención de este rasgo en la literatura es escasa, generando controversias entre de los anatomistas que la han descrito. El epónimo Huschke, anatomista alemán, quien ha sido mencionado como el primero en observarla en 1844. Sin embargo, existen antecedentes de que dicha característica ósea fue previamente descrita por otros autores casi 200 años antes. La actual denominación, dehiscencia timpánica, fue dada en 1878 por Bürkner, siendo aceptada hasta el día de hoy. El objetivo de este artículo es realizar un análisis histórico de la descripción morfológica de la dehiscencia timpánica en la literatura anatómica especializada.

SUMMARY: Tympanic dehiscence or Huschke's Foramen is considered a minor, hypostosic, non-stochastic, transitory morphological cranial feature, located in the tympanic plate of the temporal bone, whose expression is considered physiological up to 5 years of age. The mention of this feature in the literature is scarce, generating controversy among the anatomists who have described it. The eponymous Huschke, a German anatomist, who has been mentioned as the first to observe it in 1844. However, there is a history that this bone characteristic was previously described by other authors almost 200 years earlier. The current name, tympanic dehiscence, was given in 1878 by Bürkner, being accepted until today. The objective of this article is to carry out a historical analysis of the morphological description of tympanic dehiscence in specialized anatomical literature.

Endoscopic evaluation of middle ear anatomic variations in autopsy series: analyses of 204 ears / Avaliação endoscópica das variações anatômicas da orelha média em uma série de autópsias: análise de 204 orelhas

Abstract Introduction Microsurgery of the ear requires complete evaluation of middle ear surgical anatomy, especially the posterior tympanic cavity anatomy. Preoperative assessment of the middle ear cavity is limited by the permeability of eardrum and temporal bone density. Therefore, middle ear exploration is an extremely useful method to identify structural abnormalities and anatomical variations. Objective The aim of this study is to determine anatomic variations of the middle ear in an autopsy series. Methods All evaluations were performed in the Forensic Medicine Institute Morgue Department. The cases over 18 years of age, with no temporal bone trauma and history of otologic surgery included in this study. Results One hundred and two cadavers were included in the study. The mean age was 49.08 ± 17.76 years. Anterior wall prominence of the external auditory canal was present in 27 of all cadavers (26.4%). The tympanic membrane was normal in 192 ears (94%) while several eardrum pathologies were detected in 12 ears (6%). Agenesis of the pyramidal eminence and stapedial tendon was found in 3 ears. While the ponticulus was bony ridge-shaped in 156 of 204 ears (76.4%), it was bridge-shaped in 25 ears (12.3%). The ponticulus was absent in 23 ears (11.3%). While complete subiculum was present in 136 of all ears (66.7%), incomplete subiculum was present in 21 ears (10.3%). Subiculum was absent in 47 ears (23%). Facial dehiscence was found in 32 ears and the round window niche was covered by a pseudomembrane in 85 ears (41.6%). A fixed footplate was present in 7.4% of all ears, and no persistent stapedial artery was seen in any cases. Conclusion The pseudomembrane frequency covering the round window niche was found different from reports in the literature. In addition, the frequency of the external auditory canal wall prominence has been reported for the first time.

Resumo Introdução A otomicrocirurgia requer avaliação completa da anatomia cirúrgica da orelha média, especialmente da anatomia da cavidade timpânica posterior. A avaliação pré-operatória da cavidade timpânica é limitada pela permeabilidade do tímpano e densidade do osso temporal. Portanto, a exploração da orelha média é um método extremamente útil para identificar anormalidades estruturais e variações anatômicas. Objetivo Determinar as variações anatômicas da orelha média em uma série de autópsias. Método Todas as avaliações foram realizadas no necrotério do Instituto Médico-Legal. Os casos com mais de 18 anos, sem trauma do osso temporal e história de cirurgia otológica foram incluídos neste estudo. Resultados Cento e dois cadáveres foram incluídos no estudo. A média de idade foi de 49,08 ± 17,76 anos. A proeminência da parede anterior do conduto auditivo externo estava presente em 27 de todos os cadáveres (26,4%). A membrana timpânica era normal em 192 orelhas (94%), enquanto várias alterações do tímpano foram detectadas em 12 orelhas (6%). Agenesia da eminência piramidal e do tendão do estapédio foi encontrada em 3 orelhas. Enquanto o pontículo tinha formato de crista óssea em 156 das 204 orelhas (76,4%), tinha o formato de ponte em 25 orelhas (12,3%). O pontículo estava ausente em 23 orelhas (11,3%). Enquanto o subículo completo estava presente em 136 de todas as orelhas (66,7%), encontrava-se incompleto em 21 orelhas (10,3%). O subículo estava ausente em 47 orelhas (23%). Deiscência facial foi encontrada em 32 orelhas e o nicho da janela redonda estava coberto por uma pseudomembrana em 85 orelhas (41,6%). A platina fixa foi observada em 7,4% de todas as orelhas e a artéria estapediana persistente não foi vista. Conclusão A frequência da pseudomembrana que cobre o nicho da janela redonda foi diferente daquela encontrada na literatura. Além disso, a frequência da proeminência da parede do canal auditivo externo foi relatada pela primeira vez.

Evaluation of the Facial Recess and Cochlea on the Temporal Bone of Stillbirths regarding the Percutaneous Cochlear Implant

Abstract Introduction The literature shows that there are anatomical changes on the temporal bone anatomy during the first four years of life in children. Therefore, we decided to evaluate the temporal bone anatomy regarding the cochlear implant surgery in stillbirths between 32 and 40 weeks of gestational age using computed tomography to simulate the trajectory of the drill to the scala timpani avoiding vital structures. Objectives To measure the distances of the simulated trajectory to the facial recess, cochlea, ossicular chain and tympanic membrane, while performing the minimally invasive cochlear implant technique, using the Improvise imaging software (Vanderbilt University, Nashville, TN, US). Methods An experimental study with 9 stillbirth specimens, with gestational ages ranging between 32 and 40 weeks, undergoing tomographic evaluation with individualization and reconstruction of the labyrinth, facial nerve, ossicular chain, tympanic membrane and cochlea followed by drill path definition to the scala tympani. Improvise was used for the computed tomography (CT) evaluation and for the reconstruction of the structures and trajectory of the drill. Results Range of the distance of the trajectory to the facial nerve: 0.58 to 1.71mm. to the ossicular chain: 0.38 to 1.49 mm; to the tympanic membrane: 0.85 to 1.96 mm; total range of the distance of the trajectory: 5.92 to 12.65 mm. Conclusion The measurements of the relationship between the drill and the anatomical structures of the middle ear and the simulation of the trajectory showed that the middle ear cavity at 32 weeks was big enough for surgical procedures such as cochlear implants. Although cochlear implantation at birth is not an indication yet, this study shows that the technique may be an option in the future.

Methods for estimating the volume of the tympanic bulla in the big hairy armadillo Chaetophractus villosus (Mammalia, Xenarthra, Dasypodidae) / Métodos para la estimación del volumen de bula timpánica en el quirquincho grande Chaetophractus villosus (Mammalia, Xenarthra, Dasypodidae)

Two methods of measurement of bullar dimensions (callipers and scaling from digital images) and subsequent application of four volume formulae (rectangular prism, cylinder, ellipse and elliptical cone) were tested to find the most appropriate non-destructive method for estimating the bullar volume in Chaetophractus villosus. Material for the study consisted in clean adult skull (n=22). Real volume was obtained from latex casts of the tympanic bulla. Each estimation was corrected by a factor based on the differences between the estimated and the real volumes. Highest accuracy (5-7 % of underestimation) and precision (coefficient of variation: 13.27 %) were obtained from callipers and application of rectangular prism, cylinder and ellipse formulae. The corresponding correction factors were 0.31, 0.39 and 0.58, respectively.

Se evaluaron dos métodos para la obtención de medidas de la bula (calibre y escalado a partir de imágenes digitales), con posterior aplicación de cuatro fórmulas de volumen (prisma rectangular, cilindro, elipse y cono elíptico), a fin de hallar el método no destructivo más adecuado para el cálculo de volumen de bula en Chaetophractus villosus. El material de estudio consistió en cráneos limpios de individuos adultos (n=22). El volumen real fue obtenido a partir de moldes de látex de la bula timpánica. Cada estimación fue corregida mediante un factor basado en las diferencias entre los volúmenes reales y estimados. La mayor precisión (coeficiente de variación: 13,27 %) y exactitud (subestimaciones del 5-7 %) fueron obtenidas a partir de mediciones con calibre y aplicación de fórmulas de prisma rectangular, cilindro y elipse (factores de corrección: 0,31, 0,39 y 0,58, respectivamente).

Characterization of tympanic cavity volume in newborns using computerized tomography scanning / Caracterización del volumen de la cavidad timpánica en recién nacidos usando tomografía computadorizada

This study reports tympanic cavity (TC) volume in newborns, which was missing in the literature. Ex vivo histology and computerized tomography (CT) scans were performed on temporal bone and data were analyzed in part using software developed in house. CT images with a slice thickness of 0.5 mm were obtained from 5 newborn cadavers and analyzed independently by two expert researchers. The border of the TC was delineated manually and measurement of area of interest was calculated on masked images. Then, the area measurements from all sections were added to estimate the total volume. The agreements between the histological and CT findings were then compared for accuracy, repeatability and reliability. The Dice and Jaccard similarity coefficient measures were used as a statistical validation metric to evaluate the assessor's performance in manual volume segmentation. Good assessor agreement was observed with average Dice values above 0.8 indicating that consistent and reliable volume measurements were feasible. The proposed protocol was shown to be accurate in calculating the TC volume, and thus can be used for computer-assisted presurgical planning or for diagnosing structural alterations in TC.

El objetivo fue determinar el volumen de la cavidad timpánica (CT) en recién nacidos, información no encontrada en la literatura. Se realizaron escaners a través de tomografia computadorizada (TC) y estudios histológicos en el hueso temporal; los datos se analizaron utilizando un software desarrollado en nuestra institución. Se obtuvieron imágenes de secciones de TC, de 0,5 mm de grosor, a partir de 5 cadáveres de recién nacidos, los que fueron analizados de forma independiente por dos investigadores expertos. El margen de los cortes de TC fue delineado manualmente y la medición del área de interés se estimó sobre imágenes ocultas. Después, se añadieron las mediciones de área de todas las secciones para estimar el volumen total. Las concordancias entre el estudio histológico y los hallazgos de la TC se compararon en cuanto a precisión, repetibilidad y confiabilidad. Se utilizaron las medidas de coeficiente de similitud de Jaccard y Dice como métrica de validación estadística para evaluar el desempeño del asesor en la medición manual del volumen. Se observó una buena correlación del evaluador con los valores medios de Dice, por encima de 0,8 indicando que es factible obtener mediciones coherentes y confiables de volumen. El protocolo propuesto ha demostrado ser preciso para calcular el volumen de la CT, y por lo tanto se puede utilizar para la planificación prequirúrgica asistida o para el diagnóstico de alteraciones estructurales en la CT.

Características biométricas de los osículos del oído de individuos chilenos / Biometric characteristics of ear ossicles in Chilean subjects

El crecimiento y desarrollo de los osículos del oído medio no muestran grandes variaciones después del nacimiento. Nuevas tecnologías en cirugía de implantes, corrección y tratamiento de las enfermedades del oído medio necesitan un detallado conocimiento biométrico de estos osículos. Basados en lo anterior, se estudiaron 22 Malleus, 16 Incus y 3 Estapedios de individuos adultos de sexo masculino, de cadáveres secos, todos individuos de la Región Central de Chile. Los osículos fueron analizados y fotografiados con un Microscopio quirúrgico de diagnóstico OPMI Pico, Carl Zeiss, imagen estereoscópica. Los datos métricos se obtuvieron con un calyper digital Mitutoyo y sometidos a análisis digital con el AxioVision LE 4.8.2.0. Software de Carl Zeiss. El malleus tuvo una longitud promedio desde la cabeza al ápice del manubrio de 8,08 mm y su proceso anterior una longitud de 0,76 mm; el proceso largo del incus tuvo una longitud promedio de 3,37 mm y el proceso corto de 3,07 mm; la base del estapedio tuvo una longitud antero-posterior de 2,53 mm. Los resultados obtenidos son un aporte al conocimiento de los osículos del oído en nuestra población.

The growth and development of the ossicles of the middle ear do not show large variations after birth. New technologies in implant surgery, correction and treatment of diseases of the middle ear require an increasingly larger biometric knowledge of these ossicles. Therefore, we studied 22 Malleus, 16 Incus and 3 Stapes of male adult subjects, from dry corpses, and, one Malleus, one Incus and one Stapes of a seven-month-old male fetus, all Chilean subjects from the Central Region in Chile. These bones were analyzed and photographed with a model OPMI Microscope tilting binocular tube with stereoscopic 3D image. Metric data were obtained with the AxioVision L.E 4.8.2.0. Carl Zeiss software. The malleus had an average length from head to apex of 8.08 mm, the anterior process had a length of 0.76 mm, the long limb of the incus was an average length of 3.37 mm and the short limb 3.07 mm, the base of the stapes measured 2.53 mm. The results are a contribution to the knowledge of ear ossicles in our population.

Macroscopic description of the external and middle ear of paca (Cuniculus paca Linnaeus, 1766) / Descrição macroscópica da orelha externa e media da paca (Cuniculus paca Linnaeus, 1766)

Paca (Cuniculus paca), one of the largest rodents of the Brazilian fauna, has inherent characteristics of its species which can conribute as a new option for animal experimantation. As there is a growing demand for suitable experimental models in audiologic and otologic surgical research, the gross anatomy and ultrastructural ear of this rodent have been analyzed and described in detail. Fifteen adult pacas from the Wild Animals Sector herd of Faculdade de Ciências Agrárias e Veterinárias, Unesp-Jaboticabal, were used in this study. After anesthesia and euthanasia, we evaluated the entire composition of the external ear, registering and ddescribing the details; the temporal region was often dissected for a better view and detailing of the tympanic bulla which was removed and opened to expose the ear structures analyzed mascroscopically and ultrastructurally. The ear pinna has a triangular and concave shape with irregular ridges and sharp apex. The external auditory canal is winding in its path to the tympanic mebrane. The tympanic bulla is is on the back-bottom of the skull. The middle ear is formed by a cavity region filled with bone and membranous structures bounded by the tympanic membrane and the oval and round windows. The tympanic membrane is flat and seals the ear canal. The anatomy of the paca ear is similar to the guinea pig and from the viewpoint of experimental model has major advantages compared with the mouse ear.

A paca (Cuniculus paca), um dos maiores roedores da fauna brasileira, possui características inerentes à sua espécie que podem contribuir como uma nova opção de animal experimental; assim, considerando-se que há crescente busca por modelos experimentais apropriados para pesquisas audiológicas e otológica cirúrgicas foram analisados e descritos em detalhes a anatomia macroscópica e ultraestrutural da orelha desse roedor. Para o estudo, utilizaram-se 15 animais adultos provenientes do plantel do Setor de Animais Silvestres da Faculdade de Ciências Agrárias e Veterinárias, Unesp-Jaboticabal, Jaboticabal/SP. Após anestesia e eutanásia, avaliou-se toda a composição da orelha externa, registrando-se e descrevendo-se os detalhes, também se dissecou a região temporal para melhor visibilização e detalhamento da bula timpânica e estas foram removidas e abertas a fim de expor as estruturas da orelha, as quais foram analisadas, macroscopicamente e ultraestruturalmente. O pavilhão auricular apresenta forma triangular e côncava com cristas irregulares e ápice pontiagudo; o conduto auditivo externo é sinuoso em seu trajeto até a membrana timpânica; a bula timpânica encontra-se na parte posterior-inferior do crânio; a orelha média é formada por uma região cavitária preenchida por estruturas ósseas e membranosas. É delimitada pela membrana timpânica e as janelas redonda e oval, sendo a membrana timpânica de forma plana e que veda todo o conduto auditivo. A anatomia da orelha da paca é semelhante à da cobaia e do ponto de vista de modelo experimental apresenta grandes vantagens em comparação com a orelha do rato.

Micro-endoscopic ear anatomy of guinea pig applied to experimental surgery

PURPOSE: To describe topographic and endoscopic anatomy of guinea pig ear for development of surgical approaches in experimental studies. METHODS: Experimental study. Eight adult guinea pigs (Cavia porcellus) were used in this study. Four animals were described through endoscopic view and four animals were used to describe topographic anatomy. RESULTS: The main structures of middle ear were well identified through endoscopy view: oval and round window, ossicles and vascular structures. Temporal bone position, landmarks and its relations to skull are perceived with topographic description. CONCLUSION: Topographic anatomic description allowed exposition of temporal bone relations for external surgical approaches. Alternatively, grooves and middle ear structures were identified and may be used to transcanal accesses. .

Morphology of the Middle Ear in Three Species of Armadillos (Dasypodidae, Xenarthra) from Argentina / Morfología del Oído Medio en Tres Especies de Armadillos (Dasypodidae, Xenarthra) de Argentina

Middle ears of adult Chaetophractus villosus, C. vellerosus and Zaedyus pichiy were studied for qualitative and quantitative comparisons. A great similarity in the overall shape of the middle ear structures was observed in the three species. The well-developed auditory bulla was formed by the intimate fusion of the tympanic and entotympanic. Internally, a recessus meatus and a wide epitympanic recess extending dorsally into an epitympanic sinus were recognized. The petrosal promontorium, nearly triangular, was the most salient feature in the tympanic cavity. The auditory ossicles corresponded to the transitional middle ear type. The m. tensor tympani and the m. stapedius were conspicuous. The lack of a stapedial artery was confirmed in all cases. The tympanic area and middle ear ossicles were relatively larger in C. vellerosus than in the other two species. It is hoped that the results of the present paper coupled to the bullar hypertrophy found in a previous work will provide a significant basis for future functional studies on the hearing capabilities in the dasypodids.

Se estudió cualitativa y cuantitativamente la morfología del oído medio en adultos de Chaetophractus villosus, C. vellerosus y Zaedyus pichiy. Se observó una gran similitud en las estructuras del oído medio de las tres especies. La bula auditiva, bien desarrollada, se observó formada por la fusión del timpánico y entotimpánico. Internamente se pudo reconocer un recessus meatus y un amplio receso epitimpánico que se extendía dorsalmente en un seno epitimpánico. El promontorio, casi triangular, fue la estructura más notoria del interior de la cavidad timpánica. Los huesecillos auditivos correspondieron al tipo transicional. Se observó un gran desarrollo en los músculos tensor del tímpano y estapedial. Se confirmó la falta de una arteria estapedial en las tres especies. El área del tímpano y los huesecillos auditivos fueron relativamente más grandes en C. vellerosus que en las otras dos especies. Se espera que los resultados del presente trabajo, sumados a la hipertrofia de la bula timpánica reportada previamente, provean una base significativa para futuros estudios sobre la capacidad auditiva en los dasipódidos.

Anatomia do osso temporal de ovelhas sob aspectos didáticos / Lambs' temporal bone anatomy under didactic aspects

É difícil encontrar ossos temporais humanos para o ensino de cirurgia otológica. Ossos temporais de ovelhas podem representar uma possível alternativa. MATERIAIS E MÉTODOS: Os ossos temporais de ovelhas foram dissecados em um programa convencional de dissecação de osso temporal no laboratório. Incluímos mastoidectomia, abordagens endaurais, mas também analisamos a aparência externa, o meato acústico externo e o hipotímpano. Algumas etapas são diferentes das preparações de ossos humanos. Os resultados morfométricos foram comparados à anatomia conhecida de humanos para verificar se o osso temporal de ovelhas seria utilizável para o ensino de cirurgia otológica. RESULTADOS: O osso temporal de ovelhas parece menor do que o humano. Encontramos uma área bolhosa se estendendo ao hipotímpano abaixo do meato acústico externo. A membrana timpânica é muito semelhante à humana. O meato acústico externo é menor e mais curto. A cadeia ossicular exibe analogias para com a humana. DISCUSSÃO: Esse estudo mostra que especificamente o ouvido médio, a membrana timpânica e o conduto auditivo externo são morfologicamente semelhantes às suas contrapartidas encontradas nos ossos temporais humanos. A ovelha parece ser um modelo viável para o ensino da anatomia do ouvido. A menor escala de algumas estruturas, especialmente dos componentes externos do osso temporal representa uma desvantagem. CONCLUSÕES: A ovelha parece representar uma alternativa viável no ensino de cirurgia otológica.

Human temporal bones in teaching ear surgery are rare. The lamb's temporal bone might be a possible alternative. MATERIAL AND METHODS: Temporal bones of the lamb were dissected with a typical temporal bone lab drilling program. We included a mastoidectomy, endaural approaches, but also analyzed the outer appearance, the external ear canal and the hypotympanon. Some steps differed from preparation done in humans. The morphometric results were compared to the known anatomy of human in order to verify the lambs' temporal bone for suitability in otosurgic training. RESULTS: The lambs' temporal bone appears smaller than the human one. We found a bullous extended hypotympanon located under the external ear canal. The tympanic membrane is very similar to the human one. The external ear canal is smaller and shorter. The ossicular chain shows analogies to human one. DISCUSSION: This study shows, that especially the middle ear, the tympanic membrane and the external ear canal are morphologically equal to the structures found in human temporal bones. The lamb seems feasible for teaching the anatomy of the ear. The smaller scales of some structures, especially the outer components of the temporal bone are a disadvantage. CONCLUSIONS: The lamb seems to be an alternative in teaching ear surgery.