Anatomical and morphometric study of goat middle ear ossicles (Capra aegagrus hircus) / [Estudo anatômico e morfométrico dos ossículos da orelha média de caprinos (Capra aegagrus hircus)]

The social and economic roles of goat farming in Northeastern Brazil, allied to the fact that the use of goat middle ear ossicles for research and human ear surgery training has not yet been proposed, justify the study of their applicability as an experimental model. The middle ears of 19 goats (Capra aegagrus hircus) from the bone collection of the Laboratory and Didactic Anatomy Museum of Domestic and Wild Animals of the Federal University of Vale do São Francisco (UNIVASF) were dissected. The malleus, incus, and stapes were evaluated regarding their macroscopic morphology and biometry (length, width, and height). Ossicle morphology was similar to sheep, human, and bovine morphology. The malleus was 1.3 times heavier and 2.2 times longer than the incus, and 9.0 times heavier and 3.7 times longer than the stapes. The size relationship was positive between the stapes and the malleus and negative between the stapes and the incus. It is concluded that the middle ear size and the anatomical similarities with human ossicles make goats a useful model for experimental scientific studies, reconstructive surgery practice of the ossicular chain, and human ear surgery training.(AU)

Tanto o papel social quanto o econômico da caprinocultura na região Nordeste do Brasil, somados ao fato de que o uso de ossículos da orelha média de caprinos para estudos e treinamento cirúrgico otológico humano ainda não foi proposto, justificam o estudo de sua aplicabilidade como modelo experimental. Foram dissecadas as orelhas médias de 19 caprinos (Capra aegagrus hircus), provenientes do ossuário do Laboratório e Museu Didático de Anatomia dos Animais Domésticos e Silvestres - Universidade Federal do Vale do São Francisco. Martelos, bigornas e estribos tiveram a morfologia macroscópica e a biometria (comprimento, largura e altura) avaliadas. A morfologia dos ossículos assemelhou-se a de ovinos, humanos e bovinos. O martelo foi 1,3 vez mais pesado e 2,2 vezes mais comprido que a bigorna e 9,0 vezes mais pesado e 3,7 vezes mais comprido que o estribo. A relação de tamanho entre o estribo e o martelo foi positiva, e entre o estribo e a bigorna negativa. Conclui-se que o tamanho da orelha média e as semelhanças anatômicas com os ossículos humanos tornam os caprinos um modelo útil para estudos científicos experimentais, prática cirúrgica reconstrutiva da cadeia ossicular e treinamento cirúrgico otológico humano.(AU)

Navigational guidelines and positional relationships of the human auditory ossicles from three-dimensional topography for ensuring safe and effective malleostapedotomy : Stereotactic topography of the auditory ossicles and its clinical implication.

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.

Comparison of sheep and human middle-ear ossicles: anatomy and inertial properties.

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

The discomallear ligament: anatomical, microscopical, and radiologic analysis.

BACKGROUND: Several anatomic relationships between the ear and the temporo-mandibular joint have been proposed to account for the presence of tinnitus during temporo-mandibular disorders. Among the otomandibular structures, the discomallear ligament (DML) is interposed between the malleus and the retrodiscal capsular complex. The aim of present paper was to study through dissection the frequency and morphology of DML, to characterize its type of collagen, and to evaluate the DML on routine computed tomography (CT). METHODS AND RESULTS: The study has been conducted on five un-embalmed adult cadavers, and in all cases, the DML was present (100%). It was constituted mainly by fibers of collagen I, with abundant elastic fibers. On CT exams of 40 patients with no reported pathology of the ear, on axial images, a dense structure, going from the upper end of the petrotympanic fissure to the neck of the malleus, was present in all the cases. In 90%, it showed a triangular shape, in 5% a rectangular shape, and in 5% a curved course. The mean length of the antero-medial side was 2 ± 0.6 mm and that of the antero-lateral side was 1.63 ± 0.5, and the mean area was 1.29 ± 0.83 mm2. CONCLUSION: The DML could represent an anatomical structure that joining the temporo-mandibular joint and the malleus may play a role in the otologic symptoms during temporo-mandibular disorders.

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

PURPOSE: 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. METHODS: 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. RESULTS: 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". CONCLUSIONS: 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.

Presencia y relaciones anatomofuncionales del ligamento discomaleolar: una revisión de la literatura / Presence and anatomofunctional relations of the discomaleolar ligament: a literature review

El Ligamento Discomaleolar es una estructura que no se describe en los textos clásicos de anatomía a pesar de ser descrito por primera vez por Rees, Pinto y luego por diversos autores como una estructura ligamentosa de tejido fibroelástico que conecta el cuello y el proceso anterior del martillo a través de la fisura petrotimpánica hasta la parte medioposterosuperior de la cápsula de la articulación temporomandibular (ATM), el disco articular y el ligamento esfenomandibular. Diversos estudios han reportado las implicaciones clínicas del ligamento discomaleolar y la relación entre los trastornos temporomandibulares con los síntomas asociados al oído medio. El objetivo de este estudio fue realizar una revisión sobre estudios que describen el ligamento discomaleolar y determinar si se considera una estructura independiente anatómica y funcionalmente y su relación con el oído medio. Se realizó una búsqueda de literatura científica identificó artículos donde se identifican las estructuras anatómicas asociadas a la articulación témporomandibular y el oído medio, fueron seleccionados 24 artículos según los criterios de selección. Los resultados obtenidos en los estudios seleccionados en esta revisión sugieren la existencia de una lámina o fascículo fibroso que conecta el disco de la ATM con el maléolo del oído medio, lo que validaría la presencia y relación entre el ligamento discomaleolar y los trastornos del oído medio.

The Discomaleolar Ligament is a structure that is not described in the classic texts of anatomy despite being described for the first time by Rees, Pinto and later by various authors as a ligamentous structure of fibroelastic tissue that connects the neck and the anterior process of the malleus through the petrotympanic cleft to the mid-superior part of the capsule of the temporomandibular joint (TMJ), the articular disc and the sphenomandibular ligament. Several studies have reported the clinical implications of the discomaleolar ligament and the relationship between temporomandibular disorders and symptoms associated with the middle ear. The aim of this study was to conduct a review of studies that describe the discomaleolar ligament and determine if an anatomically and functionally independent structure and its relation to the middle ear is considered. A search was performed of scientific literature identified articles where the anatomical structures associated with the temporomandibular joint and the middle ear were identified, 24 articles were selected according to the selection criteria. The results obtained in the studies selected in this review suggest the existence of a lamina or fibrous fascicle that connects the TMJ disc with the malleolus of the middle ear, which would validate the presence and relationship between the discomaleolar ligament and middle ear disorders.

The anterior process of the malleus in extant Lagomorpha (Mammalia).

The anterior anchoring of the malleus of 30 extant species of Lagomorpha (rabbits, hares, pikas) has been studied on the basis of histological serial sections and µCT-scans. It is shown that former studies of Oryctolagus, Lepus, and Ochotona are incomplete, because the rostral part of the processus anterior of the malleus is always lacking due to damage of this extremely delicate structure. Our study shows that in perinatal stages of Leporidae the praearticulare develops a prominent processus internus that fits into a groove at the ventral side of the tegmen tympani; this "tongue and groove"-arrangement may act as a hinge. In adult stages, the rostral end of the praearticulare fuses synostotically with the medial process of the ectotympanic. Torsional strain produced by rotation around the axis of the middle ear ossicles at sound transmission must, therefore, be experienced by the extremely thin but highly elastic bony pedicle of the processus internus praearticularis. The free ending processus anterior of a late fetal Ochotona shows a short processus internus praearticularis, which does not articulate with the tegmen tympani. During postnatal development the middle ear of Ochotona becomes considerably remodelled: not only does excessive pneumatization of the tegmen tympani and tympanic cavity wall occur, but the short processus anterior is fused synostotically to a bone trabecula of the tegmen tympani meshwork. The thin and elastic bone bridges are not equivalent in Leporidae and Ochotonidae, that is, they must have evolved convergently. Fleischer's classification with Oryctolagus possessing a "freely mobile type" of middle ear ossicles cannot be supported by our observations. The same holds true for Ochotona, which does not represent a "freely mobile type" either. Thus, we suggest for the lagomorph middle ear ossicles a new category: the "bone elasticity type."

The middle and inner ears of the Palaeogene golden mole Namachloris: A comparison with extant species.

Many living species of golden moles (Chrysochloridae) have greatly enlarged middle ear ossicles, believed to be used in the detection of ground vibrations through inertial bone conduction. Other unusual features of chrysochlorids include internally coupled middle ear cavities and the loss of the tensor tympani muscle. Our understanding of the evolutionary history of these characteristics has been limited by the paucity of fossil evidence. In this article, we describe for the first time the exquisitely preserved middle and inner ears of Namachloris arenatans from the Palaeogene of Namibia, visualised using computed tomography, as well as ossicles attributed to this species. We compare the auditory region of this fossil golden mole, which evidently did not possess a hypertrophied malleus, to those of three extant species with similarly sized ear ossicles, Amblysomus hottentotus, Calcochloris obtusirostris, and Huetia leucorhinus. The auditory region of Namachloris shares many common features with the living species, including a pneumatized, trabeculated basicranium and lateral skull wall, arteries and nerves of the middle ear contained in bony tubes, a highly coiled cochlea, a secondary crus commune, and no identifiable canaliculus cochleae for the perilymphatic duct. However, Namachloris differs from extant golden moles in the apparent absence of a basicranial intercommunication between the right and left ears, the possession of a tensor tympani muscle and aspects of ossicular morphology. One Namachloris skull showed what may be pneumatization of some of the dorsal cranial bones, extending right around the brain. Although the ossicles are small in absolute terms, one of the Huetia leucorhinus specimens had a more prominent malleus head than the other. This potentially represents a previously unrecognised subspecific difference.

The malleus cap: Anatomic description of cartilage of the lateral process of the malleus.

PURPOSE: To anatomically describe a cartilaginous cap attached to the lateral process of the malleus. STUDY DESIGN: Histologic and gross anatomic review. METHODS: Twenty temporal bones were histologically reviewed. The anatomical relationship between the tympanic membrane and malleus was then defined at the level of the lateral process of the malleus and the long process of the malleus. Separately, gross evaluation of these levels at the macroscopic level was undertaken through endoscopic imaging in five subjects. RESULTS: All temporal bones reviewed revealed the presence of a cartilaginous cap articulating between the tympanic membrane and the lateral process of the malleus. The cartilaginous cap was also readily identifiable in gross evaluation of the tympanic membrane from views lateral and medial to the tympanic membrane during endoscopic evaluation. CONCLUSION: The cartilaginous cap of the lateral process of the malleus is an important and reliable anatomical structure of the middle ear that has not previously been described. Through knowledge of the structure surgeons may exploit its presence by creating a cleavage plane between the cartilaginous cap and the malleus during tympanoplasty, possibly allowing for safer and more efficient surgery.

Controlled exploration of the effects of conductive hearing loss on wideband acoustic immittance in human cadaveric preparations.

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

Early development of the malleus and incus in humans.

It is widely accepted by developmental biologists that the malleus and incus of the mammalian middle ear are first pharyngeal arch derivatives, a contention based originally on classical embryology that has now been backed up by molecular evidence from rodent models. However, it has been claimed in several studies of human ossicular development that the manubrium of the malleus and long process of the incus are actually derived from the second arch. This 'dual-arch' interpretation is commonly presented in otolaryngology textbooks, and it has been used by clinicians to explain the aetiology of certain congenital abnormalities of the human middle ear. In order to re-examine the origins of the human malleus and incus, we made three-dimensional reconstructions of the pharyngeal region of human embryos from 7 to 28 mm crown-rump length, based on serial histological sections from the Boyd Collection. We considered the positions of the developing ossicles relative to the pharyngeal pouches and clefts, and the facial and chorda tympani nerves. Confirming observations from previous studies, the primary union between first pharyngeal pouch and first cleft found in our youngest specimens was later lost, the external meatus developing rostroventral to this position. The mesenchyme of the first and second arches in these early embryos seemed to be continuous, but the boundaries of the developing ossicles proved to be very hard to determine at this stage. When first distinguishable, the indications were that both the manubrium of the malleus and the long process of the incus were emerging within the first pharyngeal arch. We therefore conclude that the histological evidence, on balance, favours the 'classical' notion that the human malleus and incus are first-arch structures. The embryological basis of congenital ossicular abnormalities should be reconsidered in this light.

Intraoperative assessment of ossicular fixation.

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.

Morfología y morfometría comparada entre los huesecillos auditivos del cerdo común (Sus scrofa domestica) y el Humano (Homo sapiens sapiens) / Comparative study of the morphology between the ossicles of the common pig (Sus scrofa domestica) and human (Homo sapiens sapiens)

El cerdo doméstico (Sus scrofa domestica) ha sido utilizado como modelo para estudiar métodos de implante en el oído medio previo a estudios clínicos humanos. Diferentes investigaciones han destacado la utilidad en este ámbito, como también su alta comparabilidad morfológica en relación con los humanos. Sin embargo, las descripciones anatómicas sobre sus huesecillos auditivos son insuficientes, al igual que las comparaciones en relación con el humano. Por ello, con el objetivo de realizar una descripción detallada de la anatomía de dichos huesecillos comparados con los del humano, se procedió a disecar seis cabezas de cerdo, de las cuales se extrajeron sus huesecillos para observar su morfología. Los resultados preliminares demostraron que la cadena de huesecillos del Cerdo comparte la presencia de las mismas formaciones anatómicas que se pueden identificar en los huesecillos del hombre, pero aún así existen diferencias descriptivas y morfométricas en la morfología de ellas. Los resultados permitieron concluir que existe alta comparabilidad morfológica entre ambas cadenas de huesecillos debido a sus diferencias y similitudes, lo cual lo hace ser un buen modelo didáctico para el estudio y la enseñanza de la morfología auditiva en distintos niveles educacionales.

The domestic Pig (Sus scrofa domestica)has been used as a model to study implants methods in clinical cases of the human middle ear. Different studies have highlighted the usefulness in this area, as well as its high morphological comparability with regard to humans. However, the anatomical descriptions about its ear bones are scarce, as comparisons in relation to the human. Therefore, in order to make a detailed description of the anatomy of these bones compared to human, it was necessary to dissect six pig heads of which its ossicles were removed to observe its morphology. Preliminary results showed that the pig'sossicles share the same anatomical formations that can be identified in the human ones, but there are some descriptive and morphometric differences in its morphology. The results concluded that there is high comparability between both morphological ossicular chains due to their differences and similarities, which makes it a great teaching model for the study and teaching of auditory morphology at different educational levels.

3D morphometric analysis of the human incudomallear complex using clinical cone-beam CT.

Human middle ears show large morphological variations. This could affect our perception of hearing and explain large variation in experimentally obtained transfer functions. Most morphological studies focus on capturing variation by using landmarks on cadaveric temporal bones. We present statistical shape analysis based on clinical cone beam CT (CBCT) scans of 100 patients. This allowed us to include surface information on the incudomallear (IM) complex (joint, ligaments and tendon not included) of 123 healthy ears with a scanning resolution of 150 µm and without a priori assumptions. Statistical shape modeling yields an average geometry for the IM complex and the variations present in the population with a high precision. Mean values, variation and correlations among anatomical features (length of manubrium, combined length of malleus head and neck, lengths of incus long and short process, enclosing angles, ossicular lever ratio, incudomallear angle, and principal moments of inertia) are reported and compared to results from the literature. Most variation is found in overall size and the angle between incus and malleus. The compact representation provided by statistical shape modeling is demonstrated and its benefits for surface modeling are discussed.

The anterior process of the malleus in Cetartiodactyla.

The anterior fixation of the anterior process of the malleus has been studied in a number of Cetartiodactyla. This anterior process, also known as processus gracilis, is provided by the prearticular (gonial), a dermal bone, whereas the cartilage of Meckel becomes resorbed in perinatal ontogenetic stages. Posteriorly, the prearticular fuses with the cartilaginous caput of the malleus; rostrally, the prearticular (= processus gracilis) is always fixed to the anterior crus of the ectotympanic by an extremely thin splint (thickness < 50 µm). From the rostral part of the processus gracilis all studied cetartiodactyls develop a processus internus of considerable size. This process was known as 'ossiculum accessorium mallei' in former times, and its homology has been disputed; from our microscopic-anatomical study we can definitely state that it is always a 'processus internus praearticularis'. This process contacts the fascia of the tensor tympani muscle. In non-ruminants, it articulates dorsally with the tegmen tympani and dorsolaterally with the ectotympanic; whereas the processus gracilis becomes more and more slender, the processus internus may grow to considerable size and normally is fused to the adjacent bones already in juveniles. However, in ruminants, the tegmen tympani tends to disappear and the processus internus praearticularis appears as relatively small bony knob at the floor of the medial cranial cavity, and it seems not to be fused to the surrounding bones; in later age stages, it may become secondarily overgrown by the petrosal. This dorsally exposed processus internus praearticularis seems to be a synapomorphy of the Ruminantia. The functional meaning of this internal process of the prearticular, which is also developed to a minor degree in Carnivora, remains unclear at the moment - but we present some speculations about this.

On the connection between the tympanic membrane and the malleus.

BACKGROUND: The tympano-mallear connection (TMC) is the soft-tissue connection between the tympanic membrane (TM) and the manubrium of the malleus. Some studies suggest that its mechanical properties may have a substantial influence on the mechanics and transfer function of the middle ear. However, relatively little is known about the dimensions of the TMC and its variability among individuals. METHOD: Thirteen samples were collected from human temporal bones, consisting of only the malleus and the TM. They were imaged using µCT without contrast enhancing agent. From the µCT images, the TMC dimensions were measured in both anterior-posterior direction (TMC width) and medial-lateral direction (TMC thickness). Three selected samples were examined using histological microscopy. RESULTS: Both TMC width and thickness featured a large variability among individuals. The minimal TMC width along the manubrium for different individuals covered a range between 83 and 840 µm. The minimal thickness ranged from 48 to 249 µm and the maximal thickness from 236 to 691 µm. Histological sections showed that the TMC consists of a narrow core of dense regular connective tissue, surrounded by loose connective tissue. In some samples, either of these two components was absent in the TMC at some manubrium locations. The configuration of these components varied among the samples as well. CONCLUSION: Our data confirm that a large inter-individual variability exists in the properties of the TM-malleus connection in humans in terms of its dimensions, tissue composition and configuration. Average data and their variability margins will be useful input for testing the importance of the TMC in finite element models.

Análisis de los términos utilizados en la literatura científica para referirse a los ligamentos extracapsulares de la articulación témporomandibular: Parte I: Ligamentum sphenomandibulare / A study of terms used in scientific literature to refer to the extracapsular ligaments of the temporomandibular joint: Part I: Ligamentum sphenomandibulare

La Terminología Anatómica es la base de correcta comunicación anatómica y establece la unificación internacionalmente aceptada para diversas estructuras anatómicas. Sin embargo, su uso en la literatura pedagógica y científica no se ha aplicado por completo. El objetivo de esta investigación fue analizar la literatura en relación al uso correcto de los términos referentes al Ligamento esfenomandibular de la Articulación témporomandibular (ATM). Se realizó una revisión en libros de anatomía y artículos científicos relacionados y se comparó el uso de términos referentes al ligamento esfenomandibular con la Terminología Anatómica Internacional (TAI). Se encontraron diferencias en cuanto a los términos usados (sinonimia) para referirse tanto al ligamento esfenomandibular, así como a las estructuras que sirven de origen e inserción a este con los términos establecidos por la TAI en latín, inglés y algunos términos traducidos al español. La sinonimia y uso de epónimos encontrados dificultan la comunicación entre los científicos del área, así como el aprendizaje de los alumnos de pregrado y postgrado, cuya principal fuente de estudio continúan siendo los libros de anatomía.

Terminología Anatómica is currently the international standard for anatomical terminology, and establishes an internationally accepted and unified nomenclature for several anatomical structures. However, International Anatomical Terminology (IAT) is not always used correctly in scientific literature. The purpose of this review is to examine scientific literature in order to determine whether the terms that refer to the sphenomandibular ligament of the temporomandibular joint (TMJ) are being used correctly. Scientific books and articles were reviewed, and the terms used were compared with those established by the IAT. Our study found differences between the terms actually used (Synonyms) to refer to the sphenomandibular ligament and to the anatomical structures where the ligament originates and where it is inserted and those established by the IAT in Latin, English and some terms translated into Spanish. The use of eponyms and synonyms found, creates difficulties in communication between scientists and in the learning process of undergraduate students, who frequently use textbooks.

Three-dimensional vibration of the malleus and incus in the living gerbil.

In previous studies, 3D motion of the middle-ear ossicles in cat and human was explored, but models for hearing research have shifted in the last few decades to smaller mammals, and gerbil, in particular, has become a popular hearing model. In the present study, we have measured with an optical interferometer the 3D motion of the malleus and incus in anesthetized gerbil for sound of moderate intensity (90-dB sound pressure level) over a broad frequency range. To access the ossicles, the pars flaccida was removed exposing the neck and head of the malleus and the incus from the malleus-incus joint to the plate of the lenticular process. Vibration measurements were done at six to eight points per ossicle while the angle of observation was varied over approximately 30 ° to enable calculation of the 3D rigid-body velocity components. These components were expressed in an intrinsic reference frame, with one axis along the anatomical suspension axis of the malleus-incus block and a second axis along the stapes piston direction. Another way of describing the motion that does not assume an a priori rotation axis is to calculate the instantaneous rotation axis (screw axis) of the malleus/incus motion. Only at frequencies below a few kilohertz did the screw axis have a maximum rotation in a direction close to that of the ligament axis. A slight slippage in the malleus-incus joint developed with increasing frequency. Our findings are useful in determining the sound transfer characteristics through the middle ear and serve as a reference for validation of mathematical middle-ear models. Last but not least, comparing our present results in gerbil with those of previously measured species (human and cat) exposes similarities and dissimilarities among them.

Morphologic variations of clinically normal mallei and incudes.

OBJECTIVES: Various features and shapes of malleus and incus are reported. Partially or unaddressed are their bilateral symmetry, correlation with otitis media, and concordance of features and shapes. Such information may contribute to the understanding of malleus and incus ontogeny and the installation and function of implantable middle ear devices. We sought to address the following hypotheses: (1) a cranium's malleus and incus have bilateral symmetry, with respect to their features and shapes; (2) features and shapes of malleus and incus are unrelated to the mastoid size indicator of childhood otitis media; and (3) an ear's malleus and incus have concordant features and shapes (ie, the presence or absence of a feature or shape of a malleus or incus is associated with the presence or absence of another feature or shape in that ear's malleus or incus). METHODS: Postmortem material-analysis prevalence study of 41 adult crania without clinical otitis media. Mastoid sizes were assessed radiographically. RESULTS: Most mallei had lateral processes and inflected manubrium tips. Most incudes had concave superior borders of their short processes, non-notched inferior borders of their short processes, and anteriorly curved anterior edges of their long processes. Only I feature, absence of the lateral process of the malleus, was suggested to have a relationship to small mastoid size. Concordance was not found for any shape or feature of the malleus or incus. CONCLUSION: Clinically normal mallei and incudes have feature and shape variations that are mostly bilaterally symmetric.

Viscoelastic properties of the human tympanic membrane studied with stroboscopic holography and finite element modeling.

A new anatomically-accurate Finite Element (FE) model of the tympanic membrane (TM) and malleus was combined with measurements of the sound-induced motion of the TM surface and the bony manubrium, in an isolated TM-malleus preparation. Using the results, we were able to address two issues related to how sound is coupled to the ossicular chain: (i) Estimate the viscous damping within the tympanic membrane itself, the presence of which may help smooth the broadband response of a potentially highly resonant TM, and (ii) Investigate the function of a peculiar feature of human middle-ear anatomy, the thin mucosal epithelial fold that couples the mid part of the human manubrium to the TM. Sound induced motions of the surface of ex vivo human eardrums and mallei were measured with stroboscopic holography, which yields maps of the amplitude and phase of the displacement of the entire membrane surface at selected frequencies. The results of these measurements were similar, but not identical to measurements made in intact ears. The holography measurements were complemented by laser-Doppler vibrometer measurements of sound-induced umbo velocity, which were made with fine-frequency resolution. Comparisons of these measurements to predictions from a new anatomically accurate FE model with varied membrane characteristics suggest the TM contains viscous elements, which provide relatively low damping, and that the epithelial fold that connects the central section of the human manubrium to the TM only loosely couples the TM to the manubrium. The laser-Doppler measurements in two preparations also suggested the presence of significant variation in the complex modulus of the TM between specimens. Some animations illustrating the model results are available at our website (www.uantwerp.be/en/rg/bimef/downloads/tympanic-membrane-motion).