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Stapes

The stapes, commonly known as the stirrup bone, is the smallest and most medial of the three ossicles in the middle ear, measuring approximately 3 mm in length and weighing about 2.5 mg.^[1]^[2] It plays a pivotal role in auditory transduction by mechanically coupling vibrations from the incus to the oval window of the cochlea, thereby amplifying and transmitting sound energy into the fluid-filled inner ear to facilitate hearing.^[3] Shaped like a stirrup, the stapes is unique among human bones for its high degree of morphological variability and its derivation primarily from Reichert's cartilage of the second pharyngeal arch during embryogenesis.^[3] Structurally, the stapes comprises a head that articulates with the incus via a synovial joint, two slender crura (anterior and posterior legs) that converge at the base, and an oval footplate that embeds into the oval window membrane, forming an angle of about 10.7° relative to the tympanic membrane.^[3] This configuration allows the footplate to piston-like displace the perilymph fluid in the scala vestibuli, converting airborne sound waves into hydraulic pressure waves essential for cochlear hair cell stimulation.^[3] The bone receives its blood supply from the anterior tympanic artery, a branch of the maxillary artery, and is stabilized by the stapedius muscle, which attaches to its posterior crura and dampens excessive vibrations to protect against loud sounds, with innervation from the facial nerve.^[3] In clinical contexts, the stapes is central to conditions like otosclerosis, where abnormal bone remodeling fixes the footplate and impairs sound transmission, often requiring surgical intervention such as stapedotomy to restore hearing.^[3] It also features in congenital anomalies, such as those seen in Treacher Collins syndrome, and its proximity to critical structures like the facial nerve and chorda tympani during middle ear surgery underscores the need for precise anatomical knowledge to avoid complications.^[3] Embryologically, ossification begins around 18 weeks of gestation and completes by 26 weeks, with the footplate's annular ligament deriving from mesoderm to ensure flexible coupling with the inner ear.^[3]

Anatomy

Gross structure

The stapes, the smallest and lightest bone in the human body, possesses a distinctive stirrup-shaped morphology that facilitates its role within the middle ear. It comprises a rounded head (capitulum), a slender neck, two delicate crura (anterior and posterior limbs), and an oval footplate at the base. The head features a concave articular surface covered in cartilage, while the crura are thin, arched struts that converge at the footplate; the anterior crus is typically shorter and more robust than the posterior. Between the crura lies the obturator foramen, a central aperture that traverses the superstructure.^[4]^[3]^[5] The stapes measures approximately 3 mm in height from the head to the footplate and spans about 2.5 mm in width across the crura, with an average weight of 2.5 mg. Its articulations include a synovial ball-and-socket joint at the head with the lenticular process of the incus, enabling pivotal movement, and the footplate, which is embedded in the oval window of the cochlea and encircled by the annular ligament for flexible attachment. The neck provides the insertion site for the tendon of the stapedius muscle, which dampens vibrations.^[3]^[6]^[1] Blood supply to the stapes derives primarily from the anterior tympanic artery, a branch of the maxillary artery, nourishing the head and neck regions. Venous drainage follows the arterial pathways, ultimately converging into the internal jugular vein via the jugular bulb.^[3]^[5]

Microscopic structure

The stapes bone is composed primarily of a type I collagen matrix mineralized with hydroxyapatite crystals, characteristic of compact cortical bone found in auditory ossicles. The crura consist of compact bony tissue with thin cortical bone layers, providing structural support while minimizing weight for efficient vibration transmission.^[7] The footplate exhibits a layered histological structure, including an outer endosteum lining the bony surface, remnants of hyaline cartilage from developmental origins, and an inner interface with perilymph in the oval window vestibule.^[8] This arrangement allows for a flexible connection to the inner ear while maintaining mechanical integrity.^[9] The annular ligament, connecting the footplate to the oval window margins, has a fibrocartilaginous composition with uncalcified fibrocartilage and embedded elastic fibers, measuring approximately 0.1-0.2 mm in thickness to form a flexible yet secure seal.^[10] This structure facilitates piston-like movement of the stapes during sound conduction.^[11] Sensory nerve endings, derived from branches of the facial nerve associated with the stapedius muscle, are present in the stapes region.^[12] With age, the stapes undergoes increasing ossification and rigidity post-infancy, including calcification at joint interfaces and reduced osteocyte density, which may alter biomechanical properties.^[13] These changes reflect progressive bone tissue aging in auditory ossicles.^[14]

Development and variation

Embryonic development

The stapes originates from mesenchyme of the second pharyngeal (hyoid) arch, derived specifically from Reichert's cartilage.^[15] Neural crest cells, migrating from the posterior hindbrain region, populate this arch by the fourth week of embryonic development, forming ectomesenchyme that contributes substantially to the stapes structure.^[16] Approximately 80-90% of the stapes arises from this neural crest-derived ectomesenchyme, with the remainder from mesodermal sources.^[17] By the sixth week, a cartilaginous model of the stapes begins to form within Reichert's cartilage, independent yet connected via the interhyale to the surrounding otic capsule.^[17] Endochondral ossification initiates around 18-24 weeks, transforming the cartilage into bone while preserving the footplate's attachment to the oval window.^[18] This process advances through the fetal period, achieving near-completion perinatally, with full maturation of the stapes articulations by approximately 35 weeks gestation.^[19] Key regulatory genes orchestrate this development, including Hoxa2, which patterns the second arch identity, and Prx1/2, which influence mesenchymal condensation.^[20] Dlx genes further specify proximal-distal identities within the arch derivatives, ensuring proper stapes morphology. Disruptions, such as developmental arrest around weeks 5-6 due to facial nerve anomalies, can lead to stapes agenesis observed in syndromes like isolated congenital stapes absence.^[21]

Anatomical variations

The stapes exhibits a range of congenital anatomical variations in humans, primarily affecting the footplate, crura, and overall superstructure. Footplate deformities, which may occur unilaterally or bilaterally, are among the more frequently reported congenital anomalies, with an incidence of congenital stapes footplate fixation estimated at 0.28 to 0.31 per 100,000 person-years based on population-based surgical data. These deformities often involve partial or complete fixation of the footplate to the oval window niche, potentially linked to disrupted embryonic mesenchymal differentiation around the eighth gestational week. Crus variations, such as fusion of the anterior and posterior crura or absence of one crus (monocrural stapes), represent additional common congenital alterations, observed in morphological studies of ossicles where the stapes demonstrates the highest variability among the middle ear bones.^[22] Rarer congenital variants include complete absence or severe hypoplasia of the stapes (stapes aplasia), typically identified through isolated case reports or small series due to their extreme scarcity. These anomalies often present with the superstructure absent or malformed, while the footplate may remain partially intact or dysplastic. These may occur in isolation or as part of syndromes such as Treacher Collins syndrome. Overall, congenital stapes anomalies constitute a subset of middle ear malformations, occurring in less than 1 in 15,000 births.^[23]^[24] Acquired variations in stapes morphology frequently result from otosclerosis, a condition characterized by abnormal bone remodeling that leads to footplate immobilization and fixation to the oval window margins. The clinical prevalence of otosclerosis, which predominantly affects the stapes, ranges from 0.3% to 1% in white adult populations (as of studies up to 2025), with histological involvement noted in up to 10% of Caucasians but symptomatic progression in only a subset. This acquired fixation alters the footplate's mobility without inherently changing its shape, distinguishing it from congenital forms.^[25]^[26] Ethnic and geographic differences influence stapes morphology, particularly crus thickness and overall dimensions. Studies on Eastern Indian populations report significantly thicker posterior crura (average 0.45 mm) compared to Western cohorts, suggesting potential adaptive or genetic factors contributing to these variations. Otosclerosis itself shows ethnic disparities, with higher prevalence in Caucasians (up to 2.1%) than in Asian or African populations (less than 0.5%).^[27]^[28] Detection of these variations relies on high-resolution computed tomography (CT) imaging, which provides detailed preoperative assessment of footplate shape, crus integrity, and fixation status with submillimeter resolution. Ultra-high-resolution CT enhances visualization of subtle crus hypoplasia or footplate protrusions, aiding surgical planning for stapedotomy.^[29]^[30]

Comparative anatomy

In mammals

The stapes is conserved across all mammals as the third middle ear ossicle, homologous to the hyomandibula of the hyoid arch in reptilian ancestors, facilitating sound transmission from the tympanic membrane to the oval window of the cochlea.^[31] This structure remains fundamentally similar in form and function among mammalian species, underscoring its evolutionary stability despite diverse ecological niches.^[32] Structural variations in the stapes reflect adaptations to body size and habitat. In larger mammals, such as elephants, the stapes is significantly scaled up, with ossicles approximately 10 times more massive than in humans, weighing around 23 mg compared to 2.4 mg in humans, which supports enhanced low-frequency sound transmission suited to their large ear canal dimensions.^[33] Aquatic mammals like whales exhibit specialized modifications, including ultra-high bone mineral density in the stapes (up to 1708 mgHA cm⁻³) and solid, void-free crura that increase stiffness to withstand underwater pressure and improve impedance matching for high-frequency hearing in dense media.^[34] Functional scaling of the stapes correlates with body mass and auditory demands across mammals, optimizing vibration transfer efficiency. For instance, in bats relying on echolocation, the stapes features unusual footplate positions relative to the cochlea, enabling rapid transmission of ultrasonic frequencies (up to 212 kHz) for precise prey detection and navigation in cluttered environments.^[35] Overall middle ear scaling follows allometric patterns, where stapes size increases predictably with body mass to maintain acoustic sensitivity across species.^[36] Fossil evidence indicates that the mammalian stapes evolved from the reptilian hyomandibula during the late Triassic period, approximately 200 million years ago, as part of the broader transformation of synapsid jaw elements into auditory ossicles that enhanced terrestrial hearing capabilities.^[37] Pathological conditions analogous to human otosclerosis, involving stapes fixation or ankylosis leading to conductive hearing loss, are documented in rodents like the LP/J mouse model.^[38]

In non-mammals

In non-mammalian vertebrates, the stapes is represented by homologous structures that evolved from the hyomandibula, a bone in ancestral fish that primarily supported the gill arches and jaw apparatus.^[37] This evolutionary transition occurred during the Late Devonian period, approximately 375 million years ago, as evidenced by fossils like Tiktaalik roseae, where the hyomandibula began adapting for auditory functions in early tetrapods while retaining some skeletal support roles. In modern fish, there is no true stapes; instead, the hyomandibula contributes to jaw mechanics and vibration detection through direct transmission to the inner ear fluids, without a dedicated middle ear ossicle.^[39] Amphibians lack a fully developed stapes but possess a columella auris, a slender cartilaginous or bony structure homologous to the stapes, which transmits vibrations from the tympanic membrane to the oval window.^[40] This columella is often augmented by an extracolumella, a accessory element that couples the eardrum to the columella and enhances sensitivity to airborne sounds, as seen in frogs where it forms a lever system for low-frequency detection.^[41] Additionally, an opercular bone in many amphibians connects to the pectoral girdle via muscles, providing a secondary pathway for substrate-borne vibrations to reach the inner ear, particularly important in semi-aquatic species.^[42] In reptiles and birds, the columella auris serves as the direct homolog of the stapes, functioning as a single rod-like ossicle that bridges the middle ear cavity to transmit sound vibrations from the tympanic membrane to the oval window of the inner ear.^[31] This structure is elongated and lightweight, optimized for efficient sound conduction in terrestrial and aerial environments, with the footplate interfacing directly with the perilymph.^[43] In crocodilians, such as alligators and crocodiles, the columella retains an evolutionary dual role, primarily dedicated to hearing but with attachments that stabilize the skull during jaw movements, reflecting its hyomandibular ancestry.^[37] Fossils of extinct therapsids, the synapsid group ancestral to mammals, reveal intermediate forms of the auditory ossicles, where the columella-stapes coexisted with jaw elements gradually detaching to form additional middle ear bones, marking a key step in the diversification of tetrapod hearing mechanisms.^[44] These transitional structures in Permian therapsids, like Dimetrodon, demonstrate a progressive reduction in jaw-support functions for the hyomandibula-derived ossicle, enhancing its specialization for audition.^[45]

Physiology

Role in sound transmission

The stapes serves as the final link in the ossicular chain of the middle ear, vibrating in response to movements transmitted from the incus and executing a primarily piston-like motion with its footplate against the oval window of the cochlea. This action displaces the perilymph fluid in the scala vestibuli, initiating pressure waves that propagate through the cochlear duct to stimulate hair cells for sound perception.^[3]^[46] In humans, the stapes effectively transmits acoustic signals across the audible frequency range of 20 Hz to 20 kHz, with the ossicular chain's lever system—arising from the relative lengths of the malleus manubrium and incus long process—providing an amplitude amplification ratio of approximately 1.3:1, equivalent to about 2 dB of gain.^[47]^[48] The structural attachments of the stapes to the incus via the incudostapedial joint and to the oval window via its annular ligament facilitate this precise vibrational transfer.^[3] A key function of the stapes is to contribute to acoustic impedance matching, bridging the substantial difference between the low acoustic impedance of air in the external and middle ear (approximately 415 rayls) and the high impedance of the cochlear fluid (approximately 10^6 rayls); the combined effects of the ossicular lever, tympanic membrane-to-stapes footplate area ratio (about 17:1 to 21:1), and phase differences yield a total pressure gain of roughly 25 to 30 dB, optimizing energy transfer to the inner ear.^[47]^[49] The stapes integrates with the middle ear's protective mechanisms, particularly through the stapedius muscle, which contracts in response to intense sounds to dampen excessive vibrations of the ossicular chain and reduce sound transmission to the cochlea, thereby preventing potential damage from overstimulation.^[3]^[50] Although the tensor tympani muscle primarily influences the malleus to attenuate low-frequency self-generated noises, both muscles participate in the acoustic reflex to collectively stiffen the ossicular system.^[51]^[52] Neural feedback modulates the overall sensitivity of the auditory pathway, with the olivocochlear bundle providing efferent innervation to cochlear outer hair cells that adjusts the gain of the cochlear amplifier, indirectly influencing the effectiveness of stapes-driven fluid waves in varying acoustic environments.^[53]^[54]

Biomechanics

The biomechanics of the stapes involves its role as the final ossicle in the middle ear chain, facilitating efficient sound transmission to the inner ear through piston-like motion and impedance matching. The stapes footplate, embedded in the oval window, primarily exhibits translational displacement along the pistonic axis, with minimal rocking at low frequencies, enabling pressure wave propagation into the cochlear fluid.^[46] During acoustic stimulation at sound pressure levels of 60-120 dB SPL, the stapes footplate undergoes piston displacements ranging from approximately 0.1 to 1 μm, scaling linearly with intensity to accommodate conversational to loud sounds. Peak velocities reach up to 10 mm/s at higher intensities, reflecting the dynamic range of auditory input while maintaining structural integrity.^[55] The pressure amplification at the oval window is primarily due to the area ratio of the tympanic membrane to the stapes footplate (approximately 17:1), in combination with the ossicular lever action.^[56] The stapes system exhibits a resonance frequency of 1-2 kHz in adults, optimizing sound transmission in the speech range, with damping provided by the viscoelastic properties of the annular ligament, which absorbs excess energy and prevents excessive oscillations.^[11] The middle ear transfer function, describing the gain from ear canal pressure to stapes velocity, peaks around 1 kHz with an average of 26-27 dB, and is often modeled as a second-order linear system to capture its bandpass characteristics and phase response.^[57] With advancing age, middle ear stiffness may increase slightly due to ligamentous and ossicular changes, potentially reducing transmission efficiency by a few dB, particularly at higher frequencies in individuals over 60 years.^[58]

Clinical significance

Associated disorders

Otosclerosis is the most common disorder directly affecting the stapes, characterized by focal bone resorption and remodeling around the stapes footplate, which leads to progressive conductive hearing loss.^[25] This condition typically manifests with an onset between 20 and 40 years of age and has a histologic prevalence of up to 10% in White individuals, though clinical cases are less frequent at approximately 0.3-0.5%.^[25] Symptoms often include gradual hearing impairment, tinnitus, and occasionally vertigo, with the disease showing a higher incidence in females and a familial pattern in about 50% of cases.^[59] Stapes fixation, which can be congenital or acquired, results in immobilization of the stapes within the oval window, causing moderate to severe conductive hearing loss ranging from 30 to 60 dB.^[60] Congenital forms may arise from developmental anomalies of the ossicular chain, while acquired fixation is frequently due to otosclerotic changes or chronic middle ear inflammation.^[61] Associated symptoms commonly include tinnitus and vertigo, particularly during episodes of pressure changes, with the condition affecting sound transmission efficiency and potentially leading to mixed hearing loss if untreated.^[62] Superior canal dehiscence syndrome indirectly impacts stapes function through abnormal pressure transmission in the inner ear, creating a "third window" effect that dissipates sound energy and alters middle ear mechanics.^[63] This leads to symptoms such as autophony, dizziness with straining, and low-frequency conductive or mixed hearing loss, as the dehiscence enhances fluid motion that bypasses normal stapes-mediated vibration.^[64] The condition is relatively rare, with an estimated prevalence of 0.5-2% based on temporal bone studies, and it may mimic stapes-related disorders in presentation.^[65] Trauma to the stapes, typically from temporal bone fractures in high-impact head injuries, is a rare complication of such cases.^[66] These fractures often involve the stapes superstructure or footplate, resulting in sudden conductive hearing loss, tinnitus, and potential vertigo due to disruption of the ossicular chain.^[67] Temporal bone involvement itself affects 14-22% of severe skull fractures, but isolated stapes injuries are uncommon and usually require significant force, such as from motor vehicle accidents.^[68] Stapes fragility is notably associated with syndromic conditions like osteogenesis imperfecta, a genetic disorder of collagen synthesis that predisposes to ossicular fractures and malformations.^[69] In osteogenesis imperfecta, up to 50% of affected individuals develop progressive hearing loss by adulthood, often due to stapes crura fractures or footplate abnormalities leading to conductive deficits.^[70] This syndromic link highlights the stapes' vulnerability in connective tissue disorders, with symptoms including recurrent fractures and mixed hearing loss patterns.^[71]

Diagnostic and therapeutic approaches

Diagnosis of stapes-related conditions, such as otosclerosis leading to stapes fixation, primarily relies on audiometric and imaging evaluations. Pure-tone audiometry often reveals a conductive hearing loss with an air-bone gap, characteristically featuring a Carhart notch—a dip in bone conduction thresholds at 2 kHz—present in approximately 93% of otosclerosis cases.^[72] Tympanometry typically shows a Type As curve, indicating reduced middle ear compliance due to the stiffened ossicular chain.^[25] High-resolution computed tomography (HRCT) of the temporal bone is used to confirm otosclerotic foci, particularly measuring stapes footplate thickness, with sensitivity reaching 95% for detecting anterior footplate involvement.^[73] Therapeutic approaches for stapes dysfunction focus on restoring sound transmission, with non-surgical options serving as initial or adjunctive management. Hearing aids amplify airborne sounds to compensate for the impedance mismatch at the oval window caused by stapes fixation, providing effective rehabilitation for conductive losses up to 60 dB in purely conductive cases.^[74] Bisphosphonates, such as third-generation agents like zoledronate, may slow disease progression and stabilize sensorineural hearing loss in cochlear otosclerosis over 5- to 9-year periods.^[75] Surgical intervention via stapedotomy is the definitive treatment for stapes fixation, involving fenestration of the footplate using a laser (e.g., CO2 or diode) or microdrill, followed by insertion of a prosthesis such as a Teflon piston to bridge the incus and footplate remnant. Recent advancements include endoscopic techniques and optimized prosthesis designs for improved outcomes.^[76]^[77]^[78] Laser-assisted fenestration offers precise control with comparable outcomes to microdrill techniques, though both achieve high success rates of 90-95% in closing the air-bone gap. For far-advanced otosclerosis, cochlear implantation may be considered.^[79] Intraoperative electrocochleography monitors cochlear function to minimize sensorineural damage during prosthesis placement and mobilization.^[80] Postoperative outcomes demonstrate significant hearing improvement, with air-bone gap closure to less than 10 dB achieved in approximately 80% of cases, and sustained benefits in long-term follow-up.^[81]

History

Discovery and early descriptions

The earliest references to structures in the ear, including indirect mentions of bony elements, appear in the works of the Roman physician Galen in the 2nd century AD, who described the ear's anatomy in terms of cartilage and general skeletal components without specifying the ossicles.^[82] These vague allusions laid foundational groundwork for later anatomists but did not identify the stapes distinctly. During the Renaissance, Eustachi depicted and named the stapes in his 1563 work Explicatio tabularum anatomicarum Bartholomaei Eustachii, providing an early published illustration and the term "stapes" owing to its resemblance to a stirrup, building on earlier descriptions by contemporaries like Giovanni Filippo Ingrassia in 1546.^[83]^[84] This illustration marked a precise visual representation of the third bone in the ossicular chain. In 1600, Girolamo Fabrici d'Acquapendente further confirmed the complete ossicular chain, including the stapes, in his treatise De visione, voce, auditu, emphasizing its integration with the malleus and incus in auditory transmission.^[85] By the late 18th century, anatomists offered more refined anatomical details of the stapes through comparative dissections.^[86] The etymology of "stapes" stems from the Latin term for stirrup (stapes), adopted in anatomical nomenclature during the 16th century due to the bone's characteristic shape and becoming the standard term universally by the 1700s.^[87]

Key advancements

In the 19th century, significant strides were made in understanding the biomechanics of the stapes and its role in sound transmission. Hermann von Helmholtz's 1863 treatise On the Sensations of Tone provided a foundational analysis of ossicular chain vibrations, describing how the stapes footplate transmits mechanical energy to the oval window and cochlea fluids, laying the groundwork for modern auditory physiology. Concurrently, Adam Politzer advanced clinical examination techniques through innovations in otoscopy during the 1860s and 1870s, enabling improved visualization of middle ear structures and indirect assessment of stapes-related pathologies like fixation, which facilitated earlier diagnosis of conductive hearing loss.^[88] The late 19th and early 20th centuries saw pioneering surgical interventions for stapes immobility. In 1878, Johannes Kessel performed the first documented stapedectomy attempt, mobilizing or partially removing the fixed stapes in patients with otosclerosis to restore sound conduction, though outcomes were limited by infection risks and incomplete techniques.^[89] This approach evolved dramatically in 1956 when John J. Shea introduced the modern stapedectomy procedure, involving partial footplate removal and implantation of a prosthetic piston (initially Teflon-vein graft), which achieved hearing restoration in over 90% of cases and transformed otosclerosis management from symptomatic relief to curative intervention.^[90] Imaging advancements in the late 20th century enhanced surgical precision. The advent of high-resolution computed tomography (HRCT) in the 1980s revolutionized preoperative planning for stapes surgery by delineating temporal bone anatomy, identifying footplate involvement, and assessing complications like facial nerve proximity with submillimeter resolution.^[91] By the 2000s, micro-computed tomography (micro-CT) enabled detailed 3D reconstructions of the stapes footplate, revealing microstructural variations and aiding in prosthesis design, as demonstrated in studies quantifying footplate thickness and annular ligament integrity for improved biomechanical modeling.^[92] Molecular and genetic insights emerged in the late 20th and early 21st centuries, elucidating otosclerosis pathogenesis. A 1990 study identified transforming growth factor-beta 1 (TGF-β1) as a key regulator in otic capsule bone remodeling, with elevated expression linked to abnormal spongiotic bone formation around the stapes footplate.^[93] Genetic research mapped the first susceptibility locus, OTSC1 on chromosome 15q26, in 1998, followed by OTSC2-10 across chromosomes 7q, 6p, 16q, 3q, 6q, 9q, and 1q through the 2000s and 2010s, implicating genes like ACAN and RELN in hereditary stapes fixation. More recently, a 2023 genome-wide association study (GWAS) identified 27 genetic loci associated with otosclerosis susceptibility in population biobanks, underscoring its polygenic nature.^[94]^[95] Post-2010 developments have focused on minimally invasive and regenerative techniques. Endoscopic stapedotomy, refined since 2010, offers superior visualization of the stapes niche via transcanal approaches, reducing bone removal and postoperative vertigo compared to microscopic methods, with air-bone gap closure rates exceeding 95% in large cohorts.^[96] Emerging regenerative strategies explore mesenchymal stem cells seeded on osteoinductive scaffolds to repair otosclerotic footplate lesions, showing promise in preclinical models for promoting targeted bone remodeling without prosthesis implantation.^[97]

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Reduction of Spiral Ganglion Neurons in the Aging Canine with ...
No evidence of ankylosis of the stapes footplate to the oval window or incus was found in any dog. In many macerated specimens, the stapes had fallen into ...
[38]
Genetic and functional analysis of the otosclerosis-like condition of ...
The LP/J mouse is the only available genetic model for otosclerosis. The otosclerosis-like condition of the LP/J mouse resembles the human condition in ...
[39]
The Evolution of the Spiracular Region From Jawless Fishes to ...
Beginning in tetrapods, the hyomandibula ceases to be involved in jaw suspension and instead becomes dedicated eventually to hearing as the stapes (or columella) ...
[40]
Functional Aspects of Anuran Middle Ear Structures
The columella, with its foot plate and extra-columella, is a derivative of the hyomandibular of fish and is homologous to the columella or stapes of amniotes.
[41]
Mechanics of the frog ear - PMC - PubMed Central - NIH
The tympanic membrane is coupled to the otic capsule via the extrastapes and the stapes (also referred to as extracolumella and columella). The ...
[42]
Palaeos Vertebrates: Bones: Ear: Overview (2)
In amphibians, the columella shares the oval window with a second bone, the operculum, which communicates by way of an opercular muscle with the pectoral girdle ...<|control11|><|separator|>
[43]
Trifold origin of the reptilian ear ossicle and its relation to the ...
Sep 19, 2024 · Whereas mammals are characterized by the presence of three middle ear ossicles, reptiles have only one, the columella (stapes).
[44]
Evolution of the Mammalian Ear: An Evolvability Hypothesis
May 27, 2020 · The transformation of the primary jaw joint into the mammalian ear ossicles is one of the most iconic transitions in vertebrate evolution, but ...Missing: hyomandibula timeline
[45]
Evolution of the mammalian middle ear and jaw - ResearchGate
Aug 10, 2025 · All reptiles and birds have only one middle ear ossicle, the stapes or columella. ... role of masticatory and facial muscles (lips and ...Missing: crocodiles | Show results with:crocodiles<|control11|><|separator|>
[46]
Complex Stapes Motions in Human Ears - PMC - NIH
The physiological motion of the stapes in human and several animals in response to acoustic stimulation is mainly piston-like at low frequencies.
[47]
Ossiculoplasty - StatPearls - NCBI Bookshelf - NIH
Dec 11, 2024 · Systematic Review of Ossicular Chain Anatomy: Strategic Planning for Development of Novel Middle Ear Prostheses. Otolaryngol Head Neck Surg ...
[48]
Mapping the phase and amplitude of ossicular chain motion using ...
Oct 17, 2018 · ... system is limited to the Nyquist frequency of 22.5 kHz. This frequency range is adequate for hearing research in humans (20 Hz to 20 kHz hearing ...
[49]
An Analysis of the Acoustic Input Impedance of the Ear - PMC - NIH
The acoustic input impedance of the ear quantifies how the ear receives sound. The ear canal, the middle ear, and the cochlea all contribute to this acoustic ...
[50]
Neuroanatomy, Auditory Pathway - StatPearls - NCBI Bookshelf
Oct 24, 2023 · The stapedius limits the stapes' excessive vibration and subsequent cochlear stimulation, especially on exposure to loud sounds (see Image. ...
[51]
Tensor Tympani Syndrome - StatPearls - NCBI Bookshelf - NIH
Jul 6, 2025 · The tensor tympani muscle activates during a startle reflex, while the stapedius muscle responds to loud sounds. Together, these muscles are ...Missing: excessive | Show results with:excessive
[52]
The function of the tensor tympani muscle: a comprehensive review ...
One major question is whether the tensor tympani muscle contributes to sound damping; and if it does, what specific role it serves. The primary purpose of this ...
[53]
The cochlear amplifier: augmentation of the traveling wave within ...
Efferent modulation of the cochlear amplifier. The gain of the cochlear amplifier appears to be regulated by the medial olivocochlear bundle. These efferent ...
[54]
Hair cell transduction, tuning and synaptic transmission in the ...
The macroscopic MET current increases in amplitude along the cochlea, generated by variations in both unitary conductance and numbers of stereocilia per bundle ...
[55]
Dynamic X-ray Microtomography vs. Laser-Doppler Vibrometry - NIH
The stapes footplate moves approximately 10 nm at a stimulus of 80 dB SPL [6]. Several measurement techniques have been proposed to study the dynamic ...
[56]
[PDF] Mechanics of the middle ear - UA-repository.
Sep 17, 2019 · The stapes footplate to TM area ratio is about 17, resulting in a ... Figure 6.3: Stapes footplate velocity ratio of middle ear models and ...
[57]
Human Middle Ear Transfer Function Measured by Double Laser ...
Aug 6, 2025 · ... middle ear; the mean peak gain was 26.6 dB. Above 1.0 kHz, the second pressure gain decreased at a rate of -8.6 dB/octave, with a mean gain ...
[58]
Otosclerosis - American Hearing Research Foundation
Usually, people only realize they have otosclerosis after the abnormal bone growth has reached the stapes or the other auditory ossicles, causing hearing loss.Missing: ossification rigidity
[59]
Otosclerosis: Symptoms, Causes & Treatment - Cleveland Clinic
Otosclerosis can happen if there's abnormal bone growth in your middle or inner ear. It can lead to hearing loss. Hearing aids or surgery can help.Missing: rigidity | Show results with:rigidity
[60]
Otosclerosis: Practice Essentials, History of the Procedure ...
Aug 29, 2023 · Successful stapes surgery may improve hearing thresholds to a point at which conventional hearing aids may be beneficial. McCabe described ...
[61]
Stapedotomy (Endaural) | Journal of Medical Insight - JOMI
Aug 8, 2024 · Stapes fixation prevents the ear's normal conducting mechanism, leading to progressive hearing loss, tinnitus, and dizziness. Treatment of ...Missing: acquired | Show results with:acquired
[62]
Vertigo Associated with Otosclerosis and Stapes Surgery—A ... - MDPI
Aug 18, 2023 · This condition progressively leads to hearing loss, tinnitus, and vertigo. Stapedotomy, a surgical procedure involving the removal of the stapes ...
[63]
Assessment of the effects of superior canal dehiscence location and ...
Dec 13, 2014 · Abnormal absence of bone between the superior semicircular canal ... stapes velocity increased at varying frequencies after creating a dehiscence.Missing: indirect | Show results with:indirect
[64]
Superior Canal Dehiscence Syndrome (SCDS)
This can happen during sneezing, straining and coughing, which create pressure changes in the skull. The sound pressure from loud sounds can also cause abnormal ...Missing: stapes indirect
[65]
Superior Canal Dehiscence Syndrome: Lessons from the First 20 ...
A key insight that led to the discovery of SCDS was observing that when patients were exposed to pressure changes or loud sounds they had eye movements in the ...Diagnostic Criteria · Canal Plugging And... · Round Window ProceduresMissing: indirect | Show results with:indirect
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Traumatic fracture of the stapes suprastructure following minor head ...
Traumatic fracture of the stapes occurs rarely following head injury. Ossicular dislocation is more commonly encountered.Missing: trauma | Show results with:trauma
[67]
Middle Ear and Temporal Bone Trauma - Ento Key
May 24, 2016 · When the head trauma is of sufficient magnitude to fracture the skull, 14% to 22% of those injured sustain a temporal bone fracture (3, 4). In ...<|separator|>
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[PDF] Imaging of Temporal Bone Trauma
The temporal bone is at risk for injury in the setting of high-impact craniofacial trauma occurring in 3% to 22% of patients with trauma with skull ...
[69]
Osteogenesis Imperfecta - Endotext - NCBI Bookshelf - NIH
Jul 26, 2020 · The hallmark feature of OI is bone fragility, with a tendency to fracture from minimal trauma or from the work of bearing weight against gravity ...Missing: syndromic | Show results with:syndromic
[70]
Treatments for hearing loss in osteogenesis imperfecta - Nature
Oct 12, 2022 · Ossicular discontinuity, mainly caused by fractures in the stapes crura, is commonly reported in cases of conductive hearing loss in OI31,33,34, ...
[71]
Association between bone mineral density and hearing loss in ...
In half of the patients, progressive hearing loss develops, which is associated with abnormal bony changes involving the middle ear ossicles and stapes ...Missing: syndromic | Show results with:syndromic
[72]
Predictive Role of Carhart's Notch in Pre-Operative ... - PubMed
In patients with otosclerosis and tympanosclerosis, a Carhart's notch was seen at 2 kHz in 28 (93 per cent) patients but at 1 kHz in only two (7 per cent).
[73]
Reliability of high-resolution CT scan in diagnosis of otosclerosis
In our series, the sensitivity of HRCT scan to otosclerosis was 95.1%. Hypodense otosclerotic foci were mostly localized at the anterior part of footplate.
[74]
Hearing aids and otosclerosis - PubMed
Patients with losses of 60 dB or less and with purely conductive lesions may be able to use aids well.
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Third-generation bisphosphonates for cochlear otosclerosis ...
Sep 21, 2017 · Treatment with third-generation bisphosphonates is associated with stability in otosclerosis-related sensorineural hearing over 5- to 9-year period.
[76]
Microdrill Versus Diode Laser in Endoscopic Stapedotomy - PubMed
Jun 1, 2024 · Microdrill and diode laser are two different methods used in endoscopic stapedotomy for otosclerosis. These two methods have not been compared in endoscopic ...
[77]
Short- and long-term results of stapedotomy and stapedectomy with ...
Short- and long-term results of stapedotomy and stapedectomy with a teflon-wire piston prosthesis. Ann Otol Rhinol Laryngol. 2001 Oct;110(10):907-11. doi ...
[78]
Surgical Treatment of Otosclerosis: Eight years' Experience at ... - NIH
The stapes surgery success rate, in which ABG ≤ 10, among surgeons with a large series (20-22) is close to 95%; but in other studies with smaller series (23-26, ...
[79]
Intra-operative electrocochleography in stapedectomy and ossicular ...
Intraoperative ECOG appears to be an effective tool for verifying the functional integrity of ossicular reconstructions as in stapedectomies.
[80]
Long-term hearing results of stapedotomy: analysis of ... - PubMed
Feb 16, 2018 · Results: The postoperative air-bone gap was 10 dB or less in 77.0% of cases early post-surgery and in 70.7% of cases in long-term follow-up. ...
[81]
An otolaryngological tour of Vesalius' De Humani Corporis Fabrica
Mar 10, 2023 · The main authority for medicine, and anatomy in particular, was the Roman Galen. ... ear; however, the stapes is not featured yet at this point.
[82]
Bartolomeo Eustachi | Encyclopedia.com
May 18, 2018 · Eustachi's claim to discovery of the stapes is inadmissible, however, since it was mentioned orally by Giovanni Filippo Ingrassia in 1546 and in ...
[83]
The discovery of stapes - PMC - NIH
Ingrassia firstly attributed a sensorial function to the middle ear bones, which he called fifth particular function. He also added some details to the ...
[84]
Hieronymi Fabricij ab Aquapendente De visione voce auditu
Hieronymi Fabricij ab Aquapendente De visione voce auditu. Front Cover · Girolamo Fabrizi : d' Acquapendente. per Franciscum bolzettam, 1600 - 254 pages ...
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VICQ D'AZYR, FELIX. 1748-1794. Traite d'anatomie et de ... - Bonhams
Paris: Didot l'aine, 1786. Folio atlas (495 x 330 mm). Colored frontispiece, 35 plain (outline) and 34 colored plates. Modern quarter calf and boards. Repaired ...Missing: stapes | Show results with:stapes
[86]
Stapes - Etymology, Origin & Meaning
Originating in 16th-century Modern Latin from Medieval Latin stapes "stirrup," related to Latin stare "to stand," stapes means a stirrup-shaped bone in the ...
[87]
The role of Adam Politzer (1835-1920) in the history of otology
He invented, in particular, a revolutionary method of making the eustachian tube permeable--a method that made him famous and carries his name. He also ...Missing: stapes | Show results with:stapes
[88]
General history of stapedectomy - PubMed
The article gives an overview of the historical development of stapedectomy beginning with Kessel in 1876.Missing: 1878 | Show results with:1878
[89]
Evolution of stapedectomy prostheses over time - PubMed
Shea first described the microsurgical technique of the stapedectomy procedure in which an otosclerotic stapes was replaced with a prosthesis made of Teflon.
[90]
CT Scan of the Temporal Bone - Medscape Reference
Mar 20, 2024 · The advent of high-resolution computed tomography (CT) scanning in the 1980s revolutionized diagnostic imaging of the temporal bone.
[91]
Osseointegration of Prostheses on the Stapes Footplate
Sep 8, 2007 · Geometrical data of the stapes footplate were extracted from micro-CT scans of a temporal bone specimen and are consistent with the ...
[92]
Transforming Growth Factor Beta: Does it Direct Otic Capsule ...
TGFβ1 was identified in otosclerosis but not in the normal control temporal bone specimen. Aside from TGFβ1, many proteins and predicted cDNA-encoded ...
[93]
Entry - %166800 - OTOSCLEROSIS 1; OTSC1 - OMIM - (OMIM.ORG)
The locus associated with otosclerosis-1 (OTSC1) has been mapped to chromosome 15q26.1. Other loci associated with otosclerosis include OTSC2 (605727) on ...
[94]
Endoscopic and Robotic Stapes Surgery: Review with Emphasis on ...
Jan 6, 2022 · Endoscopic stapes surgery is used on a regular basis with excellent outcomes similar to the microscopic approach, while reducing surgical morbidity.Missing: post- advancements
[95]
(PDF) Beyond the stapes: The future of otosclerosis management
Oct 29, 2025 · Regenerative approaches represent a paradigm shift. Mesenchymal stem cells combined with osteoinductive. scaffolds have demonstrated potential ...