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Journal of Anatomy Jul 2023The middle ear muscles have vital roles, yet their precise function in hearing and protection remains unclear. To better understand the function of these muscles in...
The middle ear muscles have vital roles, yet their precise function in hearing and protection remains unclear. To better understand the function of these muscles in humans, the morphology, fiber composition, and metabolic properties of nine tensor tympani and eight stapedius muscles were analyzed with immunohistochemical, enzyme-histochemical, biochemical, and morphometric techniques. Human orofacial, jaw, extraocular, and limb muscles were used as references. The immunohistochemical analysis showed that the stapedius and tensor tympani muscles were markedly dominated by fibers expressing fast contracting myosin heavy chain MyHC-2A and MyHC-2X (79 ± 6% vs. 86 ± 9%, respectively, p = 0.04). In fact, the middle ear muscles had one of the highest proportions of MyHC-2 fibers ever reported for human muscles. Interestingly, the biochemical analysis revealed a MyHC isoform of unknown identity in both the stapedius and tensor tympani muscles. Muscle fibers containing two or more MyHC isoforms were relatively frequently observed in both muscles. A proportion of these hybrid fibers expressed a developmental MyHC isoform that is normally absent in adult human limb muscles. The middle ear muscles differed from orofacial, jaw, and limb muscles by having significantly smaller fibers (220 vs. 360 μm , respectively) and significantly higher variability in fiber size, capillarization per fiber area, mitochondrial oxidative activity, and density of nerve fascicles. Muscle spindles were observed in the tensor tympani muscle but not in the stapedius muscle. We conclude that the middle ear muscles have a highly specialized muscle morphology, fiber composition, and metabolic properties that generally showed more similarities to orofacial than jaw and limb muscles. Although the muscle fiber characteristics in the tensor tympani and stapedius muscles suggest a capacity for fast, fine-tuned, and sustainable contractions, their difference in proprioceptive control reflects different functions in hearing and protection of the inner ear.
Topics: Humans; Stapedius; Tensor Tympani; Ear, Middle; Myosin Heavy Chains; Mitochondria; Phenotype; Protein Isoforms
PubMed: 36914412
DOI: 10.1111/joa.13861 -
The Journal of International Advanced... Aug 2020Although basal cell carcinoma (BCC) often occurs in the head and neck region, BCC in the middle ear is extremely rare. As far as we could determine, only five cases of... (Review)
Review
Although basal cell carcinoma (BCC) often occurs in the head and neck region, BCC in the middle ear is extremely rare. As far as we could determine, only five cases of BCC in the middle ear have been reported previously in the literature. We present the case of a 54-year-old Japanese man with BCC in the middle ear. Preoperative histopathologic examination indicated the possibility of skin appendage tumor. Mastoidectomy and extirpation of the lesion were performed, and the resected tumor was finally diagnosed as BCC. Four months after the initial surgery, the patient had local recurrence and reoperation, and postoperative radiotherapy was given. The patient had repeat local recurrence in the parapharyngeal space 3 years and 2 months following postoperative radiotherapy. The patient did not respond to two courses of chemotherapy with cisplatin and 5-fluorouracil, and eventually died of the primary disease 4 years and 7 months after the initial surgical treatment. We reviewed the five cases previously reported in the literature concerning BCC in the middle ear. More case reports concerning BCC in the middle ear are needed to determine its appropriate management.
Topics: Carcinoma, Basal Cell; Ear Neoplasms; Ear, Middle; Fatal Outcome; Humans; Male; Middle Aged; Skin Neoplasms
PubMed: 32784170
DOI: 10.5152/iao.2020.6779 -
Journal of the Association For Research... Aug 2011Scleraxis (Scx) is a basic helix-loop-helix transcription factor expressed in tendon and ligament progenitor cells and the differentiated cells within these connective...
Scleraxis (Scx) is a basic helix-loop-helix transcription factor expressed in tendon and ligament progenitor cells and the differentiated cells within these connective tissues in the axial and appendicular skeleton. Unexpectedly, we found expression of the Scx transgenic reporter mouse, Scx-GFP, in interdental cells, sensory hair cells, and cochlear supporting cells at embryonic day 18.5 (E18.5). We evaluated Scx-null mice to gain insight into the function of Scx in the inner ear. Paradoxical hearing loss was detected in Scx-nulls, with ~50% of the mutants presenting elevated auditory thresholds. However, Scx-null mice have no obvious, gross alterations in cochlear morphology or cellular patterning. Moreover, we show that the elevated auditory thresholds correlate with middle ear infection. Laser interferometric measurement of sound-induced malleal movements in the infected Scx-nulls demonstrates increased impedance of the middle ear that accounts for the hearing loss observed. The vertebrate middle ear transmits vibrations of the tympanic membrane to the cochlea. The tensor tympani and stapedius muscles insert into the malleus and stapes via distinct tendons and mediate the middle ear muscle reflex that in part protects the inner ear from noise-induced damage. Nothing, however, is known about the development and function of these tendons. Scx is expressed in tendon progenitors at E14.5 and differentiated tenocytes of the stapedius and tensor tympani tendons at E16.5-18.5. Scx-nulls have dramatically shorter stapedius and tensor tympani tendons with altered extracellular matrix consistent with abnormal differentiation in which condensed tendon progenitors are inefficiently incorporated into the elongating tendons. Scx-GFP is the first transgenic reporter that identifies middle ear tendon lineages from the time of their formation through complete tendon maturation. Scx-null is the first genetically defined mouse model for abnormal middle ear tendon differentiation. Scx mouse models will facilitate studies of tendon and muscle formation and function in the middle ear.
Topics: Animals; Auditory Threshold; Basic Helix-Loop-Helix Transcription Factors; Biomechanical Phenomena; Cell Differentiation; Ear, Middle; Female; Hearing Loss; Male; Mice; Mice, Knockout; Mice, Transgenic; Models, Animal; Morphogenesis; Organ of Corti; Stapedius; Tensor Tympani
PubMed: 21399989
DOI: 10.1007/s10162-011-0264-5 -
Otology & Neurotology : Official... Apr 2017We hypothesize that current clinical treatment strategies for the disarticulated or eroded incus have the effect of combining the incus and stapes of the human middle...
HYPOTHESIS
We hypothesize that current clinical treatment strategies for the disarticulated or eroded incus have the effect of combining the incus and stapes of the human middle ear (ME) into one rigid structure, which, while capable of adequately transmitting lower-frequency sounds, fails for higher frequencies.
BACKGROUND
ME damage causes conductive hearing loss (CHL) and while great progress has been made in repairing or reconstructing damaged MEs, the outcomes are often far from ideal.
METHODS
Temporal bones (TBs) from human cadavers, a laser Doppler vibrometer (LDV), and a fiber-optic based micro-pressure sensor were used to characterize ME transmission under various ME conditions: normal; with a disarticulated incus; repaired using medical glue; or reconstructed using a partial ossicular replacement prosthesis (PORP).
RESULTS
Repairing the disarticulated incus using medical glue, or replacing the incus using a commercial PORP, provided similar restoration of ME function including almost perfect function at frequencies below 4 kHz, but with more than a 20-dB loss at higher frequencies. Associated phase responses under these conditions sometimes varied and seemed dependent on the degree of coupling of the PORP to the remaining ME structure. A new ME-prosthesis design may be required to allow the stapes to move in three-dimensional (3-D) space to correct this deficiency at higher frequencies.
CONCLUSIONS
Fixation of the incus to the stapes or ossicular reconstruction using a PORP limited the efficiency of sound transmission at high frequencies.
Topics: Cadaver; Ear, Middle; Hearing Loss, Conductive; Humans; Incus; Ossicular Prosthesis; Sound; Stapes; Temporal Bone
PubMed: 28079680
DOI: 10.1097/MAO.0000000000001330 -
Scientific Reports Nov 2020Electronic cigarettes (e-cigarettes) are the most widely used electronic nicotine delivery systems and are designed to imitate smoking and aid in smoking cessation....
Electronic cigarettes (e-cigarettes) are the most widely used electronic nicotine delivery systems and are designed to imitate smoking and aid in smoking cessation. Although the number of e-cigarette users is increasing rapidly, especially among young adults and adolescents, the potential health impacts and biologic effects of e-cigarettes still need to be elucidated. Our previous study demonstrated the cytotoxic effects of electronic liquids (e-liquids) in a human middle ear epithelial cell (HMEEC-1) line, which were affected by the manufacturer and flavoring agents regardless of the presence of nicotine. In this study, we aimed to evaluate the gene expression profile and identify potential molecular modulator genes and pathways in HMEEC-1 exposed to two different e-liquids (tobacco- and menthol-flavored). HMEEC-1 was exposed to e-liquids, and RNA sequencing, functional analysis, and pathway analysis were conducted to identify the resultant transcriptomic changes. A total of 843 genes were differentially expressed following exposure to the tobacco-flavored e-liquid, among which 262 genes were upregulated and 581 were downregulated. Upon exposure to the menthol-flavored e-liquid, a total of 589 genes were differentially expressed, among which 228 genes were upregulated and 361 were downregulated. Among the signaling pathways associated with the differentially expressed genes mediated by tobacco-flavored e-liquid exposure, several key molecular genes were identified, including IL6 (interleukin 6), PTGS2 (prostaglandin-endoperoxide synthase 2), CXCL8 (C-X-C motif chemokine ligand 8), JUN (Jun proto-oncogene), FOS (Fos proto-oncogene), and TP53 (tumor protein 53). Under menthol-flavored e-liquid treatment, MMP9 (matrix metallopeptidase 9), PTGS2 (prostaglandin-endoperoxide synthase 2), MYC (MYC proto-oncogene, bHLH transcription factor), HMOX1 (heme oxygenase 1), NOS3 (nitric oxide synthase 3), and CAV1 (caveolin 1) were predicted as key genes. In addition, we identified related cellular processes, including inflammatory responses, oxidative stress and carcinogenesis, under exposure to tobacco- and menthol-flavored e-liquids. We identified differentially expressed genes and related cellular processes and gene signaling pathways after e-cigarette exposure in human middle ear cells. These findings may provide useful evidence for understanding the effect of e-cigarette exposure.
Topics: Cell Line; Cell Survival; Ear, Middle; Electronic Nicotine Delivery Systems; Flavoring Agents; Gene Expression Profiling; Gene Regulatory Networks; Genetic Markers; Humans; Menthol; Proto-Oncogene Mas; RNA-Seq; Signal Transduction; Nicotiana
PubMed: 33247188
DOI: 10.1038/s41598-020-77816-2 -
Scientific Reports Mar 2017The middle ear conducts sound to the cochlea for hearing. Otitis media (OM) is the most common illness in childhood. Moreover, chronic OM with effusion (COME) is the...
The middle ear conducts sound to the cochlea for hearing. Otitis media (OM) is the most common illness in childhood. Moreover, chronic OM with effusion (COME) is the leading cause of conductive hearing loss. Clinically, COME is highly associated with Primary Ciliary Dyskinesia, implicating significant contributions of cilia dysfunction to COME. The understanding of middle ear cilia properties that are critical to OM susceptibility, however, is limited. Here, we confirmed the presence of a ciliated region near the Eustachian tube orifice at the ventral region of the middle ear cavity, consisting mostly of a lumen layer of multi-ciliated and a layer of Keratin-5-positive basal cells. We also found that the motile cilia are polarized coordinately and display a planar cell polarity. Surprisingly, we also found a region of multi-ciliated cells that line the posterior dorsal pole of the middle ear cavity which was previously thought to contain only non-ciliated cells. Our study provided a more complete understanding of cilia distribution and revealed for the first time coordinated polarity of cilia in the epithelium of the mammalian middle ear, thus illustrating novel structural features that are likely critical for middle ear functions and related to OM susceptibility.
Topics: Animals; Cell Polarity; Cilia; Cochlea; Ear, Middle; Epithelial Cells; Eustachian Tube; Hearing; Mice
PubMed: 28358397
DOI: 10.1038/srep45870 -
Ear, Nose, & Throat Journal Nov 2012
Topics: Aged; Ear Diseases; Ear, Middle; Humans; Male; Tympanic Membrane
PubMed: 23288789
DOI: 10.1177/014556131209101104 -
Journal of the Association For Research... Dec 2022Tympanometry provides an objective measurement of the status of the middle ear. During tympanometry, the ear-canal pressure is varied, while the response of the ear to...
Tympanometry provides an objective measurement of the status of the middle ear. During tympanometry, the ear-canal pressure is varied, while the response of the ear to sound pressure is measured. The effects of the pressure on the mechanics of the middle ear are not well understood. This study is a continuation of our previous work in which the vibration response of the gerbil eardrum was measured in vivo under quasi-static pressure steps. In this study, we delivered a continuous pressure sweep to the middle ear and measured the vibration response at four locations for six gerbils. Vibrations were recorded using a single-point laser Doppler vibrometer and glass-coated reflective beads (diameter ~ 40 µm) at the umbo and on the mid-manubrium, posterior pars tensa and anterior pars tensa.The vibration magnitudes were similar to those in the previous step-wise pressurization experiments. Most gerbils showed repeatability within less than 10 dB for consecutive cycles. As described in the previous study, as the frequency was increased at ambient pressure, the vibration magnitude on the manubrium increased slightly to a broad peak (referred to as R1) and then decreased until a small peak appeared (referred to as R2), followed by multiple peaks and troughs as the magnitude decreased further. The low-frequency vibration magnitude (at 1 kHz) decreased monotonically as the pressure became more negative except for a dip (about 500 Pa wide) that occurred between - 700 and - 1800 Pa. The lowest overall magnitude was recorded in the dip at mid-manubrium. The vibration magnitudes also decreased as the middle-ear pressure was made more positive and were larger than those at negative pressures. R1 was only visible at negative and small positive middle-ear pressures, while R2 was visible for both positive and negative pressures. R2 split into multiple branches after the middle-ear pressure became slightly positive. No magnitude dip was visible for positive middle-ear pressures.The low-frequency vibration magnitudes at negative middle-ear pressures on the pars tensa were higher than those on the manubrium. R1 was not visible for large negative middle-ear pressures on the pars tensa. R2 appeared as a multi-peak feature on the pars tensa as well, and a higher-frequency branch on the posterior pars tensa appeared as a trough on the anterior pars tensa. The magnitude dip was not present on the pars tensa. The largest overall magnitude was recorded at the R2 peak on the posterior pars tensa.The results of this study expand on the findings of the step-wise pressurization experiments and provide further insight into the evolution of the vibration response of the eardrum under quasi-static pressures.
Topics: Animals; Tympanic Membrane; Vibration; Gerbillinae; Ear, Middle; Sound
PubMed: 36100816
DOI: 10.1007/s10162-022-00867-x -
European Archives of... Oct 2022The Eustachian tube plays a vital role in middle ear physiology. There has been evidence that Eustachian tube (ET) and angle are correlated with middle ear function. The...
SETTING
The Eustachian tube plays a vital role in middle ear physiology. There has been evidence that Eustachian tube (ET) and angle are correlated with middle ear function. The measurements of these Eustachian tube features are now made possible with computed tomography and multiplanar reconstruction techniques. However, there has not been a standardised protocol devised to these measurements in limited window cone-beam CT scans of temporal bones.
OBJECTIVE
The primary object of the present study is to establish and validate a new landmark in closer proximity to the middle ear that is consistently captured, thereby allowing ET angle and length to be measured from the majority of cone-beam CT scans. Secondarily, the ET anatomies of patients with middle ear dysfunction manifesting as acquired cholesteatoma are analysed with this new method of measurement.
METHODS
This study undertook a step-by-step method to first validate the methods of ET measurement with Reid's standard plane, then identifying an alternative landmark, thus a new plane visible on limited window cone-beam CT scans of temporal bones and lastly, validating the application of this new plane in the measurements of ET angle and length. This new method of measurement was coined the Ku-Copson plane and was applied to 30 cochlear implant patients and 30 patients with acquired cholesteatomas. Their ET anatomies were analysed and compared.
RESULTS
It was found that the new Ku-Copson mandibular fossa plane was a reliable and accurate plane for the measurement of ET angle and length. Furthermore, it was found that patients with acquired cholesteatomas have statistically significant smaller ET angles and shorter ET lengths when compared with patients with cochlear implants, of normal middle ear function.
CONCLUSION
The newly proposed method utilising the right mandibular fossa as an anatomical landmark for ET angles and lengths measurement appears to be viable. The close proximity of this landmark to the middle ear means that it is highly likely to be captured in most cone-beam CT scans of the petrous temporal bones. This enables the retrospective examination ET angles and lengths to be conducted on CB CT scans. This study reports statistically significant difference in ET anatomy in patients with middle ear dysfunction.
Topics: Cholesteatoma; Ear, Middle; Eustachian Tube; Humans; Retrospective Studies; Temporal Bone
PubMed: 35355112
DOI: 10.1007/s00405-022-07345-3 -
Journal of Visualized Experiments : JoVE Jan 2018The middle ear is located in the center of the temporal bone and bears a highly complex anatomy. The recently introduced exclusively endoscopic transcanal approach to...
The middle ear is located in the center of the temporal bone and bears a highly complex anatomy. The recently introduced exclusively endoscopic transcanal approach to the middle ear is a minimally invasive technique sparing the bone and mucosa of the mastoid bone, since the middle ear is accessed through the external auditory canal. This emerging method has several advantages over the traditional (microscopic) approaches to the middle ear such as the panoramic wide-angle views of the anatomy, the possibility to approach and magnify tiny structures, and the possibility of looking around the corner using angled endoscopes. The cadaveric dissection method presented here consists of an overview on the technical requirements and a precise description of a step-by-step protocol to discover the anatomy of the middle ear. Each step and anatomical structure is carefully described in order to provide a comprehensive guide to endoscopic ear anatomy. In our opinion, this is particularly important to any novice in endoscopic ear surgery as it provides thorough anatomical knowledge and may improve surgical skills.
Topics: Ear, Middle; Endoscopy; Humans; Manuals as Topic; Otologic Surgical Procedures
PubMed: 29364219
DOI: 10.3791/56390