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Restoration: Nanotechnology in Tissue Replacement and Prosthetics
Published in Harry F. Tibbals, Medical Nanotechnology and Nanomedicine, 2017
The cochlea is a hollow tapering helix supported by a bony spiral shelf, the osseous spiral lamina, which winds around a central core, the modiolus. The cochlea’s spiral cone geometry, like a French horn or conch shell, acts as a mechanical acoustical transform to select for different vibration frequencies along its interior. The interior of the cochlea is separated into two fluid-filled chambers (the scala vestibuli and scala tympani or upper and lower ducts) by a thin sac, called the cochlear duct, filled with gelatinous material. The large end of the spiral is sealed from the outer ear by two membranes, the oval and round windows, on either side of the cochlear duct. The duct separates the two chambers all the way up the spiral to its apex, where there is a small opening between them. The sensory hair cells are inside the cochlear duct adjacent to a thin layer of tissue (the tectorial membrane). Each hair cell has a group of stereo-cilia projecting into the viscous gelatin, which resonate with sound [286,287].
Anatomy
Published in Stanley A. Gelfand, Hearing, 2017
The cochlea is the part of the inner ear concerned with hearing. An extensive albeit rather advanced review of cochlear anatomy and physiology may be found in Dallos et al. (1996). The human cochlea is about 35 mm long, and forms a somewhat cone-shaped spiral with about two 3/4 turns. It is widest at the base, where the diameter is approximately 9 mm, and tapers toward the apex. It is about 5 mm high. The modiolus is the core, which forms the axis of the cochlear spiral, as illustrated in Figure 2.14. Through the modiolus course the auditory nerve and the blood vessels that supply the cochlea. The osseous spiral lamina is a bony ramp-like shelf that goes up the cochlea around the modiolus much like the spiral staircase of a lighthouse, as illustrated in Figure 2.15. Notice how the basilar membrane is attached to the osseous spiral lamina medially, as it proceeds up the cochlea. Figure 2.16 illustrates how the osseous spiral lamina separates the scala vestibuli above from the scala tympani below. It also shows the orientation of the helicotrema at the apical turn, and the relationship between the round window and the scala tympani at the base of the cochlea.
The ear
Published in Rogan J Corbridge, Essential ENT, 2011
The scala media or cochlear duct contains endolymph and is linked to the saccule. The scala tympani and vestibuli contain perilymph and communicate with one another at the apex of the cochlea. The sensory unit of the cochlea is called the organ of Corti and lies on the basilar membrane. It is a complex structure also composed of hair cells. These hairs are associated with the tectorial membrane that arises from the osseous spiral lamina. The VIII nerve endings that supply the hair cells descend down the modiolus before perforating the base of the cochlea.
Slope of electrically evoked compound action potential amplitude growth function is site-dependent
Published in Cochlear Implants International, 2021
Oliver C. Dziemba, Aristotelis Aristeidou, Stefan Brill
The two surgical techniques used in this study, cochleostomy and round window insertion, are the most commonly used methods for cochlear implantation. Prior research demonstrated that particular outcome parameters of a cochlear implantation can be influenced by the surgical technique used: For instance, implantations performed using the round window approach were shown to have a higher probability of complete insertion into the scala tympani (Jiam and Limb, 2016; Wanna et al., 2014, 2015). Another publication showed that with the round window approach, the position of the electrode array was closer to cochlear neural structures (central axis of the modiolus and osseous spiral lamina) than with cochleostomy, particularly in the basal region (Jiam et al., 2016). Two studies on human temporal bones addressed the questions on whether insertion depth is affected by surgical technique (Abdel Salam et al., 2013; Zhou et al., 2014): One found significantly greater angular insertion depth with cochleostomy compared to round window approach with electrode arrays from Cochlear Ltd (Zhou et al., 2014). Another study with MED-EL electrode arrays found that the cochleostomy approach resulted in a 0.7 mm (on average) deeper insertion than round window approach, however, this difference was not statistically significant (Abdel Salam et al., 2013). The preferred approach may also depend on whether the array is lateral wall or perimodiolar.
Expression of Na/K-ATPase subunits in the human cochlea: a confocal and super-resolution microscopy study with special reference to auditory nerve excitation and cochlear implantation
Published in Upsala Journal of Medical Sciences, 2019
Wei Liu, Maria Luque, Rudolf Glueckert, Niklas Danckwardt-Lillieström, Charlotta Kämpfe Nordström, Anneliese Schrott-Fischer, Helge Rask-Andersen
Type I neurons were positively stained around the soma as well as the peripheral and central process (Figure 6(A)). Occasionally, there was more intense immunostaining in the axon hillock region (Figure 6(F)). Type II neurons were immune-reactive confirming staining in basilar fibers (Figure 6(D)). Cross-sections in the osseous spiral lamina located α3 immunostaining in the axoplasm. In the organ of Corti, tunnel spiral bundle (TSB), outer spiral bundles (OSB) such as the basilar fibers (BF) at the base of the tunnel (type II afferents), tunnel-crossing fibers (TCF, medial efferents), and nerve fibers of the inner spiral plexus (SPI-spiral plexus) were also stained (Figure 6(B,C)). The IHCs were void of immunoreactivity, but afferent processes contacting them were highly positive.
Protecting against electrode insertion trauma using dexamethasone
Published in Cochlear Implants International, 2019
Scott Chambers, Carrie Newbold, Dimitra Stathopoulos, Karina Needham, Chris Miller, Frank Risi, Ya Lang Enke, Godofredo Timbol, Robert Cowan
The osseous spiral lamina was also assessed for evidence of trauma in all groups. In all cochleae retrieved from the high trauma model groups, the osseous spiral lamina was fractured. This was accompanied by evidence of scala vestibuli insertion in 7 of 8 cochleae in the HCS and HDD groups, and in 2 of the 8 cochleae in the HDS group. In contrast, no damage to the osseous spiral lamina was observed in the LCS cochleae, nor insertion into the scala vestibuli. Post-implantation status of the organ of Corti was also analysed in five positions along the cochlea (Fig. 5), and showed that a high number of cochleae sustained damage in the lower basal turn in each of the high trauma model groups. The rate of cochleae displaying organ of Corti damage lessened at the upper basal and lower middle turns. In the upper middle and apical turn, evidence of organ of Corti trauma was still present in 1–2 cochleae from the HCS and HDD groups.