Tectorial membrane

The tectoria membrane (TM) is one of two acellular membranes in the cochlea of the inner ear, the other being the basilar membrane (BM). "Tectorial" in anatomy means forming a cover. The TM is located above the spiral limbus and the spiral organ of Corti and extends along the longitudinal length of the cochlea parallel to the BM. Radially the TM is divided into three zones, the limbal, middle and marginal zones. Of these the limbal zone is the thinnest (transversally) and overlies the auditory teeth of Huschke with its inside edge attached to the spiral limbus. The marginal zone is the thickest (transversally) and is divided from the middle zone by Hensen's Stripe. It overlies the sensory inner hair cells and electrically-motile outer hair cells of the organ of Corti and during acoustic stimulation stimulates the inner hair cells through fluid coupling, and the outer hair cells via direct connection to their tallest stereocilia.

For the membrane situated within the vertebral canal, see Tectorial membrane of atlanto-axial joint.
Tectorial membrane (cochlea)
Section through the spiral organ of Corti. (Membrana tectoria labeled at center top.)
Section through the spiral organ of Corti. (Membrana tectoria labeled at center top.)
Details
Identifiers
Latinmembrana tectoria ductus cochlearis
MeSHD013680
NeuroLex IDbirnlex_2531
TA98A15.3.03.108
TA27034
FMA75805
Anatomical terminology

Structure

The TM is a gel-like structure containing 97% water. Its dry weight is composed of collagen (50%), non-collagenous glycoproteins (25%) and proteoglycans (25%).[1] Three inner-ear specific glycoproteins are expressed in the TM, α-tectorin, β-tectorin and otogelin. Of these proteins α-tectorin and β-tectorin form the striated sheet matrix that regularly organises the collagen fibres. Due to the increased structural complexity of the TM relative to other acellular gels (such as the otolithic membranes),[2][3] its mechanical properties are consequently significantly more complex.[4] They have been experimentally shown to be radially and longitudinally anisotropic[5][6] and to exhibit viscoelastic[7][8] properties.

Function

The mechanical role of the tectorial membrane in hearing is yet to be fully understood, and traditionally was neglected or downplayed in many models of the cochlea. However, recent genetic[9][10][11] , mechanical[7][8][12] and mathematical[13] studies have highlighted the importance of the TM for healthy auditory function in mammals. Mice that lack expression of individual glycoproteins exhibit hearing abnormalities, including, most notably, enhanced frequency selectivity in Tecb−/− mice,[11] which lack expression of β-tectorin. In vitro investigations of the mechanical properties of the TM have demonstrated the ability of isolated sections of TM to support travelling waves at acoustically relevant frequencies. This raises the possibility that the TM may be involved in the longitudinal propagation of energy in the intact cochlea.[13] MIT research correlates the TM with the ability of the human ear to hear faint noises.

The TM influences inner ear sensory cells by storing calcium ions. When calcium store is depleted by loud sounds or by the introduction of calcium chelators, the responses of the sensory cells decrease. When tectorial membrane calcium is restored, sensory cell function returns.

Additional images
  • Floor of ductus cochlearis.
  • Cross section of the cochlea.

Notes
  1. Thalmann, I.; Thallinger, G.; Comegys, T.H.; Thalmann, R. (1986). "Collagen – The Predominant Protein of the Tectorial Membrane". ORL. 48 (2): 107–115. doi:10.1159/000275855. ISSN 1423-0275. PMID 3010213.
  2. Goodyear, Richard J.; Richardson, Guy P. (2002). "Extracellular matrices associated with the apical surfaces of sensory epithelia in the inner ear: Molecular and structural diversity". Journal of Neurobiology. 53 (2): 212–227. doi:10.1002/neu.10097. ISSN 0022-3034. PMID 12382277.
  3. Freeman, Dennis M.; Masaki, Kinuko; McAllister, Abraham R.; Wei, Jesse L.; Weiss, Thomas F. (2003). "Static material properties of the tectorial membrane: a summary". Hearing Research. 180 (1–2): 11–27. doi:10.1016/S0378-5955(03)00072-8. ISSN 0378-5955. PMID 12782349. S2CID 29548566.
  4. Freeman, Dennis M.; Abnet, C.Cameron; Hemmert, Werner; Tsai, Betty S.; Weiss, Thomas F. (2003). "Dynamic material properties of the tectorial membrane: a summary". Hearing Research. 180 (1–2): 1–10. doi:10.1016/S0378-5955(03)00073-X. ISSN 0378-5955. PMID 12782348. S2CID 24187159.
  5. Richter, C; Emadi, G; Getnick, G; Quesnel, A; Dallos, P (2007). "Tectorial Membrane Stiffness Gradients☆". Biophysical Journal. 93 (6): 2265–2276. Bibcode:2007BpJ....93.2265R. doi:10.1529/biophysj.106.094474. ISSN 0006-3495. PMC 1959565. PMID 17496047.
  6. Gueta, R.; Barlam, D.; Shneck, R. Z.; Rousso, I. (2006). "Measurement of the mechanical properties of isolated tectorial membrane using atomic force microscopy". Proceedings of the National Academy of Sciences. 103 (40): 14790–14795. Bibcode:2006PNAS..10314790G. doi:10.1073/pnas.0603429103. ISSN 0027-8424. PMC 1595430. PMID 17001011.
  7. Ghaffari, R.; Aranyosi, A. J.; Freeman, D. M. (2007). "Longitudinally propagating traveling waves of the mammalian tectorial membrane". Proceedings of the National Academy of Sciences. 104 (42): 16510–16515. Bibcode:2007PNAS..10416510G. doi:10.1073/pnas.0703665104. ISSN 0027-8424. PMC 2034249. PMID 17925447.
  8. Jones, Gareth; Russell, Ian; Lukashkin, Andrei; Shera, Christopher A.; Olson, Elizabeth S. (2011). "Laser Interferometer Measurements of the Viscoelastic Properties of Tectorial Membrane Mutants". American Institute of Physics Conference Series. AIP Conference Proceedings. 1403 (1): 419–420. Bibcode:2011AIPC.1403..419J. doi:10.1063/1.3658122. ISSN 0094-243X.
  9. Legan, P.Kevin; Lukashkina, Victoria A.; Goodyear, Richard J.; Kössl, Manfred; Russell, Ian J.; Richardson, Guy P. (2000). "A Targeted Deletion in α-Tectorin Reveals that the Tectorial Membrane Is Required for the Gain and Timing of Cochlear Feedback". Neuron. 28 (1): 273–285. doi:10.1016/S0896-6273(00)00102-1. ISSN 0896-6273. PMID 11087000. S2CID 17510891.
  10. Legan, P Kevin; Lukashkina, Victoria A; Goodyear, Richard J; Lukashkin, Andrei N; Verhoeven, Kristien; Van Camp, Guy; Russell, Ian J; Richardson, Guy P (2005). "A deafness mutation isolates a second role for the tectorial membrane in hearing". Nature Neuroscience. 8 (8): 1035–1042. doi:10.1038/nn1496. ISSN 1097-6256. PMID 15995703. S2CID 417936.
  11. Russell, Ian J; Legan, P Kevin; Lukashkina, Victoria A; Lukashkin, Andrei N; Goodyear, Richard J; Richardson, Guy P (2007). "Sharpened cochlear tuning in a mouse with a genetically modified tectorial membrane". Nature Neuroscience. 10 (2): 215–223. doi:10.1038/nn1828. ISSN 1097-6256. PMC 3388746. PMID 17220887.
  12. Ghaffari, Roozbeh; Aranyosi, Alexander J.; Richardson, Guy P.; Freeman, Dennis M. (2010). "Tectorial membrane travelling waves underlie abnormal hearing in Tectb mutant mice". Nature Communications. 1 (7): 96. Bibcode:2010NatCo...1...96G. doi:10.1038/ncomms1094. ISSN 2041-1723. PMC 2982163. PMID 20981024.
  13. Meaud, Julien; Grosh, Karl (2010). "The effect of tectorial membrane and basilar membrane longitudinal coupling in cochlear mechanics". The Journal of the Acoustical Society of America. 127 (3): 1411–1421. Bibcode:2010ASAJ..127.1411M. doi:10.1121/1.3290995. ISSN 0001-4966. PMC 2856508. PMID 20329841.
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