Scanning electron micrograph of the spiral ligament beneath the attachment of the basilar membrane to the lateral cochlear wall (the attachment zone of the basilar membrane is indicated by the dotted line at upper left). As in Figure 26, note the porous, mesh-like texture of the spiral ligament. In the region shown here three blood vessels (arrows) are seen coursing very near the surface of the spiral ligament.

Scanning electron microscopic view of the surface of the spiral ligament in the area immediately below the attachment of the basilar membrane. (The site of attachment of the basilar membrane to the lateral wall tissues in indicated by the dotted line.) Note the highly porous, mesh-like structure of the spiral ligament surface. From Roland PS, Wright C.G. Surgical aspects of cochlear implantation: Mechanisms of insertional trauma. Adv Otorhinolaryngol 2006;64:11-30. Copyright S. Karger

Lower basal cochlear turn showing the common modiolar vein as it enters the cochlear aqueduct (arrow). The white arrow indicates the vestibulocochlear vein which joins the common modiolar vein. ST, floor of scala tympani.

Cross sections of the modiolus region showing veins coursing near the surface of the modiolar wall. In “A” the vein indicated by the arrow has a very thin covering of bone. In an adjacent section, shown in “B” , a similar vein (arrow) appears entirely exposed to the perilymphatic space. (In this case the vein does not contain RBC’s, but it certainly does appear to be a vein .) It would seem that such vessels might easily be injured by a perimodiolar electrode. OL, osseous lamina; SG, spiral

Dissection in which the osseous lamina and basilar membrane have been removed so as to show the modiolar wall in the basal cochlear turn of an osmium-stained specimen. Neural elements associated with the modiolar wall are well displayed. “G” indicates the spiral ganglion. Peripheral (P) and central (C) processes of spiral ganglion cells are seen emerging from the ganglion along the length of the basal turn. ST, floor of scala tympani. This preparation shows the same anatomical features

Cochlear dissection after insertion of an Advanced Bionics Thin Lateral electrode array designed to track the lateral wall of scala tympani. With this array, contacts are placed immediately beneath the basilar membrane. From Wright, CG, Roland PS, Kuzma J. Advanced Bionics Thin Lateral and Helix II electrodes: a temporal bone study. Laryngoscope 115(11);2005:2041-2045. Copyright Lippincott, Williams and Wilkins. Reproduced with permission. http://lww.com

Cochlear dissection after insertion of a cochlear implant electrode array (Advanced Bionics Thin Helix). The array has been colored blue to provide better contrast of the silicon carrier. The array lies in scala tympani and is situated beneath the translucent basilar membrane. The apical cochlear turn has been removed to provide an unobstructed view of the basal turn. From Wright, CG, Roland PS, Kuzma J. Advanced Bionics Thin Lateral and Helix II electrodes: a temporal bone study

Osseous lamina with its nerve fibers in a specimen oriented in nearly horizontal plane.

A preparation in which the modiolus and osseous lamina are seen in profile after removal of the otic capsule bone covering the human cochlea.

A: Otic capsule bone drilled to a thin shell to reveal contours of the cochlea. The membranous labyrinth has been stained with osmium so that it appears dark through the thinned bone. An implant electrode array had been inserted into this specimen and a portion of the array can be seen at lower left. B: Similar preparation in which the bone overlying scala vestibuli has been removed to show the osmium-stained basilar membrane and osseous spiral lamina.