from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The central, conical, bony core of the cochlea.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The central core of the cochlea
- n. A chiasma of facial muscles held together by fibrous tissue
from the GNU version of the Collaborative International Dictionary of English
- n. The central column in the osseous cochlea of the ear.
from The Century Dictionary and Cyclopedia
- n. Pl. modioli (-lī). In anatomy, the columella cochleæ or central pillar around which the cochlear lamina winds in a spiral like a staircase.
- n. . 2. [capitalized] In conchology, same as Modiola.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the central conical bony pillar of the cochlea
Occupying the spiral canal of the modiolus is the spiral ganglion of the cochlea (ganglion of Corti) (Fig. 933), consisting of bipolar nerve cells, which constitute the cells of origin of this nerve.
The modiolus is the conical central axis or pillar of the cochlea.
The central ones pass down the modiolus and then through the foramina of the tractus spiralis foraminosus or through the foramen centrale into the lateral or outer end of the internal auditory meatus.
The cochlear branch subdivides into twelve or fourteen twigs, which traverse the canals in the modiolus, and are distributed, in the form of a capillary net-work, in the lamina spiralis and basilar membrane.
The veins of the vestibule and semicircular canals accompany the arteries, and, receiving those of the cochlea at the base of the modiolus, unite to form the internal auditory veins which end in the posterior part of the superior petrosal sinus or in the transverse sinus.
The cochlear nerve (n. cochlearis) divides into numerous filaments at the base of the modiolus; those for the basal and middle coils pass through the foramina in the tractus spiralis foraminosis, those for the apical coil through the canalis centralis, and the nerves bend outward to pass between the lamellæ of the osseous spiral lamina.
In the recent state a membrane, the basilar membrane, stretches from the free border of this lamina to the outer wall of the bony cochlea and completely separates the canal into two passages, which, however, communicate with each other at the apex of the modiolus by a small opening named the helicotrema.
As already stated, the osseous spiral lamina extends only part of the distance between the modiolus and the outer wall of the cochlea, while the basilar membrane stretches from its free edge to the outer wall of the cochlea, and completes the roof of the scala tympani.
From the spiral canal of the modiolus numerous canals pass outward through the osseous spiral lamina as far as its free edge.
The osseous spiral lamina (lamina spiralis ossea) is a bony shelf or ledge which projects from the modiolus into the interior of the canal, and, like the canal, takes two-and three-quarter turns around the modiolus.