Microstructures of the bony modiolus in the human cochlea: a scanning electron microscopic study.

The structures of the bony modiolus of the human cochlea are studied by scanning electron microscopy after macerating the organic material with a NaOCl solution. The modiolus on the scala vestibuli side had a canal for the spiral modiolar artery. Ducts for the radiating arterioles spread radially from the canal, and opened to furrows in the roof of the scala vestibuli. The surface of the modiolus facing the scala tympani was lace-like with numerous pores. Just beneath the bone surface were a modiolar canal for the spiral ganglion and spirally-arranged spaces for the anterior and posterior spiral veins. The spiral spaces for the veins had windows (fenestrations) leading to the scala tympani. The openings in the bone on the scala vestibuli and tympani sides of the modiolus are considered to be communication routes for the transport of fluids from the perineural and perivascular spaces in the modiolus to the perilymph in the scalae.