The surgical approach to the endolymphatic sac and the cochlear aqueduct in the guinea pig.

The endolymphatic sac and cochlear aqueduct are primary passages of the endolymphatic and perilymphatic fluid compartments in the labyrinth. Closure of the endolymphatic sac and duct in the guinea pig will result in the development of endolymphatic hydrops. Although obstruction of the cochlear aqueduct in this species does not seem to result in any dysfunction, this structure may serve in the dynamics of inner ear fluid physiology. The anatomy of the guinea pig temporal bone is described with special emphasis on the endolymphatic sac and cochlear aqueduct. Surgical techniques to gain access to these structures through both a middle and posterior cranial fossa approach are described.