. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 62 ANNALS OF THE SOUTH AFRICAN MUSEUM a tube leaves, the perilymphatic duct; in lower tetrapods the latter is applied against the basilar papilla for part of its length by the intermediary of the basilar membrane. Beyond this papilla it attains the lower posterior bony wall of the otic capsule, a wall that it traverses by the perilymphatic foramen (called in error by some authors the fenestra cochleae). From there it spreads out into another evagination, the perilymphatic sac. The latter, apart from
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 62 ANNALS OF THE SOUTH AFRICAN MUSEUM a tube leaves, the perilymphatic duct; in lower tetrapods the latter is applied against the basilar papilla for part of its length by the intermediary of the basilar membrane. Beyond this papilla it attains the lower posterior bony wall of the otic capsule, a wall that it traverses by the perilymphatic foramen (called in error by some authors the fenestra cochleae). From there it spreads out into another evagination, the perilymphatic sac. The latter, apart from its dorsal opening into the duct, opens mesially into the cerebral cavity (by an internal jugular foramen, so-called because it is utilized at the same time by the jugular or posterior cerebral vein) and extends into the subarachnoid lacunae. Laterally, it comes in contact with the tympanic cavity, where an opening -> med Stapes ,. Interrelationship of the peri- and endolymphatic systems in Sphenodon (from De Burletj. pierces the wall of the otic capsule, the fenestra rotunda sensu lato, or pseudo- tra rotunda. Thus, not only are the vibrations transmitted by the stapes i <-' eived by the perilymphatic liquid, which fills all of the system described, and conducted to the level of the basilar papilla where the sensorial cells receive the excitation, but the lower part of the system has, in addition, a compensating role necessitated by the incompressibility of liquids; thus a mesiad depressing of the tympanum results in a laterad depressing of the secondary tympanic membrane, which obstructs this pseudo-fenestra rotunda. ()n this u heme a < ertain number of variations are realized. It is necessary, if not logical, to begin with mammals, because it is with them that the terms were fir t defined In this class, then, the lagena has acquired such a length that ii coiled up iri a cochlea. The perilymphatic sac has become intraotic, and it is this true
Size: 1790px × 1397px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
