Cochlea to structures in the brainstem for further processing. The "stapes" (stirrup) ossicle bone of the middle ear transmits vibrations to the "fenestra ovalis" (oval window) on the outside of the cochlea, which vibrates the perilymph in the "vestibular duct" (upper chamber of the cochlea). The ossicles are essential for efficient coupling of sound waves into the cochlea, since the cochlea environment is a fluid–membrane system, and it takes more pressure to move sound through fluid–membrane waves than it does through air; a pressure increase is achieved by the area ratio of the tympanic membrane to the oval window, resulting in
Stirrup did not have stirrups. It is speculated that stirrups may have been used in China as early as the Han dynasty (206 BC–220 AD); however, verified archaeological evidence of stirrups in this period is scant. Stirrups were used in China at the very latest by the early 4th century AD. A funerary figurine depicting a stirrup dated AD 302 was unearthed from a Western Jin dynasty tomb near Changsha. The stirrup depicted is a mounting stirrup, only placed on one side of the horse, and too short for riding. The earliest reliable representation of a full-length, double-sided riding stirrup was