a. Anat. [f. Eustachi-us name of a celebrated Italian anatomist (died 1574) + -AN.] Used as the distinctive epithet in the names of certain anatomical structures or organs which were discovered by Eustachius. † Eustachian medulla: the medullary portion of the kidneys. Eustachian tube (occas. E. canal): a canal leading from the upper part of the pharynx to the cavity of the tympanum, which it appears to supply with air; hence Eustachian Catheter, an instrument for inflating the Eustachian tube with air. Eustachian valve: a membranous fold at the orifice of the vena cava inferior, which in the fœtus directs the current of blood from this vessel to the foramen ovale and left auricle.
1741. Monro, Anat. Nerves (ed. 3), 15. The Kidneys … have a reticulated Cortex of Vessels, from which the Eustachian or Bellinian Medulla, consisting of longitudinal Fibres and a few longitudinal Blood Vessels, proceeds. Ibid., 114. Part of the Eustachian Tube.
1755. Wathen, Hearing, in Phil. Trans., XLIX. 215. I took that opportunity to examine the eustachian tube of each ear.
1831. R. Knox, Cloquet’s Anat., 636. The … Eustachian Valve.
1870. T. Holmes, Syst. Surg. (ed. 2), III. 289. Recourse must be had to the Eustachian catheter.
1872. Huxley, Physiol., viii. 213. The function of the Eustachian tube is, probably, to keep the air in the tympanum … of about the same tension as that on the outer side.
