Interstate medical journal . w in the oppositedirection. Before the ear is douched it should be inspected so asto exclude a cerumen impaction or any other obstruction whichwould prevent the cold water from reaching the part to be af- 64 INTERSTATE MEDICAL JOURNAL fected. Normally there occurs, after forty seconds of douching,a rotary nystagmus to the opposite side. The exact time requiredto produce the first sign of nystagmus is noted; the douching isthen continued until the nystagmus becomes marked. With theeyes closed, the pointing tests are made. Next the head is placed60° backward and the
Interstate medical journal . w in the oppositedirection. Before the ear is douched it should be inspected so asto exclude a cerumen impaction or any other obstruction whichwould prevent the cold water from reaching the part to be af- 64 INTERSTATE MEDICAL JOURNAL fected. Normally there occurs, after forty seconds of douching,a rotary nystagmus to the opposite side. The exact time requiredto produce the first sign of nystagmus is noted; the douching isthen continued until the nystagmus becomes marked. With theeyes closed, the pointing tests are made. Next the head is placed60° backward and the horizontal nystagmus observed; then witheyes closed the pointing tests are again made. The other ear istested in the same way. The nystagmus as well as the distance ofpast-pointing is normally greater for the horizontal canals thanfor the verticals. This is due to the fact that the horizontal canalsare larger and the possible range of ocular movement much greaterwith horizontal than with rotary nystagmus. In addition to the. 9 2 3 Fig. 9.—Membranous labyrinth of the right side prepared from a normal tem-poral bone. Anteriorly is the cochlea (1). At the beprinning of its basalturn is the fenestra rotunda (2). Just above and anterior to the roundwindow is the sacculus (3). Communicating with the sacculus superiorlyand to its posterior side is the utriculus (4). Posteriorly are seen the threesemicircular canals; above the anterior vertical (5), in the center, the hori-zontal (6); below, the posterior vertical (7). The ampulla; (8) of the anteriorvertical and horizontal canals are seen together superiorly. Inferiorly. in theregion of the round window, is the ampulla (9) of the posterior vertical canal. nystagmus and past-pointing, there must be noted the degree ofvertigo and the falling from rotary nystagmus. After the testshave been completed they are studied in connection with the testsof the cochlear division of the eighth. There are many practical points in connection with t
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