A manual of otology for students and practitioners . Fig. 104.—Diagram for rotation to right with head backward 90° =rotatory nystagmus to right. a stream of cold water, say at a temperature of 50° F.,is directed against the membrana tympani, the air inthe tympanic cavity becomes colder and this change oftemperature is communicated to the vestibular fluidadjacent to the internal tympanic wall. It thus becomescondensed, and gravitating, produces a current downward. FUNCTIONAL TESTS OF STATIC LABYRINTH 311 This draws fluid from the superior semicircular canal,producing a current toward the ampul
A manual of otology for students and practitioners . Fig. 104.—Diagram for rotation to right with head backward 90° =rotatory nystagmus to right. a stream of cold water, say at a temperature of 50° F.,is directed against the membrana tympani, the air inthe tympanic cavity becomes colder and this change oftemperature is communicated to the vestibular fluidadjacent to the internal tympanic wall. It thus becomescondensed, and gravitating, produces a current downward. FUNCTIONAL TESTS OF STATIC LABYRINTH 311 This draws fluid from the superior semicircular canal,producing a current toward the ampulla as shown inFig. 105. iVccording to Ewalds law, this makes thecanal minus. The opposite crista would therefore beplus, as normally the stimuli emanating from the oppositelabyrinths are exactly balanced and this syringing withcold water creates an imbalance or disharmony. Suppose the right ear be syringed with cold water,with head erect (Fig. 106). This produces a current CAa/. Fig. 105.—The method of the production of the gravity current. toward the ampulla in the right superior canal. Rightcanal—, left canal+, left centers+. Slow componentto the right, rapid component to the left = rotatorynystagmus to the left produced by syringing the right earwith cold water with the head erect. Suppose the right ear be syringed with hot usually produces less effect than cold, as it is impos-sible to use water as many degrees above the normaltemperature of the labyrinthine fluid as can be usedbelow with cold water. Thus, water at a temperature 312 SUPPURATIVE DISEASES OF LABYRINTH of 50° F. will produce more effect, other conditions beingthe same, than water at 115° F., the difference being as49 to 16, which is the amount these temperatures varyfrom the temperature of the labyrinthine fluid, say 99°F. As the hot water flows into the meatus it raises thetemperature of the labyrinthine fluid adjacent to the /xP»C>
Size: 1610px × 1551px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1900, bookdecade1910, booksubjectear, bookyear1916
