Special Senses When emergency personnel arrived on the scene of the bus crash, they found Brian Rhen, 42, sitting on the side of the road holding his head in his hands. He complained of a severe headache and nausea, 1. The ear is divided into three major areas (compartments). What are these three areas, and which of these areas is involved in Mr. Rhen's BPPV? and was evaluated and treated for a concussion. Several days later, Mr. Rhen began to experience recurring episodes of vertigo and was referred to a neurologist. (Vertigo is a sensation of motion or movement while the person is stationary, and can be accompanied by nausea and vomiting.) Mr. Rhen was diagnosed with benign paroxysmal positional vertigo (BPPV). With this condition, which can be caused by head trauma, vertigo can be provoked by specific changes in head position. Mr. Rhen reported that his vertigo usually occurred when rolling over in bed, or when turning his head from side to side while sitting up, and that these movements provoked the sensation of a spinning room, which led to nausea. The neurologist confirmed the diagnosis of BPPV by using a test called the Dix-Hallpike maneuver. During this test, the neurologist looks for nystagmus (involuntary, jerking eye movements) as he makes specific rotational changes to Mr. Rhen's head position. 2. What are the three main sources of sensory input that the body uses in order to control balance and equilibrium? 3. Name the two functional divisions of the vestibular apparatus. Identify the sensory receptor associated with each division, and state which aspect of equilibrium each receptor senses. 4. BPPV can be caused by otoliths that have been dislodged from the otolithic membrane of the maculae. Based on Mr. Rhen's symptoms and the head movements that provoke these symptoms, what part of the vestibular apparatus are the displaced otoliths now affecting? 5. Explain why nystagmus is associated with the Dix-Hallpike maneuver. For answers, see Answers Appendix.