6. A 25-year-old man took a severe blow to the head. He is rushed to a neurologi
ID: 3482890 • Letter: 6
Question
6. A 25-year-old man took a severe blow to the head. He is rushed to a neurologist and undergoes a series of test. For one particular test, the doctor spins the patient in a chair counter clockwise. The patient's eyes are rapidly moving side to side when the chair is stopped thus showing a normal reflex. When the doctor first asks him if he is okay, the patient can't hear him. When the doctor yells "ARE YOU OKAY?" the patient replies yes calmly. What is most likely damaged and why? Explain how normal hearing is accomplished. How come when the doctor yells, he is able to hear him? Draw the change in AP amplitude and frequency on the graph below and use it to help with your reasoning. . Stimulus Intensity
Explanation / Answer
1. there is conductive deafness. due to concussion or broken cranial bones.Conductive deafness caused by head injury usually disappears in two months time. If conductive deafness remains, the suspicion of dislocation of the ossicular bones .
arises.
as vestibulo ocular reflex is intact so there is no damage of vestibulo cochlear nerve.
2. normal hearing:
The sound waves are received by the external ear pinna. These sounds waves then move in the ear and vibrate the tympanic membrane ( also called ear drum ). See illustration
The tympanic membrane is attached to a bone called malleus , which in turn is joined to a bone called incus and which is again joined to abone called stapes. When the tympanic membrane vibrates it also vibrates the chain of bones with it accordinglyand with the vibration of the last bone the stapes, the fluid within the inner ear cochlea is moved. Thus the cells generate an impulse in the system of inner ear(contained in the bony snail shaped portion of the ear called coclea ). From cochlea the nerve impulses are then carried to the brain where the details of the sound are analysed. It is at the brain level the sound is differentiated and the speech is understood in minute details.
3. as there is intact 8th cranial nerve. pt is able to hear him after yelling.
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