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Tutorial 5 stretch reflex + Functions of external and middle ear

 OBJECTIVES:

By the end of this tutorial students should !e a!le to understand

and ex"lain:

1. Describe the relation between stretch reflex and muscle tone

2. List the factors (physiological & pathological that affect the muscle

tone

3. describe the steps involved in the perception of sound

. describe the mechanism of magnification of sound by the middle ear

ossicales and its significance

Choose only O#E T$%E ans&er:

'( )uscle tone is:

a. ! dynamic form of the stretch reflex. b. Diminished in upper motor neuron lesion ("#$L%.

c. !ffected by the cerebellum.

d. Decreased on the same side of the stimulated semicircular canals

(''s%.

  *( Inhi!ition of the muscle contraction due to increase in muscle

tension is

  called:

  a. $egative stretch reflex. b. nverse stretch reflex ()*+ reflex%.

c. tatic stretch reflex.

d. 'erebellar stretch reflex.

 

( The follo&in, is characteristic to nuclear !a, fi!ers of the muscle

s"ind they:

  a. !re type of extra,fusal muscle fibers.

  b. Detect dynamic changes in muscle length.

  c. )ive rise to type b nerve fibers.  d. -eceive fibers from alpha motor neurons.

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-( .rimary endin,s of the muscle s"indle can !e stimulated !y:

  a. hortening of extra,fusal muscle fibers.

  b. #ared increase in muscle tension.  c. timulation of gamma efferent fibers.

  d. timulation of alpha motor fibers.

5( Secondary endin,s of the muscle s"indle:

  a. nnervate both nuclear bag and nuclear chain intra,fusal muscle

fibers.

  b. -espond to changes in muscle tension or over,stretch.

  c. )ive rise to type a nerve fibers. b. Discharge on maintained stretch of the muscle to give idea about

degree of stretch.

/( The ,amma motor neurons:

  a. nnervate extra,fusal muscle fibers.

  b. Directly cause muscle contraction.

  c. !re not activated during alpha motor neuron stimulation.

 b. nnervate intra,fusal muscle fibers.

0( Stretch reflex:

  a. /as the ability to produce oscillations of body movements.

  b. t is responsible for muscle tone.

  c. s suppressed by signals from motor area .

  d. s exaggerated by stimulation of area 0.

1( )uscle tone is reduced !y:

  a. L#$L paralysis.

  b. "#$L paralysis.

  c. arinsons disease.  d. timulation of gamma efferent fibers.

2( 3ol,i tendon or,ans:

  a. !re located parallel to extra,fusal muscle fibers.

  b. timulate alpha motor neurons.

  c. Decrease muscle length.

  d. xcite inhibitory inter,neurons causes muscle relaxation.

'4( urin, 6oluntary mo6ements 3ol,i tendon or,ans inform theC#S a!out:

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  a. *he length of muscle being moved.

  b. 4elocity of movement.

  c. *ension developed by the muscle or its over,stretch.

  d. 'hange in 5oint angle produced by movement.

''( 7nee 8er9:

  a. s a static stretch reflex.

  b. s pendular in neocerebellar lesion.

  c. s lost in hemiplegic patient.

  d. /as its center in the sacral region.

  '*( )uscle s"indles:

a. !re activated alpha motor neurons.

 b. )ive information about the muscles force of contraction.

c. !re activated to contract by alpha motor neurons.

d. ncrease their fre6uency of action potential firing when stretched.

 

' ;hich statement a!out the functionin, of the inner ear is

CO$$ECT<

(a% *he structure of the basilar membrane is stiff all a along its length

(b% ndolymph in the cochlear duct has a high sodium concentration and

a low potassium concentration.

(c% *he organ of 'orti contains hair cells that transduce mechanicalenergy into electrical energy.

(d% t magnifies the intensity of the sound.

'- The attenuation =Tym"anic> reflex caused !y loud sounds lead to:

(a% 'ontraction of both stapedius and tensor tympani muscle.

(b% -elaxation of the above two muscles.

(c% 'ontraction of the stapidius and relaxation of the tensor tympani

muscle.

(d% 'ontraction of the tensor tympani muscle mainly.

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'5The cochlear endolym"h:

(a% s electrically negative with respect to the perilymph.

(b% s confined to the scala tympani.

(c% s in direct contact with the perilymph.

(d% /as higher 7 8

 concentration than that of the perilymph.

'/ Concernin, the sense of hearin, &hich of the follo&in, statements is

true:

(a% *he bony ossicles of the middle ear amplify the sound 2 times.

(b% *he endocochlear potential is about ,9: m4.

(c% *he basilar membrane displacement causes bending of the hairs of the

hair cells &

  initiate nerve impulse.

(d% *he eardrum is attached to the incus.

'0 The tym"anic mem!rane:

a. s sensitive for sound vibrations.

 b. s periodic membrane.

c. eparates the middle & inner ear.

d. s essential for pitch analysis.

19.. $e,ardin, the or,an of corti:

a. t magnifies the sound intensity.

 b. t changes pressure energy of sound into action potential.

c. the outer as well as the inner hair cells are attached to the techtorial

membrane.

d. t e6uali;es the pressure on the eardrum.

1<, *he endolymph=

a, 'ontains high content of 7 8

 b, resent in the scala vestibule and tympani.

c, has positive potential in relation to perilymph.

d, has high 7 8 and low $a8 concentrations.

21, n the middle ear=

a, t is separated from the inner ear by the tympanic membrane.

 b, ustachian tube e6uali;es pressure on the drum.

c, the tensor tympani contraction decreases vibrations of the oval

window.

d, *ympanic reflex protects against sounds of gunshot.

** .itch discrimination de"ends on:

a, *he part of the basilar membrane which is maximally displaced. b, *he site of the hair cells where the wave pea is maximum.

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', *he amplification capacity of the middle ear.

d, *he natural fre6uenxcy of the tympanic membrane.

e, >oth a and b.

* The attenuation reflex is associated &ith:a, 'ontraction of both tensor tympani and stapedius.

 b, relaxation of both tensor tympani and stapedius.

c, rotection against intense brief sounds lie gun shots.

d, ncreased amplification capacity of middle ear ossicles.

*- ;hich of the follo&in, is least li9ely to increase &hen intensity of

sound increases<

a, 7nocing force of the stapes.

 b, displacement of basilar membrane.c, -ate of discharge from the auditory nerve.

d, ?re6uency of the travelling wave in the endolymph.

*5 The endococchlear "otential is:

a, $egative to the perilymph.

>, negative to hair cell potential.

c, 89: to the perilymph.

d, , 0: in relation to the hair cell potential.

 

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