Chapter 55: Spinal Cord Motor Functions; the Cord Reflexes PDF

Chapter 55: Spinal Cord Motor Functions; the Cord Reflexes Hall: Guyton and Hall Textbook of Medical Physiology, 14th Edition MULTIPLE CHOICE 1. The Golgi tendon organ is most likely to sense which of the following? a. Fine touch b. Length c. Pressure d. Tension e. Vibra...

Chapter 55: Spinal Cord Motor Functions; the Cord Reflexes Hall: Guyton and Hall Textbook of Medical Physiology, 14th Edition MULTIPLE CHOICE 1. The Golgi tendon organ is most likely to sense which of the following? a. Fine touch b. Length c. Pressure d. Tension e. Vibration ANS: D 2. Type II sensory afferents from the muscle spindle receptor are attached to which of the following structures? a. Extrafusal muscle fiber b. Dynamic nuclear bag fiber c. Nuclear chain fiber d. Gamma S fiber ANS: C 3. Which of the following is most likely to increase the sensitivity of the stretch reflex? a. Cutting dorsal root fibers b. Increasing activity of medullary reticular nuclei c. Bending head forward d. Increased activity in fusimotor (gamma motor neuron) system ANS: D 4. Assuming all sensory, motor, and reflex neuronal pathways are intact, skeletal muscle contraction can be caused by stimulation of which of the following? a. Type 1a sensory nerve endings b. Type 1b sensory nerve endings c. Neurons in ventromedial hypothalamus d. Preganglionic parasympathetic vagal nerves ANS: A 5. The dynamic response of the muscle spindle receptor can best be described as a. an increase in the activity of the nuclear chain fibers as a result of the change in length of the muscle fiber. b. an increase on activity of the group II sensory afferents in response to the rate of change in length of the muscle fiber. c. a decrease in the activity of the group 1a sensory afferents in response to a change in length of the muscle fiber. d. an increase in the activity of the muscle spindle receptor that is proportional to the rate of change in length of the muscle fiber. ANS: D  6. Stimulation of type II sensory fibers innervating a muscle spindle a. will inhibit muscle contraction. b. will activate an inhibitory interneuron in the anterior horn of the spinal cord and lead to inhibition of Golgi tendon response. c. will activate a gamma motor neuron connected to the muscle containing the spindle receptor. d. will activate an alpha motor neuron connected to the muscle containing the spindle receptor. ANS: D 7. Which fiber is responsible for the dynamic response in a muscle spindle receptor? a. Extrafusal muscle fiber b. Static nuclear bag fiber c. Nuclear chain fiber d. Nuclear bag fiber ANS: D 8. Which of the following best describes the primary function of the Golgi tendon organ? a. To sense the length of the muscle tendon in which it is located b. To provide the cerebellum with feedback information concerning which motor impulses have arrived at the anterior motor neurons of the spinal cord c. To transmit muscle stretch information to higher brain centers d. To sense muscle tension and equalize the contractile force exerted by groups of muscle fibers in a muscle ANS: D 9. Activation of a type 1b sensory neuron is most likely to have which of the following effects? a. Contraction of muscle fiber associated with this neuron b. An initiation of a complex spike output signal c. Central nystagmus d. Inhibition of muscle contraction in muscle fiber associated with this neuron ANS: A 10. Muscle contraction can be caused by stimulation of which of the following types of neurons, assuming all sensory, motor, and reflex pathways are intact? a. Alpha motor neurons b. Gamma motor neurons c. Type 1a sensory endings from a nuclear bag fiber d. All of these ANS: D 11. Type 1a afferents innervate which of the following types of receptors in the muscle spindle apparatus? a. Nuclear chain fibers b. Static nuclear bag c. Dynamic nuclear bag fibers  d. All of these ANS: D 12. The sensitivity of the stretch reflex can be altered by a. activity in the olivocerebellar tract. b. simultaneous stimulation of primary motor cortex and supplemental motor area of cortex. c. activity of pontine reticular nuclei. d. activity of corticospinal tract. ANS: C 13. The stretch reflex initiated by tapping on the patellar tendon causes muscle contraction by activation of which of the following? a. Type Ia sensory fibers b. Type Ib sensory fibers c. Gamma motor neurons d. Inhibitory interneurons ANS: A 14. Activation of which of the following can lead to muscle contraction under basal conditions? a. Free nerve endings b. Type Ia sensory fibers c. Nuclear chain fibers d. All of these ANS: B 15. A muscle spindle is most likely to sense which of the following? a. Fine touch b. Length c. Pressure d. Tension e. Vibration ANS: B 16. A 30-year-old man with bare feet steps on a broken bottle with his right foot. His right leg immediately lifts while his left leg extends before he can consciously react to the pain. Which of the following best describes the name of this reflex? a. Walking reflex b. Stretch reflex c. Patellar tendon reflex d. Golgi tendon reflex e. flexor withdrawal reflex ANS: E 17. Which of the following best describes the type of reflex arc and sensory receptor for the flexor withdrawal reflex? a. Reflex arc: disynaptic; sensory receptor: pacinian corpuscle  b. Reflex arc: disynaptic; sensory receptor: nociceptor c. Reflex arc: monosynaptic; sensory receptor: pacinian corpuscle d. Reflex arc: monosynaptic; sensory receptor: Golgi tendon organ e. Reflex arc: polysynaptic; sensory receptor: nociceptor f. Reflex arc: polysynaptic; sensory receptor: muscle spindle ANS: E 18. Which of the following best describes anterior motor neurons and their innervation targets? a. Alpha-extrafusal fibers; gamma-intrafusal fibers b. Alpha-intrafusal fibers; gamma-extrafusal fibers c. Alpha-extrafusal fibers; gamma-extrafusal fibers d. Alpha-intrafusal fibers; gamma-intrafusal fibers ANS: A 19. Which of the following best describes the reflex arc and muscle response of the Golgi tendon organ? a. Monosynaptic reflex arc; relaxation of muscle b. Monosynaptic reflex arc; contraction of muscle c. Disynaptic reflex arc; relaxation of muscle d. Disynaptic reflex arc; contraction of muscle e. Polysynaptic reflex arc; relaxation of muscle f. Polysynaptic reflex arc; contraction of muscle ANS: C 20. Which of the following best describes the transmitter released from Renshaw cells and the primary action of Renshaw cells under normal physiologic conditions? a. Glycine—inhibitory b. Glycine—excitatory c. Acetylcholine—inhibitory d. Acetylcholine—excitatory e. Strychnine—excitatory f. Strychnine—inhibitory ANS: A