The Spinal Cord, Spinal Nerves, and Somatic Reflexes
The Spinal Cord, Spinal Nerves, and Somatic Reflexes
1. Ascending signals in the spinal cord travel via gray matter, while descending signals travel via white matter.
True False
2. Cervical and lumbar enlargements are wide points in the spinal cord marking the emergence of motor nerves.
True False
3. Each portion of the spinal cord, from which a spinal nerve emerges, is called a “segment” of the cord. True False
4. Nerve fibers in a given white matter tract are similar in origin, destination, and function.
True False
5. Voluntary motor signals typically begin in an upper motor neuron in the thalamus. True False
6. Most nerves are motor nerves.
True False
7. A nerve fiber is enclosed in its own fibrous sleeve called perineurium. True False
8. A ganglion is a swelling along a nerve containing the cell bodies of peripheral neurons.
True False
9. A dermatome is a nerve innervating a specific region in the skin. True False
10. Posterior root ganglia contain neurosomas of unipolar neurons.
True False
11. Somatic reflexes are responses of skeletal, smooth, and cardiac muscles. True False
12. The stretch reflex is the tendency of a muscle to stretch when it is overcontracted. True False
13. A stretch reflex is often accompanied by reciprocal inhibition.
True False
14. The tendon reflex is the inhibition of a muscle’s contraction that occurs when its tendon isexcessively stretched.
True False
15. The crossed extension reflex is the contraction of the extensors on one side of the body when the flexors are contracted on the other side.
True False
Multiple Choice Questions
16. The upper motor neurons that control skeletal muscles begin with a neurosoma in the .
A. posterior horn of the spinal cord
B. anterior horn of the spinal cord
C. motor association cortex of the cerebrum
D. postcentral gyrus of the cerebrum
E. precentral gyrus of the cerebrum
17. The signals that control your handwriting travel down the spinal cord in the tracts.
A. tectospinal
B. corticospinal
C. lateral vestibulospinal
D. medial vestibulospinal
E. spinocerebellar
18. Many upper motor neurons synapse with lower motor neurons in the .
A. posterior horn
B. anterior horn
C. posterior column
D. anterior column
E. posterior root ganglion
19. Which of the following sensory functions involves neurons in the posterior root ganglion?
A. Smell
B. Hearing
C. Touch
D. Taste
E. Vision
20. Which of the following is not considered a region of the spinal cord?
A. Cervical
B. Thoracic
C. Lumbar
D. Pelvic
E. Sacral
21. Which of the following is not a function associated with the spinal cord?
A. Protect neurons in both the ascending and descending tracts
B. Mediate a reflex, such as the withdrawal of a hand from pain
C. Conduct sensory information up to the brain
D. Conduct motor information down the cord
E. Coordinate the alternating contraction of several muscle groups associated with locomotion
22. Which of the following fractures would be the least likely to cause a spinal cord injury?
A. A fracture of vertebra C2
B. A fracture of vertebra C6
C. A fracture of vertebra T5
D. A fracture of vertebra T12
E. A fracture of vertebra L4
23. The structure found between the posterior rootlets and the posterior root ganglion is called the .
A. anterior horn
B. anterior root of a spinal nerve
C. posterior root of a spinal nerve
D. posterior horn
E. spinal nerve
24. The middle layer of the meninges is called the .
A. gray matter
B. white matter
C. dura mater
D. arachnoid mater
E. pia mater
25. Epidural anesthesia is introduced to the epidural space between the to block pain signals during pregnancy.
A. dural sheath and dura mater
B. dural sheath and vertebral bones
C. dura mater and arachnoid mater
D. arachnoid mater and pia mater
E. dura mater and pia mater
26. Voluntary motor impulses leave the spinal cord via the of gray matter.
A. anterior horn
B. posterior horn
C. anterior column
D. posterior column
E. lateral horn
27. Cerebrospinal fluid fills the space between the .
A. dural sheath and dura mater
B. dural sheath and vertebral bones
C. dura mater and arachnoid mater
D. arachnoid mater and pia mater
E. dura mater and pia mater
28. Which of the following structures is the richest in lipid content?
A. Gray matter
B. White matter
C. Arachnoid mater
D. Dura mater
E. Pia mater
29. Which of the following is contained within gray matter?
A. Glial cells, axons of motor neurons, and Schwann cells
B. Glial cells and myelinated fibers
C. Neurosomas, dendrites, and proximal parts of axons of neurons
D. The distal part of axons of lower order motor neurons
E. Glial cells only
30. Motor commands are carried by from the brain along the spinal cord.
A. both anterior and posterior roots
B. ascending tracts
C. spinal nerves
D. cranial nerves
E. descending tracts
31. Second-order neurons synapse with third-order neurons in the .
A. thalamus
B. dorsal root ganglion
C. spinal cord
D. cerebral cortex
E. medulla oblongata
32. Nerve fibers are insulated from one another by .
A. perineurium
B. endoneurium
C. fascicles
D. epineurium
E. blood vessels
33. Eyes and ears are innervated by fibers.
A. white
B. visceral
C. somatic
D. special
E. general
34. A ganglion is a .
A. bundle of axons in the CNS
B. cluster of dendrites in either the CNS or the PNS
C. cluster of neurosomas in the PNS
D. bundle of axons in the PNS
E. cluster of neurosomas in the CNS
35. There are pairs of spinal nerves.
A. 12
B. 24
C. 31
D. 35
E. 62
36. The connective tissue that surrounds a nerve fascicle is called the .
A. myelin
B. perimysium
C. epineurium
D. endoneurium
E. perineurium
37. Which of the following is comprised of anterior rami from C5-T1?
A. Cervical plexus
B. Brachial plexus
C. Coccygeal plexus
D. Sacral plexus
E. Lumbar plexus
38. The anterior rami of the spinal nerves form nerve plexuses in all regions except the region.
A. thoracic
B. cervical
C. lumbar
D. sacral
39. The cervical plexus is the origin of the nerve(s).
A. oculomotor
B. sciatic
C. musculocutaneous
D. radial
E. phrenic
40. Which of the following nerves originates in the lumbosacral plexus?
A. Axillary
B. Sciatic
C. Phrenic
D. Ilioinguinal
E. Obturator
41. A patient with no sensation in the left thumb would most likley have nerve damage of the
spinal nerve.
A. T1
B. T5
C. C5
D. C6
E. L3
42. Which of the following is an ascending tract of the spinal cord?
A. Lateral tectospinal tract
B. Medial reticulospinal tract
C. Ventral corticospinal tract
D. Vestibulospinal tract
E. Gracile fasciculus
43. A mixed nerve consists of both and .
A. myelinated; unmyelinated fibers
B. glial cells; nerve cells
C. afferent; efferent fibers
D. interneurons; efferent neurons
E. spinal; cranial fibers
44. Which of the following branches of a spinal nerve has the neurosomas of only sensory neurons?
A. Posterior (dorsal) root
B. Anterior (ventral) root
C. Posteror ramus
D. Anterior ramus
E. Meningeal branch
45. The bundle of nerve roots that occupy the vertebral canal from L2 to S5 is called the .
A. medullary cone
B. cauda equina
C. lubar enlargement
D. cervical enlargement
E. spinal cord
46. “Somatosensory” does not refer to sensory signals from .
A. bones and muscles
B. joints
C. proprioceptors
D. the viscera
E. the skin
47. Neurosomas of the anterior root are located in the .
A. gray matter
B. posterior root ganglion
C. white matter
D. anterior rootlets
E. anterior root ganglion
48. A is a cordlike organ composed of numerous .
A. nerve fiber; nerves
B. nerve fiber; axons
C. nerve; axons
D. nerve fiber; neurosomas
E. nerve; neurosomas
49. Which one of the following best describes the order of a somatic reflex?
A. Somatic receptor ? interneuron ? afferent nerve fiber ? efferent nerve fiber ? skeletal
muscle
B. Somatic receptor ? efferent nerve fiber ? interneuron ? afferent nerve fiber ? skeletal muscle
C. Somatic receptor ? afferent nerve fiber ? interneuron ? efferent nerve fiber ? skeletal muscle
D. Somatic receptor ? efferent nerve fiber ? afferent nerve fiber ? interneuron ? skeletal
muscle
E. Somatic receptor ? afferent nerve fiber ? interneuron ? efferent nerve fiber ? smooth
muscle
50. Which of the following groups of muscles has the most muscle spindles?
A. Muscles of the hand
B. Muscles of the back
C. Muscles of the thigh
D. Muscles of the middle-ear
E. Muscles of the torso
51. Which of the following is not a property of reflexes?
A. Reflex responses are very predictable.
B. Reflexes are responses to sensory inputs.
C. Reflexes are quick responses of the nervous system.
D. Reflexes are not voluntary.
E. Reflexes do not require a stimulus.
52. A nurse pricks your finger to type your blood. You flinch at the pain, pulling your hand back. This is called the reflex.
A. painful
B. stretch
C. flexor (withdrawal)
D. tendon
E. crossed extension
53. Reflex arcs that only use two neurons are called reflex arcs.
A. ipsilateral
B. contralateral
C. polysynaptic
D. monosynaptic
E. autonomic
54. The flexor (withdrawal) reflex employs a , which maintains a sustained contraction.
A. parallel after-discharge circuit
B. diverging circuit
C. converging circuit
D. closed circuit
E. reverberating circuit
55. If a bee sting on the right thigh causes a quick involuntary reaction of the right arm, this would be an example of a(n) reflex.
A. bilateral
B. intersegmental
C. withdrawal
D. crossed extensor
E. contralateral
56. The sensitivity of the muscle spindle is maintained by .
A. a stretch reflex
B. alpha motor neurons
C. gamma motor neurons
D. anulospiral endings
E. secondary afferent (group II) fibers
57. The fibers that carry the action potentials that cause skeletal muscle to contract are .
A. gamma motor neurons
B. anulospiral endings
C. intrafusal fibers
D. extrafusal fibers
E. alpha motor neurons
58. You go to the movies after a long day and you begin to nod off as soon as the movie starts. Your headstarts to lower a little, but a reflex causes your head to rise. This is called the reflex.
A. tendon
B. crossed extension
C. withdrawal
D. stretch (myotatic)
E. flexor (withdrawal)
59. In the patellar tendon reflex arc, the patellar ligament is stretched, which stretches the quadriceps femoris muscle of the thigh. This reflex will cause the quadriceps femoris to and the hamstrings to
.A. contract; relax
B. contract; contrac t
C. relax; contract
D. relax; relax
60. A reflex in which the sensory input and motor output are on opposite sides of the spinal cord, is called a(n)
reflex arc.
A. intersegmental
B. contralateral
C. ipsilateral
D. polysynaptic
E. monosynaptic
61. Which of the following is true regarding the tendon reflex?
A. It causes a muscle that is being stretched to contract.
B. It makes the contralateral motor neurons contract.
C. It makes the ipsilateral motor neurons relax.
D. It prevents overcontraction of a muscle.
E. It causes a tendon to contract.
62. Which reflex shows the least synaptic delay?
A. A polysynaptic reflex
B. The cross extension reflex
C. The withdrawal reflex
D. The flexor reflex
E. The tendon reflex
63. Tendon organs are .
A. chemoreceptors
B. visceral receptors
C. proprioceptors
D. pain receptors
E. nociceptors
64. Which of the following is not a distal branch of the spinal nerve?
A. Anterior ramus
B. Posterior ramus
C. Posterior root
D. Meningeal branch
E. Communicating rami
True / False Questions
65. The spinal cord is vitally important in processing complex information. True False
66. The anterior ramus in the thoracic region becomes an intercostal nerve. In other regions, the anterior ramus
form spinal plexuses. True False
67. A typical reflex contains a sensory neuron attached directly to an effector.
True False
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