Chapter 13 Workbook Questions

Question 1

Ventral root

What is the function of this structure in the spinal region?

Answer 1

Contains efferent axons, including axons that innervate skeletal muscle.

Question 2

Dorsal root

What is the function of this structure in the spinal region?

Answer 2

Contains sensory axons that connect with a single segment of the spinal cord.

Question 3

Spinal nerve

What is the function of this structure in the spinal region?

Answer 3

Contains all of the motor, sensory, and autonomic axons of a single spinal segment.

Question 4

Dorsal root ganglion

What is the function of this structure in the spinal region?

Answer 4

Contains cell bodies of primary sensory neurons.

Question 5

Tract cell

What is the function of this structure in the spinal region?

Answer 5

Neuron with a long axon that conveys information from the spinal cord to the brain.

Question 6

Propriospinal neuron

What is the function of this structure in the spinal region?

Answer 6

Neuron that begins and ends within the spinal cord.

Question 7

Dorsal ramus

What is the function of this structure in the spinal region?

Answer 7

Innervates paravertebral muscles, posterior vertebral structures, and overlying cutaneous areas.

Question 8

Ventral horn

What is the function of this part of gray matter?

Answer 8

Location of neurons that integrate sensory and motor signals and innervate skeletal muscles

Question 9

Lateral horn (T1-L2)

What is the function of this part of gray matter?

Answer 9

Location of neurons that integrate and transmit signals for sympathetic regulation

Question 10

Rexed lamina

What is the function of this part of gray matter?

Answer 10

Histologic and functionally specific regions in the spinal cord gray matter

Question 11

Dorsal horn

What is the function of this part of gray matter?

Answer 11

Location of neurons that convey sensory information from peripheral mechanoreceptors

Question 12

Dorsal column-medial lemniscus tract (DCML)

What is the origin of this tract?

Answer 12

The origin of the DCML is the peripheral somatosensory receptors.

Question 13

Lateral corticospinal tract

What is the origin of this tract?

Answer 13

The origin of the lateral corticospinal tract is motor neurons in the supplemental motor, premotor, and primary motor areas of the cerebral cortex.

Question 14

Reticulospinal tract

What is the origin of this tract?

Answer 14

The origin of the reticulospinal tract is motor nuclei of the pontomedullary reticular formation (see Table 13-2).

Question 15

Spinothalamic tract

What is the origin of this tract?

Answer 15

The origin of the spinothalamic tract is sensory neurons in the dorsal horn of spinal cord.

Question 16

Ceruleospinal tract

What is the origin of this tract?

Answer 16

The origin of the ceruleospinal tract is motor neurons of the locus coeruleus.

Question 17

What anatomic division marks the end of the spinal region and beginning of the peripheral nervous system?

Answer 17

The anatomic division is marked at the point where the spinal nerve is exterior to the intervertebral foramen and branches into dorsal and ventral primary rami.

Question 18

What type of neural circuit ensures that antagonists are inhibited during contraction of the agonist?

Answer 18

Reciprocal inhibition of motor neurons in the spinal cord inhibit alpha motor neurons that elicit antagonist contraction.

Question 19

What is the function of Renshaw cells?

Answer 19

Renshaw cells are interneurons that regulate recurrent inhibition of the motor neuron to the agonist.

Question 20

When the bladder is empty, what efferent control inhibits contraction of the bladder wall and maintains closure of the external sphincter?

Answer 20

The sympathetic efferents from T11 to L2 inhibit contraction of the bladder wall and maintain closure of the internal sphincter.

Question 21

Decreased strength in right deltoid and biceps; decreased sensation in anterolateral right upper arm; sensation and motor function intact for the remainder of the body

What type of lesion would cause these symptoms?

Answer 21

Right C5 spinal nerve lesion

Question 22

Lack of posterolateral sensation in digits four and five of the right hand; intact sensation of all fingertips; paralysis of long extensors for right wrist and finger; paralysis of the right supinator; sensation and motor function intact for remainder of the body

What type of lesion would cause these symptoms?

Answer 22

Right radial nerve lesion

Question 23

Paralysis of the right iliopsoas and all muscles in the right lower limb; loss of discriminative touch and conscious proprioception in the right lower limb; loss of discriminative pain and temperature sensation in the left lower limb and left buttock region

What type of lesion would cause these symptoms?

Answer 23

Right hemi-lesion of spinal cord, L1 segment

Question 24

Weakness of the quadriceps on the right side; no other motor or sensory loss

What type of lesion would cause these symptoms?

Answer 24

Right L3 ventral root lesion

Question 25

Babinski’s sign; paralysis; hyperreflexia; muscle hypertonia; complete loss of all sensation below the level of the umbilicus What type of lesion would cause these symptoms?

Answer 25

Complete T10 spinal cord lesion

Question 26

Name the Syndrome associated with the following signs and symptoms.... Sensory impairment and flaccid paralysis of the lower limbs, bladder, and bowels

Answer 26

Cauda equina syndrome

Question 27

Name the Syndrome associated with the following signs and symptoms.... Low back and lower limb pain, difficulty in walking, excessive lordosis and scoliosis, bowel and bladder control problems, foot deformities

Answer 27

Tethered cord syndrome

Question 28

Name the Syndrome associated with the following signs and symptoms.... Loss of pain and temperature information at several cervical segments; all sensations and motor and autonomic functions intact throughout remainder of body

Answer 28

Central cord syndrome

Question 29

Name the Syndrome associated with the following signs and symptoms.... Segmental loss of all sensation and paresis of muscles innervated by the involved spinal segment(s); ipsilateral loss of voluntary motor control, conscious proprioception, and discriminative touch below level of lesion, contralateral loss of pain and temperature sensations below level of lesion

Answer 29

Brown-Séquard syndrome

Question 30

Name the Syndrome associated with the following signs and symptoms.... Loss of discriminative pain and temperature sensation and paralysis of muscles below the level of the lesion; conscious proprioception and discriminative touch remain intact

Answer 30

Anterior cord syndrome

Question 31

``` Reciprocal activation of a stepping pattern generator (SPG) is thought to be coordinated by signals conveyed in the: A. DCML B. Golgi tendon organs (GTOs) C. Posterior commissure of spinal cord D. Anterior commissure of spinal cord E. Ventral horn gamma motor neurons ```

Answer 31

B: Reciprocal activation of stepping pattern generators is essential for swing phase of one lower limb to occur simultaneously with the stance phase of the other lower limb. The signals to coordinate the right and left stepping pattern generators are conveyed in the anterior commissure of the spinal cord.

Question 32

``` Which one of the following is NOT a sign of an upper motor neuron lesion? A. Muscle paresis B. Hyperreflexia C. Dystonia D. Positive Babinski’s sign E. Spasticity ```

Answer 32

C: Muscle paresis, hyperreflexia, positive Babinski’s sign, and spasticity are all signs of an upper motor neuron (UMN) lesion. Dystonia is a basal ganglia sign and does not occur in UMN lesions.

Question 33

``` After a complete spinal cord injury affecting S2-4, a bladder that cannot be emptied is which of the following? A. Hypertonic and hyperreflexive B. Flaccid and paralyzed C. Spastic D. Autoreflexive E. None of the above ```

Answer 33

B: Complete lesions that damage any part of the reflexive bladder emptying circuit, that is, levels S2-S4—or afferents or parasympathetic efferents—produce a flaccid, paralyzed bladder. With an S2-4 lesion, the sympathetic efferents are intact and their signals inhibit contraction of the bladder wall and facilitate closure of the internal spincter. Complete lesions above the sacral cord interrupt descending axons that normally control bladder function but do not interrupt sacral level reflexive control of the bladder. This results in a hypertonic, hyperreflexive bladder with reduced bladder capacity. Hyperreflexive bladder and spastic bladder are synonymous. Autoreflexive is not a neuroscience term.

Question 34

``` Complete spinal cord lesions above which one of the following level results in long-term ventilator dependence? A. C4 B. C5 C. C6 D. C7 E. All of the above ```

Answer 34

A: Lesions above C4 interrupt most fibers of the phrenic nerve (C3 and C5 make small contributions to the phrenic nerve), so the diaphagm does not receive adequate signals for breathing. If C4 is intact, the diaphragm receives adequate signals for breathing.

Question 35

``` Loss of descending sympathetic control as a result of complete spinal cord lesions above T6 result in which of the following? A. Orthostatic hypotension B. Autonomic dysreflexia C. Poor thermoregulation D. Both A and B E. A, B, and, C ```

Answer 35

E: Complete spinal cord lesions above T6 cause serious abnormalities of autonomic regulation because many segments of the cord below the lesion are free from descending sympathetic control. The loss of descending sympathetic control results in orthostatic hypotension, autonomic dysreflexia, and poor thermoregulation.

Question 36

Autonomic dysreflexia is characterized by which one of the following? A. Abrupt decrease in blood pressure because of sympathetic vasoconstriction B. Abrupt increase in blood pressure and pounding headache C. Profuse sweating below the level of the lesion D. Excessive activation of the parasympathetic nervous system E. Excessive shivering associated with hyperthermia

Answer 36

B: Autonomic dysreflexia occurs when a complete spinal cord lesions above the T6 level prevents most of the spinal cord from receiving signals from the brain that inhibit sympathetic activity. Autonomic dysreflexia is an excessive sympathetic response, usually to stretch of the bladder or bowel, characterized by an abrupt increase in blood pressure, a pounding headache. In addition, flushing of the skin and profuse sweating occur above the level of the lesion. The sudden spike in blood pressure may be life threatening.

Question 37

``` Dorsal rhizotomy is the selective surgical ablation of which of the following? A. Dorsal horn neurons B. Posterior commissural axons C. Dorsal roots D. Dorsal columns E. Nucleus dorsalis ```

Answer 37

C: Dorsal rhizotomy is selective surgical ablation of the dorsal roots. The purpose of the surgery is to decrease or eliminate hyperreflexia by interrupting the afferent limb of the stretch reflex. The procedure is selective because individual dorsal rootlets are stimulated electrically before ablation to determine whether activity in that specific dorsal rootlet contributes to hyperreflexia. If stimulating the rootlet does not contribute to hyperreflexia, the rootlet is left intact to provide somatosensation.

Question 38

``` Loss of pain and temperature sensation in a capelike distribution over the shoulders, lower limb paresis, hyper-reflexia, and loss of bowel and bladder function are characteristic of which of the following? A. Multiple sclerosis B. Cervical spondylosis C. Meningomyelocele D. Syringomyelia E. Erb’s paralysis ```

Answer 38

D: The loss of pain and temperature sensation in a cape-like distribution over the shoulders, lower limb paresis, hyperreflexia, and loss of bowel and bladder function are characteristic of syringomyelia. In syringomyelia, a syrinx, or a fluid-filled cavity, develops in the spinal cord, almost always in the cervical region. Syringomyelia usually is congenital but may occur secondary to trauma or tumor. Accumulation of cerebrospinal fluid in the syrinx causes increased pressure inside the spinal cord, expanding the cavity and compressing adjacent nerve fibers. The loss of sensitivity to pain and temperature stimuli is due to interruption of spinothalamic axons crossing the midline in the anterior white commissure.

Question 39

Klumpke’s paralysis is the result of which of the following? A. Avulsion of the C5 to C6 ventral roots B. Mechanical irritation of the C7 to C8 dorsal roots C. Traction force applied to the cervico-occipital region D. Lesion of the dorsal root ganglion because of a herniated disk E. Avulsion of the C8 through T1 motor nerve roots

Answer 39

E: Traction on the abducted arm can cause avulsion of the motor roots of C8 and T1, resulting in Klumpke’s paralysis. Loss of lower motor neuron output from the C8 and T1 spinal levels results in paralysis and atrophy of the hand intrinsic muscles and the long flexors and extensors of the fingers.

Question 40

Vertebral canal stenosis is associated with which one of the following? A. Narrowing of the vertebral canal caused by bone growth or tissue hypertrophy B. Compression of neural and vascular structures of the spinal cord C. Radiating pain with numbness and loss of proprioception D. All of the above E. None of the above

Answer 40

D: Vertebral canal stenosis causes narrowing of the vertebral canal (by bone growth or tissue hypertrophy), compression of neural and vascular structures of the spinal cord, and radiating pain with numbness and loss of proprioception. Clumsiness occurs secondary to lack of proprioception. Upper motor neuron signs may occur with cervical stenosis.