Quiz 6: Sidman (Ch 47)

Question 1

The nucleus gracilis lies in the lower medulla. The primary axons that ascend the spinal cord and make synaptic contact with secondary neurons of the nucleus gracilis are axons of the fasciculus _____. Axons of the fasciculus cuneatus terminate in the lower medulla in synaptic contact with neurons of the nucleus _____.

Answer 1

gracilis; cuneatus

Question 2

Blockage of the posterior spinal artery would affect the blood supply to the nucleus gracilis and cause a lack of information regarding the _____thetic senses from the lower limb.

Answer 2

kinesthetic

Question 3

Information about muscle tone ordinarily does not reach consciousness; impulses may be relayed via the _____ _____ peduncle to the _____lateral side of the cerebellum. Information about the kinesthetic senses ascends the spinal cord in the _____ gracilis and cuneatus; these axons belong to neuron number _____ in the afferent pathway.

Answer 3

inferior cerebellar; ipsilateral; fascicule; one

Question 4

As the fibers of the posterior columns ascend into the medulla (passing in a predominantly _____ior direction), they run along the _____ior surfaces of the nuclei gracilis and cuneatus. Label the two indicated nuclei in the section.

Answer 4

superior; posterior

Top right: Nucleus gracilis
Bottom right: Nucleus cuneatus

Question 5

In the pathway for position sense, the neurons of the nuclei gracilis and cuneatus are the _____ary neurons. Cell bodies of these neurons lie in the region of the brainstem called the _____.

Answer 5

secondary; medulla

Question 6

At progressively higher levels of the lower medulla, the fasciculi gracilis and cuneatus gradually disappear and are replaced by _____ with the same names. In the appropriate cross section(s) place an “X” on the cell bodies of secondary neurons mediating position sense in the left hand.

Answer 6

nuclei

“X” on inner bottom right of both

Question 7

In all the sensory pathways, the cell bodies of primary and secondary neurons lie on the _____ side. In the pathway mediating pain in the left foot, the cell body of the secondary neuron lies in the _____ side of the lumbar spinal cord. In the pathway mediating position sense in the left foot, the cell body of the secondary neuron lies in the _____ side of the _____.

Answer 7

same; left; left; medulla

Question 8

In the pain and temperature pathways, the axon that crosses the midline belongs to the _____ary neuron; it then ascends and synapses with a tertiary neuron whose cell body is in the _____. In the kinesthetic pathway, the axon of the secondary neuron crosses the midline and terminates in synaptic contact with a _____iary neuron in the _____ thalamus.

Answer 8

secondary; thalamus; tertiary; contralateral

Question 9

In the ascending pathway for cold in the right hand, the first synapse in the posterior horn of the _____ region of the _____ _____. Kinesthetic fibers in the right hand make the analogous first synapse in the nucleus _____ in the _____. In both systems, the axons of the secondary neuron ascend slightly as they _____ the midline and then pass upward to their highest site of synapse in the _____.

Answer 9

cervical; spinal cord; cuneatus; medulla; cross; thalamus

Question 10

Label the central canal (CC) in each of the two lower cross sections. Most of the tissue posterior to the central canal in the cervical cord is _____ matter, and most of the tissue in the lower medulla is _____ (the nuclei _____ and _____). The most posterior structure higher in the medulla is the fluid-filled _____ _____.

Answer 10

Middle circle of middle and bottom cross section is labeled CC

white; gray; gracilis; cuneatus; 4th ventricle

Question 11

Draw a circle around the superior colliculi on both pictures. Anterior to the cerebellum are two regions of the brainstem, the _____ and the _____. The fluid-filled cavity between between the structures and the cerebellum is the _____ _____.

Answer 11

Middle back circle on left picture and top middle circle on right picture

medulla; pons; 4th ventricle

Question 12

Kinesthetic impulses arising in the left arm and ascending toward the Cortes first cross a synapse in the nucleus _____ on the _____ side. As the axons emerge from the nuclei gracilis and cuneatus, do they travel in same direction as the axons in the fasciculi gracilis and cuneatus? _____

Answer 12

cuneatus; left; no

Question 13

Axons emerging along the length of the nuclei gracilis and cuneatus follow the course of an arc around the central canal. For this reason, they are called the _____ _____ fibers.

Answer 13

internal arcuate

Question 14

Encircle the right internal arcuate fibers and label the nuclei from which such fibers emerge.

Answer 14

Circle both lines middles (2 for each circle)

Left to right + bottom to top: Left internal arcuate fibers; Left nucleus cuneatus; Left Nucleus gracilis: Right nucleus gracilis; Right nucleus cuneatus

Question 15

When the internal arcuate fibers complete their arc, they turn sharply in a superior direction and continue uninterrupted all the way to the contralateral _____. En route, the decussated fibers are given a new name, medial lemniscus. With an arrow, indicate the medial lemniscus.

Answer 15

thalamus

Arrow to middle shaded region of Medulla

Question 16

Internal arcuate fibers from the left and right sides cross in the _____ of the _____ _____.

Answer 16

decussation; medial lemniscus

Question 17

In the kinesthetic pathway, the axon of the second neuron is initially called an _____ _____ fiber and then changes its name by becoming part of the _____ _____ on the _____ side of the brainstem.

Answer 17

internal arcuate; medial lemniscus; contralateral

Question 18

The medial lemniscus receives arterial supply primarily from branches of the vertebral arteries; _____ sense, _____ure, and _____ is lost in relation to the medial lemniscus from blockage of the vertebral artery.

Answer 18

position; pressure; touch

Question 19

Information in the right posterior columns of the spinal cord comes to the _____ side of the thalamus. In the kinesthetic pathway from the right foot, the first synapse is in the _____ _____ on the _____ side, and the next synapse is in the _____ on the _____ side.

Answer 19

left; nucleus gracilis; right; thalamus; left

Question 20

As the internal arcuate fibers curve anteriorly and medially, they also curve in a somewhat _____ior direction. Most of the internal arcuate and medial lemniscus fibers cut in any given transverse section arose from cell bodies in a more _____ior section.

Answer 20

superior; inferior

Question 21

Circle the internal arcuate fibers on both sides of the left image and draw an arrow to the medial lemniscus on both sides of the right image.

Answer 21

Circle middle of lines with two each on left picture
Arrows into middle shaded region on right picture

Question 22

Label the nuclei gracilis (G) and cuneatus (C) on the right side of each picture. In the top section, label the fibers of the kinesthetic pathway with the name given to them in the first portion of their course after they leave cell bodies in the two nuclei.

Answer 22

Top picture: G on top right, C on bottom right
Circle two right lines and label “Internal arcuate fibers”

Bottom picture: G on top right, C on bottom right

Question 23

The fibers at “X” belong to the _____ _____. They arise from cell bodies in the nuclei gracilis and cuneatus on the _____ side. The fibers marked “Y” arise mainly in the _____ lobe of the cortex on the _____ side.

Answer 23

medial lemniscus; contralateral; frontal; ipsilateral

Question 24

The internal arcuate fibers course obliquely to higher levels of the medulla at the same time that they form an arc from posterior to anterior positions. Label the internal arcuate fibers (IA) on the left picture and the medial lemnisci (ML) bilaterally on the right picture. At the level of the medulla, illustrated in the right picture, all internal arcuate fibers have entered the left or right _____ _____.

Answer 24

Label “IA” on both sides in between the two lines on left picture
Label “ML” on both sides from middle shaded region on right picture

medial lemniscus

Question 25

The arrow at this cervical cord level points to a headless “homunculus” representing the layout of one side of the body in the posterior columns. If a corresponding simple homunculus were drawn on the other side of the cervical section, the part of this body nearest the midline would be the _____.

Answer 25

foot

Question 26

Kinesthetic impulses from the leg reach the nucleus gracilis and pass along its axons in a curving and mainly _____ior direction; forming the leg are _____ _____ fibers that _____ the midline and join the _____ _____. The left medial lemniscus carries somesthetic information from the _____ side of the body. The midline is crossed by axon number _____ in the afferent chain.

Answer 26

anterior; internal arcuate; cross; medial lemniscus; right; two

Question 27

The most inferior internal arcuate fibers arise from the nucleus gracilis and carry kinesthetic information from the most _____ region of the body. Information from the arm passes along internal arcuate fibers at more _____ior levels.

Answer 27

inferior; superior

Question 28

The homunculus “stands upright” in the medial lemniscus of the medulla. Beyond the inferior olive, the “feet slide out from under him,” so that information from the legs is transmitted along fibers _____ to those carrying information from the arms.

Answer 28

lateral

Question 29

The somesthetic pathway exhibits somatotopic organization. Information from the left foot lies in the most _____ part of the posterior columns, in the most _____ior part of the medial lemniscus in the mid and upper medulla, and in the most _____ position in the medial lemniscus from the pons all the way to the _____.

Answer 29

medial; anterior; lateral; thalamus

Question 30

The primary neurons conveying information on pain and temperature senses from the left hand enter the cervical cord and synapse with secondary afferent cell bodies in the _____ior horn. The secondary axons decussate in the _____ _____ of the cord and ascend to the _____ in the _____ _____ tract on the _____ side.

Answer 30

posterior; anterior commissure; thalamus; lateral spinothalamic; contralateral

Question 31

In the left or right lateral spinothalamic tract, as in the left or right medial lemniscus, the fibers conveying information from the leg lie most _____. This somatotopic organization is reversed in only one location: the _____ _____ of the spinal cord.

Answer 31

lateral; posterior columns

Question 32

Comparing central pathways for pain and position sense in the fingers of the left hand: (1) nerve cell bodies in the posterior horn of the left side of the cervical cord correspond to nerve cell bodies in the nucleus _____ of the _____ side of the lower _____; (2) fibers in the anterior commissure correspond to the _____ _____ fibers; and (3) decussated secondary fibers in the right lateral spinothalamic tract correspond to secondary fibers in the _____ _____ on the _____ side of the brainstem.

Answer 32

cuneatus; left; medulla; internal arcuate; medial lemniscus; right

Question 33

On the section, draw outlines of the right lateral and both anterior spinothalamic tracts. All three transmit afferent information from the same side of the body, the _____ side.

Answer 33

Draw three circles, two on bottom of picture and one to the right of right bottom circle. left

Question 34

The diagram shows that pain and kinesthetic pathways are anatomically separated from each other in the spinal cord and most of the brainstem. In the upper medulla, the spinothalamic tract is well separated from the medial lemniscus and lies close to the posterior and lateral part of the _____ _____. Both pathways become virtually confluent by the time they enter the _____.

Answer 34

inferior olive; thalamus

Question 35

The name of the pathway serving for position sense, pressure, and touch is called the _____ sensory pathway. The cell bodies of primary neurons in this pathway are in _____ _____. In this pathway, the midline is crossed by _____ _____ fibers arising in cell bodies of the nuclei _____ and _____. These are _____ary afferent neurons. The secondary axons make synaptic contact with cell bodies of the tertiary neurons of the _____.

Answer 35

kinesthetic; spinal ganglia; internal arcuate; gracilis; cuneatus; secondary; thalamus

Question 36

At the junction of the spinal cord and the medulla, the fibers in the _____ columns are passing superiorly toward the nuclei gracilis and cuneatus. On the anterior side, descending fibers of the left and right _____ tracts are crossing to become the _____ _____ tracts of the cord.

Answer 36

posterior; corticospinal; lateral corticospinal

Question 37

The minimum number of neurons encompassed by the terms spinal ganglion cell and fasciculus gracilis is _____. The minimum number of neurons encompassed by the terms nucleus gracilis, internal arcuate fiber, and medial lemniscus is _____.

Answer 37

one; one

Question 38

In the pons, the leg fibers of the medial lemniscus swing laterally, but in the medulla, the “homunculus is held upright” by the inferior olive. Within the encircled medial lemniscus, place an “L” for leg fibers and a “T” for trunk fibers.

Answer 38

Label “T” on top and “L” on bottom in middle shaded region

Question 39

Label the sections with a “1,” “2,” and “3” from inferior to superior. Circle the medial lemniscus in all three images.

Answer 39

Label pictures from top to bottom: 3, 2, 1 Circle left side of middle shaded region for all three pictures

Question 40

Function: Temperature sense Joint sense _____ and _____ senses Muscle tone

Answer 40

touch; pressure

Question 41

1st synapse in: Posterior horn of the cord Nuclei _____ and _____ All the sites listed above Nucleus _____

Answer 41

gracilis; cuneatus dorsalis

Question 42

2nd axon ascends in the: _____ _____ tract _____ _____ _____ _____ tracts and the _____ _____ _____ tracts

Answer 42

lateral spinothalamic medial lemniscus anterior spinothalamic; medial lemniscus spinocerebellar

Question 43

2nd axon terminates in the: _____ _____ _____ _____

Answer 43

Thalamus Thalamus Thalamus Cerebellum