Chapter 15 A&P Mastering

All of the following are true of the organization and patterns of spinal cord tracts, except:

The number of synapses is the same for all tracts; there are always 3 neurons in each ascending and descending tract.

Which of the following statements regarding the spinocerebellar tracts is true?

The posterior spinocerebellar tract carries axons that ascend to the cerebellar cortex by way of the inferior cerebellar peduncle.

All of the following are true of the reticular formation, except:

The reticular formation receives input from almost every descending tract, but not from ascending tracts.

All of the following are true of the organization of motor tracts, except:

The somatic nervous system (SNS) issues motor commands to the smooth muscles, cardiac muscle, and glands.

All of the following statements are true of the subconscious motor pathways, except:

The tectospinal tracts help control the distal limb muscles that perform precise movements.

All of the following statements are true of the corticospinal tracts, except:

They are sometimes called the anterolateral system.

Subconscious regulation of balance and muscle tone is a function of which of the following tracts?

Vestibulospinal tracts

Afferent sensory and efferent motor information travels by several different routes, depending on which of the following factors?

Where the information is going, The priority level of the information, Where the information is coming from

Which of the ascending tracts have no third-order neurons?

anterior and posterior spinocerebellar tracts

All of these sensory tracts carry information regarding proprioception except the ____________.

anterior spinothalamic tracts

Over which of the following do the pons and superior medulla oblongata have somatic motor control?

balance reflexes and more-complex respiratory reflexes

Which of the following structures control(s) simple cranial and spinal reflexes?

brain stem and spinal cord

What somatic motor control does the hypothalamus possess?

controls stereotyped motor patterns related to eating, drinking, and sexual activity, and modify respiratory reflexes

Axons in the ___________ (descending) tracts synapse on lower-motor neurons in the motor nuclei of several cranial nerves, and control skeletal muscles that move the eye, jaw, face, and some of the neck and pharynx muscles.

corticobulbar

All of the following principal descending tracts are subconscious motor pathways, except:

corticobulbar tracts

Which of the following tracts are not major somatic sensory tracts?

corticospinal tracts

Which of the following sensations is/are interpreted in the primary sensory cortex?

crude touch, pain, fine touch, proprioception

The crossover of nerves that occurs in many nerve tracts, in which sensory information from one side of the body is delivered to the other side of the brain, and motor information from one side of the brain is delivered to muscles on the other side of the body, is called:

decussation

The cell body of which sensory neuron may be located in a dorsal root ganglion or a cranial nerve ganglion?

first-order neuron

In the planning stage of somatic motor control, when a conscious decision is made to perform a specific movement, information is relayed from the __________ to the ___________; these areas then relay the information to the ___________ .

frontal lobes; motor association areas; cerebellum and basal nuclei

Which parts of the body are the largest on the motor homunculus?

hands, face and tongue

Damage to which nucleus is associated with changes in interpretation of fine touch and pressure from levels inferior to T6?

nucleus gracilis

Fine-touch, vibration, pressure, and proprioception sensations are carried by the __________.

posterior columns

The fasciculus gracilis and the fasciculus cuneatus make up the:

posterior columns

Although normally insignificant, which motor tracts can be important in maintaining motor control and muscle tone in the upper limbs if the lateral corticospinal tracts are damaged?

rubrospinal tracts

In ascending tracts, the cell bodies of second-order neurons are located in the:

spinal cord or brain stem

The axon of which type of neuron carries sensory information from the thalamus to the proper region of the cerebral cortex?

third-order neuron

Which of the following tracts do NOT cross over?

vestibulospinal tracts

Along the length of pyramids, what is the percentage of axons that cross the midline (decussate) to enter the descending lateral corticospinal tracts?

85 percent

Which somatic motor control modifies voluntary and reflexive motor patterns at the subconscious level?

Basal nuclei

Why are the proportions of the sensory homunculus very different from those of an actual human being?

Because the area of sensory cortex devoted to a particular region is proportional to the number of sensory receptors the region contains.

Which somatic motor control plans and initiates voluntary activity?

Cerebral cortex

What somatic motor control is under the command of the inferior medulla oblongata?

Controls basic respiratory reflexes

What somatic motor control does the cerebellum possess?

Coordinates complex motor patterns

Which of the following may issue somatic motor commands as a result of processing performed at a subconscious level?

Diencephalon, Brain stem, Cerebrum

The sensation of proprioception, fine touch, pressure, and vibration from levels at or superior to T6 is controlled by which tract(s)?

Fasciculus cuneatus

Which of the following sensory neurons deliver the action potential to the Central Nervous System?

First-order neuron

All of the following are true of amyotrophic lateral sclerosis, except:

It affects both sensory and motor neurons.

Which corticospinal tracts provide conscious motor control of skeletal muscles?

Lateral corticospinal tracts, Anterior corticospinal tracts, Corticobulbar tracts

What is the function of the lateral spinothalamic tract?

Pain and temperature sensations

Which of the following is the site of decussation of the lateral corticospinal tracts?

Pyramids of medulla oblongata

Subconscious regulation of upper limb muscle tone and movement is a function of which of the following tracts?

Rubrospinal tracts

Which item is an anatomical principle of neurons within sensory tracts?

Somatotopic arrangement, Medial-lateral rule Sensory modality arrangement

What tract carries sensations of pain, temperature, and "crude" sensations of touch and pressure?

Spinothalamic tract

Which somatic motor control controls reflexes in response to visual and auditory stimuli?

Thalamus and mesencephalon