Page 569 - Fundamentals of anatomy physiology

556 Unit 3 Control and Regulation LEVEL 2 Reviewing Concepts

of sensory receptors in the area of the body, (e) size of the nerves that 14. Efferent output from the brain stimulates which tissues and organs?
serve the area of the body. 15. What is a motor homunculus? How does it differ from a sensory
5. Identify and shade in the locations of all the ascending sensory tracts
in the following diagram of the spinal cord. homunculus?
16. Describe the relationship among first-, second-, and third-order
Dorsal root
neurons in a sensory pathway.
Dorsal root 17. Damage to the posterior spinocerebellar tract on the left side of the
ganglion
spinal cord at the L1 level would interfere with the coordinated move-
Ventral root ment of which limb(s)?
18. What effect does injury to the primary motor cortex have on periph-
15 6. Identify six types of tactile receptors located in the skin, and describe eral muscles?
19. What is muscle tone? When does muscle tone fail?
their sensitivities. 20. Explain the phenomenon of referred pain in terms of labeled lines and
7. What three types of mechanoreceptors respond to stretching, compres- organization of sensory tracts and pathways.

sion, twisting, or other distortions of their plasma membrane? LEVEL 3 Critical Thinking and Clinical Applications
8. What are the three major somatic sensory pathways and their functions?
9. Which three pairs of descending tracts make up the corticospinal 21. Kayla is having difficulty controlling her eye movements and has lost
some control of her facial muscles. After an examination and testing,
pathway? Kayla’s physician tells her that her cranial nerves are perfectly normal
10. Which three motor tracts make up the medial pathway? but that a small tumor is putting pressure on certain fiber tracts in her
11. In pain perception, describe the roles of the (a) Type A, and brain. This pressure is the cause of Kayla’s symptoms. Where is the
tumor most likely located?
(b) Type C fibers.
12. The corticospinal tract (a) carries motor commands from the cerebral 22. Harry, a construction worker, suffers a fractured skull when a beam
falls on his head. Diagnostic tests indicate severe damage to the motor
cortex to the spinal cord, (b) carries sensory information from the cortex. His wife is anxious to know if he will ever be able to move or
spinal cord to the brain, (c) starts in the spinal cord and ends in the walk again. What would you tell her?
brain, (d) does all of these.
13. List the general senses and the special senses. 23. Denzel had to have his arm amputated at the elbow after an acci-
dent. He tells you that he can sometimes still feel pain in his fingers
even though the hand is gone. He says this is especially true when he
bumps the stub. How can this be?

Clinical Case Wrap-Up

Living with Cerebral Palsy He was a pioneer and became
a catalyst in introducing the
Communication between the periphery and concept of self-determination
the central nervous system follows neural path- to the field of education. He
ways. Somatic sensory tracts are ascending, ending in the brain. has been an educator, writer,
Somatic motor tracts are descending, beginning in the brain. and motivator his entire life.
Between the input and the output, nerve impulses are analyzed, He is not just living, but thriv-
influenced, and modified in various parts of the brain, includ- ing despite his cerebral palsy.
ing the cerebrum, cerebellum, basal nuclei, hippocampus, and
thalamus. These were the very areas of Michael's brain that were 1. Name the principal descending motor pathways that carry
injured during birth. information that would be affected by the brain damage
The damage affected the sensory and motor processing causing Michael’s cerebral palsy.
centers in the brain. As a result, Michael’s voluntary movements,
muscle tone, postural muscle control, and balance were all af- 2. Besides aspiration pneumonia, what other difficulties could
fected. These deficits were stable and did not get worse. There result from poor motor control of the muscles used in
was no limit to the development of the rest of Michael’s brain, or swallowing?
how brilliant he could become.
In spite of his disabilities, Michael chose to define himself in See the blue Answers tab at the back of the book.
terms of his abilities. He earned his Ph.D. in special education.