Fundamentals of Nursing Q 360
A 12-year-old student falls off the stairs, grabs his wrist, and cries, “Oh, my wrist! Help! The pain is so sharp, I think I broke it.” Based on this data, the pain the student is experiencing is caused by impulses traveling from receptors to the spinal cord along which type of nerve fibers?
A. Type A-delta fibers
B. Autonomic nerve fibers
C. Type C fibers
D. Somatic efferent fibers
Correct Answer: A. Type A-delta fibers
Type A-delta fibers conduct impulses at a very rapid rate and are responsible for transmitting acute sharp pain signals from the peripheral nerves to the spinal cord. Only type A-delta fibers transmit sharp, piercing pain. They respond to stimuli such as cold and pressure, and as nociceptors stimulation of them is interpreted as fast/first pain information.
Option B: The autonomic system regulates involuntary vital functions and organ control such as breathing. An autonomic nerve pathway involves two nerve cells. One cell is located in the brainstem or spinal cord. It is connected by nerve fibers to the other cell, which is located in a cluster of nerve cells (called an autonomic ganglion). Nerve fibers from these ganglia connect with internal organs.
Option C: Type C fibers transmit sensory input at a much slower rate and produce a slow, chronic type of pain. The C group fibers are unmyelinated and have a small diameter and low conduction velocity, whereas Groups A and B are myelinated. Group C fibers include postganglionic fibers in the autonomic nervous system (ANS), and nerve fibers at the dorsal roots (IV fiber). These fibers carry sensory information.
Option D: Somatic efferent fibers affect the voluntary movement of skeletal muscles and joints. General somatic efferent fibers carry motor impulses to somatic skeletal muscles. In the head, the tongue and extraocular muscles are of this type. Cranial nerves III, IV, VI, and XII carry these fibers.