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Ch. 13 The Peripheral Nervous System
Amerman - Human Anatomy & Physiology 2nd Edition
Erin C. Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822Not the one you use?Change textbook
All textbooksErin C. Amerman 2nd EditionCh. 13 The Peripheral Nervous SystemProblem 7
Chapter 13, Problem 7

First-order somatic sensory neurons are_____neurons whose cell bodies are located in the_____.


a. Multipolar, posterior horn
b. Pseudounipolar, posterior root ganglion
c. Bipolar, anterior horn
d. Pseudounipolar, posterior horn

Verified step by step guidance
1
Step 1: Understand the structure of first-order somatic sensory neurons. These neurons are responsible for transmitting sensory information from the periphery (e.g., skin, muscles) to the central nervous system (CNS).
Step 2: Recall the classification of neurons based on their structure. Neurons can be multipolar, bipolar, or pseudounipolar. Pseudounipolar neurons are specialized for sensory functions and have a single process that splits into two branches: one extending to the periphery and the other to the CNS.
Step 3: Identify the location of the cell bodies of first-order somatic sensory neurons. These cell bodies are located in the posterior root ganglion (also called the dorsal root ganglion), which is part of the peripheral nervous system and lies just outside the spinal cord.
Step 4: Eliminate incorrect options based on the structural type and location. For example, multipolar neurons are typically motor neurons, and bipolar neurons are found in special sensory systems like the retina. The posterior horn is part of the spinal cord's gray matter and does not house sensory neuron cell bodies.
Step 5: Conclude that the correct answer is the option describing pseudounipolar neurons with cell bodies located in the posterior root ganglion, as this matches the anatomy and physiology of first-order somatic sensory neurons.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

First-order somatic sensory neurons

First-order somatic sensory neurons are responsible for transmitting sensory information from the periphery to the central nervous system. They are the initial neurons in the sensory pathway, detecting stimuli such as touch, pain, and temperature. Understanding their role is crucial for grasping how sensory information is processed in the nervous system.
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Pseudounipolar neurons

Pseudounipolar neurons are a type of neuron characterized by a single axon that splits into two branches, one extending to the periphery and the other to the central nervous system. This structure allows for efficient transmission of sensory information. They are commonly found in sensory ganglia, such as the posterior root ganglion, where they relay sensory signals.
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Posterior root ganglion

The posterior root ganglion is a cluster of sensory neuron cell bodies located just outside the spinal cord. It serves as a relay point for sensory information entering the spinal cord from the body. Understanding its location and function is essential for identifying the pathways through which sensory information is processed and integrated.
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Related Practice
Textbook Question

First, write the Roman numeral that corresponds to each named cranial nerve (after the abbreviation CN). Second, match the cranial nerve with its correct function from the column on the right.


CN____               

______Vestibulocochlear nerve

CN____           

______Trigeminal nerve

CN____           

_______Hypoglossal nerve

CN____           

_______Abducens nerve

CN____           

_______Vagus nerve

CN____           

_______Olfactory nerve

CN____            

_______Accessory nerve

CN____           

_______Oculomotor nerve

CN____           

_______Facial nerve

CN____           

_______Optic nerve

CN____           

_______Glossopharyngeal nerve

CN____           

_______Trochlear nerve


a. Motor to the lateral rectus muscle

b. Motor to the muscles of facial expression; lacrimation; salivation; taste to the anterior two-thirds of the tongue

c. Sense of smell

d. Motor to the muscles for swallowing; salivation; taste to the posterior one-third of the tongue; somatic sensation from the throat

e. Senses of hearing and equilibrium

f. Motor to the superior oblique muscle

g. Motor to the tongue

h. Motor to the sternocleidomastoid and trapezius muscles

i. Sense of vision

j. Motor to muscles of swallowing and speaking; parasympathetic innervation to thoracic and abdominal viscera; sense of taste from the throat

k. Sensory to the face; motor to the muscles of mastication

l. Motor to four of six extrinsic eye muscles; constricts the pupil; changes the shape of the lens; opens the eyelid

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Textbook Question

Which cranial nerves are sensory only, primarily motor, and mixed?

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Textbook Question

Match the following nerves with the structures they innervate.     


____Phrenic nerve     

____Median nerve     

____Femoral nerve     

____Tibial nerve     

____Radial nerve     

____Intercostal nerves     

____Common fibular nerve     

____Musculocutaneous nerve


a. Motor to the triceps brachii muscle and muscles in the forearm that extend the hand; sensory from the posterior hand

b. Motor to the muscles in the anterior arm that flex the forearm; sensory from skin over the lateral forearm

c. Motor to the muscles in the anterior and lateral leg that evert and dorsiflex the foot; sensory from the skin of the anteroinferior leg

d. Motor to the diaphragm muscle

e. Motor to the muscles in the anterior thigh extend the knee; sensory from the skin over the anterior thigh and leg

f. Motor to the hamstring muscles that extend the thigh and flex the leg, muscles of the leg that plantarflex the foot, and muscles of the foot; sensory from the skin over the posterior and lateral leg and foot

g. Motor to the muscles between the ribs and the abdominal muscles; sensory from the skin over the abdomen

h. Motor to the muscles in the forearm that flex the hand, certain intrinsic hand muscles; sensory from the skin of the anterior hand

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Textbook Question

A receptor potential:

a. Always leads to an action potential

b. Never leads to an action potential

c. Causes hyperpolarization of the neuron

d. Leads to an action potential if the stimulus is strong enough

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Textbook Question

Why is visceral pain often perceived as cutaneous pain?

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Textbook Question

Place the following sequence of events for the detection of somatic sensation in the proper order. Place a 1 by the first event, a 2 by the second event, and so on.     

a. ______The central process transmits the action potential to a second-order sensory neuron in the CNS.     

b. ______The action potential is transferred to the central process in the posterior root ganglion.     

c. ______The stimulus triggers an action potential.     

d. ______The signal is transferred to other CNS sensory neurons for eventual perception and interpretation.     

e. ______The action potential is propagated along the peripheral process of the neuron.

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