Textbook Question
Which parts of the body have the greatest amount of space dedicated to them in the primary somatosensory cortex? Why?
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Ch. 13 The Peripheral Nervous System
Erin C. Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822
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Table of contents
- Ch. 1 Introduction to Anatomy and Physiology26
- Ch. 2 The Chemistry of Life38
- Ch. 3 The Cell55
- Ch. 4 Histology47
- Ch. 5 The Integumentary System30
- Ch. 6 Bones and Bone Tissue36
- Ch. 7 The Skeletal System40
- Ch. 8 Articulations19
- Ch. 9 The Muscular System36
- Ch. 10 Muscle Tissue and Physiology29
- Ch. 11 Introduction to the Nervous System and Nervous Tissue28
- Ch. 12 The Central Nervous System42
- Ch. 13 The Peripheral Nervous System41
- Ch. 14 The Autonomous Nervous System and Homeostasis31
- Ch. 15 The Special Senses39
- Ch. 16 The Endocrine System42
- Ch. 17 The Cardiovascular System I: The Heart30
- Ch. 18 The Cardiovascular System II: The Blood Vessels43
- Ch. 19 Blood32
- Ch. 20 The Lymphatic System and Immunity45
- Ch. 21 The Respiratory System27
- Ch. 22 The Digestive System27
- Ch. 23 Nutrition and Metabolism7
- Ch. 24 The Urinary System39
- Ch. 25 Fluids, Electrolytes, and Acid-Base Homeostasis39
- Ch. 26 The Reproductive System10
- Ch. 27 Development and Heredity5
Erin C. Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822Not the one you use?Change textbook
Chapter 13, Problem 14
The lower motor neurons that innervate contractile skeletal muscle fibers are called:
a. α-motor neurons
b. β-motor neurons
c. upper motor neurons
d. γ-motor neurons
Verified step by step guidance1
Understand the role of motor neurons: Motor neurons are responsible for transmitting signals from the central nervous system to muscles, causing them to contract. They are divided into upper motor neurons and lower motor neurons.
Differentiate between upper and lower motor neurons: Upper motor neurons originate in the brain and send signals to lower motor neurons. Lower motor neurons directly innervate skeletal muscle fibers to cause contraction.
Learn about the types of lower motor neurons: Lower motor neurons are further classified into α-motor neurons, β-motor neurons, and γ-motor neurons, each with specific functions.
Focus on α-motor neurons: α-motor neurons specifically innervate extrafusal muscle fibers, which are the contractile fibers of skeletal muscles responsible for generating force.
Eliminate incorrect options: β-motor neurons innervate intrafusal fibers and are involved in muscle spindle sensitivity. γ-motor neurons also innervate intrafusal fibers to adjust spindle tension. Upper motor neurons do not directly innervate skeletal muscle fibers. Therefore, the correct answer is α-motor neurons.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Lower Motor Neurons
Lower motor neurons are the neurons that directly innervate skeletal muscle fibers, facilitating muscle contraction. They originate in the spinal cord and extend to the muscles, transmitting signals that lead to voluntary movements. Understanding their role is crucial for identifying how motor commands are executed in the body.
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α-Motor Neurons
α-motor neurons are a specific type of lower motor neuron responsible for innervating extrafusal muscle fibers, which are the primary contractile units of skeletal muscles. They play a vital role in generating force and movement by transmitting action potentials that lead to muscle contraction. Recognizing their function is essential for answering questions about muscle innervation.
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Motor Neuron Types
Motor neurons can be categorized into different types, including α-motor neurons, β-motor neurons, and γ-motor neurons. Each type has distinct functions; for instance, γ-motor neurons innervate intrafusal fibers in muscle spindles, while β-motor neurons are involved in modulating muscle tone. Understanding these distinctions is important for comprehending the overall motor control system.
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Related Practice
Textbook Question
List and describe the basic steps involved in producing movement, beginning with the upper motor neurons in the cerebral cortex.
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Textbook Question
Which of the following statements is false?
a. The spinothalamic tracts are part of the anterolateral system.
b. Pain, temperature, and crude touch stimuli are carried by the anterolateral system.
c. Descending pathways from the brain and spinal cord can make the spinal cord less receptive to pain stimuli.
d. The thalamus serves as the 'gateway' for entry of all special sensory stimuli into the cerebral cortex, with the exception of audition (hearing).
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Textbook Question
The cell bodies of upper motor neurons reside in the ________ and function to ________, whereas the cell bodies of lower motor neurons reside in the ________ and function to ________.
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Textbook Question
______detect the degree to which a muscle is stretched, whereas______detect the force of a muscle contraction.
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Textbook Question
Label the following components of the corticospinal tracts with numbers 1 through 6, with 1 being the origin of the tracts and 6 their destination.
_____ Medullary pyramids where most fibers decussate.
_____ Anterior horn of the spinal gray matter.
_____ Midbrain and pons.
_____ Upper motor neurons in the primary motor and premotor cortices.
_____ Corona radiata and internal capsule.
_____ Lateral funiculus of the spinal cord.
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