Textbook Question
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
Ch. 13 The Peripheral Nervous System
Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814
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Table of contents
- Ch. 1 Introduction to Anatomy and Physiology24
- Ch. 2 The Chemistry of Life37
- Ch. 3 The Cell54
- Ch. 4 Histology46
- Ch. 5 The Integumentary System30
- Ch. 6 Bones and Bone Tissue36
- Ch. 7 The Skeletal System40
- Ch. 8 Articulations19
- Ch. 9 The Muscular System35
- Ch. 10 Muscle Tissue and Physiology29
- Ch. 11 Introduction to the Nervous System and Nervous Tissue28
- Ch. 12 The Central Nervous System41
- Ch. 13 The Peripheral Nervous System41
- Ch. 14 The Autonomic Nervous System and Homeostasis31
- Ch. 15 The Special Senses39
- Ch. 16 The Endocrine System42
- Ch. 17 The Cardiovascular System I: The Heart28
- Ch. 18 The Cardiovascular System II: The Blood Vessels43
- Ch. 19 Blood32
- Ch. 20 The Lymphatic System and Immunity41
- Ch. 21 The Respiratory System27
- Ch. 22 The Digestive System27
- Ch. 23 Metabolism and Nutrition7
- Ch. 24 The Urinary System39
- Ch. 25 Fluid, Electrolyte, and Acid-Base Homeostasis39
- Ch. 26 The Reproductive System10
- Ch. 27 Development and Heredity5
Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814Not the one you use?Change textbook
Chapter 13, Problem 12
The tracts of the posterior columns decussate in the ________, whereas the tracts of the anterolateral system decussate in the ________.
Verified step by step guidance1
Understand the term 'decussate': In anatomy, 'decussate' refers to the crossing of nerve fibers from one side of the central nervous system to the other. This is a key concept in understanding how sensory and motor pathways function.
Identify the posterior columns: The posterior columns, also known as the dorsal columns, are responsible for transmitting fine touch, vibration, and proprioception (sense of body position). These tracts decussate at a specific location in the central nervous system.
Determine where the posterior columns decussate: The sensory information carried by the posterior columns crosses over (decussates) in the medulla oblongata, a part of the brainstem.
Identify the anterolateral system: The anterolateral system, which includes the spinothalamic tracts, is responsible for transmitting pain, temperature, and crude touch. These tracts also decussate, but at a different location compared to the posterior columns.
Determine where the anterolateral system decussates: The sensory information carried by the anterolateral system crosses over (decussates) at the level of the spinal cord, near the point of entry of the sensory nerve fibers.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Decussation
Decussation refers to the crossing over of nerve fibers from one side of the central nervous system to the other. This process is crucial for the integration of sensory and motor pathways, allowing the brain to process information from the opposite side of the body. Understanding where decussation occurs helps in localizing neurological functions and understanding the pathways of sensory information.
Posterior Columns
The posterior columns, also known as the dorsal columns, are a pair of pathways in the spinal cord that carry sensory information related to fine touch, vibration, and proprioception. These tracts ascend to the brainstem and decussate at the level of the medulla oblongata before reaching the thalamus. This pathway is essential for the perception of detailed sensory information.
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Anterolateral System
The anterolateral system, which includes the spinothalamic tract, transmits pain, temperature, and crude touch sensations. Unlike the posterior columns, the fibers of the anterolateral system decussate at the level of the spinal cord shortly after entering. This system is vital for the rapid response to potentially harmful stimuli, allowing for quick reflex actions.
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Related Practice
Textbook Question
Mark the following statements about the spinal cord as true or false. If a statement is false, correct it to make a true statement.
The corticospinal tracts are the main sensory tracts in the spinal cord.
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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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Textbook Question
How do upper and lower motor neurons differ?
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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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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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