Textbook Question
Why do the three parts of the trapezius muscle have three different actions?
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Ch. 9 The Muscular System
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 Autonomic 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 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
Chapter 9, Problem L2.2
Explain how the diaphragm muscle is able to increase the size of the thoracic cavity even though it doesn't insert into a bone.
Verified step by step guidance1
Understand the anatomy of the diaphragm: The diaphragm is a dome-shaped sheet of skeletal muscle that separates the thoracic cavity from the abdominal cavity. It is unique because it does not insert into a bone but attaches to structures such as the central tendon, the lower ribs, the sternum, and the lumbar vertebrae.
Learn the mechanism of contraction: When the diaphragm contracts, its muscle fibers shorten, causing the dome-shaped structure to flatten and move downward. This movement increases the vertical dimension of the thoracic cavity.
Explore the role of the central tendon: The diaphragm's central tendon is a strong, fibrous structure that serves as the insertion point for the muscle fibers. When the diaphragm contracts, the central tendon is pulled downward, facilitating the expansion of the thoracic cavity.
Understand the pressure changes: As the diaphragm moves downward, it reduces the pressure in the thoracic cavity relative to the atmospheric pressure. This creates a vacuum effect, allowing air to flow into the lungs during inhalation.
Connect the movement to respiration: The diaphragm's ability to increase the size of the thoracic cavity is essential for breathing. By expanding the thoracic cavity, the diaphragm enables the lungs to fill with air, supporting the process of gas exchange necessary for oxygen delivery and carbon dioxide removal.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Diaphragm Anatomy
The diaphragm is a dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. It is primarily composed of skeletal muscle fibers and is innervated by the phrenic nerve. Although it does not insert into a bone, it is anchored to the lower ribs, sternum, and lumbar vertebrae, allowing it to function effectively during respiration.
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Clitoral Anatomy
Mechanics of Breathing
Breathing involves the expansion and contraction of the thoracic cavity, which is essential for inhalation and exhalation. When the diaphragm contracts, it flattens and moves downward, increasing the volume of the thoracic cavity. This decrease in pressure allows air to flow into the lungs, demonstrating how muscle contraction can influence cavity size without direct bony attachment.
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Pressure Gradient in Respiration
The principle of pressure gradient is crucial in respiration, as air moves from areas of higher pressure to lower pressure. When the diaphragm contracts and the thoracic cavity expands, the pressure inside the cavity decreases relative to atmospheric pressure. This pressure difference is what drives air into the lungs, illustrating the diaphragm's role in respiratory mechanics despite its lack of bony insertion.
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Related Practice
Textbook Question
If 'adductor' is part of the name of a muscle, what does that tell you about the muscle?
a. It is a wide muscle.
b. It is a long muscle.
c. It raises a body part.
d. It pulls a body part toward the midline.
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Textbook Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
The common function of all types of muscle tissue is to generate tension.
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Textbook Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
A property of all muscle cells is elasticity, which means that the tissue is able to stretch.
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Textbook Question
Predict the location and function of the flexor digitorum profundus muscle based only on its name.
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Textbook Question
The rectus femoris muscle originates from the anterior superior iliac spine and inserts into the tibial tuberosity. Predict its main actions with only this information.
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