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Ch. 9 The Muscular System
Amerman - Human Anatomy & Physiology 2nd Edition
Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822Not the one you use?Change textbook
All textbooksAmerman 2nd EditionCh. 9 The Muscular SystemProblem 10
Chapter 9, Problem 10

Which of the following muscle groups is considered muscles of inspiration?
a. External intercostal muscles
b. Internal intercostal muscles
c. External oblique muscles
d. Internal oblique muscles

Verified step by step guidance
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Step 1: Understand the process of inspiration (inhalation). During inspiration, the thoracic cavity expands to allow air to enter the lungs. This expansion is facilitated by muscles that increase the volume of the thoracic cavity.
Step 2: Identify the primary muscles involved in inspiration. The diaphragm is the main muscle responsible for inspiration, but other accessory muscles also play a role, such as the external intercostal muscles.
Step 3: Analyze the function of external intercostal muscles. These muscles are located between the ribs and contract during inspiration to elevate the rib cage, increasing the thoracic cavity's volume.
Step 4: Compare the functions of the other muscle groups listed. Internal intercostal muscles are primarily involved in forced expiration, while external and internal oblique muscles are part of the abdominal wall and assist in movements like trunk rotation and forced expiration, not inspiration.
Step 5: Conclude that external intercostal muscles are considered muscles of inspiration because they actively contribute to expanding the thoracic cavity during inhalation.

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Key Concepts

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

Muscles of Inspiration

Muscles of inspiration are those that facilitate inhalation by expanding the thoracic cavity. The primary muscles involved include the diaphragm and external intercostal muscles, which work together to increase lung volume and decrease pressure, allowing air to flow into the lungs.
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External Intercostal Muscles

The external intercostal muscles are located between the ribs and play a crucial role in the breathing process. During inhalation, these muscles contract to elevate the ribs and expand the chest cavity, thereby aiding in the intake of air into the lungs.
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Internal Intercostal Muscles

The internal intercostal muscles are also situated between the ribs but primarily assist in forced expiration rather than inspiration. They work to depress the ribs and reduce the volume of the thoracic cavity during exhalation, contrasting with the role of the external intercostals.
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Related Practice
Textbook Question

Mr. Bell presents with the inability to move certain muscles on one side of his face. You ask him to make various facial expressions and find that on his right side he is unable to purse his lips, pull in his cheeks, elevate his upper lip, and smirk. What muscles is Mr. Bell unable to contract?

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Textbook Question

Which of the erector spinae muscles is most lateral to the vertebral column?

a. Spinalis muscle

b. Iliocostalis muscle

c. Semispinalis muscle

d. Longissimus muscle

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Textbook Question

Match the muscle with its main action:

_____Sternocleidomastoid muscle     

_____Transversus abdominis muscle     

_____Internal oblique muscle     

_____Rectus abdominis muscle     

_____Splenius capitis muscle     

_____Quadratus lumborum muscle.

a. Laterally flexes the trunk

b. Flexes the trunk

c. Compresses the abdominal cavity

d. Extends the vertebral column

e. Flexes the head

f. Extends the head

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Textbook Question

Mark the following statements as true or false. If the statement is false, correct it to make a true statement.

The pectoralis major and coracobrachialis muscles are antagonists.

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Textbook Question

Which of the following is not a muscle of the rotator cuff?

a. Teres major muscle

b. Teres minor muscle

c. Subscapularis muscle

d. Infraspinatus muscle

e. Supraspinatus muscle

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Textbook Question

The thick, bandlike muscle of mastication that covers much of the ramus of the mandible is the:

a. masseter muscle.

b. temporalis muscle.

c. lateral pterygoid muscle.

d. risorius muscle.

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