Question 1

Which muscle is primarily responsible for increasing the volume of the thoracic cavity during inspiration, and what is its main mechanism of action?

Accepted Answer

Diaphragm; contracts and flattens, increasing the vertical dimension of the thoracic cavity

Question 2

A patient presents with difficulty in forceful expiration. Which muscle group is most likely compromised?

Accepted Answer

M. intercostal intern

Question 3

During a deep inspiration, which accessory muscle can assist by elevating the ribs and expanding the thoracic cavity?

Accepted Answer

M. pectoralis major

Question 4

Which muscle originates from the upper surface of the first rib and inserts on the inferior surface of the clavicle, functioning to stabilize the clavicle during shoulder movements?

Accepted Answer

M. subclavius

Question 5

If the phrenic nerve is damaged, which physiological process will be most directly affected?

Accepted Answer

Inspiration

Question 6

Which muscle is located on the inner surface of the anterior thoracic wall, originates from the posterior surface of the lower sternum, and functions mainly in expiration?

Accepted Answer

M. transversus thoracis

Question 7

A trauma patient has a fractured clavicle and is unable to elevate the first rib during inspiration. Which muscle is most likely affected?

Accepted Answer

M. subclavius

Question 8

Which muscle group is responsible for elevating the ribs during inspiration, and what is their anatomical position relative to the ribs?

Accepted Answer

M. intercostal extern; located superficially between the ribs

Question 9

Which muscle has a triangular shape, originates from the anterior surface of ribs 3-5, and inserts on the coracoid process of the scapula, functioning to stabilize the scapula?

Accepted Answer

M. pectoralis minor

Question 10

A patient with a lesion affecting the lumbar portion of the diaphragm would most likely have impaired function in which anatomical region?

Accepted Answer

The region between the vertebral column and the central tendon

Question 11

Which muscle is most active during forced expiration, and what is its main action?

Accepted Answer

M. intercostal intern; depresses the ribs

Question 12

Which muscle originates from the lower margin of the costal cartilage and inserts on the central tendon, playing a key role in increasing intra-abdominal pressure?

Accepted Answer

Diaphragm

Question 13

A patient is unable to stabilize the scapula against the thoracic wall during arm movement. Which muscle is most likely weak or paralyzed?

Accepted Answer

M. pectoralis minor

Question 14

Which muscle is found deep to the intercostal extern muscles, runs obliquely downward and backward, and is involved in expiration?

Accepted Answer

M. intercostal intern

Question 15

Which muscle group is most important for maintaining the negative pressure required for inspiration, and what is the physiological consequence if they fail?

Accepted Answer

Diaphragm; inability to draw air into the lungs

Question 16

Which muscle originates from the posterior surface of the lower sternum and inserts on the costal cartilages of ribs II-VI, and what is its function?

Accepted Answer

M. transversus thoracis; depresses the ribs during expiration

Question 17

A patient with paralysis of the diaphragm will have difficulty with which of the following equations describing pressure changes during inspiration?

Accepted Answer

$$P_{intra-alveolar} = P_{atmospheric} - \Delta P_{muscle}$$

Question 18

Which muscle is most likely to be involved in stabilizing the first rib during forced inspiration, and what is its insertion point?

Accepted Answer

M. subclavius; inferior surface of the clavicle

Question 19

Which muscle group is most active during quiet breathing, and what is their main action?

Accepted Answer

M. intercostal extern; elevates the ribs

Muscles of the Thorax: Anatomy, Attachments, and Functions

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