These questions are designed to test your knowledge and help you solidify key concepts about the respiratory system. Take your time, think through each question, and don’t worry—this is all about learning, not perfection. Good luck!
Question 1: Which of the following is a primary muscle of respiration?
A) Internal oblique
B) Diaphragm
C) Serratus posterior inferior
D) Rectus abdominis
Explanation: There are only 2 primary muscles of respiration: The diaphragm and the external intercostals. They function in driving inspiration by increasing the intrathoracic volume thus decreasing intrathoracic pressure. Expiration is entirely passive.
Question 2: Which muscles are primarily involved in quiet expiration?
A) Internal intercostal muscles
B) Abdominal muscles
C) No muscles, it is a passive process
D) External intercostal muscles
Explanation: Quiet (resting) expiration is driving by recoil of the thoracic cage and the diaphragm which reduce intrathoracic volume thus increasing intrathoracic pressure, driving air out of the lungs.
Question 3: Which of the muscles listed is activated during forced inspiration?
A) Sternocleidomastoid and scalenes
B) Diaphragm and external intercostals
C) Abdominal muscles
D) Internal intercostals
Explanation: Various lists exist compiling muscles of forced inspiration. However, sternocleidomastoid and the scalenes remain constants. Other constants include latissimus dorsi, pectoralis minor and major, and serratus anterior. Abdominal muscles and the internal intercostals function in forced expiration.
\Question 4: What is the primary function of the external intercostal muscles?
A) Depress the ribs during forced expiration
B) Elevate the ribs during inspiration
C) Stabilize the diaphragm during breathing
D) Expand the thoracic cavity during expiration
Explanation: This expands the thoracic cavity during inspiration, reducing pressure, allowing air to rush into the lungs. The external intercostals are primary muscles of respiration.
Question 5: Which muscle aids in forced expiration by compressing the abdominal cavity?
A) Rectus abdominis
B) Pectoralis minor
C) Diaphragm
D) Scalenes
Rectus abdominis and other abdominal muscles contract to increase intraabdominal pressure, pushing the diaphragm up and reducing intrathoracic volume, forcing air out of the lungs.
Question 6: What is the role of the internal intercostal muscles?
A) Elevate the ribs during inspiration
B) Depress the ribs druing expiration
C) Stabilize the thoracic cage during quiet breathing
D) Flex the vertebral column during respiration
They are accessory muscles employed during forced expiration.
Question 7: Which muscle is both a muscle of respiration and a key postural muscle?
A) Trapezius
B) Diaphragm
C) Scalenes
D) Serratus anterior
The scalene muscles are a group of three muscles (anterior, middle, and posterior) located in the neck that elevate the first and second ribs during inspiration and help with neck flexion and lateral movement.
Question 8: Which muscle is not directly involved in respiration but stabilizes the shoulder girdle during forced breathing?
A) Pectoralis major
B) Trapezius
C) Pectoralis minor
D) Serratus anterior
The trapezius is a large, triangular muscle in the upper back that stabilizes and moves the scapula, supports shoulder and neck movements, and assists in extending the neck. It is not directly involved in respiration.
Question 9: Which part of the diaphragm attaches to the lumbar vertebrae?
A) Central tendon
B) Costal part
C) Crura
D) Sternal part
The crura of the diaphragm are two tendinous structures (right and left) that anchor the diaphragm to the lumbar vertebrae, helping maintain its position and assist in its contraction during respiration.
Question 10: Which accessory muscles are primarily involved during labored expiration?
A) External intercostals and diaphragm
B) Internal intercostals and abdominal muscles
C) Scalenes and sternocleidomastoid
D) Serratus posterior superior and inferior
The abdominal muscles contract to increase intraabdominal pressure, pushing the diaphragm up and reducing intrathoracic volume, forcing air out of the lungs. Internal intercostals depress the ribs to reduce intrathoracic volume.
Question 11: The diaphragm is innervated by which nerve?
A) Vagus nerve
B) Phrenic nerve
C) Intercostal nerve
D) Hypoglossal nerve
The phrenic nerve is a bilateral nerve originating from cervical spinal roots C3-C5 that provides motor and sensory innervation to the diaphragm.
Question 12: Which structure passes through the central tendon of the diaphragm?
A) Esophagus
B) Aorta
C) Inferior vena cava
D) Thoracic duct
The structures that pass through the central tendon of the diaphragm include the inferior vena cava and the right phrenic nerve. The esophagus passes through the diaphragm at the esophageal hiatus in the muscular part of the diaphragm.
Question 13: At what level does the inferior vena cava pass through the central tendon of the diaphragm?
A) T4
B) T6
C) T8
D) T10
The caval opening in the central tendon is at T8. The esophageal hiatus in the muscle diaphragm is at T10.
Question 14: Which part of the diaphragm is primarily responsible for increasing thoracic volume during inspiration?
A) Sternal part
B) Costal part
C) Lumbar part
D) Central tendon
The central tendon flattens and moves downward when the diaphragm contracts.
Question 15: Which muscles are responsible for the lateral expansion of the thoracic cavity during quiet respiration?
A) External intercostals
B) Internal intercostals
C) Abdominal muscles
D) Transversus thoracis
This increases the volume of the chest to drive air into the lungs.
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