Muscles of the Thoracic Wall Quiz

Muscles of Respiration

• The serratus posterior inferior muscle is said to depress the inferior ribs and prevent them from being pulled superiorly by the diaphragm.
• Recent studies suggest that the serratus posterior inferior muscle functions to stabilize the scapula and assist in forceful inspiration.

Muscles Implicated in Chronic Pain

• The serratus posterior inferior muscle is implicated as a source of chronic pain in myofascial pain syndromes.

Role of Levatores Costarum Muscles

• The levatores costarum muscles assist in normal inspiration by elevating the ribs.

Layers of Intercostal Muscles

• The external intercostal muscles form the superficial layer of the intercostal muscles.
• The internal intercostal muscles form the inner layer of the intercostal muscles.

Accessory Muscles of Respiration

• The pectoralis minor muscles primarily act on the upper limbs but can also function as accessory muscles of respiration.

Non-True Muscles of the Thoracic Wall

• The pectoralis major muscle is NOT considered a true muscle of the thoracic wall.

Elevation of the Ribs

• The scalene muscles are responsible for elevating the superior four ribs and increasing the anterior-posterior dimension.

Forced Inspiration

• The scalene muscles primarily elevate the ribs during forced inspiration.

Depression of the Ribs

• The internal intercostal muscles are responsible for depressing the ribs during active (forced) respiration.
• The serratus posterior inferior muscle weakly depresses the ribs.
• The levatores costarum muscles are believed to act similarly to the internal intercostal muscles, depressing the ribs during active (forced) respiration.

Test your knowledge of the muscles of the thoracic wall and their attachments with this quiz.