Question

_____ muscle is found on the inner surface of the rib cage, originating on the margin of the sternum, with fibers coursing to the inner chondral surface of ribs 2 through 6. Contraction of this muscle resists elevation of the rib cage and decreases the volume of the thoracic cavity. a) Pectoralis major

b) Deltoid
c) Internal intercostal
d) External oblique

Answer 1

The internal intercostal muscle is found on the inner surface of the rib cage and assists with expiration by drawing the ribs together, decreasing the thoracic cavity volume.

Step-by-step explanation:

The muscle being described is the internal intercostal muscle, which is found on the inner surface of the rib cage. This muscle originates on the margin of the sternum and has fibers that course to the inner chondral surface of ribs 2 through 6. When the internal intercostal muscles contract, they draw the ribs together and decrease the volume of the thoracic cavity, which assists with expiration by resisting the elevation of the rib cage during breathing. The external intercostal muscles, on the other hand, aid in inspiration by raising the rib cage and expanding it.