Question

Place the correct word into the sentence to describe the muscles of respiration.

a. elevate

b. depress

c. flex

d. extend

1. The internal intercostals  ____________  the ribs and expand the thoracic cavity during inspiration.

2. The external intercostals  ____________  the ribs causing a partial vaccuum effect resulting in an influx of air.

Answer 1

1. The internal intercostals depress the ribs and expand the thoracic cavity during inspiration.

(The intercostal muscles are mainly involved in the mechanical aspect of breathing. These muscles help expand and shrink the size of the chest cavity to facilitate breathing.)

2. The external intercostals elevate the ribs causing a partial vaccuum effect resulting in an influx of air.

(The external intercostal muscles are responsible for forced and quiet inhalation. They raise the ribs and expand the chest cavity.)

Both external and internal intercostal muscles are supplied by the intercostal nerve.