As ventilatory muscles, the sternocleidomastoids do which of the following?
A) They elevate the upper chest, increasing chest anteroposterior diameter.
B) They elevate the ribs and decrease chest anteroposterior diameter.
C) They increase lateral chest movement during inspiration.
D) They lower the sternum, thus increasing chest anteroposterior diameter.

Question

Quizplus · Accepted Answer

The sternocleidomastoid muscles can function to lift the upper chest. They receive nerve impulses from branches of the accessory nerves (cranial nerve XI) and cervical nerves C1 and C2. These muscles are active during forceful inspiration and become visible as thick bands on either side of the neck during the inspiratory phase in an individual who is in respiratory distress. This motion increases the anteroposterior diameter of the chest.

As Ventilatory Muscles, the Sternocleidomastoids Do Which of the Following