Question

when a person is in respiratory distress, the origin and insertion of the serratus anterior muscle may actually switch, and the part of the muscle attached to the medial border of the scapula acts as the origin. how will this change the muscle's action

Answer 1

When a person is in respiratory distress, if the origin and insertion of the serratus anterior muscle switch, it will change the muscle's action. Normally, the serratus anterior muscle protracts and stabilizes the scapula, but in this case, it will cause retraction of the scapula instead.

Step-by-step explanation:

When a person is in respiratory distress, the origin and insertion of the serratus anterior muscle may switch, with the part attached to the medial border of the scapula acting as the origin. This change in the muscle's attachment will alter its action. The serratus anterior muscle is normally responsible for protracting and stabilizing the scapula. However, when the origin and insertion switch, the muscle's action will be reversed, causing retraction of the scapula instead.

Answer 2

The normal origin of the serratus muscle is the lateral surface of the 1st to 8th ribs, and the insertion is on the rib surface of the medial border of the scapula. As the origin of a muscle indicates that's the fixed structure when the muscle contracts, in opposition to the insertion which indicates the moving structure, the structure that moves, when in normal conditions, is the scapula, being rotated, allowing the arm to rise more than what the glenohumeral joint allows.
When in respiratory distress, the need to increase the volume of the thoracic cage is so great that the medial border of the scapula works as the origin of the muscle, becoming fixed, and the muscle's contraction pulls the 1st-8th ribs instead, becoming the ribs the insertion location.