What can cause the serratus anterior muscle to weaken?

The serratus anterior muscle can weaken for several reasons, and each of the options presented contributes to its dysfunction. Recognizing how each factor impacts the muscle’s integrity helps in understanding the overall health of the upper extremities.

Trauma to the shoulder can lead to direct injury of the muscle or the surrounding structures. This may result in inflammation, pain, and limited range of motion, ultimately affecting the muscle's strength and function. The shoulder is a complex joint, and when it is injured, nearby muscles like the serratus anterior may compensate or become inhibited, leading to weakness.

Improper posture, particularly in positions that involve protraction or elevation of the shoulders, can contribute to decreased activation of the serratus anterior. Poor posture can create muscular imbalances, causing certain muscles to work harder while others weaken due to disuse or overactivation. When the serratus anterior does not engage properly due to these postural imbalances, its strength and endurance can diminish.

Nerve injury, particularly affecting the long thoracic nerve which innervates the serratus anterior, can lead to weakness as well. If the nerve is damaged, it can cause a condition known as winged scapula, where the scapula protrudes away from the back, indicating that