Final answer:
The supraspinatus muscle is part of the rotator cuff in the shoulder, responsible for arm abduction and stabilizing the shoulder joint. It is prone to injury, especially with repetitive overhead movements such as pitching in baseball.
Step-by-step explanation:
The supraspinatus muscle is one of the four muscles of the rotator cuff that provides structural support to the shoulder joint. This muscle originates superior to the spine of the scapula and inserts onto the greater tubercle of the humerus. The main function of the supraspinatus is to abduct the arm at the shoulder, which is moving the arm away from the body. It also plays a crucial role in stabilizing the shoulder by holding the head of the humerus securely within the glenoid cavity. The supraspinatus, along with the other rotator cuff muscles, the infraspinatus, teres minor, and subscapularis, form a musculotendinous cuff around the shoulder joint that acts as dynamic ligaments, adjusting their contraction strength to counteract forces acting on the shoulder.
During activities like baseball pitching where the arm is repeatedly brought over the head to throw fast pitches, the rotator cuff can become inflamed and may be prone to injuries such as pinching or tearing of the tendons. These injuries necessitate interventions like shoulder surgery. Prevention measures may include training for proper pitching mechanics and building up strength and flexibility in the shoulder muscles.