APEA 3P Practice Exam 2025 – Complete Test Preparation

The supraspinatus muscle is primarily responsible for initiating the abduction of the arm at the shoulder joint. Its specific characteristic that enables this action is its attachment on the scapula. This muscle originates from the supraspinous fossa of the scapula, allowing it to stabilize and support the shoulder while facilitating movement.

The muscle's attachment to the scapula plays a crucial role in positioning the shoulder joint for effective arm movement. As the supraspinatus contracts, it pulls on the greater tubercle of the humerus, assisting in lifting the arm. The anatomical positioning provided by its attachment ensures that it occupies an optimal angle to exert a force that effectively initiates arm abduction.

Other factors, such as the location of the muscle or innervation, contribute to its function, but the direct anatomical connection between the supraspinatus and the scapula is the characteristic that primarily facilitates its ability to initiate its main action effectively.