The internal and external rotation of the shoulder are movements that occur at the glenohumeral joint (the ball-and-socket joint of the shoulder), referring to the rotation of the humerus (upper arm bone) around its long axis.
Internal Rotation
Internal rotation (also known as medial rotation) involves rotating the humerus inwards towards the midline of the body. An easy way to visualize this is to bring your hand across your stomach. Muscles primarily responsible for internal rotation include:
- Subscapularis
- Pectoralis Major
- Latissimus Dorsi
- Teres Major
- Anterior Deltoid
External Rotation
External rotation (also known as lateral rotation) involves rotating the humerus outwards, away from the midline of the body. A simple way to visualize this is moving your hand away from your stomach and outwards. Muscles primarily responsible for external rotation include:
- Infraspinatus
- Teres Minor
- Posterior Deltoid
Importance of Shoulder Rotation
Both internal and external rotation are crucial for a wide range of activities, from everyday tasks like reaching and dressing to athletic movements like throwing and swimming. Maintaining proper shoulder rotation strength and range of motion is essential for shoulder health and preventing injuries. Using a theraband, as suggested in the video (0:17-1:29), can help in strengthening these rotator muscles.
