Supraspinatus
The supraspinatus is the uppermost muscle of the rotator cuff. Its origin is the body of the scapula above the acromion process. Its insertion is at the top of the outside edge of the humerus - known as the greater tubercle.
Its primary function is abduction of the humerus up to 30° of abduction (laterally raising the arm). After 30°, the deltoid takes over abduction.
Functionally, the supraspinatus opposes the comparatively weak gravitational force. Follow-throughs with large downward components create forces much greater than gravity. The stress it creates is magnified by powerful internal rotation because it moves the muscle's insertion further from its origin.
It plays a very small role in external rotation.
Finally, the supraspinatus is also important for joint stabilizatoin, holding the humerus firmly against the glenoid fossa.
See also: infrapsinatus, teres minor, subscapularis.
Recent Posts
- Pitch Movement, Part IV: Tunnel Vision
- June 25, 2020
- Scouting Grades: Power
- June 22, 2020
- Pitch Movement, Part III: The River of Seams
- April 2, 2020
- Pitch Movement, Part II: Sweet Seams (Are Made of This)
- March 15, 2020
- Pitch Movement, Part I: You Spin Me Round (Like a Baseball)
- February 28, 2020
- Scouting Grades: Speed
- February 20, 2020
- Still Learning 11 Years Later
- February 5, 2020
- Is it really supported by science?
- February 8, 2017
- To athletes seeking "exposure"
- February 1, 2017
- Discovering the Intent to Throw Hard
- January 25, 2017
- [posts archive]