Infraspinatus is the second, in this series, of four muscles that comprise the group commonly known as the rotator cuff muscles. This group of muscles is key in the movement of the shoulder. The name infraspinatus literally means “below the spine”, but in this case means below the spine of the scapula or shoulder blade. The bony ridge that can be felt as a part of the shoulder blade, if you start at the “point” of the shoulder and work towards the midline of the body while also moving downwards on the body is the “spine” of the scapula. Infraspinatus one of the muscles that helps stabilize the shoulder joint, and is also responsible for rotation of the shoulder outwards (also known as lateral or external rotation – think of bringing a stop-sign up using your shoulder to rotate it upwards). This muscle is also extremely prone to trigger points in those people that work with arms above their heads, people who drive extensively with their arms up high on the wheel, and people who sit at desks on chairs with no arm rest support.
Location: on the outward facing portion of the shoulder blade below the ridge / spine (infra-below; spinatus – spine)
Main Action(s) of the Muscle:
- lateral/external rotation of the shoulder
- stabilizing the shoulder joint
Strengthening Exercise: Laying on side on floor or weight bench. Bring upper arm across the body with elbow bent to 90o, holding weight in hand. Lift weight up and away from the body, keeping elbow locked against the body, until the weight is directly overtop of the body (if possible). (Videos coming soon!!)
Stretching Exercise: For the side being stretched, put the back of the hand on the hip. This will start the stretch. If possible, with the hand of the other arm, grasp the elbow and draw it gently towards the other side of the body. A stretching sensation should be felt on the back of the shoulder. (Videos coming soon!!!)
Activities of Daily Living: brushing hair back, back-hand in racket sports, cocking phase before throwing a ball
Common Injuries: repetitive strain from forceful external rotation of the arm (too much throwing of a ball, etc.) can lead to tendonitis; work that keeps the arms above the head a lot and working at a keyboard without elbow support can lead to overworked infraspinatus
Trigger Point Referrals: Trigger points in the infraspinatus muscle commonly refer pain to the front of the shoulder and the outside of the shoulder, and occasionally down into the thumb side of the hand. Pain from highly activated trigger points can often also be felt deep in the shoulder joint.
- Biel, A. (2005) Trail Guide to the Body, 3rd Edition. p.82-86. Boulder, CO: Books of Discovery.
- Davies, C and Davies, A. The Trigger Point Therapy Workbook, 2nd Ed. pg 90-92. Oakland, CA: New Harbinger
- Infraspinatus. Retrieved March 21, 2012 from http://en.wikipedia.org/wiki/Infraspinatus
- Image from Gray’s Anatomy. Retrieved March 21, 2012 from Wikipedia http://en.wikipedia.org/wiki/File:Infraspinatus.PNG
- Vizniak, NA. Muscle Manual. Infraspinatus. pg. 170-171. Canada: Professional Health Systems.
For more information or to inquire about your specific situation, please contact me:
Website: SWB Massage Therapy