The rotator cuff muscles: supraspinatus
The “rotator cuff” gets its name as a result of the common tendinous attachment of the rotator cuff muscles and the way that that attachment sits over the head of the humerus. This common tendinous attachment drapes over the top of the humerus and resembles a shirt cuff enough that someone decided to called it the rotator “cuff”!
If you want to remember which muscles are part of the rotator cuff group, try thinking of the acronym: SITS. Below, you can see that each letter stands for one of the muscles in the group.
- Teres Minor
I often refer to the rotator cuff muscles as dynamic stabilizers since they both stabilize and control the movement of the head of the humerus in the shoulder.
What does supraspinatus mean?
- Supra is similar to the word superior and means above.
- Spinatus refers to the spine of the scapula, which is the ridge on the scapula that is almost horizontal.
Where does the supraspinatus muscle attach?
- On the scapular end, the supraspinatus muscle attaches to a depression (fossa) on the top of the scapula that is technically called the supraspinous fossa.
- On the other end it attaches onto the very top of the head of the humerus.
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What actions does the supraspinatus muscle do?
- In terms of movement, supraspinatus does only one action, abduction of the humerus (first 10 degrees).
- It also stabilizes the head of the humerus in the socket.
What are the common injuries to the supraspinatus muscle?
Rotator cuff tear
The most common injury associated with the rotator cuff muscles is a muscle tear. This is especially true of the supraspinatus muscle which is the most commonly torn rotator cuff muscle.
When a tear occurs, the person typically has difficulty abducting their arm and often leans to the side in order to make it seem like their arm is abducting.
With a rotator cuff tear, symptoms can include generalized shoulder pain. In fact, it’s not uncommon for someone with a rotator cuff tear to be woken at night by the pain.
All of the rotator cuff muscles can be involved in cases of frozen shoulder. For more on this, check out the guest post on yoga and frozen shoulder.
With the condition of frozen shoulder, people often wake up one morning and have extremely limited range of motion. Sometimes the cause is completely unknown (idiopathic). But, sometimes it stems from rotator cuff tears, and sometimes it arises from an acute strain of the shoulder.