What and where are the rotator cuff muscles?
The rotator cuff muscles are a group of four muscles that come together and attach via a common tendon to the humerus (our upper arm bone). They include supraspinatus, infraspinatus, teres minor, and subscapularis. You can use the acronym SITS to help remember each of the muscles in this group.
This group of muscles all go from an attachment on the scapula to an attachment on the humerus and cross the glenohumeral joint (the shoulder joint). The tendinous attachment of these four muscles on the humerus resembles a shirt cuff, which is where the group of muscles gets its name, the rotator cuff.
Where are the rotator cuff muscles located?
The four rotator cuff muscles each originate from a different location on the scapula and then insert on either the greater or lesser trochanter of the humerus. Let’s look at the origin and insertion for each of these muscles one at a time.
Supraspinatus: supraspinous fossa of the scapula
Infraspinatus: infraspinous fossa of the scapula
Teres minor: lateral portion of the dorsal side of the scapula
Subscapularis: subscapular fossa of the scapula
Supraspinatus: greater tubercle of the humerus (superior facet)
Infraspinatus: greater tubercle of the humerus (middle facet)
Teres minor: greater tubercle of the humerus (lower facet)
Subscapularis: lesser tubercle of the humerus
What actions do the rotator cuff muscles do?
Supraspinatus: initiates abduction of the humerus
Infraspinatus: lateral rotation of the humerus
Teres minor: lateral rotation of the humerus
Subscapularis: medial rotation of the humerus
One of the most important actions that all four of the rotator cuff muscles contribute to is stabilization of the shoulder joint. These four muscles all contribute to keeping the head of the humerus in the right place within the glenoid fossa, the “socket” of the shoulder ball and socket joint.
If you want to learn more about the rotator cuff muscles or the shoulder joint, they are covered in our online course.