The Rotator Cuff Muscles

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What and where are the rotator cuff muscles?

Infraspinatus

Infraspinatus Muscle

Teres minor

Teres Minor Muscle

Subscapularis

Subscapularis Muscle

Supraspinatus

Supraspinatus Muscle

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.

Origins

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

Insertions

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.

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