Supraspinatus: origin, insertion, action and innervation
The supraspinatus arises from the supraspinous fossa of the scapula and inserts on the greater tubercle of the humerus. It starts abduction of the arm, stabilises the shoulder and is supplied by the suprascapular nerve.
Quick answer
- Latin name
- Musculus supraspinatus
- Origin
- Supraspinous fossa of the scapula
- Insertion
- Superior facet of the greater tubercle of the humerus
- Action
- Starts abduction of the arm (first 15° or so) and assists the deltoid; holds the head of the humerus in the socket
- Innervation
- Suprascapular nerve (C5–C6)
- Blood supply
- Suprascapular artery
The supraspinatus is one of the four rotator cuff muscles that hold the shoulder together. It lies above the spine of the scapula, hidden under the trapezius.
Where it is
It fills the supraspinous fossa, the hollow above the spine of the scapula. Its tendon passes under the acromion, over the top of the shoulder joint, to reach the humerus. That narrow passage under the acromion explains why the tendon is so often involved in shoulder pain.
Origin and insertion
- Origin: the medial two thirds of the supraspinous fossa.
- Insertion: the superior facet of the greater tubercle of the humerus, and the joint capsule.
What it does
- Initiates abduction: it starts lifting the arm out to the side, then the deltoid takes over.
- Stabilises the shoulder: with the other cuff muscles, it presses the head of the humerus into the shallow glenoid cavity, so the deltoid lifts the arm instead of pushing the head upwards.
Innervation and blood supply
The suprascapular nerve (C5–C6) supplies it after passing through the suprascapular notch. The suprascapular artery provides its blood.
How to remember it
- The rotator cuff is SITS: Supraspinatus, Infraspinatus, Teres minor, Subscapularis.
- Three of them (S, I, T) insert on the greater tubercle in that order from top to bottom; subscapularis goes to the lesser tubercle.
- Supra = above the spine; it starts abduction.
Frequently asked questions
Is the supraspinatus part of the rotator cuff?
Yes. It's one of the four rotator cuff muscles, with infraspinatus, teres minor and subscapularis.
What is the action of the supraspinatus?
It initiates abduction of the arm and stabilises the head of the humerus in the shoulder joint.
Which nerve supplies the supraspinatus?
The suprascapular nerve, from roots C5 and C6.