What is the supraspinatus and infraspinatus?
The supraspinatus muscle abducts the upper arm (test with the arm at the side to avoid overlap with deltoid muscle function). The infraspinatus muscle externally rotates the upper arm at the shoulder.
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What separates the supraspinatus and infraspinatus?
The spine of the scapula separates the supraspinatus muscle from the infraspinatus muscle, which originates below the spine.
Where are the supraspinatus and infraspinatus muscles?
The infraspinatus is most closely associated with the subscapularis, supraspinatus, and teres minor, as they all combine around the shoulder to encircle the glenohumeral joint. These muscles act to stabilize and move the glenohumeral joint.
Where do the supraspinatus and infraspinatus insert?
The infraspinatus muscle originated from both the infraspinatus fossa and the inferior surface of the spine of the scapula, and it ran superolaterally. The supraspinatus and infraspinatus appeared to fuse into one structure at their insertions on the humerus.
What nerve innervates the supraspinatus and infraspinatus?
The suprascapular nerve
The suprascapular nerve has a motor and sensory innervation. Its motor innervation is to the supraspinatus and infraspinatus muscles.
What movement is the supraspinatus responsible for?
arm abduction
The supraspinatus muscle originates from the supraspinous fossa of the scapula, passes under the acromion, and inserts on the superior facet of the greater tubercle of the humerus. It is responsible for the initiation of arm abduction and is in control of the motion up to the first 15 degrees of abduction.
What does the supraspinatus attach to?
Supraspinatus muscle
| Origin | Supraspinous fossa of scapula |
|---|---|
| Insertion | Greater tubercle of humerus |
| Action | Shoulder joint: abduction of arm, stabilization of the humeral head in the glenoid cavity |
| Innervation | Suprascapular nerve (C5, C6) |
| Blood supply | Suprascapular artery |
Where is supraspinatus located?
The supraspinatus muscle, the most superiorly located of the rotator cuff muscles, resides in the supraspinous fossa of the scapula, superior to the scapular spine.
Where does the supraspinatus attach to?
Greater tubercle of humerus
Supraspinatus muscle
| Origin | Supraspinous fossa of scapula |
|---|---|
| Insertion | Greater tubercle of humerus |
| Action | Shoulder joint: abduction of arm, stabilization of the humeral head in the glenoid cavity |
| Innervation | Suprascapular nerve (C5, C6) |
| Blood supply | Suprascapular artery |
What nerve controls infraspinatus?
Why is supraspinatus most commonly injured?
The supraspinatus is most commonly injured because there are three different positions that it can become compressed. Overuse of the shoulder can cause the muscle and tendon to become inflamed.
Where is the infraspinatus located?
scapula
Infraspinatus muscle is found on the dorsal surface of the scapula, arising lateral and inferior from the supraspinatus muscle and medial and superior to the teres major and minor.
What does brachial neuritis feel like?
Symptoms of brachial neuritis include: Severe pain in the upper arm or shoulder. Pain usually affecting just one side of the body. After a few hours or days, the pain transitions to weakness, limpness, or paralysis in the muscles of the affected arm or shoulder.
