Supraspinatus muscle
Muscle | Origin | Insertion | Innervation | Action |
---|---|---|---|---|
Supraspinatus | Supraspinous Fossa of scapula | Greater tubercle of Humerus | Suprascapular n. C4 - C6 |
GHJ: Initiates abduction, Stabilization |
Overview
The supraspinatus runs from its origin on the supraspinatus fossa through the supraspinatus canal and to its insertion on the humeral head6. The supraspinatus canal is bordered anteriorly by the coracoid process, posteriorly by the acromion, and superiorly by the coracoacromial ligament6.
Origin
Supraspinous Fossa of scapula7
Insertion
Innervation
Suprascapular n. (C4, C5, C6)7
Action
- GHJ: Initiates abduction7
- Stabilizes GHJ
The supraspinatus is one of the key muscles in the force-couple of the shoulder abductors6.
Tendon
Chronic inflammation in the shoulder can result in supraspinatus tendon thickening, which results in poor sliding through the canal6.
In cases of tendon dysfunction, surgical repair is difficult due to the narrowness supraspinatus canal6. As a result, an inferior acromioplasty (resection of the lower 1/2 of the acromion and coracoacromial ligament) is employed instead6.
Palpation
Tests
- Champagne toast
- ERLS (Possibly)
- Empty can / Jobe test can be used to determine if there is suprascapular nerve neuropathy or supraspinatus problems
“Supraspinatus Tests Two techniques described in the literature can be used to test the supraspinatus muscle, the empty-can position—the elbow extended, the shoulder in full IR, and the arm in the scapular plane (thumbs-down position) (Fig. 16-29) (Table 16-25), and the prone position, in the full-can position—the elbow extended and the shoulder abducted to 100 degrees and externally rotated while the patient lifts the arm into abduction (thumbs-up position) (Fig. 16-30) (Table 16-25). Park and colleagues,126 investigated 215 patients with full-thickness supraspinatus tears confirmed by arthroscopy and found the Jobe test to have a sensitivity of 52.6% and specificity of 82.4%. For partial-thickness tears, the same study showed the Jobe test to have a 32.1% sensitivity and 67.8% specificity.126”8
Dysfunction
- Supraspinatus tear
- Supraspinatus tendonitis
- Supraspinatus tendinopathy
- supraspinatus paratenonitis
Rupture
If there is a supraspinatus rupture, the shoulder will not be able to go beyond the horizontal plane (90° abduction or flexion)6.
You will also see the humeral head resting against the coraco-acromial arch, resulting in impingement and pain6.