It tests for the supraspinatus tendon or impingement.
Impingement syndrome ICD 9: 726.2
Supraspinitus
A central cord impingement is an incomplete injury to the cervical spinal cord. A central cord impingement results in extensive motor weakness in the upper extremities.
A tear of the supraspinatus is a tear of the rotator cuff of the shoulder. Arthroscopic surgery is the repair to repair for this.
Supraspinatus and deltoid
The thecal sac is the covering for the spinal cord. This can be seen on an MRI. Impingement means that something is pressing on it.
No full thickness/partial articular tear of the supraspinatus tendon
supraspinatus
lower answer
Supraspinous fossa of the Scapula
The muscle that you are looking for is probably the supraspinatus