Let's study about Rotator cuff syndrome.
Shoulder physical examinations
Among the tests for rotator cuff disease.
A positive painful arc test result and a positive external rotation resistance test result were the most accurate findings for detecting Rotator Cuff Disease.
The presence of a positive lag test( external or internal rotation) result was most accurate for diagnosis of a full-thickness rotator cuff tear.
In my clinic, I have seen many patients who have a headache or neck pain.
Some patients have family history of migraine, some have a history of traumatic injury such as traffic accident.
Most of patients have bad sitting posture that cause head-forwarded posture.
Head-forwarded posture makes our back muscles tight, neck deep flexor muscles weak, chest muscles shortened, mid-back muscles weakened.
So, these problems makes rounded-shoulder.
Here is a good exercise for head-forwarded people.
from Self-treatments for head and neck pain (Craig Liebenson, D.C.)