1° Causes - Damage to components forming CA arch, damage to Rotator cuff tendons.

E.g-

1. bony defect in Acromion, Coracoid process hence causing impingement of tendons.
2. Injury/ tear of Coracoacromial Ligament.

2° Causes - Due to other external structures.

i.e -

1. Trauma- micro repetitive/ strong sudden causing ms tear.
2. Force Couple = Deltoid + Supraspinatus dysfunction (ms weakness)
3. Lateral Rotator weakness.
4. Joint capsule tightness.
5. Etc.

Extent of tear varies. To check for the same, Resisted Isometrics are done-

1. Minor Tear - Painful, Strong ms contraction
2. Moderate Tear - Moderate pain, ROM is not complete/ weak ms contraction
3. Complete Tear - No pain, No ms contraction