Lift -off test is done to assess the function of
**Core Concept**
The lift-off test is a clinical examination used to assess the function of the **supraspinatus muscle**, which is one of the rotator cuff muscles responsible for stabilizing the shoulder joint and facilitating abduction. This test specifically evaluates the supraspinatus muscle's ability to resist external rotation and stabilize the humerus in the glenohumeral joint.
**Why the Correct Answer is Right**
During the lift-off test, the patient is asked to lift their arm against resistance, with their elbow bent at 90 degrees and their forearm pronated. The examiner then applies a downward force to the patient's forearm, attempting to rotate the humerus externally. If the supraspinatus muscle is functioning properly, the patient should be able to resist this external rotation and maintain the arm in a neutral position. The supraspinatus muscle's action is facilitated by the **suprascapular nerve**, which innervates the muscle and enables it to contract and stabilize the shoulder joint.
**Why Each Wrong Option is Incorrect**
* **Option A:** The lift-off test is not primarily used to assess the function of the **teres minor muscle**, which is another rotator cuff muscle responsible for external rotation.
* **Option B:** The lift-off test does not evaluate the function of the **subscapularis muscle**, which is also a rotator cuff muscle but is responsible for internal rotation and stabilization of the shoulder joint.
* **Option D:** The lift-off test is not used to assess the function of the **infraspinatus muscle**, which is another rotator cuff muscle responsible for external rotation.
**Clinical Pearl / High-Yield Fact**
The lift-off test is a useful clinical examination tool for diagnosing **supraspinatus tendinitis or tears**, which are common causes of shoulder pain and dysfunction. It is essential to perform the test with the patient's elbow bent at 90 degrees and their forearm pronated to accurately assess the supraspinatus muscle's function.
**Correct Answer:** C.