After the orthopedic surgeon examined the MRI of the shoulder of a 42-year-old female he informed her that the supraspinatus muscle was injured and needed to be repaired surgically. Which of the following is true of the supraspinatus muscle?
The options aren't provided, but since the correct answer is supposed to be part of the explanation, I need to figure out the possible correct statement. Common facts about the supraspinatus: it's part of the rotator cuff, it initiates abduction of the arm, and it's the most commonly injured rotator cuff muscle. Also, its nerve supply is via the suprascapular nerve.
If the question is about the function, then the correct answer might be that it initiates abduction. The deltoid takes over after 15 degrees, but the supraspinatus starts the movement. Another fact is that it's innervated by the suprascapular nerve, which comes from C5-C6. Also, it's located in the supraspinous fossa of the scapula.
Possible wrong options could be about other muscles. For example, the infraspinatus and teres minor are involved in external rotation, not the supraspinatus. The subscapularis is for internal rotation. So if an option says supraspinatus is for internal rotation, that's wrong. Also, if someone confuses the nerve supply, like thinking it's from the axillary nerve (which innervates deltoid), that's incorrect.
Another possible wrong option: origin from the clavicle. The supraspinatus originates from the supraspinous fossa of the scapula, not the clavicle. The clavicle is part of the origin for the deltoid. So if an option mentions clavicle as the origin, it's wrong.
Clinical pearl: The supraspinatus is the most commonly injured muscle in the rotator cuff, often due to overhead activities or falls. The Neer sign and Hawkins-Kennedy test are used to assess for supraspinatus injury. Also, the suprascapular nerve injury can affect its function.
Putting this together, the correct statement is likely about the function in initiating abduction. Let me structure the explanation accordingly, making sure to address the core concept, why the correct answer is right, why others are wrong, the clinical pearl, and the correct answer line.
**Core Concept**
The supraspinatus is a key rotator cuff muscle responsible for initiating shoulder abduction. It originates from the supraspinous fossa of the scapula and inserts on the greater tubercle of the humerus, functioning synergistically with the deltoid after 15° of abduction.
**Why the Correct Answer is Right**
The supraspinatus muscle initiates the first 15° of arm abduction, after which the deltoid takes over. It is innervated by the **suprascapular nerve** (C5-C6) and is the most commonly injured rotator cuff muscle due to its role in stabilizing the humeral head within the glenoid during movement. Its tendon is particularly vulnerable to impingement syndrome and degenerative tears.
**Why Each Wrong Option is Incorrect**
**Option A:** If it