| Origin | Supraspinous fossa of scapula |
| Insertion | Superior facet on greater tuberosity of humerus |
| Action | Initiates abduction of the arm from 0-15°, then assists deltoid in abduction of arm after 15° to 90°, and finally stabilizes head of the humerus in the glenoid cavity |
| Innervation | Suprascapular nerve (C4, C5 and C6) (C4, C5, C6) |
| Arterial Supply | Suprascapular artery |
Supraspinatus is an important topic in the United States Medical Licensing Examination (USMLE) and requires a comprehensive understanding. Here’s a more detailed explanation of the supraspinatus muscle, including its origin, types of injuries, studies, and treatment options:
Supraspinatus Muscle:
The supraspinatus muscle is one of the four muscles that comprise the rotator cuff in the shoulder. It is located on the posterior aspect of the scapula (shoulder blade) and plays a crucial role in initiating abduction (raising the arm away from the body) and stabilizing the shoulder joint during arm movement.
Origin and Insertion:
The supraspinatus muscle originates from the supraspinous fossa, a depression on the posterior aspect of the scapula. From there, it forms a tendon that passes beneath the acromion, a bony prominence of the scapula, and inserts on the greater tuberosity of the humerus, the upper arm bone. This tendon is susceptible to various types of injuries.
Types of Supraspinatus Injuries:
Rotator Cuff Tear: A rotator cuff tear can involve the supraspinatus tendon. It can occur due to acute trauma, such as a fall or lifting a heavy object, or develop over time due to repetitive stress. Rotator cuff tears are a common cause of shoulder pain and can result in limited range of motion. Partial or complete tears can occur.
Impingement Syndrome: This condition involves compression or irritation of the supraspinatus tendon as it passes through the subacromial space, a narrow area beneath the acromion. Impingement can lead to inflammation, pain, and reduced shoulder function. It often occurs due to repetitive overhead activities, poor shoulder mechanics, or structural abnormalities.
Studies and Evaluation:
Physical Examination: A comprehensive physical examination is performed to assess shoulder range of motion, strength, and signs of impingement or rotator cuff tears. Specific tests, such as the Neer test and Hawkins-Kennedy test, may be used to evaluate for impingement.
Imaging: X-rays are typically ordered initially to rule out other conditions, such as fractures or arthritis. However, magnetic resonance imaging (MRI) is the preferred modality for evaluating supraspinatus injuries. MRI provides detailed visualization of the tendon, allowing identification of tears, inflammation, and other abnormalities.
Treatment Options:
Conservative Management: Initial treatment often involves conservative measures for mild to moderate supraspinatus injuries. These may include rest, activity modification, physical therapy, and nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce pain and inflammation. Physical therapy aims to strengthen the rotator cuff and surrounding muscles, improve shoulder mechanics, and restore range of motion.
Corticosteroid Injections: In cases of significant inflammation and pain, corticosteroid injections may be used to provide short-term relief. These injections can help reduce inflammation around the supraspinatus tendon and alleviate symptoms.
Surgical Intervention: Severe or complete rotator cuff tears, or cases where conservative management fails, may require surgical intervention. Surgical repair can involve arthroscopic techniques or open surgery, depending on the extent and nature of the injury. The goal is to reattach the torn tendon to the bone and restore normal function.
It is crucial to note that the management of supraspinatus injuries should be tailored to each patient’s specific condition and individual needs. The information provided here serves as a general overview. When studying for the USMLE, it is recommended to refer to reputable textbooks, review materials, and online resources specifically designed for the exam to gain a comprehensive understanding of the topic.
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