The infraspinatus muscle is a muscle in the shoulder that helps to rotate the arm outward and stabilize the shoulder joint. It is one of the four rotator cuff muscles, along with the supraspinatus, teres minor, and subscapularis. The infraspinatus muscle is located on the posterior (back) side of the shoulder blade (scapula), and its main function is to help rotate the arm outward (i.e., lateral rotation) and also to help stabilize the shoulder joint during movement. It is a long, thin muscle that originates from the infraspinous fossa (a depression on the posterior side of the scapula) and inserts into the greater tubercle of the humerus (upper arm bone). The infraspinatus muscle is innervated by the suprascapular nerve.
Function of the Infraspinatus Muscle
The main function of the infraspinatus muscle is to help rotate the arm outward (i.e., lateral rotation) and also to help stabilize the shoulder joint during movement. When the arm is held at the side of the body, the infraspinatus muscle helps to rotate the arm outward when the elbow is bent. This action is known as lateral rotation of the shoulder joint.
In addition to its role in lateral rotation of the shoulder joint, the infraspinatus muscle also plays a role in stabilizing the shoulder joint during movement. It helps to keep the head of the humerus (upper arm bone) seated securely in the glenoid fossa (socket) of the scapula (shoulder blade) as the arm moves. This is important for maintaining proper shoulder joint alignment and reducing the risk of injury.
The infraspinatus muscle is also involved in other movements of the shoulder joint, including extension and abduction of the arm. It works with other muscles in the shoulder and upper back to help move the arm in these directions.
Common Issues with a Infraspinatus Muscle
There are several common issues that can affect the infraspinatus muscle, including:
- Infraspinatus muscle strain: This is a common injury that can occur as a result of overuse or overloading of the muscle. It can cause pain, swelling, and weakness in the shoulder.
- Infraspinatus muscle tear: A more severe injury, a tear of the infraspinatus muscle can be caused by trauma or repetitive strain. It can lead to significant pain and difficulty moving the arm.
- Infraspinatus muscle impingement: This occurs when the muscle becomes pinched or compressed between the humerus (upper arm bone) and the scapula (shoulder blade). It can cause pain and weakness in the shoulder.
- Frozen shoulder (adhesive capsulitis): This condition is characterized by stiffness and pain in the shoulder joint. It can be caused by a variety of factors, including inflammation or scarring of the joint capsule, and it can lead to weakness and difficulty moving the arm.
- Rotator cuff tendinitis: This is an overuse injury that occurs when the tendons of the rotator cuff muscles (including the infraspinatus muscle) become inflamed. It can cause pain and weakness in the shoulder.
If you are experiencing any issues with your infraspinatus muscle, it is important to see a healthcare provider for proper diagnosis and treatment. Treatment may include rest, physical therapy, medications, and in some cases, surgery.
How to stretch your Infraspinatus Muscle
Here is a simple stretching exercise that can help to stretch the infraspinatus muscle:
- Stand with your feet shoulder-width apart and your arms by your sides.
- Place your left hand on your right elbow, and gently press your right arm across your body towards the left side.
- Hold the stretch for 30 seconds, then release and repeat on the other side.
- Repeat the stretch 2-3 times on each side.
It is important to stretch gently and not push yourself to the point of discomfort. If you feel any pain while stretching, stop the exercise and consult a healthcare provider.
It is also important to warm up before stretching to help prepare your muscles for the stretch. A simple way to warm up is to perform some light cardio exercises, such as walking or jogging in place, for a few minutes before stretching.
Remember to breathe deeply and relax while stretching, and try to keep your body relaxed and avoid tensing up. Stretching should feel comfortable and not cause any pain.
How to Rehab your Infraspinatus Muscle
If you have an injury or condition that affects your infraspinatus muscle, it is important to follow a proper rehabilitation program to help the muscle heal and regain strength. Here are some general steps to follow when rehabilitating the infraspinatus muscle:
- Rest: It is important to rest the muscle and allow it time to heal. This may involve avoiding activities that put strain on the muscle, such as lifting heavy objects or engaging in vigorous physical activity.
- Ice: Applying ice to the affected area can help reduce inflammation and pain. Ice should be applied for 15-20 minutes at a time, several times a day.
- Physical therapy: A physical therapist can design a rehabilitation program specifically for your needs and help you safely perform exercises to strengthen and stretch the infraspinatus muscle.
- Medications: Your healthcare provider may prescribe medications to help reduce inflammation and pain. These may include nonsteroidal anti-inflammatory drugs (NSAIDs) or corticosteroid injections.
- Surgery: In some cases, surgery may be necessary to repair a torn infraspinatus muscle. Your healthcare provider will determine if surgery is necessary and discuss the options with you.
It is important to follow the recommendations of your healthcare provider and physical therapist when rehabilitating the infraspinatus muscle. They will be able to determine the most appropriate treatment plan for your individual needs.