Research Odyssey on the Long Thoracic Nerve

As physiotherapists, we often come across patients complaining of shoulder pain and weakness. One of the causes of such symptoms could be injury or dysfunction of the Long Thoracic Nerve. In this blog post, we will discuss the Long Thoracic Nerve in detail, including its anatomy, function, injury, examination, and treatment.

Description of the Long Thoracic Nerve:

The Long Thoracic Nerve (LTN) is a motor nerve that originates from the anterior rami of the C5, C6, and C7 nerve roots. It runs downwards along the posterior aspect of the brachial plexus, between the scalenus medius and anterior muscles, and finally enters the serratus anterior muscle.

The LTN provides motor innervation to the serratus anterior muscle, which plays an essential role in the movement and stability of the scapula. The serratus anterior muscle is responsible for protracting and rotating the scapula during shoulder abduction, thus helping to maintain the shoulder joint's stability.

Function of the Long Thoracic Nerve:

As mentioned earlier, the LTN provides motor innervation to the serratus anterior muscle. The serratus anterior muscle plays an essential role in the movement and stability of the scapula, which is necessary for proper shoulder function. The serratus anterior muscle helps to protract and rotate the scapula, which helps to maintain the stability of the shoulder joint during shoulder abduction. In addition, the serratus anterior muscle helps to upwardly rotate the scapula during arm elevation, which is essential for proper overhead function of the shoulder joint.

Branches of the Long Thoracic Nerve:

The Long Thoracic Nerve is a single nerve that does not give off any branches. However, the nerve fibers of the LTN may branch off and combine with other nerve fibers, forming a network of nerves known as the Thoracodorsal Nerve.

Injury of the Long Thoracic Nerve:

The most common cause of LTN injury is trauma, such as a direct blow to the neck or shoulder region, which may result in traction or compression of the nerve. Other causes of LTN injury include repetitive overhead activities, such as throwing, weightlifting, and swimming, which may cause overuse injuries.

Symptoms of LTN injury include shoulder pain, weakness, and scapular winging. Scapular winging occurs when the scapula protrudes away from the back, giving it a "wing-like" appearance. This occurs due to weakness or paralysis of the serratus anterior muscle, resulting from LTN injury.

Examination of the Long Thoracic Nerve:

Examination of the Long Thoracic Nerve includes a thorough evaluation of the patient's medical history and physical examination. During the physical examination, the therapist may check for scapular winging, which is a hallmark sign of LTN injury.

To assess the strength of the serratus anterior muscle, the therapist may ask the patient to perform a "push-up plus" maneuver. During this maneuver, the patient is asked to push their hands against a wall or other surface while protracting the scapula. This test evaluates the ability of the serratus anterior muscle to protract the scapula and maintain the stability of the shoulder joint.

In addition to the push-up plus maneuver, the therapist may also perform a manual muscle test to assess the strength of the serratus anterior muscle. If the manual muscle test indicates weakness of the serratus anterior muscle, strengthening exercises should be incorporated into the patient's rehabilitation program. These exercises may include wall slides, push-ups with a plus, and scapular punches. The goal of these exercises is to improve the patient's scapular stability and muscular endurance.

If conservative treatment does not result in significant improvement, surgical intervention may be considered. In severe cases of long thoracic nerve injury, nerve grafts or transfers may be necessary to restore function to the serratus anterior muscle.

Treatment of Long Thoracic Nerve injuries

The treatment of long thoracic nerve injury varies depending on the severity of the injury. Conservative management is often the first line of treatment and includes rest, ice, compression, and elevation (RICE), and nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce pain and inflammation.

The patient may also be prescribed physical therapy to help reduce pain and inflammation, restore normal range of motion and strength, and prevent the development of any compensatory movements that may arise due to the injury. The physiotherapist may also use modalities such as ultrasound and electrical stimulation to help reduce inflammation and pain and promote healing.

Surgical intervention may be required in cases of severe long thoracic nerve injury, especially if conservative management does not provide relief or if there is evidence of muscle atrophy. Surgery may involve nerve grafting or neurotization, which involves transferring a functioning nerve to the damaged area to restore function.

The decision to proceed with surgery depends on the patient's age, overall health, and the degree of nerve damage.

Main point

The long thoracic nerve is an important nerve that is responsible for the innervation of the serratus anterior muscle. Injury to this nerve can result in significant weakness and dysfunction of the serratus anterior muscle, which can negatively impact the patient's ability to perform activities of daily living.

As such, it is important for physiotherapists to be aware of the anatomy, function, and potential injuries associated with the long thoracic nerve. A thorough examination and treatment plan can help patients recover from long thoracic nerve injuries and return to their normal activities.