Subscapular: Origin, Insertion Point, Injury, Symptoms, Diagnosis and Treatment of Breakage

The subscapularis muscle is one of the most commonly used muscles in the shoulder joint.

The shoulder is one of the most incredible (and mobile) joints in the body. It is very versatile if we compare it, for example, with the knee joint.

Your knee can really only bend in one direction (if you bend in multiple directions, you may need to see a doctor). However, your shoulder can move your arm forward, backward, sideways and around in circles.

One of the reasons for the great mobility of the shoulder is the subscapularis muscle. The subscapular is a triangular-shaped muscle found on the inner surface of the scapula, commonly referred to as the scapula.

This muscle is the largest and strongest muscle in the rotator cuff, which is a collection of four muscles in the shoulder joint that works to stabilize the shoulder.

Origin

The subscapular originates in the subscapular fossa of the scapula. The subscapular fossa is the concave, triangular-shaped surface on the front of the scapula (the side of the scapula closest to the back of the rib cage).

Subescapular insertion point

From the subscapular fossa, the subscapularis muscle extends to one side of the body and inserts into the humerus, which is the long bone of the upper arm.

Specifically, this muscle is inserted into the minor tubercle of the humerus. The minor tubercle (also known as the minor tuberosity) is a round prominence located on the front, the upper part of the humerus.

The lesser tuber is located just next to the largest major tuber.

What does subscapular do?

There are several different subscapular muscle actions. These actions include:

Medial rotation of the humerus : turning inward or twisting the upper arm, such as when the arm is turned inward when a door slammed.

Abduction of the humerus : move the upper arm towards the body, as the downward movement of the arms when you shake the arms.

Stabilization of the shoulder joint : keep the head of the humerus in its correct location against the scapula when the arm moves along the shoulder joint.

The main arteries that cross the subscapularis muscle are the cervical artery and the subscapular artery. The subscapularis muscle is innervated by the superior and inferior subscapular nerves.

The subscapularis muscle is the most used muscle in the shoulder. It is the main muscle used in throwing, hitting, swimming and in all racquet sports. As a result, injuries to the shoulder muscle are common among athletes.

A muscle and joint prone to injury

Subscapular rupture includes rupture of the subscapularis muscle or the subscapularis tendon. The subscapularis muscle is below the lower 2/3 of the scapula.

The scapula is a flat bone found on the back of the chest wall on the ribs on the right and left sides.

The upper outer end of the scapula is known as glenoid, which forms a shoulder joint with the head of the humerus. The scapula moves horizontally along the posterior surface of the chest wall.

The medial (inner) tendon of the subscapularis muscle is attached to the inner inferior border of the scapula and the external (lateral) tendon forms the anterior boundary of the rotator cuff and adheres to the humerus.

The rupture of the subscapular tendon is located near the insertion of the tendon with the humerus or in the anterior rotator cuff. The rupture of the subscapularis muscle is located on the muscular mass of the lower average scapula.

Subscapular rupture includes tearing of the subscapularis muscle and tendon. The rupture of the subscapularis muscle is located mainly on the subscapular muscle mass, which is in front of the lower third of the scapula.

The rupture of the subscapular tendon, on the contrary, is located on the anterior shoulder joint. The subscapular tendon forms the anterior section of the rotator cuff.

The subscapular tendon or muscle rupture has a partial or total thickness and the lesions are confirmed with magnetic resonance studies. The symptoms of muscle and tendon rupture are different.

Causes of subscapular tear

Sports where this injury is frequent:

  • Baseball.
  • Volleyball.
  • Tennis.

Contact sports : The direct impact on the shoulder and scapula joints can cause tearing of the subscapular ligament or muscle.

Repetitive movements of the shoulder joint:

  • Orchestra director.
  • Battery.
  • Weightlifting.

Car accident : The direct impact caused by a solid object after an accident can cause subscapular breakage.

Occupational accident: The direct impact of the shoulder joint or the chest wall can cause a partial or total thickness breakage.

Heavy equipment handling can cause excessive stretching of the upper arm, shoulder joint, and scapula, resulting in a subscapularis muscle or tendon rupture.

Surgery: Surgery of the shoulder joint or arthroscopy can cause tearing of the subscapular muscle or muscle.

Symptoms and signs of subscapular rupture

Intensity of pain: the intensity of pain is moderate to severe. The pain is severe with the movement of the shoulder joint. The patient can not perform routine activities.

Pain to the touch : The touch and the palpation on the injured area is very painful. The pain is severe when it extends over the injured scapula or the shoulder joint.

Pain over the shoulder joint : the presence of severe pain on the anterior shoulder joint suggests that the pain is caused by the rupture of the rotator cuff tendon of the subscapularis muscle.

Pain on the lower scapula : the pain located on the lower scapula suggests that the pain may be caused by the rupture of the subscapularis muscle.

Severe pain during abduction : painful abduction of the upper arm suggests subscapular tendon or muscle tear.

Severe pain during adduction of the upper arm in the shoulder joint : suggests a possible subscapular muscle injury.

Restricted internal rotation : Internal rotation of the upper arm in the shoulder joint is restricted due to rupture of the subscapularis muscle tendon.

Restriction of abduction : abduction is restricted when the subscapular tendon or muscle is broken.

Discoloration of the skin over the anterior shoulder joint : suggests a possible lesion of the subscapular tendon

Discoloration of the skin on 2/3 inferior of the scapula : it suggests the rupture of the subscapularis muscle.

Weakness of the shoulder joint : the patient often can not lift the object with the injured arm.

Diagnosis and research

Test Bear Hug A : the test is performed in standing or sitting position. The hand of the injured arm is resting on the opposite shoulder. The examiner lifts the patient’s hand from the shoulder during the test.

The examiner then asks the patient to return the hand to rest on the shoulder. The patient will have to overcome the resistance applied by the hand of the examiner. The patient with subscapular muscle rupture always complains of intense pain onset.

Belly Press Test B : the test is performed in standing position. The injured arm is flexed at the elbow joint and rests on the front of the abdomen. The examiner will place his hand between the patient’s hand and abdomen.

The examiner will move the patient’s hand away from the belly. The examiner expects the patient to resist the push.

Severe pain will be felt in the shoulder joint or on the scapula, while preventing the arm from moving away from the belly, suggesting the subscapularis muscle rupture.

Ultrasound study : an ultrasound examination of the scapula and the shoulder joint. The test may show bruising and tears on the muscle, tendon, or anterior rotator cuff.

MRI exam : Selective magnetic resonance imaging of the muscles may show rupture of the tendon or muscles.

Treatment for subscapular rupture

Mild to moderate pain : treated with non-steroidal anti-inflammatory drugs. The most common medications prescribed are Motrin, Naproxen and Celebrex.

Severe to very severe pain : treated with opioids. The most common opioids prescribed are short-acting hydrocodone (Vicodin, Lortab or Norco) and oxycodone (Percocet or Oxy IR).

Muscle relaxants : Muscle spasm is treated with muscle relaxants. The most common muscle relaxants used are Baclofen, Flexeril and Skelaxin.

Manual therapy: Massage therapy is often used after surgery.

Physiotherapy: Physiotherapy is tested before surgery. Physiotherapy is continued for 6 to 8 weeks. Together with anti-inflammatory medications it can help relieve pain and rebuild subscapular muscle strength.

The breakage of partial thickness can heal completely after physiotherapy.

Interventional therapy: Cortisone with local anesthetics injected into and around the injured tendon and muscle. The patient is scheduled for 3 to 4 injections. Each injection is done with an interval of 2 weeks.

Surgery for subescapular rupture: The partial or total thickness of the subscapularis muscle is repaired by arthroscopic surgery. The rupture site is visualized by an arthroscopic camera and sutured with an arthroscopic device.

Open surgery: An incision is made in the skin over the injured tendon and muscle. The injured tendon or muscle is exposed and sutured.

Replacement of the shoulder joint:  Severe pain may continue after several surgeries to repair the tendon or muscle breakdown.

If multiple surgical treatments fail to alleviate the symptom, replacement of the shoulder joint can be considered.