Supraspinatus

What is Supraspinatus?

The supraspinatus is a muscle of small dimension, which is located on the upper part of the back. It is also known as one of the four rotator cuff muscles, along with the infraspinatus muscle, teres minor muscle and subscapularis muscle.

Anatomy

The supraspinatus muscle originates from the superior fossa of the shoulder blade and has its insertion at the greater trochanter of the humerus. The supraspinous fossa from which the muscle actually originates is a small and shallow depression, which is located just above the spine of the scapula. The tendon of the supraspinatus muscle is located at a close distance from the acromion, which is the bony process of the shoulder blade. The supraspinatus muscle is separated from the infraspinatus muscle by the spine of the scapula, the latter having its origin just below the spine.

After passing near the acromion, the supraspinatus muscle reaches the greater trochanter of the humerus, inserting itself on its superior and middle facet. As for the innervation, the supraspinatus muscle is innervated by the suprascapular nerve (C5 and C6 corresponding nerve roots). The suprascapular nerve has its origins in the brachial plexus (the superior trunk). It should be mentioned that this nerve can be damaged in fractures that lead to the clavicles overlying each other, preventing the injured person from abducting the arm.

Pictures

Supraspinatus Picture 1 : Anterior view of right shoulder showing Bursa, Inflammation of supraspinous tendon, acromium process of scapula, coracoacromial ligament.

Function

The main function of the supraspinatus muscle is to provide the abduction of the arm from the shoulder. For the first 10-15 degrees of the abduction movement, it is the sole muscle executing the movement. After that, the deltoid muscle will take over, becoming the main muscle to complete the movement to the full range.

As it was already mentioned, the supraspinatus is one of the rotator cuff muscles, playing an active role in the support of the shoulder (resistance to the inferior forces of gravity). Moreover, it keeps the shoulder joint in a stable position, as the head of the humerus is pressed against the glenoid fossa. The glenoid fossa or cavity is the part of the scapula that comes in direct contact with the head of the humerus, allowing for the wide range of movements in the shoulder joint.

Clinical Significance

The tendon of the supraspinatus muscle is often ruptured during contact sports, as there are a lot of sudden and forceful movements in the shoulder area. In fact, it is known that the supraspinatus muscle is one of the most commonly injured rotator cuff muscles. In the older population, the supraspinatus muscle is subjected to the general wear and tear process, leading to a shoulder joint that has become instable and also to reduced functionality in the said joint. The inflammation of the supraspinatus muscle tendon is also possible, this being often found as a clinical sign of the shoulder impingement syndrome.

Supraspinatus Tendinosis

As it was mentioned above, the inflammation of the supraspinatus muscle tendon is often associated with the shoulder impingement syndrome.

Symptoms

These are the most common symptoms of supraspinatus tendinosis:

• Instable shoulder joint
• Rotator cuff tear
  • Acute and sharp pain
  • Tearing sensation
• Impingement syndrome
  • Chronic pain
  • Gradual development of symptoms
• Location of pain
  • Shoulder area – lateral, anterior or superior part
  • Pain can also be experienced in the posterior part of the shoulder
• Muscle asymmetry or atrophy can be identified through physical examination
• Reduced abduction – the patient cannot raise the arm (however, if the first stage of the movement is done by another person, the deltoid will complete the rest of the movement)
• Tenderness to palpation is also present
• The pain can disturb the patient from sleeping, forcing him/her to adopt certain positions
• Pain can also interfere with daily living activities, ranging from mild to severe.

Causes

These are the most common causes that lead to the appearance of supraspinatus tendinosis:

• Injury through:
  • Blunt trauma
  • Repetitive micro-trauma
• Instability of the shoulder joint
• Excessive weight loaded on the shoulder
• Repeated and prolonged overhead activity
• Imbalance of the rotator cuff muscles
• Arthrosis of the acromio-clavicular joint
• Impingement
• Aging
• Tendinopathy.

Treatment

Supraspinatus tendinosis can be treated in the following ways:

• Anti-inflammatory medication
  • Recommended choices – acetaminophen, ibuprofen
  • Administered orally or topically (cream, ointment, gel)
• Physical therapy
  • Initial purpose – pain relief and reduction of inflammation
  • Secondary objectives
    • Improved range of motion
    • Prevention of muscle atrophy
    • Increase the stability in the shoulder joint
• Cryotherapy
• Transcutaneous electrical nerve stimulation
• Galvanic stimulation (high voltage)
• Ultrasound therapy
• Phonophoresis/Iontophoresis
• Occupational therapy
  • Helps the patient to perform daily living activities.

Supraspinatus Exercises

Among the exercises that the physical therapist might recommend, there are:

• Exercises destined to increase the range of motion
• Active and passive exercises, with or without resistance
• Active-passive exercises – these are performed by the patient with the help of the physical therapist
• Pendulum exercises – the patient mimics the movements of a pendulum, increasing his/her range of motion in a gradual manner
• Mobilization of the shoulder joint
• Scapular glides – these can be performed in varied directions (anterior, posterior, inferior)
• Exercises destined to strengthen the supraspinatus muscle (isometric)
• Exercises for the strengthening of the other muscles of the shoulder joint, including the rotator cuffs
  • External and internal rotators
  • Biceps
  • Deltoid
• Exercises for the development of neuromuscular control
• Exercises for the strengthening of the muscles that keep the scapula in a stable position
  • Rhomboid muscles
  • Trapezius muscle
  • Serratus anterior
  • Latissimus dorsi
  • Pectoralis major.

The education of the patient is also important in regard to the activities he/she is allowed to perform. For example, at the start of the rehabilitation program, patients are advised to avoid overhead activities, reaching for objects or lifting objects with the affected arm. Following the advice of the therapists involved in the rehabilitation program, you will recover more easily.

In conclusion, while the supraspinatus muscle is small in size, it plays a very important role in the human body. When this muscle is injured, it is important to take the necessary treatment measures and enter into a regular physical therapy program.