The Musculus supraspinatus is the upper bony muscle. It is part of the rotator cuff.

What is the supraspinatus muscle?

The supraspinatus muscle is the upper bony muscle. Together with the infraspinatus muscle (lower bones muscle), the subscapularis muscle (sub-scapular muscle) and the teres minor muscle (small round muscle), he forms the rotator cuff. This has the function of holding the humeral head in the socket.

The supraspinatus muscle is located in the shoulder joint. The skeletal muscle is located under the trapezius muscle and extends from the upper part of the scapula to the top of the humerus. At this point, the muscle is attached to a bony prominence. The supraspinatus muscle is important for bending the upper arm sideways and for turning it in the outer direction. The shoulder muscle and its tendon are often affected by impingement syndrome or tears.

Anatomy & Construction

The origin of the supraspinatus muscle is found on the posterior scapular side of the supraspinous fossa. It is a scapula above the scapula (spina scapulae).

The shoulder bone can be palpated on the scapula as ascending bone protrusion through the skin. The scapula side is largely filled by the supraspinatus muscle. Some fibers originate from the supraspinata fascia. In this case, the upper bony muscle is partially covered laterally by the trapezius muscle and partially laterally by the deltoid muscle (deltoid muscle).

The supraspinatus muscle attaches to the upper facet of the greater tuberosity. This refers to a larger bone protrusion on the humerus. It is located approximately laterally in the lower section of the bone head. Between the neck and the origin of the superior bone muscle passes through a narrowing of the shoulder. This is caused by the humerus head and the shoulder roof (Acromion).

The tendon of the supraspinatus muscle is the supraspinatus tendon, which has an anatomically close relationship to the bursa, which are located below the shoulder axis. The course of the tendon extends to the caput humeri (upper arm head). At this point it attaches laterally to the tubercle of the greater humerus. There is also an adhesion between the tendon and the shoulder joint capsule. Between shoulder-roof and end-tendon lies the subacromial bursa. This bursa provides protection against increased bone wear.

The supraspinatus muscle is supplied by the suprascapular nerve, which forms a branch of the plexus (brachial plexus).

Function & Tasks

Together with the deltoid muscle, the supraspinatus muscle spreads and externally rotates the upper arm. If the arm is put on and has an abduction angle of less than 15 degrees, it is considered the most important player in the spreading movement of the arm. Following this, the main function is taken over by the deltoid muscle.

The tasks of the upper bony muscle also include tensioning the shoulder joint capsule. Thus, the rotator cuff muscle is fused with the joint capsule and causes by the tensioning, that it does not come to the entrapment of Kapselfalten in the lifting movement of the arm. Together with the other rotator cuff muscles, the supraspinatus muscle shifts the humeral head toward the center at the beginning of the shoulder movement, centering it on the glenoid scapular cavitas.

Diseases

Of course, in the course of life there is heavy stress on the tendon of the supraspinatus muscle. Thus threaten from the age of 50 spontaneous cracks of the supraspinatus tendon.

Noticeable is this injury due to loss of function of the superior bone muscle as well as considerable shoulder pain. The external rotation and the turning away of the arm away from the trunk can be difficult or even impossible to perform.

Supraspinatus rupture is the most common variant of the rotator cuff tear. The reason for the injury is the strong mechanical stress to which the supraspinatus tendon is exposed. Partial tears or complete tendon tears can occur as a result of constant overloading, accidents or the natural aging process. The complaints usually show up after minor overloads or physical activities that are unfamiliar. Typical symptoms include shooting pain or discomfort at night, with jerky force or overhead movements.

As a rule, a tear of the supraspinatus tendon is already diagnosed by a physical examination by the doctor or by sonography (ultrasound examination). Changes are also visible on an X-ray. However, the X-ray examinations provide information about the impairments only at a later stage. For example, if a rotator cuff tear is suspected, magnetic resonance imaging (MRI) is usually performed. Because a torn supraspinatus tendon can not be healed by conservative measures, surgery must be performed. The surgeon fixes the torn portions of the tendon on the humeral head.

Another common disorder of the supraspinatus muscle is the impingement syndrome. It involves an entrapment of the supraspinatus tendon under the bony prominence of the shoulder roof. The affected persons therefore suffer from pronounced pain. The most common causes of the bottleneck syndrome are injury or degeneration of the rotator cuff. Patients will no longer be able to lift their arms over their shoulders.

Doctors differentiated between outlet impingement and non-outlet impingement in a bottleneck syndrome. There is talk of outlet impingement when the subacromion is constricted by the adjacent anatomical structures. These may be bone deposits (osteophytes) or an acromion spore. In contrast, non-outlet impingement is caused by damage to the rotator cuff muscles or inflammation of the shoulder joint capsule. The cause may be inflammation caused by an injury. The impairments are always associated with severe pain on the supraspinatus muscle or the supraspinatus tendon.

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