Synonyms in a broader sense
- Supraspinatus tendon
- Shoulder Muscles
- Musculus supraspinatus
- Musculus infraspinatus
- Musculus teres minor
Anatomy
The rotator cuff is a functionally important muscle group of the shoulder, which originates from the scapula and lies around the head of humerus like a cuff and is jointly responsible for the rotation and lifting of the arm. A distinction is made between the rotator cuff
- Subscapular Musculus
- Musculus supraspinatus
- Musculus infraspinatus
- Muscle teres minor
The Musculus subscapularis (lat. “sub”: below, “scapula”: shoulder blade) originates from the front of the shoulder blade in the Fossa subscapularis and attaches to the front of the humerus at the tuberculum minus.
Functionally, it serves to rotate the arm inwards (internal rotation), it is even the strongest internal rotator on the upper arm. It also supports the movement of the arm forward (anteversion) as well as backward (retroversion). Like all muscles of the rotator cuff, it also contributes to the tension of the joint capsule.
It is innervated by the subscapular nerve. The supraspinatus muscle (lat. “supra”: above, “spina”: spine) originates in the upper part of the back surface of the shoulder blade in the supraspinous fossa and passes under the acromion to the tuberculum majus at the humerus.
Its function is that of a lateral arm lifter (abduction), especially in the initial phase of movement up to approx. 15° abduction, it is the “abduction starter”. It shares this function with the deltoid muscle.
To a lesser extent, it is also involved in the external rotation of the arm and also tensions the joint capsule. It is innervated by the suprascapular nerve. It is the most common injury of all the muscles of the rotator cuff, especially since its tendon often becomes calcified with age.
These calcifications can lead to a so-called impingement syndrome: This clinical picture involves the impingement of the tendon of the supraspinatus muscle under the acromion. This results in pain when the arm is lifted sideways or under stress, for example when lying on the affected arm.
- Collarbone
- Acromion (shoulder roof)
- Space between humeral head and acromion
- Humerus
- Shoulder joint (Articulatio glenohumerale)
Supraskapularis syndrome is another clinical picture: In this case, the suprascapular nerve, which supplies both the supraspinatus and infraspinatus muscles, is trapped in a notch in the shoulder blade, causing pain in the shoulder and weakening external rotation and abduction.
The Musculus infraspinatus (lat. “infra”: below, “spina”: spine) originates at the lower part of the back surface of the shoulder blade, the so-called Fossa infraspinata, and also moves to the tuberculum majus of the head of humerus, slightly behind the Musculus supraspinatus. If you look at the course of the muscle – from the shoulder blade to the lateral head of the upper arm – you can easily understand its function: When the M. infraspinatus contracts, it causes a powerful rotation of the arm outwards (external rotation), it is even the strongest external rotator of the upper arm.
In addition to the external rotation, it is also involved in drawing the upper arm towards the middle of the body (adduction). When the arm is raised, however, it causes the arm to move away from the center of the body. Together with the other muscles of the rotator cuff, it stretches the capsule around the shoulder joint.
Innervation takes place via the suprascapular nerve. The musculus teres minor (lat “minor”: smaller, “teres”: round) has its origin at the lateral edge of the shoulder blade below the musculus infraspinatus. It also moves to the tuberculum majus at the humerus.
Functionally, it is a weak external twister (external rotation) of the upper arm. It also participates in the pulling of the upper arm to the body (adduction). The minor and infraspinatus muscles thus form not only an anatomical but also a functional unit. However, the two muscles differ in their innervation: The minor teres muscle is innervated by the axillary nerve.
