Shoulder muscles

Nicole Wendler holds a PhD in biology in the field of oncology and immunology. As a medical editor, author and proofreader, she works for various publishers, for whom she presents complex and extensive medical issues in a simple, concise and logical manner.

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The shoulder muscles are not only active when we move the shoulders. She is also involved in arm, head and trunk movements. Above all, unconscious actions and bad posture (such as hunching your shoulders in cold or stressful conditions) lead to painful tension in the shoulder area. Read everything you need to know about shoulder muscles!

What are the shoulder muscles?

The shoulder muscles are part of the skeletal muscles. In the upper chest area, it forms a complex construct of numerous muscles that are involved in the movements of the arms, shoulders, shoulder blades and, in the broadest sense, of the upper body and head. One notices when observing the breath that these are also the smallest movements. If we breathe deeply into the upper chest area, the shoulders, collarbones and even the head rise slightly in addition to the chest.

The shoulder muscles can be roughly divided into the following groups:

Shoulder muscles on the back of the body

Upper bone muscle (Musculus supraspinatus)
Lower bone muscle (infraspinatus muscle)
Deltoid muscle (M. deltoideus)
Large round muscle (M. teres major)
Small round muscle (M. teres minor)

Shoulder muscles of the front of the body

Subscapular muscle (Musculus subscapularis)
Hook arm muscle (M. coracobrachialis)

Rotator cuff

This is an important muscle group that surrounds the shoulder joint. It is formed by three dorsal muscles (M. supraspinatus, M. infraspinatus, M. teres minor), a ventral muscle (M. subscapularis) and a ligament (ligamentum coracohumerale). The tendons of the short shoulder rotators are fused into a tendon plate and give the rotator cuff its name.

Distant shoulder muscles

In addition to the shoulder joint muscles, there are other muscles in the shoulder girdle area that can be assigned to the shoulder muscles: the muscles of the upper arm (such as biceps and triceps), parts of the back muscles (trapezius muscles, large back muscles, rhombus muscles, shoulder blade lifters), chest muscles (large and small pectoral muscles, anterior Saw muscle) and the subclavian muscle. They also have an impact on shoulder movements.

What is the function of the shoulder muscles?

Without its surrounding musculature, the shoulder joint would be quite unstable - the reason for this is the disproportion between the large joint head of the upper arm and the relatively small and flat joint socket formed by the shoulder blade. The shoulder muscles also make extensive movements of the arms and shoulders possible, such as turning, lifting or lowering. The main stabilizer is the rotator cuff, which keeps the humerus head centered in the joint space of the shoulder blade.

Depending on which movement we want to perform with the arms, different muscles are used:

Lateral spreading of the arms (abduction):

Deltoid muscle (Musculus deltoideus, Pars acromialis), most important muscle for abduction
Upper bone muscle (M. supraspinatus)
Long head of the biceps muscle (Caput longum des M. biceps brachii)

Bringing the arms closer (adduction):

Pectoralis major (M. pectoralis major)
Very broad back muscle (M. latissimus dorsi)
Large round muscle (M. teres major)
Small round muscle (M. teres minor)
Hook arm muscle (M. coracobrachialis)
Short head of the biceps muscle (caput breve des M. biceps brachii)
Triceps muscle (M. triceps brachii)
(Parts of the deltoid muscle (pars clavicularis and pars spinalis))

Raising the arms forwards (anteversion):

Deltoid muscle (M. deltoideus, Pars clavicularis)
Pectoralis major (M. pectoralis major)
Biceps muscle (M. biceps brachii)
Hook arm muscle (M. coracobrachialis)

Raising the arms backwards (retro version):

Deltoid muscle (M. deltoideus, pars spinalis)
Very broad back muscle (M. latissimus dorsi)
Large round muscle (M. teres major)

Rotating the arms outwards (external rotation):

Deltoid muscle (M. deltoideus, pars spinalis)
Lower bone muscle (infraspinatus muscle)
Small round muscle (M. teres minor)

Turning the arms inwards (internal rotation):

Deltoid muscle (M. deltoideus, Pars clavicularis)
Subscapular muscle (M. subscapularis)
Pectoralis major (M. pectoralis major)
Very broad back muscle (M. latissimus dorsi)
Large round muscle (M. teres major)
Hook arm muscle (M. coracobrachialis)
Biceps muscle (M. biceps brachii)

Our shoulder muscles are also in demand when we shrug our shoulders (trapezius muscle), do push-ups (small chest muscle) or step into the boxing ring (boxer muscle, serratus anterior muscle).

Where are the shoulder muscles located?

The shoulder muscles explicitly include all muscles with which we move arm and shoulder, i.e. cause an activity in the shoulder joint. In a broader sense, it also includes muscles that connect the shoulder girdle to the torso and neck. These muscle regions run on the front and back of the body in the upper trunk area and pull up into the arms and over the neck and neck towards the head.

The individual muscle groups (muscle boxes) are surrounded by connective tissue (fascia). Only this special packaging, together with the tendons, makes it possible to fix the muscles to the bone and thus transmit power. Bony attachment points of the shoulder muscles are primarily the two bones of the shoulder girdle, shoulder blade and collarbone, as well as the humerus, but also cervical vertebrae, spinous processes of the thoracic vertebrae and costal cartilage.

What problems can the shoulder muscles cause?

Tension in the shoulder area is a common problem. Triggers are usually unconscious bad posture, for example when we pull our shoulders towards our ears when it is cold or stressful. The pain can sometimes even radiate into the head area and become chronic. But also through overexertion, misalignment or after an injury, complaints develop in the shoulder muscles. These are expressed in the form of: