Delta-shaped muscle

Synonyms

Latin: Musculus deltoideus English: deltoid muscle Synergists: M. pectoralis major, M. biceps brachii, M. latissiums dorsi, M. triceps brachii Antagonists: M. latissimus dorsi, M. triceps brachii, M. pectoralis major, M. biceps brachii

Definition

The delta-shaped muscle is an upper arm muscle, which in its shape is reminiscent of an inverted Greek delta and hence its name. According to its origin, it is made up of three parts, one part coming from the outer collarbone, another part from the shoulder blade and a third part from the scapula bone. As a triangular muscle, it surrounds the shoulder joint from the front, back, top and side.

It is also known as the deltoid muscle and its different parts are involved in different arm movements. Due to its position directly under the skin, the tripartition can be easily recognized in slim and defined persons. It is the largest muscle of the shoulder muscles.

The deltoid muscle is specifically trained in weight training. Due to its tension, the deltoid muscle can move the arm in all directions of movement. Its most important function is the lateral raising of the arm, especially when the arm is spread over 90°.

History

Base: humerus (Tuberositas deltoidea – roughening of the humerus) Origin: pars claviculares: lateral third of the clavicle pars acromiales: acromion – bony process of the scapula pars spinales: originates at the scapular spine – bone elevation of the scapula Innervation: N. axillaris of the brachial plexus (segments C5-6)

Function

The function of the deltoid muscle varies according to the activity of the different muscle parts. It allows the arm to move in all directions. The deltoid muscle (Musculus deltoideus) becomes the most important lifter of the arm through the central section starting from the acromion. Pars clavicularis – Collarbone part: Pars acromialis – Shoulder roof part: Pars spinalis – Shoulder blade part

  • Lifting (anteversion) from arm
  • Spreading (adduction) of the arm
  • Internal rotation of the arm
  • Abduction (abduction) from the arm
  • Abduction (abduction) from the arm
  • External rotation of the arm
  • Lifting back (retroversion) from the arm

Common diseases

The deltoid muscle is essentially involved in shoulder mobility. The shoulder joint is a predominantly muscular joint. The so-called rotator cuff, a muscle group consisting of four muscles, plays a decisive role in stability in the shoulder joint.

However, degenerative changes in the tendons of the deltoid muscle also restrict shoulder mobility and stability. Paralysis of the axillary nerve often leads to atrophy of the deltoid muscle. In addition, the deltoid muscle plays a major role in various neurological diseases, such as neuralgic shoulder atrophy.