Deltoid muscle

Deltoid Muscle :In human anatomy, the deltoid muscle is the muscle forming the rounded contour of the shoulder.

Anatomically, it appears to be made up of three distinct sets of fibers though electromyography suggests that it consists of at least seven groups that can be independently coordinated by the central nervous system.

It was previously called the deltoideus (plural deltoidei) and the name is still used by some anatomists. It is called so because it is in the shape of the Greek letter Delta (triangle). It is also known as the common shoulder muscle, particularly in lower animals (e.g., in domestic cats). Deltoid is also further shortened in slang as “delt”.

A study of 30 shoulders revealed an average mass of 191.9 grams (6.77 oz) (range 84 grams (3.0 oz)–366 grams (12.9 oz)) in humans.


Deltoid Muscle
(proximal attachments)
a. Anterior head: anterior surface of the lateral clavicle.
b. Middle head: acromion process and spine of the scapula.


(distal attachments)
a. Deltoid tuberosity of the humerus.


Anterior head:
a. Flexes the arm at the shoulder.
b. Medially rotates the arm at the shoulder.
Middle head:
a. Abducts the arm at the shoulder.


Nerve supply:

a. Nerve: Axillary nerve
b. Nerve roots: C5 and C6


Applied Anatomy :

  Rupture of the deltoid muscle


Anatomy: The large Deltoid muscle (M Deltoideus) is a thick triangular muscle, emanating around the shoulder, covering the shoulder joint and forming the rounding of the shoulder. The muscle is fastened on the humerus. The various parts of the deltoid muscle take part in nearly all movements of the shoulder joint.


Cause: When a muscle is subjected to a load beyond the strength of the muscle (butterfly swimming, weight training, weight lifting) a rupture occurs. Most ruptures in athletes are partial ruptures. The rupture can be located both in the front and the back as well as at the attachment to the upper arm (humerus).

Symptoms: In light cases a localised tenderness can be felt following the load (“muscle strain”, “imminent pulled muscle”). In more severe cases sudden shooting pains in the muscle can be felt (“partial muscle rupture”) and in the worst cases a sudden snap is felt, rendering the muscle unusable (“total muscle rupture”) this is very rare, and is almost only seen in conjunction with other damage in the shoulder. With muscle injuries the following three symptoms are characteristic: pain upon pressure, stretching and activating against resistance.

Acute treatment: Acute treatment starts as quickly as possible after the injury has been incurred. The objective of the acute treatment is primarily to prevent additional injury and reduce bleeding as much as possible. Effective acute treatment will reduce bleeding, formation of scar tissue, the number of complications, which can arise, and the rehabilitation period.
Treatment follows the so-called “RICE” principles:                                                                               R;-   Continued sports activity is immediatel  stopped(Rest)                                                                                                                                                               B:- As soon as is possible, Ice should be placed on the injured area. The cold ice makes the blood vessels contract, thereby stopping the bleeding. Cold spray has no effect in such circumstances. The ice must not come into direct contact with the skin, which should be covered with a thin layer of, for example, elastic bandage. Ice treatment should be given for twenty minutes in each of the first three hours after injury.

I:- As far as is possible the treatment should furthermore comprise:                                              

C-:   A Compression bandage should be applied, however, must not be so tight as to prevent the blood flow. The compression bandage should be removed at night, but applied again each morning until the swelling goes down. The effect of the compression can be enhanced if a piece of felt, for example, of approx. one cm. thickness is placed under the bandage and directly above the haemorrhaging.                                                                                                                                             

E:-  The injured area is kept as high as possible, and preferably above the heart (Elevation). The haemorrhaging will stop when it comes above the level of the heart. Elevation of the affected area should be performed as much as possible as long as swelling is in evidence.


Examination: Light cases with only minimal tenderness and no discomfort when using the arm do not necessarily require medical examination. The extent of the tenderness is, however, not always a mark of the degree of the injury. In case of more pronounced tenderness medical examination is advised with the aim of securing a correct diagnosis and treatment. Pain will be present when pressure is applied to the damaged muscle, which will be aggravated when the muscle is activated against resistance and when the muscle is stretched. Ultrasound is well suited to ensure the diagnosis.

Treatment: The treatment primarily involves relief, discontinuance of the injury inducing activity, stretching and increasing fitness training.

Rehabilitation: INSTRUCTION
Complications: If satisfactory progress is not made, a physician should be consulted to ensure that the diagnosis is correct and that no complications have arisen. Amongst others the following should be considered:

Rupture of the upper shoulder blade muscle
Inflammation of the upper shoulder blade muscle
Rupture of the lower shoulder blade muscle
Tendon sheath inflammation of the biceps
Luxation in the joint between the shoulder blade and the collarbone
Partial luxation in the shoulder joint
Frozen shoulder
Muscle infiltrations
Sprained shoulder (distorsio art. humeroscapularis)
Meniscus lesion in the shoulder (laesio labrum glenoidale)
Nerve entrapment on the back of the shoulder blade

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