Delta muscle

Synonyms

Latin: M. deltoideusThe shoulder forms a large, three-sided muscle about 2 cm thick. The shape of the deltoid muscle is similar to the shape of the upside-down Greek delta, which gives it its name. The muscle consists of three parts: The anterior deltoid originates from the clavicle, the middle and posterior part from the shoulder blade.

The common base of the deltoid muscle is at the upper third of the humerus. The deltoid muscle is innervated by the axillary nerve, which is a nerve from the brachial plexus. The Plexus Brachialis is a nerve plexus which originates in the neck area of the spinal cord.

The nerves that emerge from this plexus supply the muscles in the shoulder, arm and hand. The different parts of the deltoid muscle have different functions depending on their position in relation to the axis of movement and position in relation to the humerus, which can have both synergistic and antagonistic effects. The muscle is particularly important for abduction, which means spreading the arm away from the body to the side.

The anterior deltoid muscle can move the arm forward (anteversion), rotate it inwards and pull it towards the body (adduction). From an angle of 60-90°, it helps the middle muscle in abduction. The posterior part of the deltoid muscle moves the arm backwards (retroversion), rotates it outwards and – like the anterior deltoid muscle – also pulls the arm towards the body (adduction).

From 60-90° it also supports the middle part during abduction. The function of the middle part consists solely in abduction. Rotational movements are mainly performed by the rotator cuff, which is another muscle of the shoulder joint, to which the supra- and infraspinatus, subscapular and teres minor muscles belong.

The deltoid muscle supports these movements with its respective parts. Due to its position directly under the skin, the three-part division can be easily recognized in slim and defined persons. It is the largest muscle of the shoulder musculature.

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°.

Training

You can train the deltoid muscle effectively with a dumbbell. In order to train the anterior part of the muscle, the arm is stretched forward, the elbows are slightly bent, the palms of the hands point forward or upwards. Now the dumbbells are lifted to a horizontal position (approx.

head height) at a steady pace and lowered again, preferably without taking a swing first. For this exercise you should stand about shoulder width and with slightly bent knees. For the middle deltoid muscle, it is recommended to raise your arms sideways to a horizontal position, with the posture corresponding to the exercise for the front muscle part.

To train the posterior deltoid, the upper body is bent far forward. The arms are lifted sideways without swinging upwards until they are horizontal. Depending on the goal, these exercises can be performed with different intensity and to varying degrees.

It should be noted that the shoulder joint has the peculiarity of being extremely flexible compared to other joints. This range of movement is only possible at the expense of stability. This means that the shoulder joint is very prone to injury and instability, but allows complex and extensive movements.

For this reason, the personal fitness level and load capacity of the shoulders should be taken into account during training. For health sports or when starting to build up muscles, 55-60% of maximum strength with 15-20 repetitions is recommended. The amount of training should be about three sets per exercise, (i.e. 3 x 15 repetitions).

Between the sets there should be a break of about one minute. If you are doing fitness training and want to increase your muscle build-up further, you should train with about 70-75% of the maximum strength. For this purpose 10-15 repetitions are recommended, which should be performed a total of four times.

Between the sets there should again be a break of one to two minutes. For bodybuilding, targeted muscle building and definition, the exercises should be performed at high intensity, i.e. 75-80% of maximum strength. The training should include 8-10 repetitions, which should be repeated four to six times.

The break between sets should be about two to three minutes. Since the deltoid muscle (Musculus deltoideus) has several parts, it must also be stretched by different exercises. To stretch the front part of the deltoid muscle, the arm is held against a wall, similar to stretching the chest muscle.

The upper body is tried to turn away from this wall. In order to stretch the rear part of the shoulder muscles, the arm is pushed towards the head. For general information, please also see our topic: Stretching.