Deltoid Muscle - Enabling Shoulder Movements, Disorder and Symptoms

Deltoid Muscle : Enabling Shoulder Movements

Dr.Surya Rao Poodipeddi profile Authored by Dr.Surya Rao Poodipeddi on 16 May 2014 - 17:33.

Named after the Greek letter delta, which is shaped like an equilateral triangle, the deltoid muscle is a rounded, triangular muscle located on top of the shoulder and at the upper most part of the arm.

The deltoid connects to the skeleton, by tendons at the clavicle or the collar bone, scapula or the shoulder blade and humerus or the upper arm bone. It is widest at the top of the shoulder narrows as it travels down the arm. The deltoids connect the shoulder, shoulder blade and collarbone to the upper arm.

The big deltoid muscle which on the shoulder is made up of three parts - the front (anterior), middle and back (posterior). The muscle helps to lift the arm up sideways. It enables both flexion and extension movements – The front part helps to lift the arm up forwards (flexion) and the back part helps to lift the arm up backwards (extension). 

Several conditions can affect the deltoid muscle and along with it the shoulder joint. They can be due to a problem in the muscle itself, a problem in the shoulder joint, a problem due to inadequate or loss of blood supply to the muscle, a problem in the nerves supplying the muscle, any infection in and around the muscle and over use of the shoulder joint which can strain the deltoid muscle.

The commonest condition affecting the deltoid is the rupture in the deltoid and/or its associate the supraspinatus (also called the rotator cuff muscle). This is almost always due to excessive use of the muscle, like in some sport activities requiring constant use of the shoulder joint like a game of tennis followed next by over-enthusiastic exercises on the shoulder joint. Any blunt injury on the deltoid region like a fall of a heavy object on the shoulder or a hit directly over the muscle with a blunt object like a stick, can lead to a rupture in the muscle.

Some symptoms of a rupture in the deltoid are:

  1. A sudden pain in the muscle at the front of the shoulder
  2. Pain when trying to lift your arm from your side to the front keeping it straight against resistance.
  3. Pain when you try to lift your arm sideways against resistance.
  4. Tenderness (pain on touch) and swelling over the area of rupture.

A rupture in the deltoid muscle presents in two grades:

Grade I: There may be a feeling of tightness in the muscle. One may be able to use the arms properly and be able to do press ups easily. There may not be a noticeable swelling. You may escape pain while trying to lift the arm up, front or backward. Mostly occurring in athletes the victim can apply some ice for first for 24 hours at intervals of 15 minutes at a time and then apply heat.

He can do mild exercises gradually increasing the duration to build up the muscle. In cases of established sports like cricket, a sports specialist is always available who may suggest sports massages, ultrasound therapy or rehabilitation program to get ready for the next venture.

Grade II: In this type of a rupture one may not be able to use the arm properly and is unable to do press ups. He will experience sudden intermittent episodes of severe pain during an activity. There will be a noticeable swelling. Any attempt to press the area will give rise to intense pain. Any attempt to lift the arm or move forwards or backwards against resistance will give pain. In this type of a rupture one need to apply ice for 3 to 5 days. If the victim has the facility of sports specialist rehabilitation program is the best course of action. Application of heat with hot water bottles or bag gives some relief. Rest for at least a couple of weeks is absolutely necessary with gradual graded exercises to bring back the muscle to normalcy.

Activities that affect the deltoid muscle include: swimming, skiing, weight lifting, throwing a ball, lifting weights or a child, lifting up a thing, keyboard typing etc.

Disorders affecting the deltoid muscle include:

Hereditary conditions like brachial nerve involvement though very rare. In this condition which is due to autosomal-dominant inheritance, there will be recurrent attacks that are often bilateral (both arms). Besides problems with the actions of the muscle there is associated presence of long nasal bridge and asymmetry in the face.

Drugs and/or toxin induced conditions: Myopathy (a condition affecting a muscle) of the deltoid muscle can result from side effects of drugs like chloroquine, clofibrate, colchicine (an anti-gout drug), alcohol addiction and corticosteroids. A syndrome called Toxic Oil Syndrome which is due to adulterated rapeseed oil may affect the muscle(s) leading to inflammatory myopathy and/or inflammatory polyneuropathy (involving several nerves)

Myopathies, muscular dystrophies and other conditions affecting the nerves supplying a muscle  are some of the conditions that affect the deltoid muscle alone or in combination with other muscles.

Vascular problems like spasm in a blood vessel supplying the muscle can also affect the deltoid muscle. Any inflammation in and around the muscle including an abscess within the muscle can lead to malfunctioning of the muscle till the cause of infection is successfully treated after draining the abscess.

If the pain around the shoulder area is caused by the deltoids muscles, it will normally subside with resting. But if there is a continuous pain in the deltoids area even at rest, the source of the pain could be caused by other muscles in the neck, shoulder and upper body.

In case you have been diagnosed of bursitis of the shoulder but the treatment is not relieving pain, it could be because of the trigger points in the deltoid muscle.

The deltoid which gives the shoulder its round shape, is an important muscle in the human body that needs adequate care and proper use, without which one can develop avoidable problems.


*Disclaimer: This is not medical advice. The content is for educational purposes only. Please contact your doctor for any health care issues.