The deltoid muscles (sometimes called the deltoideus muscles) are thick triangular muscles that cover the shoulder joints. There is one deltoid muscle over each shoulder joint.
Each deltoid muscle can be described in terms of three parts that originate from three distinct sets of fibres or 'heads'. They are:
- Anterior Part: Originating in the anterior or 'clavicular' fibres, also known as the anterior deltoid or the front delts.
- Lateral Part: Originating in the lateral or 'acromial' fibres, also known as the lateral deltoid.
- Posterior Part: Originating in posterior or 'spinal' fibres, also known as the called posterior deltoid, or the rear deltoid or rear delts.
Origin, Insertion and Actions of the Deltoid muscles:
|Points of Origin:||Anterior Part:
|Point of Insertion:||
|Actions:||The deltoid muscles have several actions that can be summarized as:
Descriptions of the actions of the parts of the deltoid muscles vary. Which parts of the deltoid muscles perform which functions depends partly on the initial position of the body and on the stage of the movement (if movement is in progress). The different parts of the deltoid muscle work in co-operation with other muscles to perform certain movements. In some cases the relevant fibres of the deltoid muscles make only a small contribution to the force applied to produce the movement. Examples of some actions of the parts of the deltoid muscles include:
More about Muscles:
The following are some popular pages in the section about the human muscular system:
- The structure of muscle tissue
- The structure of muscle cells
- Labelled diagrams of the muscles in different parts of the body including anterior muscles, posterior muscles and facial muscles
- Types of muscle contractions
- Movements at joints
There are also more pages about the words used to describe muscles (terminology), the anatomy and physiology of muscles, muscular disorders and associated topics. See also books about sports medicine.
- Anterior Muscles
- Posterior Muscles
- Facial Muscles
- Muscle Terminology (Definitions)
- 1. Structure of Muscle
- 2. Structure of Muscle Cells
- 3. Muscle Filaments
- 4. Sliding Filament Theory
- 5. Neuromuscular Junction
- 6. Actions at Neuromuscular Junction
- Types of Muscle Contractions
- Muscular Disorders
- Effects of exercise on muscles