KNOW YOUR MUSCLES.

The Deltoid

A brief description.

Deltoid, previously called as Deltoideus or (plural- Deltoidei) is a Greek word .
The name is given as Deltoid due to its resemblance to a triangular shaped  Greek alphabet  Delta.
Therefore Deltoid is a triangular shaped  muscle in the shoulder region of our body.  Also called as "Delt" in slang. it is a thick muscle which covers the shoulder joint and helps to stabilize the head of the humerus while carrying heavy loads by preventing dislocation of the shoulder joint.
The muscle helps in initiating the movement of shoulder abduction (bringing your hand up from side to side). You can imagine the two equilateral  triangles on the upper portion of your arms  with apex of the triangles facing downwards on  both the sides to know the position of the muscle in your body.

THE THREE PARTS OF THE MUSCLE ARE:


Posterior or Rear Delts
 



Lateral or Middle Delts
 



Anterior or Front Delts
 



ORIGIN:


The muscle can be divided into three types of fibers :


  • The Anterior fibers or the Clavicular fibers:

Originating  from the anterior border border  and the upper surface of the lateral one third of the clavicle 


  •  The middle fibers or acromion fibers:

Originating from the superior surface of the acromion process of the scapula


  •  The posterior fibers or spinal fibers:

Originating from the lower lip of the posterior border of spine of scapula


 INSERTION:

Deltoid tuberosity on the middle of lateral aspect of the shaft of the humerus.

  • Anterior fibers: insert obliquely backwards
  • Middle fibers: insert vertically
  • Posterior fibers: insert obliquely forward






FUNCTIONS:

  • ·         Anterior fibers: shoulder  flexion and abduction (moving your arm upwards from the front and from the side)
  • ·         Middle fibers: shoulder abduction (moving your arm upwards from the side)
  • ·      Posterior fibers: shoulder extension (moving your arm backwards)

:

 NERVE SUPPLY:

Axillary nerve



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