Deltoideus (deltoid muscle)

 

The deltoid m. deltoid muscle (often referred to as "the shoulders") is divided into 3 parts, i.e. a front (anterior), middle (lateral) and rear (posterior) part. This is due to the different attachments on the bones, which give each of the sections a different kind of function.

 

The front part, pars clavicularis has the following functions:

• anteversion: forward movement of the arm
• Endorotation: turning the shoulder inwards
• adduction: movement towards the body after the arm has dropped to one third of the range of motion.
• abduction: movement away from the body from a point which is approx. 2/3 of the range of motion.

 

The middle part, pars acromialis has one function:

• abduction: movement away from the body until approx. a 90 degree angle (after which the trapezius muscle takes over).

 

The rear part, pars spinalis has the following functions:

• Retroversion: Backward movement of the arm.
• Exorotation: turning the shoulder outwards.
• adduction: movement of the body after the arm is lowered to 1/3 of its range of motion.
• Abduction: movement away from the body from a point of approx. 2/3 of the range of motion.

 

O: 1/3 part collarbone, acromion, scapular crest I: halfway down the humerus (nodule)

You like to know more about massaging the back and shoulders? Click here.