General Features of the Muscular Activity

At the examination of the extension of the active movement of the glenohumeral articulation we examine not only a normal state of articular structures, but simultaneously a function of muscles which move with the joint during the active movement. And it is another reason for an exact examination of the motility under standard conditions because a proper examining method is able to examine roughly a functional fitness of muscles responsible for this movement. Right and used examining technique prevents participation of other muscles which could substitute the function of examined muscles10 by their agonistic reaction.

If we were finding out the extension of the active movement during a correct examination, then the following movements are connected to the activity of these muscles11:

 

Movement in the Glenohumeral Articulation, and Muscle Responsible for the Movement

flexion is ensured with the activity of

m. coracobrachialis

m. deltoideus clavicular part

abduction  is ensured with the activity of

m. deltoideus

m. supraspinatus

 

extension is ensured with the activity of

m. latissimus dorsi

m. teres major

m. deltoideus

outer rotation is ensured with the activity of

 

m. infraspinatus

m. teres minor

inner rotation is ensured with the activity of

m. subscapularis

m. pectoralis minor

m. latissimus dorsi

m. teres major

 

With regarding to the fact that the muscular function is not sufficiently examined by a bare making of the active movement because also an expressively weakened muscle makes the movement in the full extension, it would be suitable to examine the activity of muscles by a muscular test, but it is too time-consuming, and it is also demanding technically. Therefore we try at least to diagnose the disorders of the muscle by a comparison of a muscular strength of both limbs, see orienting examining methods of individual muscles by a method of isometric contraction.

 

10f. e. m. pectoralis major also participates in flexion in the area of the glenohumeral articulation, and so it can compensate the disorders of m. coracobrachialis. Therefore f. e. a weakness of m. coracobrachialis, otherwise a very important muscle, would not show during the examination of flexion of the glenohumeral articulation at outer rotation of the limb, and not in a recommended standard position

11this survey shows only the most important muscles which participate in the movement, but for a common clinical practice this simplification should be enough