Medial rotation of the scapula corresponds to scapula downward rotation (or inferior rotation of the scapula) and not to rounded shoulders nor to protracted shoulders. Medial rotation occurs when the arms are lowered and this motion is effected by the Rhomboids. It is called medial rotation because the action causes the inferior angles of the scapulae to approach the midline of the body (shoulder elevation causes the opposite – lateral rotation or the movement of the inferior angle of the scapulae away from the midline).
The effect of a shortening of the anterior shoulder muscle is to ‘pull’ the inferior angle of the scapula upwards and towards the midline. This action is further aided if a lengthening of the upper posterior muscles exists (or occurs) i.e. does not oppose the pull of the shortened anterior shoulder muscles. The resultant effect of both presentations i.e. shortening of one group of muscles and lengthening of the other is medial rotation of the scapula.
The video below is helpful.
0
0