In addition well-defined anatomical spaces are also considered to be functional joints without which a normal movement in the shoulder girdle would not be possible.

An articular surface is made by thoracal paries and interior fascies of a shoulder blade between which there is a muscular layer m. serratus anterior and m. subscapularis.

A tendon of a long head of the biceps slides in sulcus bicipitalis humeri during all movements of the shoulder girdle. Only a free movement of this tendon makes possible the movement of the glenohumeral articulation without any restrictions.

A tendon of a long head of the humerus

It is formed by space between the head of the humerus and the ligament connecting an acromion with processus coracoideus¹. In this space the head of the humerus moves during all movements. Except muscular substance of a rotator cuff, there is also a subacromial bursa which under normal conditions makes possible a smooth movement of the head of the humerus. If this space is too narrow, it can lead to an incarceration of the rotator cuff by the acromion².

¹ ligamentum coracoacromiale

² so-called impigement syndrome