Tendon fascia continuity, the glenoid labrum: An adaptable dynamic ring Karl Jacobs - University of applied science Amsterdam / University of Amsterdam Introduction/Background Traditionally the glenoid labrum, the tendon of the long head of biceps and triceps have all been discussed as independent anatomical structures in their own right. Traditional literature has approached these structures as being unique entities (1), which inadequately explains the functional stability of the shoulder and is at odds with findings on dissection. This research aims to explain the functional anatomy of the shoulder joint by demonstrating that the glenoid labrum and the tendons of the long heads of the biceps and triceps is a continuous fascial structure. The results provide new insights in explaining the stabilising abilities of the shoulder joint as a consequence of tendon fascia continuity. Methods Dissection was performed, respecting fascia continuity, on a formalin-fixed female cadaver, with no known medical history. The glenoid labrum has a vital role in shoulder joint stability; this region was dissected to establish whether the “labrum” acts as a single structure or as a continuum, formed by the tendons of the long heads of the biceps and triceps. Results A continuation of tendon fascia was identified, starting from the tendon of the long head of the Biceps through the glenoid labrum and towards the tendon of the long head of the triceps. This continuity is a result of the continuation of the fascicular investing muscular fascia (endo, peri, epi, -mysium) with its tendon (endo, peri, para -tendon) fascia. This continuity, instead of continuing within adjacent muscle or bone, continues within the glenoid labrum creating a dynamic ring. This dynamic ring provides an optimal continually changing articular surface for the humeral head (image 2). Conclusion The demonstrated continuity of the tendon fascia through the glenoid labrum, combined with the knowledge of the innervation components of the fascia (2), shows a joint overlapping feedback system, wherein every movement, position or load change is signalised and transmitted towards the muscles acting directly or indirectly on the related joint (3)(4). This new insight into how the labrum is able to adapt its form and shape; may also explain how the shoulder joint is capable of generating surface adhesion between its articular surfaces. References 1. Standrings S, editor. Gray’s Anatomy 40th edition. Edingbourgh / London: Churcill livingstone / Elsevier; 2008. 2. Stecco C, Gagey O, Belloni A, Pozzuoli A, Porzionato A, Macchi V, et al. Anatomy of deep fascia of the upper limb. second part: study of innervation. Morphologie. 2007;91(March 2014):38–43. 3. Maas H, Sandercock TG. Force transmission between synergistic skeletal muscles through connective tissue linkages. J Biomed Biotechnol. 2010;2010. 4. Huijing PA, Baan GC. Myofascial Force Transmission Causes Interaction between Adjacent Muscles and Connective Tissue: Effects of Blunt Dissection and Compartmental Fasciotomy on Length Force Characteristics of Rat Extensor Digitorum Longus Muscle. Arch Physiol Biochem. 2001;109(2):97–109. .