Development of the Human Biceps Brachii Tendon and Coracoglenoid Ligament (7th-12th Week of Development)

Abstract

The goal of this study is to clarify the development of the long head of the biceps brachii tendon (LHBT) and to verify the existence and development of the coracoglenoid ligament. Histological preparations of 22 human embryos (7-8 weeks of development) and 43 human fetuses (9-12 weeks of development) were studied bilaterally using a conventional optical microscope. The articular interzone gives rise to the LHBT, glenoid labrum, and articular capsule. During the fetal period, it was observed that in 50 cases (58%), the LHBT originated from both the glenoid labrum and the scapula, while in 36 cases (42%), it originated only from the glenoid labrum. The coracoglenoid ligament, first described by Sappey in 1867, is a constant structure that originates at the base of the coracoid process and projects toward the glenoid labrum zone, which is related to the origin of the LHBT. The coracoglenoid ligament was more easily identifiable in the 36 cases in which the LHBT originated only from the glenoid labrum. We suggest that the coracoglenoid ligament is a constant anatomical structure, is not derived from the articular interzone unlike the LHBT, and contributes to the fixation of the glenoid labrum in the scapula in cases in which the LHBT originated only from the glenoid labrum. We postulate that, when the LHBT is fixed only at the glenoid labrum, alterations in the coracoglenoid ligament could lead to a less sufficient attachment of the glenoid labrum to the scapula which could predispose to a superior labral lesion.

Development of the human shoulder joint during the embryonic and early fetal stages: anatomical considerations for clinical practice

“…According to our observations, starting at Carnegie stage 21 (24 mm), the LHBT appears immersed in the mesenchyme that forms the joint capsule, in agreement with the suggestion posited by other authors that this tendon originates in the interzone, although in our research this finding appeared later than, for instance, the observations described by de la Cuadra‐Blanco et al. () (16 mm). In specimens 30 mm long we can already observe how the LHBT is surrounded by the synovial membrane and separated from the humeral head by a small cavity (Abe et al.…”

“…However, for other authors this is observable at earlier stages (de la Cuadra‐Blanco et al. ). The study of the intertubercular sulcus and its morphological characteristics may also be of relevance for clinical practice as it has been described that the width and depth of the bicipital groove are significantly associated with morphological variations (Gaskin et al.…”

“…The latter will form the joint cavity, which by Carnegie stage 23 already shows a synovial membrane. Such membrane was reported at earlier stages (20-mm embryos) in observations by other authors (de la Cuadra-Blanco et al 2017). In the study of the joint capsule, many authors believe it to be originated in the interzone (Gardner & Gray, 1953;Hamilton & Mossman, 1975;Williams & Warwick, 1985), whereas others point at a perichondral (Keith, 1933) or extrablastemal origin (Haines, 1947).…”

“…As far as the development of the shoulder joint is concerned, the literature offers little information, often dealing with specific structures such as the glenoid labrum, the long head (caput longum) of the biceps tendon (de la Cuadra‐Blanco et al. ) or the rotator interval (Abe et al. ), or referring to advanced gestational stages (Fealy et al.…”

“…In some cases these variations are highly prevalent, as for instance those affecting the glenoid labrum (Smith et al 1996). Some authors consider these anatomical variations (and their clinical significance) to be clearly linked to several specific pathologies (Bents & Skeete, 2005) and, although others downplay their importance and believe them to be without clinical repercussions, we must definitely account for their existence when establishing a differential diagnosis (Andrews et al 1985) As far as the development of the shoulder joint is concerned, the literature offers little information, often dealing with specific structures such as the glenoid labrum, the long head (caput longum) of the biceps tendon (de la Cuadra-Blanco et al 2017) or the rotator interval (Abe et al 2011), or referring to advanced gestational stages (Fealy et al 2000), generally fetuses over 9 weeks old, in which some important events in the development of the glenohumeral joint (articulatio glenohumeralis) have already taken place.…”