Réflexion sur le processus coracoı̈de des hominoı̈des et des atèles ; application à quelques hominidés fossiles

Abstract

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Réflexion sur le processus coracoïde des hominoïdes et des atèles ; application à quelques hominidés fossiles Jean-Luc VoisinTo cite this version: Abridged versionA lot of studies have been done about primates' scapulae [1,3,6,13,16,18,21,25,27]. However, apart from Martin and O'Brien's work [10], there are no studies about the coracoid process yet.This work is a study of the orientation and morphology of the coracoid process in hominoids, spider monkeys, colobus monkeys, two neandertal and Homo ergaster remains (table I). Among fossil hominids, there are only four remains that still possess a coracoid process. Five points are used (figure 1). Three of them (E, F, Q) define two perpendicular planes P and P , and the two others (U, R) define the great axis of the process. The projection of these five points in P and P planes allows to know the coracoid process orientation in comparison with the glenoid cavity (gleno-coracoid-p and gleno-coracoid-p * Correspondance et tirés à part.Adresse e-mail : jeanlucv@mnhn.fr (J.-L. Voisin).angles). The coracoid process morphology is described by three indexes. The coracoid indices illustrate the length of the coracoid process and the two others (maximum and minimum robustness index) its breadth. The gleno-coracoid-p and the gleno-coracoid-p angles show two groups. The first one, with the greatest value, contains only man. The second one includes all the other primates' studies here ( figures 2 and 3, table II). The coracoid index has the greatest value in gibbons and spider monkeys ( figure 4, table III), the most brachiating primates. The two coracoid robustness indices define also two groups, the spider monkey with the breadless coracoid process and the hominoids and the colobus monkey with a more robust coracoid process (figures 5 and 6, table III).When the coracoid process orientation put in relation to the glenoid cavity, there is a great difference between man and the other hominoids and spider monkeys. On 299 J.-L. Voisin / C. R. Acad. Sci. Paris, Sciences de la Terre et des planètes / Earth and Planetary Sciences 332 (2001) 299-306

The human acromion viewed from an evolutionary perspective

“…Two radio-clinical studies in humans reported in 2006 [24,25] and 2013 [19] established that a large lateral extension of the acromion was among the bone morphology factors associated with rotator cuff tears. Although scapular anatomy and morphology has been the focus of a large number of studies in hominoids (gibbons, orang-utans, gorillas, chimpanzees, and humans) since the nineteenth century [1][2][3][4][5][6][7][8][9][10], very few of them involved comparisons of acromial process, coracoid process, or coraco-acromial arch morphology across hominoid species [12,21,[26][27][28].…”

“…2), in whom the glenoid cavity faces laterally. This orientation is used as a criterion to determine whether a scapula fragment is associated with tree-climbing behaviour [12,14,[28][29][30][31]. Given the lateral orientation of the human glenoid cavity, the axis of the scapula and that of the upper limb are not aligned until a considerable degree of flexion is achieved [32] (Fig.…”