Holding a wing horizontal: Roles for muscles of the pectoral girdle other than the main two flight muscles

• Autores: Deeming, D. Charles; Mosto, María Clelia
• Año de publicación: 2025
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Allometry; Birds; Horizontal; Wing; Humerus; m. Deltoideus major; m. Pectoralis; m. Scapulohumeralis caudalis; m. Supracoracoideus; Soaring flight
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Whilst many birds glide briefly with wings held horizontally, some species maintainthis posture for extended periods during soaring. This is considered possible becauseof the contraction of the m. pectoralis that holds the wing in place, although alba-trosses seem to have a physical shoulder lock that helps with this action. However,studies of this flight style have not considered the cranially orientated long-axis rota-tion of the humerus induced by the contraction of the main flight muscles that woulddepress the ulna and change the angle of the aerofoil downwards. This study exploredwhether the m. deltoideus major helps counteract this rotation. Muscle masses werecollated from the literature and from dissections of birds to allow exploration of theallometry of muscle masses versus body mass. All muscles exhibited isometry withbody mass, but relative to the size of the m. pectoralis, the m. deltoideus major waslarge but only in a few species that regularly soar or glide for long periods. By contrast,other elevator muscles were less variable among species. The presence of relativelylarge deltoideus major muscles in soaring species was suggestive that this muscle, sinceit originates on the scapula extending caudally and inserting on the dorsal humerus,may counteract humeral long-axis rotation around its longitudinal axis during con-traction of the breast muscles. The results of this study are suggestive of previouslyunconsidered substantial roles for other muscles of the pectoral girdle and forelimbduring different flight styles in birds.
Fil: Deeming, D. Charles. Lincoln University.; Nueva Zelanda
Fil: Mosto, María Clelia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina