The arteries of the musculoskeletal system of siamangs, and a comparison with other hylobatids, greater apes, and humans.

Limited research on the gross anatomy of the blood vessels has been conducted on hylobatids, or lesser apes, so far. Here, we present a detailed study of the arteries of siamangs (Symphalangus) and compare our findings with data compiled from our previous studies as well as from the literature about other hylobatids, greater apes, and humans. In particular, a three-dimensional full-body computed tomography data set of a siamang neonate was analyzed in detail for this study, with notable findings in the head and neck, thorax, upper limb, abdomen and pelvis, and lower limb. Of the 62 arteries that we studied in detail, a total of 20 arteries that have never been described in detail in hylobatids are reported in this study. Key similarities to other apes differing from humans include the existence of a humeral common circumflex trunk and the origination of the dorsalis pedis from the posterior tibial artery or saphenous artery instead of the anterior tibial artery. Similarities to humans differing from other apes include the separation of the lingual and facial arteries and the origination of the profunda brachii from the brachial artery instead of the axillary artery. Our research and broader comparisons, therefore, contribute to knowledge about the soft tissues of hylobatids, other apes, and primates in general and facilitate a better understanding of the anatomical evolution and key differences and similarities among these taxa.