Comparative anatomy of the brachial plexus and shoulder nerves of the Sapajus.

BACKGROUND: The capuchin is a neotropical primate that presents easy reproduction in captivity and is used in scientific research. The objective of this work was to describe the structure and the branching pattern of the brachial plexus of the capuchin and to compare the results with data from the literature for humans, chimpanzees, baboons and Callithrix. METHODS: Twelve specimens were used: eight males and four females. No animals were killed for the purpose of this study. RESULTS: The brachial plexus of Sapajus sp was constituted mainly from the ventral roots of the last four cervical spinal nerves, from C5 to C8, mainly, and the first thoracic nerve (T1). CONCLUSIONS: The pattern of formation of the brachial plexus of the capuchin monkey was more similar to that of Callithrix and baboons, perhaps because they are the only primates in this study to be essentially quadrupedal.

Comparative Gross Anatomy of the Forelimb Arteries of the Japanese Monkey (Macaca fuscata) and a Comparative Pattern of Forelimb Arterial Distribution in Primates.

Macaca fuscata displays characteristic behaviours, such as stone handling, locomotor behaviour, gait position, and intermittent bipedalism. Differences in characteristic behaviours among primate species/genera could be explained by anatomical details of the body. However, the anatomical details have not been well studied in Macaca fuscata. Arterial models could be one of the anatomical bases for the phylogenetic and functional differences among species, since the arterial supply could be associated with the muscular performance, especially locomotor behaviour. In this study, five thoracic limbs of Macaca fuscata adults were dissected to analyse the vessels. Patterns of arterial distribution in the thoracic limbs of Macaca fuscata were compared with those in other primates. The results indicated that the arterial distribution in the Japanese monkeys was more similar to those in Macaca mulatta and Papio anubis, which is consistent with phylogenetic similarities. However, compared with Papio anubis and other macaques, there were anatomical differences in several points, including (1) the origin of the common, anterior, posterior circumflex, and profunda brachii, and (2) the origins of the collateralis ulnaris artery. The comparative anatomy of the arteries in the forelimb of Macaca fuscata, along with the anatomical studies in other primates, indicated characteristic patterns of brachial artery division and the number of the palmar arches in primates, which is consistent with the phylogenetic division among New World primates, Old World primates, and apes.