Anatomy of the nervous of forearm and hand of cebus libidinosus (Rylands, 2000) / Anatomía de los nervios del antebrazo y mano de cebus libidinosus (Rylands, 2000)

The knowledge on the macroscopic internal structure of Cebus will provide data for histological and biochemical studies and too will contribute to ethological studies. Behavior, memory, use of tools and encephalization index have put the Cebus genus near to chimpanzees in relation to these aspects. The objective of this study is to characterize the nervous model of the forearm and hand of the Cebus monkey. For this, the main nerves and their branches located in the forearm and hand of the Cebus monkey were anatomically characterized, taking into consideration their frequency, number, origin and distribution. The data were compared with the same nerves found in specialized literature in humans, also specialized in other non-human primates. In this study, 7 Cebus libidinosus monkeys were used. The monkeys were provided by IBAMA (Brazilian Institute for the Environment and Renewable Natural Resources), from the city of Sete Lagoas, State of Minas Gerais, in 1970, and housed at the anatomy collection of the Goißs Federal University (UFG). For the nerves of the forearm of Cebus, no variations were observed in the innervation pattern of the muscles, except for the deep flexor muscle of the fingers, which in Cebus and baboons is innervated by the ulnar nerve and in humans and chimpanzees by the median nerve; however, these nerves exchange fibers in the arm and in the brachial plexus. Innervation variations may occur in the fingers of Cebus in relation to other primates, but these variations have been reported with variations in humans. This identical innervation pattern in relation to the nerves of the arm and forearm and hand in Cebus justify its use as model for anthropological evolutionary studies.

El conocimiento sobre la estructura macroscópica del interior del Cebus proporcionará datos para los estudios histológicos y bioquímicos y también contribuirá a estudios etológicos. El comportamiento, la memoria, el uso de herramientas y el índice del encefalización del género Cebus se plantean en torno a los chimpancés, en relación con estos aspectos. El objetivo de este estudio fue caracterizar el modelo de los nervios del antebrazo y la mano del mono Cebus. Para ello, los principales nervios y sus ramos situados en el antebrazo y la mano se caracterizaron anatómicamente, teniendo en cuenta sus frecuencia, número, origen y distribución. En este estudio se utilizaron 7 monos Cebus libidinosus, todos adultos sanos, con variaciones en tamaño y edad. Los monos fueron suministradas por el Ibama (Instituto Brasileño de Medio Ambiente y los Recursos Naturales Renovables), ciudad de Sete Lagoas, Estado de Minas Gerais, en 1970 de la colección anatómica de la Universidad Federal de Goiás (UFG). En el antebrazo de Cebus no se observaron variaciones en las características de los nervios de los músculos, excepto para el músculo flexor profundo de los dedos, que en Cebus y babuinos, está inervado por el nervio ulnar y en los seres humanos y los chimpancés por el nervio mediano; sin embargo, estas fibras nerviosas cambian en el cuello y en el plexo braquial. Las variaciones de los nervios pueden ocurrir en los dedos de Cebus con respecto a otros primates, pero estos cambios están relacionados con las variaciones que ocurren en los seres humanos. Este patrón similar de los nervios de los nervios del brazo y antebrazo y mano en Cebus, justifica su uso como modelo evolutivo para estudios antropológicos.

Anatomy of the shouder and arm muscles of Cebus libidinosus

Cebus are a very cognitive species. They have expansive motor abilities, demonstrate a high levelof proficiency in using tools to obtain food; and play, using thoracic members. Our objective in thiswork is to study the shoulder and arm muscles of Cebus genus, comparing the findings with theliterature data on humans, chimpanzees and baboons, and assume these aspects are associated withbehavioral characteristics. We conclude that the shoulder and arm muscles of Cebus, in generalterms, are more similar to baboons, perhaps due to the quadruped behavior exhibited in these animals.The conventional term “hand abilities” in primates, specifically in Cebus, originate in motorabilities, generally, from thoracic members. They are controlled by a high encephalic index, and notby specific motor abilities from the intrinsic muscles of the hand and forearm which act on the hand.