Origin and antimeric distribution of brachial plexus nerves inAlouatta guariba clamitansCabrera, 1940 (Primates: Atelidae)

Abstract

The Southern brown howler monkey, Alouatta guariba clamitans, is one of the largest Neotropical primates. The objective of this study was to describe the origin and antimeric distribution of brachial plexus nerves in A. g. clamitans and, thereby, to provide information for comparative anatomy and for anatomy applied to loco-regional anaesthetic blocking in primates. For this purpose, a macrodissection of 10 thoracic limbs of corpses that were collected from highways was performed, and the corpses were stored in 10% formaldehyde solution. The brachial plexus was essentially formed from the ventral spinal branches of segments C5 to T1, although in one specimen the contribution of C4 and in another specimen the contribution of T2 was registered. There was a grouping of ventral branches in cranial, medium and caudal trunks, and branches of C5 and C7 were the ones that mostly contributed to the origin of nerves from the plexus. Comparatively, the brachial plexus from A. g. clamitans reflected characteristics that are typical in the primate order, but also of mammal species that require versatility and precision in movements of the thoracic limbs. On the basis of that similarity, it is proposed that anatomic landmarks for anaesthetic block techniques used in other primate species may be successfully applied to A. g. clamitans.

The Structure of the Brachial Plexus of the Djungarian Hamster (Phodopus sungorus)

“…The median nerve receives a connecting branch from the musculocutaneous nerve, which is also characteristic of howler monkeys (Alouatta). Such a branch was noted by Souza et al (2018) in their study on the brachial plexus of the brown howler (Alouatta guariba), where the musculocutaneous nerve derived from nerves C5-C6 or C5-C7.…”

“…However, both of them may derive simultaneously from the C7 branch. The cranial and caudal pectoral nerves of the brown howler also have fibres from the C7 branch (Souza et al 2018 ). The long thoracic nerve of the Djungarian hamster is formed from branches C7-C8.…”

Brachial plexus formation in Jaguarundi (Puma yagouaroundi)

“…Species with skilled thoracic limbs usually have the brachial plexus formed by five or more ventral spinal branches. It is the case of humans (Guday et al, 2017) and non‐humans primates (Cruz & Adami, 2010; Kikuchi et al, 2011; Santos‐Sousa et al, 2016; Souza‐Junior, Carvalho, et al, 2018), xenarthrans (Adami et al, 2013; Cruz et al, 2012; Medeiros‐Do‐nascimento et al, 2019; Souza et al, 2014) and the carnivores L. geoffroyi (Souza‐Junior, Wronski, et al, 2018), Nasua (Felipe, 2014) and Herpestes javanicus (Yoshitomi et al, 2004). According to Allam et al (1952), ungulates, which use the thoracic limbs in a restricted way, have a plexus restricted to four spinal branches, that is the case with some domestic and wild ungulates (Atoji et al, 1987; Magilton, 1966; Vieira et al, 2013).…”

“…The radial nerve was the thickest and innervated most of the muscles, which explains its origin in three ventral branches (C7, C8 and T1) in P. yagouaroundi . This formation also predominated in most of the carnivores (Allam et al, 1952; Barreto‐Mejía et al, 2022; de Souza et al, 2010; de Souza Junior et al, 2017; Ghoshal, 1972; Grzeczka & Zdun, 2022; Guimarães et al, 2007; Hermanson et al, 2020; Souza‐Junior et al, 2014; Souza‐Junior, Carvalho, et al, 2018; Souza‐Junior, Wronski, et al, 2018; Yoshitomi et al, 2004). The ventral spinal branch of C8 participated in the radial nerve composition in all individuals of the present study.…”