The Structure of the Brachial Plexus in Selected Representatives of the Caniformia Suborder

Abstract

Like most structures, the brachial plexus is subject to species variation. Analysing this structure over a wide spectrum of species, we can obtain a complex view of the changes–in a given group of animals. The aim of this study was to describe the brachial plexus anatomy of species from two families of Caniformia. We analysed the brachial plexus structure of five species from two families of Caniformia: Canidae and Mustelidae. The cadavers were obtained from breeders and hunters. All were fixed by being kept in a 10% formaldehyde solution for two weeks. This study allows us to present the similarities as well as the differences between species and families. Our study reveals different trends in the course of the individual nerves and innervations of the thoracic limb. A species-specific feature is the extent of the brachial plexus, as each species has a specific number of ventral branches of the spinal nerves in the brachial plexus. However, a characteristic of the family Mustelidae is the course of the median nerve through the epicondylar foramen. Within the Canidae, two species are characterised by a very long branch for the coracobrachialis muscle. The general conclusion is that the brachial plexus of species belonging to the Caniformia is subject to variation within families and species, as well as individual variation while maintaining a general schematic for the group.

Brachial plexus formation in Jaguarundi (Puma yagouaroundi)

“…The most frequent composition of the axillary nerve in P. yagouaroundi occurred between C6 and C7, as observed in L. geoffroyi (Souza-Junior, Wronski, et al, 2018), L. pardalis (Chagas et al, 2014), Van cats (Hakkı Nur et al, 2020), P. concolor (Barreto-Mejía et al, 2022), A. microtis (Pinheiro et al, 2013) and V. vulpes (Grzeczka & Zdun, 2022). Its innervation to the shoulder flexor muscles is consistent in many carnivore's species (de Souza et al, 2010;de Souza Junior et al, 2017;Hakkı Nur et al, 2020;Hermanson et al, 2020;Pinheiro et al, 2013;Sánchez et al, 2013;Souza-Junior et al, 2014;Souza-Junior, Wronski, et al, 2018).…”

“…However, it was not seen in a female P. concolor (Barreto-Mejía et al, 2022). Although canids do not have such foramen, this communication at the elbow level has also been recognized (Allam et al, 1952;de Souza Junior et al, 2017;Grzeczka & Zdun, 2022;Souza-Junior et al, 2014). One communicating branch at the level of axilla was reported for mustelids (Grzeczka & Zdun, 2022).…”

“…Although canids do not have such foramen, this communication at the elbow level has also been recognized (Allam et al, 1952;de Souza Junior et al, 2017;Grzeczka & Zdun, 2022;Souza-Junior et al, 2014). One communicating branch at the level of axilla was reported for mustelids (Grzeczka & Zdun, 2022). This aspect can be functionally necessary for the continuity of the transmission of the stimuli in case of injury of one of these nerves (Sharp et al, 1990) since this communicating branch conducts efferent fibres to supply the distal end of the limb (Kitchell et al, 1980).…”

“…vulpes, M. martes, M. meles (Grzeczka & Zdun, 2022) of C6 in L. pardalis (Chagas et al, 2014), of C8 in A. australis (de Souza et al, 2010, and C8 and T1 in C. thous (Souza-Junior et al, 2014). The path and innervation to the latissimus dorsi muscle are common to other carnivores (Barreto-Mejía et al, 2022;de Souza et al, 2010;de Souza Junior et al, 2017;Ghoshal, 1972;Hakkı Nur et al, 2020;Hermanson et al, 2020;Pinheiro et al, 2013;Souza-Junior et al, 2014).…”

“…In the order Carnivora, the predominance of C5 in the formation of the brachiocephalic nerve seems to be a feature restricted to felids since it also occurs in domestic cats (Ghoshal, 1972) and L. geoffroyi (Souza-Junior, Wronski, et al, 2018). However, in canid and mustelid species, the origin from C6 predominated (Allam et al, 1952;de Souza Junior et al, 2017;Grzeczka & Zdun, 2022;Souza-Junior et al, 2014).…”