Origens e ramificações do plexo braquial do veado catingueiro Mazama gouazoubira (Artiodactyla: Cervidae)

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

Simple Summary

The brachial plexus of animals is an ongoing topic of research interest among the scientific community. Research in this area allows scientists to select model animals for laboratory studies. In this way, the research contributes to the improvement of techniques for performing various procedures, not only on animals but also on humans. The most important information about the brachial plexus is the number of roots that form the plexus, from which roots the individual nerves arise, their course, and the extent of innervation of the individual nerves. In this paper, we have analysed the brachial plexus of five species of animals that commonly live in forests. In the study, we show similarities to the domestic dog but also present the individual anatomical features of the brachial plexus. Our results increase knowledge of the nervous system anatomy of wild animals and provide important information for veterinarians dealing with wild and exotic animal species.

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.

Vertebromedullary Topography of the Red-Rumped Agouti (Dasyprocta leporina Linnaeus, 1758)

The agouti is a wild rodent located almost throughout the Brazilian territory, with great scientific importance and high reproductive potential when farmed. In the clinical routine, clinical and surgical procedures are performed on the nervous system of these animals, such as epidural anesthesia and cerebrospinal fluid (CSF) collection; however, data available are limited in literature on the main points of these procedures in this species. In this aspect, the objective was to describe the vertebromedullary topography of the agouti in order to identify and quantify it, with the intention of expanding the information regarding the clinical-surgical procedures in this system. Ten animals were incised longitudinally in the dorsal median line, removing the skin, the musculature, and dorsal fascia of the vertebral column; then, removed the vertebral arches and consequent exposure of the spinal cord and meninges. The morphometry of the animals was done by obtaining the total length, body length, and crown-rump length, as well as the total length of the spinal cord and its segments. The cervical intumescence in the agouti is located between C4-T1 and measures 2.45 cm. The lumbar intumescence is between L5-L7 and is 2.52 cm long. The cauda equina arises from S2 and the filum terminale from S3. As for the medullary cone, it is located between L7-S1 and is 2.52 cm long. The suggested localization for epidural anesthesia or CSF puncture for laboratory tests in agoutis is the lumbosacral space, with the insertion of the needle to be carried out at angle of 90° in the sphinx position. Anat Rec, 303:1472-1477, 2020. © 2019 American Association for Anatomy.

Brachial Plexus in the Pampas Fox (Lycalopex gymnocercus): a Descriptive and Comparative Analysis

Twenty thoracic limbs of ten Lycalopex gymnocercus were dissected to describe origin and distribution of the nerves forming brachial plexuses. The brachial plexus resulted from the connections between the ventral branches of the last three cervical nerves (C6, C7, and C8) and first thoracic nerve (T1). These branches connected the suprascapular, subscapular, axillary, musculocutaneous, radial, median and ulnar nerves to the intrinsic musculature and connected the brachiocephalic, thoracodorsal, lateral thoracic, long thoracic, cranial pectoral and caudal pectoral nerves to the extrinsic musculature. The C7 ventral branches contribute most to the formation of the nerves (62.7%), followed by C8 (58.8%), T1 (40.0%) and C6 (24.6%). Of the 260 nerves dissected, 69.2% resulted from a combination of two or three branches, while only 30.8% originated from a single branch. The origin and innervation area of the pampas fox brachial plexus, in comparison with other domestic and wild species, were most similar to the domestic dog and wild canids from the neotropics. The results of this study can serve as a base for comparative morphofunctional analysis involving this species and development of nerve block techniques. Anat Rec, 300:537-548, 2017. © 2016 Wiley Periodicals, Inc.

Origens e ramificações do plexo braquial no cachorro-do-mato Cerdocyon thous (Linnaeus, 1766)

Este estudo teve o objetivo de descrever a origem e ramificação dos nervos de vinte plexos braquiais de cachorro-do-mato (Cerdocyon thous). Dez animais da espécie, obtidos post mortem por atropelamento em rodovias, foram utilizados para o estudo, de acordo com a autorização do IBAMA/SISBIO nº33667-1. Depois de coletados, os cadáveres foram fixados em solução de formaldeído a 50% e conservados por pelo menos 14 dias em solução de formaldeído a 10% antes das dissecções. Após remoção da pele, incisões na musculatura peitoral e afastamento dos membros, acessou-se o espaço axilar e os nervos do plexo tiveram seu trajeto dissecados individualmente até sua inserção muscular. Para melhorar a visualização dos ramos ventrais cervicais e torácicos que originavam cada nervo, removeram-se a musculatura que encobria os forames intervertebrais, os processos transversos e os corpos vertebrais ventralmente, expondo inclusive a medula espinhal. Registros fotográficos e desenhos esquemáticos documentaram a origem e ramificação dos nervos. Os vinte plexos braquiais foram resultantes das conexões entre os ramos ventrais dos três últimos nervos espinhais cervicais (C6, C7 e C8) e do primeiro torácico (T1). Estes ramos derivaram os nervos supra-escapular, subescapular, axilar, musculocutâneo, radial, mediano, ulnar para a musculatura intrínseca e os nervos braquiocefálico, toracodorsal, torácico lateral, torácico longo, peitoral cranial e peitoral caudal para a musculatura extrínseca do membro torácico. Constatou-se que os ramos ventrais de C7 foram os que mais contribuíram na formação de nervos (61,5%), seguido de C8 (55,4%), de T1 (41,2%) e de C6 (30,8%). O teste t de comparação entre as médias, ao nível de significância de 5%, não demonstrou diferenças na origem do plexo quando comparados os antímeros e os sexos. Do total dos 260 nervos dissecados, 68,8% foram originados pela combinação de dois ou três ramos, enquanto apenas 31,2% tiveram formação por um único ramo. A combinação entre C8 e T1 foi a que mais formou nervos para o plexo (23,8%) nesta espécie. Quando comparadas a origem, ramificação e área de inervação do plexo braquial do C. thous com outras espécies domésticas e silvestres, verificou-se maior semelhança com o cão doméstico. Os resultados deste estudo podem embasar o diagnóstico de disfunções neuromusculares, as técnicas de bloqueios anestésicos e análises morfofuncionais comparativas envolvendo esta espécie.