Origins of plexus brachial in Iguana iguana iguana

Abstract

ASTRACT: This paper aims to describe the origin of the brachial plexus of 12 iguanas, male and female, which were donated already dead by the Wild Animal Screening Center and Independent Company of Highway and Environmental Police of the Araguaína, Tocantins State, to Veterinary Anatomy Laboratory of Federal University of Tocantins, Araguaína campus These animals were fixed by intramuscular injections of aqueous 10% formalin. It was made a parallel incision to dorsal midline from the skull to the caudal ribs. It was pulled all the epiaxial muscles eight ribs, the periosteum, exposing and individualizing the ventral rami of spinal nerves that make up the brachial plexus. The ventral rami of spinal nerves C6, C7, C8, T1 and T2 form the brachial plexus in 12 iguanas. In 41.6% of cases, the branches involved were C6, C7, C8 and T1; in 33.4%, the branches C6, C7, C8, T1 and T2; 16.6% the branches C7, C8, T1 and T2 and in 8.4%, the branches C7, C8 and T1. The branches ventral C7, C8 and T1 formed three trunks and C6 and T2, when present, consisted of nervous fillet. There was variation in number of vertebrae in Iguana iguana iguana which caused oscillations in anastomoses, that constitute the nerves of brachial plexus. The axillary, subscapular, cutaneous, pectoral, coracobrachialis, radial, median, ulnar, thoracodorsal nerves are the main nerves that constitute the brachial plexus in iguanas.

Description of the neuroanatomy of the brachial plexus in South American lizards. Phylogenetic implications

“…Wyneken (2007) described in detail the anatomy of the NS in turtles, snakes, lizards, crocodilians, and the tuatara, mentioning the anatomy of the nerve plexuses. Arantes et al (2017) studied the nerve branches that constitute the brachial plexus of 12 Iguana iguana (Linnaeus, 1758) specimens, describing a great variation in the number of branches that constitute the brachial plexus.…”

“…Even though squamates exhibit great biodiversity and morphological variations, few studies describe the anatomy of the nervous plexuses (Table 1), more than half of which result from graduate or postgraduate theses, some yet to be published in scientific journals (Akita, 1992;Díaz, 1996;Jerez, 2007;Renous-Lécuru, 1972). Most of the studies on comparative anatomy in reptiles are mainly based on coloration, morphometry, musculature, and osteology (Lobo & Abdala, 2001;Marín & Hernando, 2016;Cánovas et al, 2006;Martins, 2016;Quipildor, 2019;Salica & Halloy, 2009;Vidal Alvarez, 2020; among others), and few on the NS (Akita, 1992;Arantes et al, 2017;Diaz, 1996;Filipski & Wilson, 1984, 1985, 1986Jerez, 2007;Mivart & Clarke, 1877;Quipildor et al, 2020;Renous-Lécuru, 2007;Wyneken, 2007). Mivart and Clarke (1877), described the lumbar plexus of many species of lizards, pointing out that in general the lumbar plexus can be formed by two or three roots.…”