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.

Morphology studies provide knowledge that allows us to understand how animals interact with their natural environment or in captivity. In this context, comparative anatomy on the formation of the brachial plexus has been a matter of interest since the 19th century, and remains one of the most intriguing topics of contemporary anatomy. The aim of this study was to describe the origin and the antimeric distribution of the brachial plexus nerves in Macaca mulatta, as well as the muscles innervated by it. Ten male rhesus monkeys (Macaca mulatta) were used. Animals came from the Laboratory Animals Breeding Centre (Cecal/Fiocruz), and were donated to the Animal Anatomy Department of the Universidade Federal Rural do Rio de Janeiro. Specimens were fixed in formaldehyde by infusion of a 10% solution. They were subsequently kept in low-density polythene containers with 500 L of 30% formaldehyde over a period of 12 months. In 11 plexus (55%) the resulting nerves were constituted by the connections between the ventral spinal branches C5, C6, C7, C8 and T1. In five plexus (25%), the participant roots were C4, C5, C6, C7, C8, T1 and T2. In two (10%) plexus, they were C5, C6, C7, C8, T1 and T2. In the other two (10%) plexus it was observed to be formed from C6, C7, C8, T1 and T2. The ventral branches formed three nerve trunks: cranial, middle and caudal. The suprascapular, subscapular, axillary, musculocutaneous, radial, median and ulnar nerves innervated the intrinsic muscles. The subclavian, thoracodorsal, medial cutaneous nerve of the arm and forearm, long thoracic, cranial pectoral and caudal pectoral innervated extrinsic muscles. Results obtained in this study contribute to the field of comparative anatomy of primates, and provide information for applied research, serving as a basis for clinical and surgical procedures that use this species as a model animal.

The characteristics of the muscles of the thoracic limb were evaluated in 22 specimens of Lycalopex gymnocercus. Descriptive and comparative analyses showed similarity with other canids in terms of topography and tendon insertions. Differences with the domestic dog were observed in the pectoralis profundus, triceps brachii and interflexorii muscles. Intraspecific variations were observed in the rhomboideus capitis, serratus ventralis cervicis, extensor carpi radialis, extensor digiti I and II, lumbricales, flexor digiti I brevis, abductor digiti I brevis, and flexor digiti V muscles. The analyses of muscle architecture carried out in nine specimens showed that there was no difference in muscle percentage mass in the thoracic limb of males and females, but a young specimen showed significant lower percentage mass. The triceps brachii caput longus muscle showed the greatest mass, the subscapularis muscle showed the greatest physiological cross‐sectional area value, and the extrinsic muscles, in general, presented the longest fascicles and higher architectural indexes. Muscle architecture data were compatible with those of a thoracic limb adapted to fast cursorial locomotion that prioritizes movements in a sagittal plane instead of rotation or adduction/abduction. There was a high association between functional percentage mass of the muscles in the thoracic limb and phylogeny in the Carnivora order. It may be inferred that carnivoran muscle mass is largely determined by phylogeny.

Chrysocyon brachyurus (maned wolf) is the biggest South American canid and has a high frequency of dental injuries, both in the wild and in captivity. Thus, veterinary procedures are necessary to preserve the feeding capacity of hundreds of captive specimens worldwide. The aim of this study was to investigate the mandibular morphometry of the maned wolf with emphasis on the establishment of anatomic references for anesthetic block of the inferior alveolar and mental nerves. Therefore, 16 measurements in 22 mandibles of C. brachyurus adults were taken. For extraoral block of the inferior alveolar nerve at the level of the mandibular foramen, the needle should be advanced close to the medial face of the mandibular ramus for 11.4 mm perpendicular to the palpable concavity. In another extraoral approach, the needle may be introduced for 30.4 mm from the angular process at a 20-25° angle to the ventral margin. For blocking only the mental nerve, the needle should be inserted for 10 mm from ventral border, close to the labial surface of the mandibular body, at the level of the lower first premolar. The mandibular foramen showed similar position, size, and symmetry in the maned wolf specimens examined. Comparison of the data observed here with those available for other carnivores indicates the need to determine these anatomic references specifically for each species.

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RESUMEN:El objetivo del estudio fue describir las características anatómicas y establecer hipótesis morfo-funcionales del esqueleto del miembro torácico de Mazama gouazoubira. Para ello, se utilizaron los miembros torácicos de cuatro adultos jóvenes. Los huesos se prepararon mediante ebullición y fueron blanqueados en una solución de peróxido de hidrógeno para obtener descripciones comparativas, mediciones osteométricas y radiografías digitales. En comparación con los rumiantes domésticos, la escápula resultó ser ancha y plana, con el acromion pequeño, el proceso coracoides muy pequeño y sin tuberosidad de la espina. El húmero se observó alargado con la diáfisis redondeada en una sección transversal y con proyecciones no articulares lisas. La ulna se unió al radio hasta la epífisis distal y juntos formaron un espacio interóseo proximal alargado y estrecho, sin surco vascular. El esqueleto de la mano presentó los metacarpianos III y IV bien desarrollados y fusionados, mientras que los metacarpianos II y V resultaron rudimentarios con disposición telemetacarpiana, filogenéticamente típico de cérvidos del Nuevo Mundo. Se encontraron cuatro dedos con tres falanges en cada uno, de los cuales, dos corresponden a los principales (III y IV) que llegan al suelo y dos son rudimentarios (II y V). Las radiografías nos permitieron visualizar los patrones de tensiones trabeculares normales y la osteometría permitió establecer relaciones con fines comparativos. Se reconocieron las adaptaciones esqueléticas del miembro torácico para favorecer la locomoción cursorial saltatoria.

Puma yagouaroundi is a wild felid with wide distribution on the American continent.This paper aims to describe the origin and motor distribution of the nerves of the brachial plexus of P. yagouaroundi and compare the findings with the available descriptions for the Carnivora order. Fourteen brachial plexuses of specimens collected dead on highways were dissected (five males and two females). In most cases (57%), the brachial plexus originated from the ventral spinal branches of C5, C6, C7, C8 and T1. The C7 branch was the one that most contributed to the formation of the plexus nerves (57.7%). Among all dissected nerves, 23.6% were unisegmental and 76.4% plurisegmental. The radial nerve was the thickest and innervated the largest number of muscles, while the caudal pectoral nerve showed the most varied formation. Intraspecific polymorphisms occurred in the plexus, although the distribution of the nerves to the muscles had an evident constancy among the individuals. Due to the similarities, locoregional blocking techniques may consider the same anatomical landmarks stipulated for domestic cats. Comparison with the descriptions of other carnivorans allows speculating a polymorphism at the plexus origin, in contrast to the conservative innervation of the muscles in the order Carnivora.