Anatomy of Lumbosacral Plexus in Hoary Fox (Lycalopex vetulus-LUND, 1842)

1Biotechnology Academic Unit, Federal University of Goiás, Catalão-GO, Brazil. 2Faculty of Veterinary Medicine and Zootechny, University of São Paulo, São Paulo -SP, Brazil. 3 Biomedical Sciences Institute, Federal University of Uberlândia, Uberlândia-MG, Brazil. *Corresponding author at: Laboratory of Human and Comparative Anatomy, Federal University of Goiás, Regional Catalão – Campus II, Avenida Castelo Branco, s/n, Setor Universitário, 75704-020, Catalão-GO, Brazil. Phone Number: +55 64 34415390 Abstract— The anatomy of wild animals is an involving and interesting area of biological studies in many countries around the world, since the major interest of understands biology, especially animals in extinction risk. Therefore, the objective of this work was dissect and describe the anatomy of lumbosacral plexus of Hoary Fox, a typical and yet little known animal in the Neotropical Cerrado. For this, two male and two female specimens obtained from accidental death on the roadsides of Brazilian Southeast of Goiás were used, both fixed in aqueous solution of 10% formaldehyde and dissected under traditional techniques of macroscopic anatomy. The findings showed that lumbosacral plexus of Hoary Fox is formed by intersecting of L5, L6, L7, S1, S2 and S3. A lumbar plexus and a sacral one are easily identified in this animal. The boundary between them is the trifurcated nerve (L7). The lumbosacral plexus provides three major nerves to the pelvic limb: femoral, obturator and sciatic, besides some small muscular branches. Discussing with specific literature, the present work demonstrated unpublished data about the anatomic standard of Hoary Fox in lumbosacral plexus, an important system in this animal biological system. Keywords— Comparative anatomy, lumbosacral plexus, Hoary Fox, Wild animals and Cerrado.


INTRODUCTION
The anatomy of wild animals is an involving and interesting area of biological studies in many countries around the world, since the major interest of understands biology, especially animals in extinction risk, in this sense many studies aimed understand the anatomy of wild mammals, however few literary quotations was made about neotropical canids biology, including some Brazilian animals in Cerrado biome, like Field Fox, one of seven lesser-known canids in the world [1].
Since wild animal's studies are developed, substantial information is discovered about the fragility of several species, mainly due to the destruction of environment which they live [2] and several species of neotropical mammals are subject of a significant number of studies, meanwhile the scientific world never focused animals that lives in areas of risk, perhaps the face of desire build sustainable development.
Hoary Fox (Lycalopex vetulus -LUND, 1842) is native animal of Cerrado, that although the second largest Brazilian biome, some components of its fauna are in danger of entering or already in process of extinction, since anthropic pressure on this biome growing stronger. According to Bocchiglieri et al. (2010) [3] the components Cerrado occupy all geographical patterns, composed of savannahs, fields and forests, therefore, Hoary Fox prefers clean fields and altitude. This animal is the smallest Brazilian canid and despite being considered a carnivore, eating small vertebrates or mainly insects, even eats fruits [1].
Is important note that Hoary Fox anatomy not presents the same level of knowledge as other species of the same biome, on the other hand, lumbosacral plexus is responsible for origin of all nerves destined to pelvic limbs and, therefore, the only responsible for movements control and is an important anatomical segment capable of arouses particular interest, especially to understand the related aspect of posture adaptations, locomotion, feeding and reproduction. Thus this work aimed to describe lumbosacral plexus of Hoary Fox, discussing the data obtained with specific literature.

II.
MATERIAL AND METHODS The present paper is a descriptive anatomical study with two male and two female specimens of Hoary The study was made in the research laboratory of human and comparative anatomy from Federal University of Goiás -RC, were the specimens were fixed in aqueous 10 % formaldehyde solution to conservation and adopted consecrated techniques in Macroscopic Anatomy. The anterior abdominal wall was opened in median sagittal plane and section of pelvis through pubic symphysis and lateral displacement of limbs, to facilitate access to abdominopelvic cavity. Once exposed the viscera of pelvic and abdominal cavity, it was removed to base of skull and exposed vertebral column as whole that the number of vertebrae could be verified. The next step was clean dorsal wall of abdominopelvic cavity until complete exposure of vertebral bodies and psoas muscles. Next, the muscles were carefully removed until vertebral bodies had been exposed. The lumbar vertebral bodies were carefully removed with the aid of osteotomies, tweezers, scalpel and scissors , until complete exposure of spinal cord involved by dura mater.
The Nikon® D7000 18-105 digital camera was used to photographical documentation and description nomenclature adopted is the standard of Nomina Anatomica Veterinaria (2012) [4], elaborated by the International Committee on Veterinary Gross Anatomical Nomenclature.

III. RESULTS
The lumbosacral plexus of Hoary Fox consists interweaving of ventral branches at last three lumbar spinal roots and three first sacral ones, in thickness of psoas major muscle. The lumbosacral plexus can easily be divided into lumbar plexus and sacral plexus. The border between them is bifurcated nerve or lumbosacral trunk corresponding to the nerve L7. The lumbosacral trunk or bifurcated nerve is named due after it shortly emergence and through intervertebral foramen, divides into two branches: cranial and caudal, cranial branch composing lumbar plexus and the caudal branch, sacral plexus. In Hoary Fox, bifurcated nerve would better know as a "trifurcated" nerve, overdue the division into three branches: cranial, middle and caudal. The cranial branch converges with L6 to form lumbar plexus and femoral nerve; Middle branch joins caudal branch of L6 to form cranial root of obturator nerve and finally, caudal branch contributes to the formation of sacral plexus (Figure 1 and Figure 2).
The lumbar plexus is restricted to intercommunications between the last three lumbar nerves, which in Hoary Fox are L5, L6 and L7. The cranial nerves at L5 not contribute to formation of lumbar plexus, although establishes interconnecting loops, frequently between L3 and L4, which contribute to form ilioinguinal and genitofemoral nerves, respectively. The root L2 follows as subcostal nerve and sometimes receives a small contribution of L1.
Sacral plexus is constituted by interlocking of ventral roots of S1, S2 and S3, receiving strong contribution of L7. All ventral roots that forms lumbosacral plexus emerges separately through intervertebral foramina and only after traveling considerable space begin the process of interlacing, some closer and other distant ( Figure 1 and Figure 2).  .org/10.22161/ijaers.6.3.25  ISSN: 2349-6495(P) | 2456-1908(O) www.ijaers.com The root of L5 forks in cranial branch and caudal branch after leaving the intervertebral foramen. Cranial branch follows as independent nerve to abdominal wall, while caudal branch joins with L6. In turn born and follows without branching, until joining with L5 and then divides into cranial branch and caudal branch. The cranial branch follows as the femoral nerve, after receiving contribution of L7. However, caudal branch follows as cranial root of obturator nerve.
The root L7 is divided into three branches: cranial, middle and caudal; hence the name of proposed trifurcated nerve. Cranial branch consist in femoral, median, obturator and flow sciatic nerve. The root S1 follows without dividing until joins caudal branch of L7 to form cranial root of sciatic nerve.
The roots of S2 and S3 follow separate until branching into cranial branch and another caudal. The cranial branch makes sciatic nerve, while caudal branch joins S3. The pattern lumbosacral plexus formation is similar in four antimeres studied. The main nerves originating from lumbosacral plexus are: femoral, obturator and sciatic. Femoral nerve receives contribution of L5, L6 and L7; as obturator nerve from L6 and L7; meanwhile L7, S1, S2 and S3 contribute to form sciatic nerve. Several small muscular branches are born, also of the Lumbosacral Plexus (Figure 1 and Figure 2).

IV. DISCUSSION
Regard the composition of Hoary Fox (Lycalopex vetulus), the involvement of iliohypogastric, ilioinguinal and genitofemoral nerves in the composition of lumbar plexus as a rule in humans is not recorded [5].
Hepburn (1892) [6] describing lumbar and sacral plexus anatomy in Gorilla, Chimpanzee, Orangutan and Gibbon, notes that lumbar plexus is similar to Man, exhibiting several loops. In Hoary Fox the structure in form of loops or intercommunications is rule, even the characteristic of plexus. In general, the literature do not show "loops" but of interlacing.
In gibbon, the only difference is the absence of loop between L1 and L2 [6]. In Hoary Fox there be "anastomoses" between cranial roots at L5, but do not contribute to formation of lumbar plexus. According to Hill (1972) [7] in Brachyteles, the first component loops of lumbar plexus occur between L1-L2 and L2-L3; and Macaca mulatta cranial limit is T12, but more frequent find between L3-S1 [8]. In Hoary Fox cranial limit is L5, an evident caudal displacement of plexus observed in relation to primates. Caudal displacement of Lumbar Plexus suggests lower characteristic in phylogeny, probably associated with a column formed by a larger number of free vertebrae. Schultz and Straus (1945) [9] consider the presence of 13 thoracic vertebrae as a primitive trait, since in arboreal Mussaranhos there are 13 vertebrae, which can be considered alive ancestors of primates. Changes in musculoskeletal structure influence adjacent neural system, so the decrease in the number of vertebrae along phylogeny led to shortening of neural system [10][11].
For Howell and Straus (1932) apud Hartmann and Straus (1932) [12] is more convenient consider the Lumbar and Sacral Plexus as single entity, since lumbar and sacral roots contribute their formations. In the case of Hoary Fox, the separation in Lumbar Plexus and Sacral Plexus seems adequate, since the only communication between the two is trifurcated nerve and yet there is clear individuality regarding the branches destined for Lumbar and Sacral Plexus.
The connection between Lumbar and Sacral plexus always done by bifurcated nerve [7], but according to Krechowiechi et al. (1972) [8] bifurcated nerve may be absent, whereas humans and gorillas always present. In Hoary Fox the connection between the two plexuses is always present, however the nerve is trifurcated and not bifurcated and its origin is in L7.
The connection between lumbar and sacral plexuses is closely associated with shortening of presacral spine, however, lifestyle, especially locomotion strongly influences spinal shortening process, as changes in lumbosacral plexus [11]. Testut and Latarjet (1979) [24] and Piasecka-Kacperska and Gladykowska-Rzeczycka (1972) [11] consider that humans a pattern for lumbosacral plexus given the large number of variations, both in limits and number of component roots. In primates there is great variability in number of roots and nerves from the plexus [25]. In domestic carnivores, the highest number of roots is associated with largest number of lumbar vertebrae [23,26]. In Hoary Fox six spinal segments, three lumbar and three sacral make up lumbosacral plexus, which is clearly divided into Lumbar Plexus and Sacral Plexus by trifurcated nerve and the seventh lumbar nerve.

V.
CONCLUSION The present study demonstrated that anatomic standard of Hoary Fox presents lumbosacral plexus formed by intersecting of L5, L6, L7, S1, S2 and S3. A lumbar plexus and a sacral one are easily identified in this animal. The boundary between them is the trifurcated nerve (L7). The lumbosacral plexus provides three major nerves to the pelvic limb: femoral, obturator and sciatic, besides some small muscular branches , showing particularities template compared to other mammalian s and detailed analysis of Hoary Fox anatomy FUNDING This work was supported by grants from "Fundação de Amparo a Pesquisa do Estado de Goiás -FAPEG".

CONFLITS OF INTERESTS
The authors declare no conflicts of interest associated with this manuscript.