1816 Original Article ORIGIN AND DISTRIBUTION OF THE BRACHIAL PLEXUS IN WILD BOAR (Sus scrofa Linnaeus , 1758) ORIGEM E DISTRIBUIÇÃO DO PLEXO BRAQUIAL DE JAVALI (Sus scrofa Linnaeus, 1758) Lázaro Antônio dos SANTOS 1; Frederico Ozanam CARNEIRO E SILVA 1; Lucas Assis RIBEIRO 1; Tânia Ribeiro Junqueira BORGES 1; Daniela Cristina Oliveira SILVA 2; Frederico Balbino LIZARDO 2; Gilmar da Cunha SOUSA 2; Roseâmely Angélica de CARVALHO-BARROS 3 1. Department of Animal Anatomy, Faculty of Veterinary Medicine, Federal University of Uberlandia, Uberlândia, MG, Brazil; 2. Departament of Human Anatomy, Institute of Biomedical Sciences, Federal University of Uberlandia, Uberlandia, MG, Brazil; 3. Laboratory of Comparative Anatomy, Faculty of Biological Sciences, University of Goias, Catalão, GO, Brazil. ABSTRACT : The origin and distribution of the brachial plexus in wild boar ( Sus scrofa) , a mammal belonging to the Suidae family were studied. Twelve specimens of wild boar, which were fixed in 10% formalin solution through different points of subcutaneous, intravenous, intramuscular, and intracavitary injections, following by immersing the specimens in the same solution were used. In present study, the brachial plexus of wild boar was a set of nerve fibers formed by the ventral branches from the fifth (C5) to eighth (C8) cervical and the first (T1) thoracic spinal nerves. The subclavian nerve was originated from C5, while the suprascapular nerve had its origin from C5 to C7. The cranial and caudal subscapular nerves were predominantly originated from C6 and C7, as well was the axillary nerve. The origin of the cranial and caudal pectoral nerves was from C7-C8 and C8-T1, respectively. The musculocutaneous nerve was mostly originated from C6 and C7, while the median and radial nerves had origin from C7 to T1. The origin of the ulnar, thoracodorsal, and lateral thoracic nerves was mostly from C8 and T1, while the long thoracic nerve was predominantly originated from C7 and C8. All nerves were responsible for the innervation of scapular girdle structures, arm, forearm, thorax and abdomen. In conclusion, the origin and distribution of the brachial plexus nerves in wild boar ( Sus scrofa ) are similar to domestic swine rather than to other wild species described in the literature. KEYWORDS: Nervous system. Suidae. Thoracic limb. INTRODUCTION The knowledge about the nerves that comprise the nervous plexuses and structures The wild boar (Sus scrofa ) is a mammal innervated by them is important to understand the belonging to the Suidae family, naturally found in anatomical, physiological and postural features Europe, Asia and North Africa, but can currently be (DYCE et al., 2010). In addition, it enables an found in several oceanic islands and all continents, effective blocking of a given region in surgical except Antarctica (OLIVER; BRISBIN, 1993). procedures, and is crucial in clinical diagnosis Although in the same family, there are several (SCAVONE et al., 2007; IGLESIAS et al., 2012) differences between the wild boar and the domestic The brachial plexus is formed by a set of pig. In S. scrofa , there is presence of mane and long nerves with origin in the cervical and thoracic hairs, the length of the thoracic limbs is slightly segments of the spinal cord and is distributed in the larger than the hind limbs, and it is a higher and forelimb structures, scapular girdle, thorax and shorter animal (NOWAK, 1999). abdomen. In pigs, the brachial plexus is composed In the early twentieth century, S. scrofa of the ventral branches of the fifth (C5), sixth (C6), specimens were brought to Argentina with the seventh (C7) and eighth (C8) cervical spinal nerves purpose of serving as sport hunting, and some and the first thoracic (T1) spinal nerve (GOSHAL, animals just escaped and spread through Northern 1986c). Argentina, Uruguay and Southern Brazil Although there are reports on the wild boar (MIRANDA, 2003). As in other countries, in Brazil anatomy (NOCETTI et al, 2002; BOMBONATO et these invasive animals are causing environmental al., 2014), studies on the peripheral nerves of this and economic impacts (IBAMA, 2010). In recent animal species are scarcely explored. Thus, this years, there has been a considerable increase in the study aimed to analyze the origin and distribution of creation of these animals as an alternative in the the brachial plexus of wild boar ( S. scrofa ). food industry (GOMES et al., 2013). Received: 10/03/15 Biosci. J., Uberlândia, v. 31, n. 6, p. 1816-1825, Nov./Dec. 2015 Accepted: 10/06/15 1817 Origin and distribution… SANTOS, L. A. et al. MATERIAL AND METHODS plexus. To verify the distribution of the nerves, the dissection in regions of the scapular girdle, arm, A total of 12 young S. scrofa specimens, forearm, thorax and abdomen was performed. five males and seven females, belonging to the Data from the plexus origin were analyzed collection of the Laboratory of Animal Anatomy, descriptively in terms of simple percentage. The Federal University of Uberlândia, MG, Brazil, were study was approved by the Ethics Committee in used. The animals were fixed in 10% formalin Animal Experimentation of the Institution (103/13 solution through different points of subcutaneous, registration protocol, CEUA/UFU). The adopted intravenous, intramuscular, and intracavitary nomenclature to describe the anatomical structures injections, following by immersion of the specimens is according to the International Committee on in containers having the same solution. Veterinary Gross Anatomical Nomenclature (2012). The dissections began with the removal of skin and adipose tissue of the back and thoracic RESULTS regions at the level of the scapular girdle, through a median craniocaudal incision from the middle third The brachial plexus was originated from the of the neck to the xiphoid process of the sternum. ventral branches of the fifth (C5), sixth (C6), Next, the trachea, the esophagus and the muscles seventh (C7) and eighth (C8) cervical spinal nerves were doubled down to display the cervical and first and the first (T1) thoracic spinal nerve in all wild thoracic vertebrae, mainly the costal process of the boar specimens studied. Thus, the brachial plexus sixth cervical vertebra and the first rib, which are consisted of fourteen nerves with different origins important points of reference. In this manner, it was from C5 to T1 (Table 1 and Figure 1). possible to identify the formation of the brachial Table 1. Origin of the brachial plexus in wild boar ( Sus scrofa ). Nerve Origin % Subclavian C5 100 Suprascapular C5-C6-C7 83,4 C5-C6 16,6 Cranial subscapular C6-C7 100 Caudal subscapular C6-C7 66,6 C7-C8 33,4 Axillary C6-C7 71 C7-C8 29 Cranial pectoral C7-C8 100 Caudal pectoral C8-T1 75 C7-C8 25 Musculocutaneous C6-C7 62,5 C7-C8 25 C7-C8-T1 12,5 Median C7-C8-T1 50 C8-T1 50 Ulnar C8-T1 91,6 C7-C8-T1 8,4 Radial C7-C8-T1 100 Thoracodorsal C8-T1 69 C7-C8 31 Long thoracic C7-C8 75 C8-T1 25 Lateral thoracic C8-T1 100 C: cervical spinal nerve; T: thoracic spinal nerve. Biosci. J., Uberlândia, v. 31, n. 6, p. 1816-1825, Nov./Dec. 2015 1818 Origin and distribution… SANTOS, L. A. et al. V4 a C5 V5 c C6 b V6 d e f g C7 h V7 C8 i j k T1 l o n m Figure 1. Ventral view of the cervicothoracic region in wild boar ( Sus scrofa ). (V4-V7) fourth, fifth, sixth and seventh cervical vertebrae, (C5-C8) fifth, sixth, seventh and eighth cervical spinal nerves, (T1) first thoracic spinal nerve ( a), subclavian nerve, (b) suprascapular nerve (c) cranial pectoral nerve (d) subscapular cranial nerve, (e) caudal subscapular nerve (f) musculocutaneous nerve (g) axillary nerve, (h) median nerve, (i) ulnar nerve, (j) radial nerve, (k) caudal pectoral nerve, (l) thoracodorsal nerve, (m) lateral thoracic nerve (n) long thoracic nerve, (o) phrenic nerve. Regarding the distribution of the nerves, the supplies the skin and fascia. In the proximal region subclavian nerve supplied branches for the of forearm, the ulnar nerve distributed to the flexor subclavian muscle; the suprascapular nerve carpi ulnaris and superficial digital flexor muscles provided branches to the supraspinous and as well as to the humeral heads of the deep digital infraspinous muscles, while the cranial subscapular flexor muscle. nerve distributed only to the subscapular muscle. The radial nerve provided branches to the The caudal subscapular nerve delivered branches to three heads of the triceps brachii, the tensor fasciae both the subscapular and teres major muscles. antebrachii and the anconeus muscles; at the elbow The axillary nerve supplied branches to the joint, the radial nerve subdivided into deep and deltoid, teres minor and brachiocephalic muscles, superficial branches. In all specimens, the and ended as cranial cutaneous nerve of forearm, superficial branch of the radial nerve gave off the which innervates the skin of this region. The cranial lateral cutaneous nerve of forearm that innervates and caudal pectoral nerves distributed to the the fascia and skin. The deep branch of the radial superficial and deep pectoral muscles. Regarding nerve distributed to the extensor carpi radialis, the musculocutaneous nerve, it provided branches to common digital extensor, extensor carpi obliquus, the coracobrachial, brachial and biceps brachii lateral digital extensor and extensor carpi ulnaris muscles; at the proximal third of forearm, the muscles. musculocutaneous nerve gave off the medial The thoracodorsal nerve provided branches cutaneous branch of forearm, which innervates the to the latissimus dorsi muscle and, in some cases, fascia and skin of this region. The median nerve was branches directed to the teres major muscle were responsible for the innervation of the pronator teres, observed; the long thoracic nerve distributed to the flexor carpi radialis, superficial digital flexor thoracic ventral serratus muscle; the lateral thoracic (superficial and deep part), and deep digital flexor nerve gave off branches to the cutaneous muscle of (ulnar, two humeral and radial heads) muscles.