ANATOMIA ÓSSEA E MUSCULAR DA ESCAPULA E BRAÇO DE Chrysocyon brachyurus (CARNÍVORA, CANIDAE)

Five-headed triceps brachii muscle, with an unusual communication between the musculocutaneous and median nerves in a cross-breed dog cadaver: a case report

In the domestic dog, the medial head (caput mediale) of the triceps brachii muscle arises via a distinct tendon from the crest of the lesser tubercle and the accessory head (caput accessorium) from the proximal caudal part of the neck of the humerus. Here the author presents a previously unreported additional point of origin of the triceps brachii muscle on both antimeres of an adult male cross-breed domestic dog cadaver. The variant head arose via fleshy fibers from the medial aspect of the neck of the humerus, just caudal to the lesser tubercle and fused at insertion with the caudal aspect of the proximal half of the medial head. Thus, it can simply be considered as the second accessory head of the triceps brachii muscle. The radial collateral artery on the left limb passed distolaterally between the medial and variant heads, whereas it passed caudal to the variant head on the right limb. The communicating branch between the musculocutaneous and median nerves extended in both directions on the left brachium. Besides a potential clinical significance, knowledge of this variant can be useful in understanding the embryogenic and phylogenetic perspectives.

Anatomy of the thoracic limb muscles of wild boars (Sus scrofa, Artiodactyla: Suidae)

The study of the muscular anatomy of wild boar (Sus scrofa) is important, because it allows the understanding of the locomotor and evolutionary aspects, besides the improvement of surgical techniques used by veterinarians in swine. Thus, the objective of this study was to describe the morphology and disposition of the shoulder and arm muscles of S. scrofa. Twelve young specimens of hybrid S. scrofa, six males and six females were fixed and dissected following usual anatomy techniques. The bones of two specimens were prepared to analyze the fixation points of the muscles. The shoulder muscles presented fixation at the scapula and humerus, in distinct bone accidents, and were divided on lateral and medial faces. On the lateral face, the deltoid (divided in acromial and scapular parts), supraspinatus, infraspinatus (divided in cranial and caudal parts) and teres minor (deep to the caudal part of the infraspinatus) muscles were found. In the medial face, the subscapular, coracobrachialis and teres major muscles were observed. The arm muscles were arranged essentially around the humerus and were seen largely on its medial face, namely biceps brachii (originated by a single tendon), brachialis, tensor fasciae antebrachii (fused with the long head of the triceps brachii), triceps brachii (divided in lateral, long and medial heads) and anconeus (located mostly on the lateral side) muscles. Thus, it can be concluded that the S. scrofa presented seven muscles in the shoulder region and six muscles in the arm region, all with morphological similarities to domestic and some wild animals. Some differences were found, for the most part, in the shape, division and fixation points of certain muscles.

Functional myology of the thoracic limb in Pampas fox (Lycalopex gymnocercus): a descriptive and comparative analysis

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.

Radiographic determination of pelvic limb orthopaedic measurements in maned wolf (Chrysocyon brachyurus)

The aim of this study was to determine some radiographic reference values for hip joint, femur and patella in maned wolves. Ten maned wolves (Chrysocyon brachyurus), five live (G1) and five cadavers (G2), were used. There were no statistically significant differences in the radiological measurements between right and left pelvic limbs of the G1 and G2, except for mechanical lateral proximal femoral angle (mLPFA) in both Groups. The comparison of the measurements between Groups showed difference only for mechanical lateral distal femoral angle (mLDFA). Norberg angle values were 113.1° and 112.9° for G1 and G2. The values of femoral angle of inclination by Hauptman A and Hauptman B methods were 139.7° and 128.6° for G1, and 139.3° and 128.7° for G2. Femoral varus angle values were 5.5° for G1 and 3.9° for G2. The values of anatomic lateral distal femoral angle and anatomic lateral proximal femoral angle were 96.8° and 95.2° for G1, and 95.0° and 95.6° for G2. The values of mLDFA for G1 and G2 were 96.5° and 95.7°. The values of mLPFA were 95.8 (right) and 93.5 (left) for G1, and 95.7 (right) and 93.8 (left) for G2. The values of patellar ligament length, patellar length and L:P ratio were 4.6, 2.4 cm and 1.9 for G1, and 4.4, 2.3 cm and 1.8 for G2. In conclusion, the radiographic reference values described for the hip joint, the femur and the patella, may be useful in the diagnosis of diseases and deformities in maned wolves.