Gross anatomy of the shoulder and arm intrinsic muscles in the white‐footed tamarin (Saguinus leucopus – Günther, 1876): Inter‐ and intraspecific anatomical variations

Abstract

Background Saguinus leucopus is a Neotropical primate with an arboreal quadrupedal locomotion pattern, which requires wide movements of the shoulder and arm. This investigation studies the muscles of these regions in order to serve as a basis for clinical and surgical procedures and to compare with other primates. Methods Gross dissections of twenty thoracic limbs were performed. Results The muscles examined were the deltoid, supraspinatus, infraspinatus, subscapularis, teres major, teres minor, coracobrachialis longus, coracobrachialis brevis, biceps brachii, brachialis, triceps brachii, tensor fasciae antebrachii, and anconeus epitrochlearis. The anconeus was absent. The following variants were found: an accessory head of the biceps brachii, the unilateral absence of the short head of the biceps brachii, an accessory head of the coracobrachialis longus, and one infraspinatus muscle innervated by the axillary nerve. Conclusions These muscles are adapted to quadrupedal locomotion and can have inter‐ and intraspecific variations in their attachments and innervation.

Gross anatomical description of the extrinsic and intrinsic scapular and brachial muscles of Sapajus apella (Linnaeus, 1758)

“…On the contrary, the origin of the acromialis part agrees with that reported in most of the primate species described above 28,34,47,53,56–59 . The origin of the pars clavicularis from the lateral two thirds of the clavicle agrees with that described in C. goeldii , 60 G. senegalensis , 45 S. oedipus , S. sciureus , 57 L. catta , P. verreauxi , 61 and S. leucopus 28 . The variant origin from the entire clavicle of S. apella has been reported as a common origin in Papio sp 50 .…”

“…The connection with the aponeurosis of the m. infraspinatus found in these species is reported in Hylobates sp., 34 S. sciureus , S. oedipus , 57 and S. leucopus , 28 whereas in H. s. sapiens , this connection is a variant 21 . On the contrary, the origin of the acromialis part agrees with that reported in most of the primate species described above 28,34,47,53,56–59 . The origin of the pars clavicularis from the lateral two thirds of the clavicle agrees with that described in C. goeldii , 60 G. senegalensis , 45 S. oedipus , S. sciureus , 57 L. catta , P. verreauxi , 61 and S. leucopus 28 .…”

“…The origin of the pars scapularis from the ventral third of the scapula and m. infraspinatus of S. apella was similar to that reported in other platyrrhine species, such as Ateles sp., 56 Saimiri sciureus , S. oedipus , 57 S. leucopus , 28 C. libidinosus , 53 C. albifrons , 58 and some catarrhines as Hylobates sp., 34 Gorilla , P. troglodytes , and P. pygmaeus 47 . The connection with the aponeurosis of the m. infraspinatus found in these species is reported in Hylobates sp., 34 S. sciureus , S. oedipus , 57 and S. leucopus , 28 whereas in H. s. sapiens , this connection is a variant 21 . On the contrary, the origin of the acromialis part agrees with that reported in most of the primate species described above 28,34,47,53,56–59 .…”

“…This species is also a victim of different accidents in its habitats, mainly due to human colonization 27 . Therefore, this study may not only contribute to providing medical‐surgical bases for the affected species, but it can also contribute to the conservation of this species, providing anatomical bases for establish a more suitable medical rehabilitation 28 . For this reason, this investigation aimed to characterize the gross anatomy of the extrinsic and intrinsic scapular and brachial muscles in S. apella .…”

Evolutionary adaptations in the flexor digitorum profundus muscle in Tamandua mexicana (Xenarthra, Myrmecophagidae)

“…In the arm, the radial nerve innervates all heads of the triceps brachii, anconeus, and tensor fasciae antebrachii muscles, whereas the ulnar nerve only innervates the anconeus epitrochlearis (AE) muscle when it is present, as observed in certain nonhuman primates (Diogo & Wood, 2012; Howell & Straus, 1932; Monroy‐Cendales, Vélez‐García, & Castañeda‐Herrera, 2020; Schultz, 1984), the domestic cat ( Felis catus ) (named as “ M. epitrochleoanconaeus ” by König, 1992; named as “anconé médial” by Barone, 1982), and rabbit ( Oryctolagus cuniculus ) (Barone, 1982). Even when the AE is present in the form of an anatomical variant, it is innervated by the ulnar nerve, similar to that in humans (Dellon, 1986) and in the crab‐eating fox ( Cerdocyon thous ) (Vélez‐García, Patiño‐Holguín, & Duque‐Parra, 2018).…”