Muscular anatomy of the forelimb of tiger (Panthera tigris)

Abstract

Dissection reports of large cats (family Felidae) have been published since the late 19th century. These reports generally describe the findings in words, show drawings of the dissection, and usually include some masses of muscles, but often neglect to provide muscle maps showing the precise location of bony origins and insertions. Although these early reports can be highly useful, the absence of visual depictions of muscle attachment sites makes it difficult to compare muscle origins and insertions in living taxa and especially to reconstruct muscle attachments in fossil taxa. Recently, more muscle maps have been published in the primary literature, but those for large cats are still limited. Here, we describe the muscular anatomy of the forelimb of the tiger (Panthera tigris), and compare muscle origins, insertions, and relative muscle masses to other felids to identify differences that may reflect functional adaptations. Our results reiterate the conservative nature of felid anatomy across body sizes and behavioral categories. We find that pantherines have relatively smaller shoulder muscle masses, and relatively larger muscles of the caudal brachium, pronators, and supinators than felines. The muscular anatomy of the tiger shows several modifications that may reflect an adaptation to terrestrial locomotion and a preference for large prey. These include in general a relatively large m. supraspinatus (shoulder flexion), an expanded origin for m. triceps brachii caput longum, and relatively large m. triceps brachii caput laterale (elbow extension), as well as relatively large mm. brachioradialis, abductor digiti I longus, and abductor digiti V. Muscle groups that are well developed in scansorial taxa are not well developed in the tiger, including muscles of the cranial compartment of the brachium and antebrachium, and m. anconeus. Overall, the musculature of the tiger strongly resembles that of the lion (Panthera leo), another large‐bodied terrestrial large‐prey specialist.

Craniolateral forearm muscles of the crab-eating raccoon (Procyon cancrivorus) and a comparative review with other carnivorans

“…In ursids, it can also have two heads similar to Ailurus, such as Ursus maritimus (Kelley, 1888) and Ailuropoda melanoleuca (Davis, 1964), whereas Ursus americanus only has one head from the lateral supracondylar crest (Haughton, 1864;Shepherd, 1883). The origin of the m. brachioradialis in felids reaches the middle third of the humerus (Julik et al, 2012;Concha et al, 2004;Viranta et al, 2016;Vargas et al, 2017;Ari et al, 2019;Dunn et al, 2022), however, it could originate from the proximal third in Panthera and Leopardus (Barone, 1967;Sánchez et al, 2019;Smith et al, 2021) or only from the lateral supracondylar crest in Caracal, Acynonyx and Leopardus (Beswick-Perrin, 1871;Hudson et al, 2011;Souza-Junior et al, 2015). Carnivorans present few variants in the insertion of m. brachioradialis, however, there are some differences, such as in herpestids (Ichneumia albicauda and Herpestes ichneumon), since the m. brachioradialis inserts onto the cranial surface of the distal extreme of the radius (Taylor, 1976); in Ailurus it also inserts onto the m. pronator teres (Fisher et al, 2009); in Leopardus pardalis, Leopardus.…”

“…In Ailurus both muscle bellies are only separated on the middle of the forearm, but both can be completely separated as an anatomical variant (Fisher et al, 2009). In felids, it was divided into two muscles (Concha et al, 2004;Icvgan, 2017;Sánchez et al, 2019;Dunn et al, 2022), but both muscle bellies can be fused proximally in Felis catus (Barone, 1980), L. pardalis (Julik et al, 2012), Panthera leo (Barone, 1980;Vargas et al, 2017), Panthera uncia (Smith et al, 2021), Panthera tigris (Dunn et al, 2022), and L. lynx (Ari et al, 2019); even the brevis belly may be fused with the m. extensor digitorum communis in L. pardalis (Julik et al, 2012). Although, in P. leo both muscles were reported independently, similar to that described in the hyaenid Hyena hyaena and the herpestid H. auropunctatus (Böhmer et al, 2020).…”

“…In canids, it originates from the lateral epicondyle (Vaz et al, 2011;Hermanson, 2013;Souza-Junior et al, 2018;Liebich et al, 2020;Smith et al, 2020), however it also originates from the intermuscular septum with the m. extensor carpi radialis and antebrachial fascia in Canis lupus familiaris (Hermanson et al, 2013) and also from the articular capsule of the elbow in Cerdocyon thous (Echeverry et al, 2015). In most felids, it originates from the lateral epicondyle, while in some species it originates from the lateral supracondylar crest, such as in L. pardalis (Julik et al, 2012), A. jubatus (Hudson et al, 2011;Nazem et al, 2017), P. leo (Barone, 1967;Vargas et al, 2017), P. uncia (Smith et al, 2021), and P. tigris (Dunn et al, 2022). In L. lynx, the muscle can originate from the lateral epicondyle of the humerus (Viranta et al, 2016) and lateral supracondylar crest (Ari et al, 2019), and it also has other origins either from the lateral margin of the radius (Viranta et al, 2016), or from the ulna and olecranon (Ari et al, 2019), which is uncommon in carnivorans.…”

“…In felids, it originates from the lateral epicondyle (Beswick-Perrin, 1871; Barone, 1986;Concha et al, 2004;Hudson et al, 2011;Nazem et al, 2017;Viranta et al, 2016;Vargas et al, 2017;Smith et al, 2021;Dunn et al, 2022), or the lateral supracondylar crest (Julik et al, 2012;Sánchez et al, 2019;Liebich et al, 2020), however in L. pardalis it also originates from the m. supinator (Julik et al, 2012). On the other side, the muscle sends tendons to the digits III to V in all felids (Beswick-Perrin, 1871; Barone, 1986;Concha et al, 2004;Hudson et al, 2011;Julik et al, 2012;Nazem et al, 2017;Viranta et al, 2016;Vargas et al, 2017;Ari et al, 2019;Sánchez et al, 2019;Böhmer et al, 2020), although in F. catus, it can also extend a tendon to the digit II (Barone, 1980;Liebich et al, 2020), similar to L. pardalis (Julik et al, 2012) and P. tigris (Dunn et al, 2022). In herpestids, viverrids, and hyaenids, it originates from the lateral epicondyle (Devis, 1868;Watson & Young, 1879;Watson, 1882;Taylor, 1976;Spoor & Badoux, 1986), and extends tendons to the digits IV-V (Devis, 1868;Watson & Young, 1879;Watson, 1882;Spoor & Badoux, 1986;Böhmer et al, 2020).…”

“…In L. lynx, it can also originate from the ulna and insert onto the extensor retinaculum (Viranta et al, 2016), but does not insert onto the accessory carpal bone (Viranta et al, 2016;Ari et al, 2019). In P. uncia and P. tigris, it does not insert onto the accessory carpal bone (Smith et al, 2021;Dunn et al, 2022), but in P. tigris, it inserts onto the accessory carpal ligament ("pisometacarpal ligament" Dunn et al, 2022). In viverrids of the genus Genetta, it also originates from the ulna (Taylor, 1976).…”