92 - Muscular Anatomy of the Tiger Hindlimb

Poster Board Number: 92
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Abstract Body : Knowledge of the comparative muscular anatomy of living mammals is crucial to the reconstruction of behavior in fossil species. Further, because most fossils consist only of bones, detailed documentation of the bony origin and insertion of muscles is especially important to accurately place muscles onto fossils for functional analysis. Whereas the muscular anatomy of the forelimb of felids has received more attention due to the use of the forelimb for prey capture and manipulation, the muscular anatomy of the hindlimb has received less attention in the scientific literature. This is due in part to the fact that it functions mainly in generating propulsive force associated with locomotion and lacks secondary manipulative functions. Additionally, because cats have been shown to be morphologically conservative in many ways, including limb proportions and posture, most researchers make the assumption that the hindlimb musculature is similarly conserved. As a result, there is a lack of documentation of basic muscular anatomy of the hindlimb in felids, which leads to a lack of understanding of potential interspecific variation that may be functionally relevant. Further, recent studies describing felid hindlimb musculature tend to focus on certain regions of the hindlimb (e.g., the hip, knee, etc.) and neglect the rest, and consequently some regions of the hindlimb, such as the hip, are better documented than others, such as the ankle. Currently, there are no muscle maps documenting the muscle attachments for the hindlimb of any pantherine felid.
The goal of this study was to create a muscle map of the origins and insertions and describe the muscles of the hindlimb of the tiger (Panthera tigris). We dissected the right hindlimb of an 18-year-old female Amur tiger that died at the Blank Park Zoo in Des Moines, IA. We used photographs and written notes to document the bony and soft tissue origin and insertion of all muscles present, and compared our muscle maps and descriptive anatomy to those of other cats. Overall the bony origins and insertions are fairly similar in the tiger to other felids, however, there were a few notable differences, including fusion of m. piriformis to m. gluteus medius, m. vastus lateralis originating from two heads on either side of the insertion of m. gluteus profundus, m. fibularis longus with a secondary attachment to the medial base of Mt V, the presence of two abductor muscles of digit V, one to the proximal phalanx (m. abductor digiti V) and one to the base of metatarsal V (m. calcaneometatarsalis), and the presence of two muscular bellies of m. flexor brevis profunda to digit I. Dissection of the left hindlimb will provide further insight into the variability of tiger hindlimb musculature.