Grizzly Bear (Ursus
arctos horribilis)
The forelimb elbow lever shows a 3rd Order lever: the humerus and radius form the fulcrum; the biceps brachii muscle is contracting, pulling the ulna anteriorly; the forelimb is moving forward.
The hindlimb lever is 1st Order: the metatarsals and phalanges form the fulcrum; the gastrocnemus muscle is contracting, pulling the calcaneous heel bone upward; the hindfoot is pushing off the ground and moving back.
The forelimb elbow lever shows a 3rd Order lever: the humerus and radius form the fulcrum; the biceps brachii muscle is contracting, pulling the ulna anteriorly; the forelimb is moving forward.
The hindlimb lever is 1st Order: the metatarsals and phalanges form the fulcrum; the gastrocnemus muscle is contracting, pulling the calcaneous heel bone upward; the hindfoot is pushing off the ground and moving back.
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The forelimb lever has a VR around 5/1; the hindfoot lever has a VR around 1 (much slower foot than an ungulate, but probably very powerful).