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Anatomy and function are usually closely related. Since locomotion on tree branches is common among mammals, we expect to find that the anatomy of the hands and feet is well-suited toward gripping narrow, cylindrical, branch-like substrates. We hypothesize that the ability of rats to grip arboreal supports relies on musculature responsible for adducting the first digit (thumb and big toe) and opposing medial-most and lateral-most digits. We dissected the hands and feet of four rat cadavers. There is a substantial muscle that may be responsible for the flexion/adduction of the thumb in the hands. We also found lumbricals, and dorsal and palmar interossei. These muscles are responsible for flexing metacarpophalangeal joints as necessary for gripping, or for adducting digits. Foot anatomy looked very similar to that of the hands. Based on the anatomy alone, rats are built for locomotion across cylindrical branches as well as terrestrial substrates. We trained four live rats to walk on cylindrical trackways, 2 cm and 1 cm in diameter. We videotaped these rats as they walked on the branch-like supports so that we could determine how they use their hands and feet to grip. We are still in the process of processing the data collected.

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Animal Sciences | Kinesiology | Life Sciences | Motor Control


Student Researcher: Jessica E. Fonce

Faculty Advisor: Andrew R. Lammers

Functional Morphology of Rat Hands and Feet: Correlation with the Ability to Grip Tree Branches During Locomotion