The Intrinsic Muscles of the Hand in the Slender Loris

SUMMARY The intrinsic muscles of the hand have been described in Loris and a comparison is made with the palmar musculature in Nycticebus and in the Potto. The presence of flexores breves superficiales has been noted for the first time among primates and the morphological significance of the muscle is discussed. The thenar and hypothenar muscles are poorly differentiated in Loris and the separation of the different components is very often artificial. There is only a single contrahentis in Loris while the full complement is present in Nycticebus. The deep branch of the ulnar nerve dominates not only in the muscular supply but even in the sensory distribution of the palm in Loris.