Dorsal interossei of the foot Dorsal interossei of the foot In human anatomy, the dorsal interossei of the foot are four muscles situated between the metatarsal bones. The four interossei muscles are bipenniform muscles each originating by two heads from the proximal half of the sides of adjacent metatarsal bones. The two heads of each muscle form a central tendon which passes forwards deep to the deep transverse metatarsal ligament. The tendons are inserted on the bases of the second, third, and fourth proximal phalanges and into the aponeurosis of the tendons of the extensor digitorum longus without attaching to the extensor hoods of the
Vancleavea parts of the hand. The second metacarpal is longer, and the third and fourth are tied for the longest bones of the hand. Unguals (claws) have not been found, and the rounded ends of certain phalanges indicates that "Vancleavea" likely did not possess them. As with other reptiles, each hip of "Vancleavea" is formed by three plate-like bones: the illium (above the hip socket), the pubis (in front of the hip socket), and the ischium (behind the hip socket). The illium of "Vancleavea" is particularly unusual. Most archosauriforms have illia which are somewhat low, directed from front to back (anteroposteriorly).