Due to the presence of the radius in Tetrpodomorph fish this element is not inherently linked to the presence of digits or flexor musculature. The corresponding bone in the posterior fin/limb is the tibia.[Phenoscape]. In four-legged animals, the radius is the main load-bearing bone of the lower forelimb. Its structure is similar in most terrestrial tetrapods, but it may be fused with the ulna in some mammals (such as horses) and reduced or modified in animals with flippers or vestigial forelimbs [ISBN:0-03-910284-X]

One of the two long bones of endochondral origin of the fore-epipodium; it is located on the lateral side of the ulna. Its upper end articulates with both the humerus and the ulna, whereas the lower articulates with the carpals.[AAO]

uberon

UBERON:0001423

• radio-ulna

• radio-carpal joint
• radio-ulnar joint
• humeroradial joint

• biceps brachii

• radius pre-cartilage condensation

• diaphysis of radius
• metaphysis of radius
• epiphysis of radius
• epiphyseal plate of radius