muscular branches of the radial nerve muscular branches of the radial nerve the muscular branches of the radial nerve supply the triceps brachii, anconæus, brachioradialis, and extensor carpi radialis longus, and are grouped as medial, posterior, and lateral. muscular branches of the radial nervethe suprascapular, axillary, and radial nerves.superficial palmar nerves.detailsfromradial nerveinnervatesposterior compartment of the arm, mobile wadidentifierslatinrami musculares nervi radialista98a14.2.03.053ta26435fma44954anatomical terms of neuroanatomy medial the medial muscular branches supply the medial head of the triceps brachii. that to the medial head is a long, slender filament, which lies close to the ulnar nerve as far as the lower third of the arm, and is therefore frequently spoken of as the ulnar collateral nerve. posterior the posterior muscular branch, of large size, arises from the nerve in the groove between the triceps brachii and the humerus. it divides into filaments, which supply the medial and lateral heads of the triceps brachii and the anconæus muscles. the branch for the latter muscle is a long, slender filament, which descends in the substance of the medial head of the triceps brachii. lateral the lateral muscular branches supply the brachioradialis, extensor carpi radialis longus, and the lateral part of the brachialis.