Margo lateralis humeri

The lateral border runs from the back part of the greater tubercle to the lateral epicondyle, and separates the anterolateral from the posterior surface.

Its upper half is rounded and indistinctly marked, serving for the attachment of the lower part of the insertion of the teres minor muscle, and below this giving origin to the lateral head of the triceps brachii muscle; its center is traversed by a broad but shallow oblique depression, the spiral groove (musculospiral groove).

The radial nerve runs in the spiral groove.

Its lower part forms a prominent, rough margin, a little curved from backward, forward the lateral supracondylar ridge, which presents an anterior lip for the origin of the brachioradialis muscle above, and extensor carpi radialis longus muscle above, a posterior lip for the triceps brachii muscle, and an intermediate ridge for the attachment of the lateral intermuscular septum.