The tricepsbrachii is the chief antagonist of the biceps brachii.
2
Cervical spinal lesions at C6 result in paralysis of the tricepsbrachii while leaving deltoid and elbow flexor function intact.
3
Flexion of this, the humeroradioulnar joint (elbow), is restrained by the tricepsbrachii and extension is checked by the biceps brachii (flexor brachii).