Question: what is the origin and insertion of the triceps brachii?
Answer: Origin of the Triceps Brachii The lateral head originates from the back surface of the humerus, just above the radial groove. The long head originates from the infraglenoid tubercle of the scapula. The glenoid cavity is a round, concave portion of the scapula where the head of the humerus meets with the scapula.