The phrase "upper forearm" refers to the portion of your arm between your elbow and wrist, closer to the elbow.
Sentences with «upper forearm»
You can also do hammer curls, as they target the upper forearms. (fitnessandpower.com)
The long and the short head converge to form a single muscle which at the lower end is attached to the upper forearm at the radius bone. (fitnessandpower.com)
Both heads arise on the scapula and form a single muscle belly attached to the upper forearm. (myobuddy.com)