Whereas superficial flexors in the anterior compartment of the forearm originate from the medial epicondyle of the humerus, the superficial extensors in the posterior compartment of the forearm originate from the lateral epicondyle of the humerus.
Explanation:
The forearm has 2 compartments: an anterior compartment responsible for the flexion of the wrist, and a posterior compartment with the function to extend the wrist.
The superficial muscles in the anterior compartment arise from the common flexor tendon that originates from the medial epicondyle of the humerus. This compartment is mostly innervated by the median nerve.
The superficial muscles in the posterior compartment originate from the lateral epicondyle of the humerus and are innervated by the radial nerve.
The ulnar nerve innervates the flexor carpi ulnaris and flexor digitorum profundus in the forearm.
This is because the basketball is the bigger object here so that should represent something bigger like the solar system. Then the tennis ball would represent earth because it is the smaller object here.