This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Upper limb, Subject name: Anatomy
The supinator muscle is supplied by 
Select and explain. 
A. Ulnar nerve, B. Anterior interosseous nerve, C. Median nerve, D. Posterior interosseous nerve
D: Posterior interosseous nerve
Answer: D: Posterior interosseous nerve 
Explanation: SupinatorOrigin1.Lateral epicondyle of the humerus. 2.Radial collateral ligament of the elbow joint. 3.Annular ligament. 4.Supinator crest of the ulna, and the posterior pa of the triangular area in front of it.Inseion: Upper one-third of the lateral surface of the radius.Nerve Supply: Posterior interosseous nerve (C6, C7).Action: Supination of the forearm.Note: The muscles have two layers, superficial and deep. The posterior interosseous nerve runs downwards between these layers.Ref: BD Chaurasia; Volume 1; 6th edition; Page no: 133