This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Which of the following muscle is spared when radial nerve is injured in the radial groove? 
Select and explain. 
A. Long head of triceps, B. Medial head of triceps, C. Lateral head of triceps, D. Anconeus
A: Long head of triceps
Answer: A: Long head of triceps 
Explanation: Long head of triceps is supplied by radial nerve before entering the radial groove. Medial head of triceps is supplied by the radial nerve before entering and while in the spiral groove. Lateral head of triceps is innervated by the radial nerve while in the groove.