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
Mastoid process is which type of epiphysis: 
Select and explain. 
A. Pressure, B. Aberrant, C. Atavistic, D. Traction
D: Traction
Answer: D: Traction 
Explanation: Traction epiphysis are present at the ends of bones and develop due to traction by the attached muscles (and are therefore extracapsular).
Mastoid process is produced due to the traction by the sternocleidomastoid muscle.