This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ocular motility and squint, Subject name: Ophthalmology
Distance of medial rectus from limbus - 
Select and explain. 
A. 4.5 mm, B. 5.5 mm, C. 7.0 mm, D. 10 mm
B: 5.5 mm
Answer: B: 5.5 mm 
Explanation: Rectus muscles originate from a common tendinous ring- the annulus of Zinn, which is attached to the apex of the orbit. Different distances from limbus are - >>medial rectus : 5.5 mm >>inferior rectus: 6.5mm >>lateral rectus : 6.9mm >>superior rectus:7.7mm Ref;A.K.Khurana; 6th edition; Page no:336