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
Inferior rectus muscle characteristics is: 
Select and explain. 
A. Inseion- 6.5 cm behind limbus, B. Lies inferior to inferior oblique muscle, C. Main depressor when adducted, D. All
A: Inseion- 6.5 cm behind limbus
Answer: A: Inseion- 6.5 cm behind limbus 
Explanation: - All extraocular muscles (all recti, superior oblique & lavatory palpebrae superioris) except inferior oblique arise from apex of orbitQ. Inferior rectus muscle originate from inferior edge of common tendinous ring (annulus of Zinn). It courses anteriorly, laterally and downwards along the orbital floor to inse on sclera anteriorly about 6.5 cm behind the limbusQ. Inferior rectus muscle courses between the eye ball and inferior oblique muscle (which passes beneath i. e. inferior to inferior rectus)Q prior to its inseion. Failure to dissect fascial attachments b/w inferior rectus, inferior oblique and lower rid retractors during IR recession or resection may 1/ eyelid fissure widening or narrowing, respectively.