system
Given the following post, respond as if you're commenting on Reddit:
human
What's the point of the obturator foramen?

The obturator foramen has always confused me.

For those of you who are unfamiliar with the obturator foramen, its a hole ("foramen") that is for the most part blocked ("obstructed") of by muscle.

My question is, what is the functional purpose of a big foramen that is mostly covered by muscle?  Is this an embryological remnant from development?  Or is there an evolutionary reason?

Why would the body develop a hole just to cover it up?  Why not make a small hole to begin with?  

The only thing I could think of would be to make the hip less dense, but I think some development reason might be more plausible.

Thanks for the help!
gpt
Try thinking about it from the opposite perspective. Evolution does not create solid sheets of bones as a default and then remove parts or create spaces for a "point" (Ignoring things like foramen in the skull that are formed due to the nervous system forming before the skull is mineralized). The shape of the pelvis is the result of life forms slowly adding bony structure where they needed anchor points for muscle or protection of vital organs. 

So the question is not why is there no bone in the obturator foramen; it is Why did the cartilage mineralize (become bone) in the places in did in the pelvic region? And the general answer is that was the best ratio of structural support for mobility, extra weight added,  and energy/minerals used to create the bone.