it actually is the inferior rectus that is trapped.. the reason you can't look up is b/c the inferior rectus is stuck. Think of it like if you have a rope attached to the bottom of the object and one attached to the top, if the bottom rope gets stuck you can't pull the object upwards. Hope that makes sense haha! Its confusing though b/c i know what you're thinking is that if the inferior rectus is stuck its not going to work but thats not exactly whats happening