Can a pinched nerve in the neck cause facil and scalp tingles and numbness to the touch as with the feet and legs? Will the emg test figure this out?

Numbness. An upper cervical nerve problem can cause posterior scalp numbness. Facial numbness is due to either a cranial nerve or brain. Tingling and numbness in face, scalp, and legs without arms involved is unusual but can be caused by what is call a peripheral neuropathy. An electrodiagnostic test involving nerve conduction and EMG may be quite helpful in determining what and how nerves are effected.
Clarification. Usually the cervical nerves will cause numbness in hands/legs/occassionally headaches/neck pain. If are having facial/scalp tingling it may be some cranial nerves/ else more systemic. If it is troubling you. You should speak to your primary M.D.
Scalp tingles. Facial tingles? Unlikely. Back of the scalp and feet? Possibly. Would recommend seeing a neurologist and depending on clinical findings, order an mri? Do you have an MRI already? A high cervical disc that presses both the nerves in the neck and the spinal cord might cause this but that would be uncommon.
No. The nerves in your face do not originate in the cervical spine. They originate from your brain. An EMG will help tell why you have numbness in the feet and legs though.