Sorry to hear that your face has been twitching throughout the day. I get the impression that this is a new phenomenon, and that it hasn't been going on for some time. If this has been going on for a long time, or if it seems to be getting worse over time, I would recommend getting evaluated by a physician. A muscle twitch can be anything from a simple single muscle fiber twitching on its own, to an entire muscle group twitching that it innervated by a motor nerve fiber. Most of the time an isolated muscle twitching is not pathologic (meaning that something bad is going on), but when twitching becomes regular, or more diffuse, it can be a sign of a neurologic disorder. There are many potential causes for twitching. I mentioned a neurologic disorder, but many more common and "less serious" causes include: stress, anxiety
, too much stimulant (such as caffeine), a side effect of a prescription medication, or just a benign twitch (that doesn't have a known cause). Some think that irritation of a motor nerve is what causes the motor unit twitches to occur, but there is not universal agreement on this. To answer your third question, I can think of no reason why your veins would be causing twitching in your face. If it continues, and it is bothersome to you, I would recommend getting evaluated by your primary care physician
. Best of luck.