Congressman Weiner has a squared off jaw line. This bony feature is the result of over development of the masseter muscles. The masseter muscles are very prominent in bruxers. Most notably a person who clenches their teeth tightly or chews gum excessively can develop these muscles.
|A weight lifter clenching|
|Close-up of clenching|
|Feeling (palpating) the masseter muscle.|