AKC STANDARD:

Clarification: The head wrinkles are important to the breed's typical expression. The wrinkles of the fore head should be deep and, in fans, set off by a darkening within the folds of the wrinkles. Wrinkles can, however, conceal an incorrect skull shape. To properly judge the head, the lead should be dropped so the head is up naturally and the bone structure can be examined more easily. The surplus skin under the throat and around the faceform a large fold and ruff.

Correct head and skull	Correct head and skull at repose
CORRECT ROUND HEAD The nose is set approximately level with the jaws.Firm lipline,thick cushion under eyes and deep underjaw. this muzzle would have the correct bite. Wrinkles do not disguise the round broad skull and full cheeks.	INCORRECT RECTANGULAR Eyes are set above the nose pad. Muzzle falls away under the eyes. Muzzle is lippy and may cover a narrow or shallow underjaw. This head type often conceals a length of nose and a scissors bite. Wrinkles disguise a narrow skull and a lack of flesh in the cheeks.This dog aso lacks black pigment. Ears are large with thick leathers and hang well below the eyes.