The head should be long in proportion to the overall length and size of the dog. In profile, the skull and muzzle should give the appearance of two parallel planes. The skull should be long and of medium width, slightly domed and covered with short, hard hair. In profile, the skull should appear flat. There should be a slight but definite stop between the skull and muzzle at eye level, allowing the eyes to be set in under the brow, contributing to proper Scottish Terrier expression. The skull should be smooth with no prominences or depressions and the cheeks should be flat and clean. The muzzle should be approximately equal to the length of skull with only a slight taper to the nose. The muzzle should be well filled in under the eye, with no evidence of snippiness. A correct Scottish Terrier muzzle should fill an average man’s hand. The nose should be black, regardless of coat color, and of good size, projecting somewhat over the mouth and giving the impression that the upper jaw is longer than the lower. The teeth should be large and evenly spaced, having either a scissor or level bite, the former preferred. The jaw should be square, level and powerful. Undershot or overshot bites should be penalized. The eyes should be set wide apart and well in under the brow.
They should be small, bright and piercing, and almond-shaped not round. The color should be dark brown or nearly black, the darker the better. The ears should be small, prick, set well up on the skull and pointed, but never cut. They should be covered with short velvety hair. From the front, the outer edge of the ear should form a straight line up from the side of the skull. The use, size, shape and placement of the ear and its erect carriage are major elements of the keen, alert, intelligent Scottish Terrier expression.