The ridge may extend from the hairline to the glabella or may be partial. The frontal suture of the skull is a dense connective tissue structure that divides the two halves of the frontal bone of the skull in infants and children and usually undergoes closure by the age of six years. A persistent frontal suture is known as a metopic suture or sutura frontalis persistens. This can lead to a ridged appearance of the forehead.