The misshapen heads described in the Mishnah are examples of craniosynostosis. In the course of the development of a child’s head, the skull is made up of a number of bones with spaces between them, allowing them to grow. In normal development, as each of these bones grows, they ultimately fuse together forming a skull of normal size, proportion and shape. Craniosynostosis is a condition in which one or more of the fibrous sutures in an infant skull fuses prematurely by ossification, thereby changing the growth pattern of the skull. Because the skull cannot expand perpendicular to the fused suture, it compensates by growing more in the direction of the open areas between the bones. Sometimes the resulting growth pattern provides the necessary space for the growing brain, but results in an abnormal head shape and abnormal facial features.