Fetal head

The fetal head is a critical structure in obstetrics because its size and shape must adapt to the maternal bony pelvis during labor. The skull consists of two frontal, two parietal, and two temporal bones, along with the upper occipital bone and the wings of the sphenoid. These bones are separated by membranous sutures, including the frontal, sagittal, coronal, and lambdoid sutures. Where sutures meet, fontanels form; the anterior fontanel is lozenge-shaped at the junction of the sagittal and coronal sutures, while the posterior fontanel is triangular at the intersection of the sagittal and lambdoid sutures.

The localization of these fontanels provides information about fetal presentation and position. The bones are connected by fibrous tissue that allows shifting during labor, a process called molding. The degree of skull ossification and head position influence cranial plasticity, and in some cases contribute to fetopelvic disproportion, a leading indication for cesarean delivery.