The human skull is made of 29 bones, connected most often by ligaments and a movable temporomandibular joint (articulatio temporomandibularis). The bones of the skull, which make up the brain (neurocranium) and facial part (splanchnocranium), are divided into even and odd ones. Temporal bones compose the brain part. It is a highly pneumatized bone. Inside, there is a bone labyrinth, which is an organ of hearing and balance. This bone, and more precisely the mastoid process, is an element of sex diagnostics. On both sides of the skull, there are two lateral fontanelles on both sides of the child's skull, also called the sphenoid (fonticulum sphenoidalis) and mastoid (fonticulum mastoideus) bones. The sphenoid bone is located between the parietal, temporal and frontal bones. In contrast, the mastoid bone is located between the temporal, parietal and scales of the occipital bone. Both of these fontanelles become overgrown in utero.