This obstetrical wax model illustrates vertex presentation: it represents the position of the head in the muscular-membranous birth canal formed by the soft parts of the pelvic floor. The occiput is now below the pubis almost up to the nape of the neck, and the back has followed the head in the rotation subsequent to engagement.

The model was commissioned by Felice Fontana, who was working on the installation of the Museo di Fisica e Storia Naturale of Florence, from the sculptor Giuseppe Ferrini and his assistant Clemente Susini.