| During week 6, the
maxillary processes bulge anteriorly and medially and begin to fuse with
the nasolateral processes. In week 7 they will join the nasomedial processes,
thereby separating the nasal pits from the stomodeum and leading to formation
of the lateral parts of the upper lip and jaw. |
This movement causes
the nasomedial processes to converge and meet in the midline and form the
intermaxillary segment.This intermaxillary segment later gives rise to:
the crest and tip of the nose, the central part of the upper lip (philtrum)
and the central portion of the maxilla and alveolus
which will bear the 4 upper incisors. Also, a triangular primary palate
by fusion of the nasomedial processes at their deep aspect. |
This primary palate corresponds to the
area of hard palate anterior to the incisive foramen in the adult. The
bony structures formed by the intermaxillary segment are known as the premaxillary
segment in the adult. The frontonasal prominence gives rise to the
bridge of the nose and the nasal septum, the nasolateral processes form
the alae of the nose and the opening of the
nasal pits become the nostrils. The mandibular processes below and lateral
to the stomodeum fuse to make the lower lip and jaw. |
