Maxillary ProminenceEdit
Maxillary prominence
The maxillary prominences are bilateral swellings on the developing face that originate from the ventrolateral region of the first pharyngeal (branchial) arch. They play a central role in shaping the midface by giving rise to the upper jaw (the maxilla), portions of the cheek, the lateral parts of the nose, and, critically, the palatal shelves that form the secondary palate. Along with the medial nasal prominences, the maxillary prominences fuse during embryogenesis to establish the contour of the upper lip and the anterior palate. Disruptions in these fusion events can produce congenital craniofacial anomalies such as cleft lip and palate.
Development and anatomy
Origins and structure - The maxillary prominences arise as bilateral outgrowths of the first pharyngeal arch and are populated by neural crest–derived mesenchyme. This ectomesenchyme supports the growth and differentiation of bone and soft tissue in the midface. - Their growth contributes to the formation of the maxilla, parts of the zygomatic bone, the lateral walls of the nose, and the infraorbital region. The prominence also gives rise to the palatal shelves, which are essential for forming the hard and soft palate.
Fusion and morphogenesis - A key step in facial morphogenesis is the fusion of the maxillary prominences with the medial nasal prominences. This fusion completes the lateral aspects of the upper lip and helps shape the philtrum, along with contributions from the medial nasal prominences. - The palatal shelves that emerge from the maxillary prominences ascend and eventually fuse with each other and with the primary palate, establishing the full palate. The primary palate itself derives from the intermaxillary segment, formed by the fused medial nasal prominences, while the secondary palate forms largely from the palatal shelves of the maxillary prominences. - Proper morphogenesis depends on coordinated signaling and cell migration, including cues from pathways such as FGF, BMP, SHH, and WNT, as well as the contribution of neural crest cells to the facial mesenchyme. For a broader view, see facial development and palatogenesis.
Clinical significance
Cleft lip and palate - One of the most common congenital craniofacial anomalies involves the improper fusion of the maxillary prominences with the medial nasal prominences or with each other, leading to cleft lip, cleft palate, or a combination thereof. - The spectrum ranges from isolated cleft lip (unilateral or bilateral) to cleft lip with cleft palate and more extensive involvement of the maxillary region, including the alveolar ridge and palate. Surgical and multidisciplinary care often addresses both functional and aesthetic aspects. - Genetic factors, including variants in genes such as MSX1, IRF6, and PAX9, interact with environmental influences (e.g., maternal smoking, certain medications, and maternal diabetes) to shape risk. The condition illustrates the complex, polygenic nature of midface development and how small perturbations in maxillary prominence growth or fusion can have outsized clinical effects.
Other congenital issues - Craniofacial anomalies linked to maxillary prominence development include variations in midface length and orbital width, which can influence occlusion, breathing, and facial harmony. - Understanding the biology of the maxillary prominences informs approaches to reconstructive surgery, orthodontics, and therapies for associated conditions. See neural crest and first pharyngeal arch for related developmental context.
See also