Cleft Lip and Palate
Crystal D. Karakochuk, Kyly C. Whitfield, Tim J. Green, Klaus Kraemer in The Biology of the First 1,000 Days, 2017
Development of the palate begins at the end of the fifth week. The primary palate is then formed by the fusion of the medial nasal processes to form the intermaxillary segment. This segment is responsible for the formation of the premaxilla, which is the triangular bony piece that will support the maxillary incisor teeth. The secondary palate is the primordia of the hard and soft palate posterior to the premaxilla, and is formed from the maxillary processes of the first branchial arches [3,4]. Two lateral palatine processes develop from the internal aspects of both maxillary processes, initially in a vertical position on each side of the developing tongue. With the development and growth of the mandible, the tongue moves inferiorly, allowing the palatine processes to move horizontally and grow toward each other. By the end of the eighth week, fusion occurs between the two palatine processes or shelves, and also with the primary palate and nasal septum. The process of palate formation is completed by the twelfth week. Bone develops in the anterior region, forming the hard palate, and the posterior part develops as the muscular soft palate. Defective fusion of the palatine processes results in a cleft palate [1–4].
Anatomy and Embryology of the Mouth and Dentition
John C Watkinson, Raymond W Clarke, Terry M Jones, Vinidh Paleri, Nicholas White, Tim Woolford in Head & Neck Surgery Plastic Surgery, 2018
During the 8th week of development, the tongue ‘drops’ and the vertically inclined palatal shelves can now occupy a horizontal position (Figures 41.21c and 41.23). The reason for the displacement of the tongue is not known. As the tongue is attached to the mandible, it has been suggested that the descent of the tongue is related to mandibular growth. Conversely, reflex movements of the tongue and/or a change in its shape may be implicated. On becoming horizontal, the palatal shelves contact each other (and the secondary nasal septum) in the midline to form the secondary palate. The shelves contact the primary palate anteriorly so that the oral and nasal cavities become completely separated from each other. After shelf contact, the medial edge epithelia of the two shelves fuse to form a midline epithelial seam. Subsequently, this seam (together with the epithelium separating the palatal shelves from the secondary nasal septum) degenerates, allowing continuity of mesenchyme to be established across the now intact and horizontal secondary palate. Fusion of the palatal processes is complete by the 12th week of development. Behind the secondary nasal septum, the palatal shelves fuse to form the soft palate and uvula.
Oral cavity
Paul Ong, Rachel Skittrall in Gastrointestinal Nursing, 2017
The secondary palate forms from palatine processes or shelves during the sixth week of gestation. These arise as outgrowths from each of the maxillary processes. The shelves initially grow vertically down the side of the tongue, which sits between the two palatine shelves. At the seventh week of gestation the palatine shelves lift to sit horizontally over the tongue. Growth of the shelves continues until they meet at their midpoint. Total fusion occurs in both anterior and posterior directions. The palatine shelves fuse with the primary palate anteriorly and with each other posteriorly. The epithelial tissue covering the edges of the shelves joins forming an epithelial seam. The line gradually degenerates to allow continuity of mesenchymal tissue across the palate. Fusion of the palate relies on adhesion of epithelial tissues. Failure of closure of the palatine shelves results in a cleft palate.
Extracellular Matrix Remodeling During Palate Development
Published in Organogenesis, 2020
Xia Wang, Chunman Li, Zeyao Zhu, Li Yuan, Wood Yee Chan, Ou Sha
The morphogenesis of the mammalian secondary palate begins with the outgrow of two palatal shelves from the maxillary processes on both sides of the tongue on an embryonic day (E) 12.1 The two vertically oriented palatal shelves soon elevate horizontally and opposite each other on E 14–15.1 Then, the palatal shelves epithelia disintegrate in the midline and their mesenchymal compartment fuse completely to form an intact palatal roof.1 Cells in the palatal shelves originate from three sources of embryonic tissue/structures: the superficial palatal epithelium is derived from the embryonic ectoderm, the underlying palatal mesenchyme mainly from the neural crest.1,2 Supporting these cells is the infrastructure composed by complex extracellular matrix network.
Global, regional and national burden of orofacial clefts from 1990 to 2019: an analysis of the Global Burden of Disease Study 2019
Published in Annals of Medicine, 2023
Dawei Wang, Boyu Zhang, Qi Zhang, Yiping Wu
The aetiology of orofacial clefts is complex, relating to different embryological origins and times of development [6,7]. The failure of the formation of the primary palate leads to a cleft lip, while a cleft palate arises from the failed formation of the secondary palate [4]. The cause of orofacial clefts can be considered as the interaction between genetic alterations and environmental factors [8,9]. Recently, many candidate genes and loci have been demonstrated to be associated with the occurrence of orofacial clefts [10–12]. The environmental factors, including smoking, alcohol consumption, dietary and vitamin deficiencies, parental age, environmental toxins and socioeconomic status, may also affect the presence of orofacial clefts [13–17].
Related Knowledge Centers
- Incisive Foramen
- Mouth
- Embryology
- Hard Palate
- Nasal Cavity
- Pregnancy
- Primary Palate
- Secondary Palate Development
- Cleft Lip & Cleft Palate
- Warm-Blooded