Development of Soft & Hard Palate Dr. Muhammad Rafique Anatomy, DIMC Objectives Know the development of face Have knowledge of development of primary palate Mention the development of Secondary palate Discuss the development of Hard Palate Describe the development of Soft Palate Know developmental anomalies of Palate Development of face Development of face requires five prominences One Fronto-nasal Prominence Two Maxillary Prominence Two Mandibular Prominence Development of Palate Development of palate depends upon the proper development of frontonasal prominence and maxillary prominences and than proper fusion of all three prominences Development of Palate The palate develops in two stages: 1. Development of a primary palate 2. Development of a secondary palate Palatogenesis begins in the sixth week; however, development of the palate is not completed until the 12th week. The critical period of palate development is from the end of the sixth week until the beginning of the ninth week. Primary Palate Early in the sixth week, the primary palate-median palatal process (intermaxillary segment)- begins to develop. Initially, this segment, formed by merging of the medial nasal prominences, is a wedge- shaped mass of mesenchyme between the internal surfaces of the maxillary prominences of the developing maxillae. Primary Palate The primary palate forms the anterior/midline aspect of the maxilla, the premaxillary part of the maxilla. It represents only a small part of the adult hard palate (i.e., anterior to the incisive fossa). Secondary Palate The secondary palate is the primordium of the hard and soft parts of the palate. The secondary palate begins to develop early in the sixth week from two mesenchymal projections that extend from the internal aspects of the maxillary prominences. Initially these structures-the lateral palatal processes (shelves)- project inferomedially on each side of the tongue. As the jaws elongate, they pull the tongue away from its root, and, as a result, it is brought lower in the mouth. Secondary Palate During the seventh and eighth weeks, the lateral palatal processes assume a horizontal position above the tongue. This change in orientation occurs by a flowing process facilitated in part by the release of hyaluronic acid by the mesenchyme of the palatal processes. Bone gradually develops in the Development of primary palate, Hard Palate forming the premaxillary part of the maxilla, which lodges the incisor teeth Bone extends from the maxillae and palatine bones into palatal processes to form the hard palate. The posterior parts of these processes do not become ossified. They extend Soft Palate posteriorly beyond the nasal septum and fuse to form the soft palate, including its soft conical projection-the uvula. The median palatine raphe indicates the line of fusion of the palatal processes. A small nasopalatine canal persists in the Nasopalatine median plane of the Canal palate between the anterior part of the maxilla and the palatal processes of the maxillae. This canal is represented in the adult hard palate by the incisive fossa, which is the common opening for the small right and left incisive canals Development of Palate Developmental Anomalies of Palate Clefts of the lip and palate are the most common craniofacial anomalies. The defects are usually classified according to developmental criteria, with the incisive fossa as a reference landmark. These clefts are especially conspicuous because they result in an abnormal facial appearance and defective speech. There are two major groups of cleft lip and cleft palate (Figs. 9-39 to 9-41): Cleft Palate Unilateral and bilateral clefts of the palate are classified into three groups: 1. Clefts of the primary or anterior palate 2. Clefts of the secondary or posterior palate 3. Clefts of the primary and secondary parts of the palate Clefts of the Primary or Anterior Palate Clefts of the primary or anterior palate (i.e., clefts anterior to the incisive fossa) result from failure of mesenchymal masses in the lateral palatal processes to meet and fuse with the mesenchyme in the primary palate. Clefts of the Secondary or Posterior Palate Clefts of the secondary or posterior palate (i.e., clefts posterior to the incisive fossa) result from failure of mesenchymal masses in the lateral palatal processes to meet and fuse with each other and the nasal septum. Clefts of the Primary and Secondary parts of the Palate Clefts of the primary and secondary parts of the palate (i.e., clefts of the anterior and posterior palates) result from failure of the mesenchymal masses in the lateral palatal processes to meet and fuse with mesenchyme in the primary palate, with each other, and the nasal septum. Etiology of Cleft Palate Most clefts of the lip and palate result from multiple factors (multifactorial inheritance. Genetic and nongenetic, each causing a minor developmental disturbance. How teratogenic factors induce cleft lip and palate is still unclear.
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