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Case 2.12
Published in Monica Fawzy, Plastic Surgery Vivas for the FRCS(Plast), 2023
You’ve mentioned the failure of the facial prominences to fuse as a possible cause of a facial cleft. What is the embryology of facial development?Development of the face occurs between the 3rd and 8th week of gestation.In the 3rd week, the neural folds fuse to form a neural tube: the cranial neural tube forms a central frontonasal prominence and six paired branchial arches – each of which form a cartilage precursor, an artery, nerve, muscle, and skeletal structure:The frontonasal prominence is destined to form the forehead, nose, and the central upper lip.The first branchial arch develops the maxillary and mandibular prominences, which form the midface and lower face respectively.The maxillary prominence will form the cheeks, maxillae, and lateral upper lips.The mandibular prominences become the lower lip, chin, and mandible.The second branchial arch forms the facial nerve and muscles of facial expression.
A Study of Facial Growth in Patients with Unilateral Cleft Lip and Palate Treated by the Oslo CLP Team
Published in Niall MH McLeod, Peter A Brennan, 50 Landmark Papers every Oral & Maxillofacial Surgeon Should Know, 2020
The skeletal and soft tissue features were characterised by a short and retrusive maxilla, vertical elongation of the anterior face, and a retrusive mandible. Posterior face height was reduced and cranial base angulation was slightly increased, as was interocular distance. The pattern of growth differed from non-cleft individuals, with almost no increase in length of the maxilla between 5 and 18 years of age. A marked and progressive reduction in maxillary prominence (S-N-SS) of 5.4 degrees was observed in the pooled UCLP patients which compares with an expected increase of 3.3 degrees in the non-cleft data. Mandibular retrusion was observed in the sample with an increase of only 3.8 degrees in mandibular prominence (S-N-PG), when compared with the 6.2 degree increase from pooled Bolton standards. The facial soft tissue profile differed from non-cleft individuals with nasal growth in a more backward and downward direction, a receded upper lip, and a progressively straighter profile. Further analysis of the surgical effects on facial growth failed to reveal any differences between the surgical groups and surgical variation during the 25-year period. The cephalometric outcomes are compared with outcomes from other centres and were found to be similar. Shortcomings of the previous reports in the literature in addition to those within the present study are acknowledged.
Head and Neck
Published in Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno, Understanding Human Anatomy and Pathology, 2018
Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno
The 1st (mandibular) branchial arch is the embryonic structure that gives rise to the upper jaw and lower jaw including bones, muscles and connective tissues, and upper and lower dentition (teeth) (Plate 3.2). Early in embryonic development, this arch subdivides into two major, paired (left and right) tissue swellings, the ventral mandibular prominence and the dorsal maxillary prominence (Plates 3.2 and 3.3). The mandibular prominence gives rise to all lower jaw bones, muscles, and associated connective tissues. Its contributions vary somewhat among mammals and vertebrates in general, but in humans the maxillary prominence contributes to the upper jaw, cheeks, and secondary palate, and associated connective tissues. These paired prominences fuse with crest-derived populations of the frontonasal prominence to complete formation of the midface. Failure of any or all of these prominences to properly contact and fuse will result in a congenital clefting defect of the palate, lip, or face. These clefts, which can be caused by genetic and/or environmental factors and occur as often as 1 per 800 births, can be surgically corrected. The earlier after birth surgery is performed, the better the prognosis.
Studying factors influencing facial developmental instability
Published in Annals of Human Biology, 2021
In this paper we evaluated three modularity hypotheses in order to detect the developmental architecture of the human face. Regarding the performance of the modularity hypotheses, we are in agreement with Quinto-Sánchez et al. (2018) that the function-related hypothesis showed lower covariation among modules when compared to the other hypotheses, particularly the midline-related hypothesis. This indicates that the eyes, nose, mouth and facial outline are relatively independent. As expected (Linden et al. 2018), our study indicated that the facial thirds are relatively independent, since the partitions according to the three main anatomical parts of the facial area (the neurocranium, maxilla, and mandible) showed the lowest possible covariance in some age categories. This indicates that facial thirds are distinct units, and thus the developmental integrations in the face occur within units as stated by Enlow (1990). It is, however, well known that integration among anatomical regions (basicranium, facial skeleton, and cranial vault) is looser in the human skull compared to other species (Porto et al. 2009); and yet, cranial components develop in a morphologically integrated manner (Enlow 1990; Bastir et al. 2006) through numerous morphogenetic (e.g. neural) and functional (e.g. masticatory, respiratory) interactions (Lieberman et al. 2000). More importantly, as a result of independence among the modules, the effect of a stressor which leads to higher fluctuating asymmetry (Leamy and Klingenberg 2005) is transmitted less readily among modules. Our study showed a stronger theoretical dependency among vertical modules than among horizontally neighbouring modules. Thus, the effect of a stressor which leads to higher fluctuating asymmetry can be transmitted among modules more easily in a horizontal direction. This strong relationship among modules related to the midline is most likely a result of a biomechanical load of attached muscles. Moreover, this load of attached muscles can facilitate a formation of asymmetry, since it can impact both facial sides unequally. In contrast, horizontally neighbouring modules exhibited different timing of growth (particularly during adolescence) and thus these modules are less interconnected. In addition, horizontal modules originate from diverse embryonic structures, since the maxillary prominences give origin to the maxilla, os zygomaticum and a part of the os temporal, whereas the mandibular prominences give origin to the mandible (Moore and Persaud 2002).