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Anatomy of the Pharynx and Oesophagus
Published in John C Watkinson, Raymond W Clarke, Terry M Jones, Vinidh Paleri, Nicholas White, Tim Woolford, Head & Neck Surgery Plastic Surgery, 2018
Musculus uvulae lies between the two laminae of the palatine aponeurosis and arises from the posterior nasal spine on the palatine bone as well as from the superior surface of the aponeurosis. It sits above the V-shaped sling formed by the two levator veli palatini muscles and runs backwards above it to insert into the uvular mucosa. Most of this small muscle is fused in the midline. Its function is to act in conjunction with the levator veli palatini muscles to retract and thicken the mid-third of the soft palate, thus closing the nasopharyngeal isthmus. As the two muscle bellies run at 90 degree angles to each other, when they contract, a ‘levator eminence’ is formed. This helps in the finally sealing off of the nasopharynx during swallowing.
Growth of the Cranial Base HHiH
Published in D. Dixon Andrew, A.N. Hoyte David, Ronning Olli, Fundamentals of Craniofacial Growth, 2017
Laitman and others, in a series of publications, related an exocranial, sagittal, basicranial axis, involving the palatal plane and the external base from vomer to basion, to the positioning of upper pharyngeal, palatal and laryngeal soft tissues (Laitman and Crelin, 1976; Laitman et al., 1978, 1979, 1989; Laitman and Heimbuch, 1982). There is an intimate relationship between the structure and function of the basicranium and the soft anatomy of the upper respiratory tract (Laitman and Crelin, 1976). Apposition of the epiglottis to the soft palate allows a continuous airway, present in mammals and newborn humans. This correlates with a flat exocranial surface of the basicranium (from hard palate to posterior nasal spine to basion). This human condition, present from birth to 2 years, gradually changes from 4 years as the tongue and larynx descend, to the adult stage, where epiglottis-palate contact is never possible. During these years, a strictly exocranial basal flexure develops (from palate to basion). In the human neonate, there is a relatively long interval from vomer to basion (the mammalian condition), but by the adult stage the vomer approaches and may overlie the fused spheno-occipital synchondrosis. This relatively shorter interval is compensated by the descent of the tongue, enlarging the supralaryngeal pharynx: a speech-modifying chamber peculiar to man. Using these criteria, Laitman and co-workers (loc. cit. supra) were able to suggest from reconstructions of the basicranium of fossil hominids the outline of their upper respiratory systems.
Nasal Airway Anatomy and Inhalation Deposition in Experimental Animals and People
Published in D. V. M. Gerd Reznik, Sherman F. Stinson, Nasal Tumors in Animals and Man, 2017
Computed tomography was used by Montgomery et al.9 to generate coronal tomograms of four human cadaver specimens. The tomograms were made at 4-mm intervals from the base of the nostrils to the level of the posterior nasal spine. In addition to providing a picture of the human nasal airways, the tomograms were also used to determine the cross-sectional area of the airways at various positions. This work will be considered later in comparison to the experimental animals.
Biomechanical evaluation of maxillary protraction with an orthodontic anchor screw: a three-dimensional finite element analysis
Published in Orthodontic Waves, 2021
Tomohiro Ebisawa, Hidenori Katada, Kenji Sueishi, Yasushi Nishii
Changes in ANS, posterior nasal spine (PNS), incisal margin of central incisor, and mesiobuccal cusp of first molar positions were placed on the X-axis (horizontal direction), Y-axis (sagittal direction), and Z-axis (vertical direction) to analyse the dynamics of initial load for each traction direction. We evaluated the initial displacement at each site and the rotation of the maxilla based on differences in ANS and PNS vertical displacements. We also determined von Mises stress concentrations for the zygomaticofrontal, zygomaticomaxillary, and zygomaticotemporal sutures. Stress distributions in the facial bones, skull bones, and sutures were displayed as results for the sagittal and axial views.
Biomechanical effects of corticotomy facilitated orthodontic anterior retraction: a 3-dimensional finite element analysis
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
Yang Liu, Yan Wu, Chongshi Yang, Jinlin Song, Yubo Fan
To better display the initial displacement, a new coordinate system was defined. The origin was set at anterior nasal spine and the X axis went through posterior nasal spine and the XY plane was correspondence with the middle sagittal plane.