Assessment of the relationship of the Frankfort horizontal plane and the orbitomeatal line with attainment of the natural head position

2019 ◽  
Vol 48 ◽  
pp. 119
Author(s):  
G. Gasperini ◽  
R. Laís Almeida Cruz ◽  
R. Tavares de Sá ◽  
L. Lara Cardoso ◽  
I. Batalha de Cavalho
Keyword(s):  
Horizontal Plane ◽  
Head Position ◽  
Relationship Of ◽  
Frankfort Horizontal Plane ◽  
The Relationship

Variation in Cephalometric Reference Lines

1981 ◽  
Vol 8 (4) ◽  
pp. 183-187 ◽  
Author(s):  
T. D. Foster ◽  
A. P. Howat ◽  
P. J. Naish
Keyword(s):  
Clinical Judgment ◽  
Head Position ◽  
The Other ◽  
Cephalometric Analysis ◽  
Head Posture ◽  
Positioning Method ◽  
Relationship Of ◽  
The Relationship ◽  
Range Of Variation

The use of intracephalic reference lines in cephalometric assessment is valid only if these lines bear some constant relationship to the true horizontal and to each other. Otherwise, the use of a true horizontal would give the benefit that cephalometric assessment would be based on the same standards as clinical judgment. In using a true horizontal, however, the radiograph must be taken with the head in a reproducible natural posture. A study was carried out to assess the reproducibility of a natural head posture using a simple positioning method in a standard cephalostat, and to assess the variation in the relationship of the sella-nasion, Frankfort, maxillary and mandibular reference lines, to a true horizontal and to each other. Though in their mean inclinations the Frankfort and the maxillary reference lines were almost parallel to each other and to the true horizontal, the range of variation for all the reference lines was considerable. The range of variation in the reference lines was greater than the error of reproduction of head position, and the range of variation of the slope of the mandibular line was no greater than that for the slope of each of the other three lines. The sella-nasion line was reproduced more accurately that the other reference lines, using a digitizer. The possibilities of a simple cephalometric analysis based on a true horizontal are outlined.

scholarly journals A New Horizontal Plane of the Head

2018 ◽  
Vol 6 (5) ◽  
pp. 767-771 ◽  
Author(s):  
Ehab El Kattan ◽  
Mohamed El Kattan ◽  
Omnia A. Elhiny
Keyword(s):  
Soft Tissue ◽  
Horizontal Plane ◽  
Head Position ◽  
The Other ◽  
Reference Plane ◽  
Head Orientation ◽  
Mean Values ◽  
The Subject ◽  
Frankfurt Horizontal ◽  
Frankfort Horizontal Plane

AIM: This study aimed to attempt to introduce a new extracranial horizontal plane of the head (K plane that extends from SN to SAE bilaterally) that could act as a substitute to the Frankfurt horizontal intracranial reference plane; both clinically and radiographically.MATERIAL AND METHODS: The new K plane depended on three points of the head. The first was the soft tissue nasion (NS) on the interpupillary line when the subject looked forward at a distant point at eye level. The other two points were the superior attachments of the ears (SAE).RESULTS: The student “t” test comparing mean values of K/V and FH/V was not significant; -0.21.  The coefficient of correlation between different variables was highly positively significant (r = 0.98 with probability = 0.001).CONCLUSION: Within the limitations of this prospective study, the new K plane was found to be both reliable and reproducible. It can be used as a reliable reference plane instead of Frankfort horizontal plane both clinically and radiographically; as it is an accurate tool for head orientation in the natural head position.

Natural Head Position, Posture, and Prognathism: The Chapman Prize Essay, 1986

1988 ◽  
Vol 15 (4) ◽  
pp. 227-239 ◽  
Author(s):  
S. C. Cole
Keyword(s):  
Class Ii ◽  
Cranial Base ◽  
Head Position ◽  
Head Posture ◽  
Significant Difference ◽  
Skeletal Pattern ◽  
Base Orientation ◽  
Head Positions ◽  
Relationship Of ◽  
The Relationship

Natural head position and natural head posture are terms which have been used synonymously to describe the spatial relationships of the head with reference to the true vertical, the cervical column, or both. This is confusing, and it would seem logical to ascribe one term to one reference and consider the phenomena separately. For the purposes of this prospective cephalometric survey, natural head position will describe the relationship of the head to the true vertical, while natural head posture will describe the relationship of the head to the cervical column. In order to investigate these two relationships of the head, five groups were formed, three representing horizontal discrepancies selected on ANB differences (class I, II and III dental base relationships) and two representing vertical discrepancies selected on Bjork's posterior angles (‘high angle’ and ‘low angle’ groups). Despite the marked differencesin ‘skeletal’ pattern shown between the five groups, the values obtained for the saddle angles (N-S-Ar) showed no significant difference. However, the natural head positions and natural head postures were significantly different (P < 0.01). Natural head position affected cranial base orientation and this alone produced class II or III effects. Natural head position was also associated with maxillary prognathism whilst natural head posture appeared more closely related to mandibular prognathism. These phenomena may help to explain an apparent class II or III tendency in cases where the saddle angle is normal.

scholarly journals Evaluating the Reliability of CBCT Airway Measurement: A Pilot Study

2020 ◽  
Author(s):  
Brent L. Jorgensen ◽  
Jae Hyun Park ◽  
R. Curtis Bay
Keyword(s):  
Horizontal Plane ◽  
Head Position ◽  
Average Difference ◽  
Cross Sectional ◽  
Significant Difference ◽  
Tongue Position ◽  
T1 And T2 ◽  
Jaw Position ◽  
Volume Acquisition ◽  
Frankfort Horizontal Plane

Abstract Background Many studies have analyzed treatment effects on the airway using CBCT scans of the airway as evidence, but no study to date has been published that validates a repeatable protocol for acquiring CBCT airway measurements. Our objective is to evaluate a protocol for standardization of CBCT volume acquisition of the airway. Methods Ten participants (6 females and 4 males, median age 30.03 ± 3.53 years) were radiographed 2 times each (T1 and T2, the average time between T1-T2 was 15.8 ± 3.65 days), for a total of 20 CBCT scans. The participants’ head position was placed so that the Frankfort horizontal plane was parallel to the floor. Participants were given specific instructions regarding jaw position, tongue position, swallowing and breathing before each of the 2 scans. Minimum cross-sectional area (MCA) and total volume (TV) of each airway scan were measured between the distal most point of the hard palate (superior limit) and the superior most point of the epiglottis (inferior limit). T1 and T2 were compared to determine the repeatability of our proposed protocol for CBCT airway acquisition. Results There was no statistically significant difference between T1 and T2 measurements for TV and MCA. The average difference between T1 and T2 MCA and TV measurements for each participant was 34.18 ± 30.55 mm2 and 2.51 ± 2.05 cc, respectively. Conclusions Using our proposed standardization protocol, the measurements of MCA and TV of the airway were reliable to within 34.18 ± 30.55 mm2 and 2.51 ± 2.05 cc, respectively.

scholarly journals The Role of the Fins in the Equilibrium of the Swimming Fish

1936 ◽  
Vol 13 (4) ◽  
pp. 476-493 ◽  
Author(s):  
J. E. HARRIS
Keyword(s):  
Wind Tunnel ◽  
Horizontal Plane ◽  
Vertical Plane ◽  
The Body ◽  
Pectoral Fins ◽  
Two Factors ◽  
Air Speed ◽  
Mustelus Canis ◽  
Relationship Of ◽  
The Relationship

1. An attempt was made to determine the relationship of the fins to the equilibrium of the swimming dogfish. 2. Two factors at least are involved in this equilibrium; passive mechanical forces and reflex motions of the fins themselves. The part played by the automatic (passive) components was estimated by experimenting on a model of Mustelus canis mounted in a wind tunnel tested at a suitable air speed. 3. The equilibrium in the horizontal plane (yawing equilibrium--for turning movements) is unstable without fins, completely stable only in the absence of the first dorsal fin, and is neutral when all fins are present. 4. In the vertical plane (pitching equilibrium--for rising and diving turns) the equilibrium is unstable without fins, and this instability is greatly increased by the presence of the pectorals. The pelvics have little or no effect. 5. Stability and controllability are inversely related. The fish is comparatively stable in the horizontal plane, extremely controllable in the vertical plane. This fact is closely related to the flexibility of the body for lateral movements. 6. The results obtained in the wind tunnel were confirmed by amputation of the fins of the living dogfish. 7. The normal equilibrium of the swimming dogfish in the vertical plane is determined largely by the pectoral fins and the heterocercal tail. 8. The relationship of these facts to the problem of the evolution of the swimming chordates is considered.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Studies on Leukemogenic and Sarcomagenic Viruses

1970 ◽  
Vol 28 ◽  
pp. 156-157
Author(s):  
Leon Dmochowski
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Morphological Properties ◽  
Mode Of Development ◽  
Relationship Of ◽  
The Relationship

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.

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