Nasal Septal and Premaxillary Developmental Integration: Implications for Facial Reduction in Homo

The influence of the chondrocranium in craniofacial development and its role in the reduction of facial size and projection in the genus Homo is incompletely understood. As one component of the chondrocranium, the nasal septum has been argued to play a significant role in human midfacial growth, particularly with respect to its interaction with the premaxilla during prenatal and early postnatal development. Thus, understanding the precise role of nasal septal growth on the facial skeleton is potentially informative with respect to the evolutionary change in craniofacial form. In this study, we assessed the integrative effects of the nasal septum and premaxilla by experimentally reducing facial length in Sus scrofa via circummaxillary suture fixation. Following from the nasal septal‐traction model, we tested the following hypotheses: (1) facial growth restriction produces no change in nasal septum length; and (2) restriction of facial length produces compensatory premaxillary growth due to continued nasal septal growth. With respect to hypothesis 1, we found no significant differences in septum length (using the vomer as a proxy) in our experimental (n = 10), control (n = 9) and surgical sham (n = 9) trial groups. With respect to hypothesis 2, the experimental group exhibited a significant increase in premaxilla length. Our hypotheses were further supported by multivariate geometric morphometric analysis and support an integrative relationship between the nasal septum and premaxilla. Thus, continued assessment of the growth and integration of the nasal septum and premaxilla is potentially informative regarding the complex developmental mechanisms that underlie facial reduction in genus Homo evolution. Anat Rec, 2010. © 2010 Wiley‐Liss, Inc.     

Microscopic study of holoprosencephalic facial anomalies in trisomy 13 fetuses

The cerebral and facial anatomy of four trisomy 13 fetuses was studied in order to delineate the varying degrees of expression of severity of holoprosencephaly. Fetal heads were serially sectioned and analyzed microscopically in the horizontal plane. Examples of cyclopia, cebocephaly, and a proposed new category, premaxillary dysgenesis, were studied. The last category represents the least severe end of the facial spectrum of holoprosencephaly in this series. In this condition, there are deficiencies or clefts within the premaxilla, in contrast to the usual site of clefting between the maxilla and the premaxilla. There is asymmetry of the defects in the anterior midface of all four cases.     

The lateral incisive canals of the adult hard palate - aberrant anatomy of a minor form of clefting?

Except the oral clefts and their associated dental development disturbances, no other discrete morphologies are reported in the literature as related to altered fusions of the fetal maxilla and premaxilla. We report here two cases related by the persistence in adult of an aberrant canal at the fusion site of the fetal premaxilla and maxilla. The first case presents an anastomosis of the superior anterior alveolar and greater palatine nerves, encountered during the dissection of a human adult male cadaver; that anastomosis, bilaterally present, projected on the aforementioned fusion site and traversed the hard palate to continue within the maxillary sinus wall. The second case evidenced on CT the unilateral presence of aberrant lateral incisive canals (LIC) at the level of the fetal premaxilla and maxilla fusion site; those canals, external (1.5 mm diameter) and internal (1.07 mm diameter), were corresponding as location to that one traversed by the aberrant anastomosis in the first case. Both LIC opened inferiorly but not superiorly, rather seeming to communicate with the bony canals within the nasal fossa floor at that level. We consider that such aberrant canals and nerves may represent very rare forms of clefting, previously undescribed; the possible anastomoses of the superior anterior alveolar and greater palatine nerves can be altered during a Le Fort I fracture and may be the morphology that can explain aberrant clinical nervous distributions at the level of the upper dentoalveolar arch and hard palate.     

单侧完全性唇腭裂胎儿颌面部血供的应用解剖

目的为单侧完全性唇腭裂胎儿宫内手术修复提供解剖学基础。方法制作和观察21～32周正常和单侧完全性唇腭裂胎儿头颈部血管铸型标本,比较它们颌面部血供的来源及吻合情况。结果①正常胎儿颌面部血供主要来源于面动脉、颏下动脉、下唇动脉、上唇动脉、鼻翼下缘动脉、鼻翼动脉、鼻外侧动脉、鼻背动脉、眶下动脉及面横动脉等,这些动脉及其分支构筑颌面部组织丰富的血管网;②单侧完全性唇腭裂胎儿患侧上唇动脉沿裂缘向上至鼻翼基底部与鼻翼下缘动脉等相吻合,患侧部分腭骨缺损暴露的腭大动脉穿过骨残端与患侧鼻腔内的血管相吻合。结论对单侧完全性唇腭裂胎儿颌面部进行宫内修复手术,重点在鼻部和上唇部的血供,主要以上唇动脉、鼻翼下缘动脉和腭大动脉为主。     

Skull development in the Iberian newt,Pleurodeles waltl (Salamandridae: Caudata: Amphibia): timing,sequence, variations,and thyroid hormone mediation of bone appearance

The cranial ossification sequence in Pleurodeles waltl is widely used in phylogenetic analyses of amphibian origin and evolution. However, the patterns published to date are far from completely resolved and contain certain discrepancies. Based on a large sample of P. waltl specimens ranging from early post-hatching larvae to post-metamorphic newts, we determined the most common cranial ossification sequence and revealed its intraspecific variations. Since thyroid hormones (THs) are involved in the mediation of skull development in salamanders, we studied the role of THs in the cranial development of P. waltl. The normal sequence and timing of bone appearance were compared with those in larvae reared under conditions of high (in 1 and 2 ng mL^-1 triiodothyronine) and low [in 0.02% thiourea (TU), which inhibits thyroid gland activity] TH levels. Metamorphosis was greatly accelerated in the TH-treated larvae and was arrested in the TU-treated larvae, which retained the larval pattern of the palate and rudimentary external gills even after 2 years of the experiment. Early-appearing bones (the coronoid, vomer, palatine, dentary, squamosal, premaxilla, parasphenoid, pterygoid, prearticular, vomer, frontal, parietal, exoccipital, in this order) arise at the same stages and ages, and follow the same ossification sequence under different TH levels. The timing of the appearance of bones normally arising in the late larval and metamorphic periods (the quadratojugal, orbitosphenoid, prootic, maxilla, nasal, os thyroideum, prefrontal, quadrate, in this order) changes depending on the TH level. The maxilla and nasal display the most pronounced reaction to changes in the TH level: they appear precociously in TH-treated animals, while their appearance is postponed and they remain rudimentary in TU-treated animals. Because of different responses to THs, the order in which late-arising bones appear changes depending on the TH level. Although bones appearing early in larval ontogeny (e.g. the premaxilla, vomer, squamosal, palatine) display no TH-induced reaction when they start to develop, their further differentiation shows dependence on THs, and these bones become TH-inducible closer to metamorphosis. These findings indicate that TH involvement in the mediation of cranial development changes from minimal (if at all) in its early stages to maximal during metamorphosis. It is likely that the appearance of bones early in development is mediated by factors other than THs. Their further development is accompanied by changes in the mechanisms mediating their morphological differentiation. That is, likely non-hormonal mediation becomes replaced or/and complemented by hormonal mediation. The constituent parts of the same bone may exhibit differences in their reactions to changes in TH levels. Although in normal development, the overall cranial ossification sequence is constant, there was variation in the order in which late-appearing bones was recorded. These observations suggest that this variation results from individual variability in the internal TH level. Comparison with other salamanders suggests that (a) the pattern of TH mediation described in P. waltl is common for cranial development of metamorphosing urodeles and (b) the same bone may differ in its TH dependence in different salamanders, e.g. there are interspecific variations in the degree of TH dependence of individual cranial bones.     

New Interpretation of the Palate of Pterosaurs

On the basis of a new, three‐dimensionally preserved specimen of the Early Jurassic pterosaur Dorygnathus banthensis we present a reinterpretation of the pterosaur palate. The hard palate is formed by the extensive palatal plate of the maxilla and not by the palatine as has been generally reconstructed. This palatal plate of the maxilla emarginates the choana rostrally and rostrolaterally as in other archosaurs and lepidosaurs. The longitudinally elongate and dorsoventrally flat palatine in Dorygnathus is an isolated bone caudal to the palatal plate of the maxilla and morphologically and topographically it resembles that of crocodilians and birds, respectively. The palatine separates the choana laterally from the suborbital fenestra demonstrating the homologous nature of the (primary) choana in all archosaurs and lepidosaurs. Our study indicates that in basal pterosaurs the pterygo–ectopterygoid fenestra existed caudal to the suborbital fenestra, which became confluent with the adductor chamber in pterodactyloids thereby increasing the relative size of the adductor chamber and hence the mass of the jaw adductors. The choana in basal pterosaurs was relatively small compared with the interpterygoid vacuity. With increasing rostroventral inclination of the quadrates in more derived pterosaurs, the interpterygoid vacuity was reduced considerably, whereas the choana increased in size. This exceptional Dorygnathus specimen also shows a hitherto unknown pair of fenestrae situated at the palatal contact of the premaxilla–maxilla and might represent the aperture for the vomeronasal organ. Anat Rec, 2010. © 2009 Wiley‐Liss, Inc.     

单侧完全性唇腭裂胎儿宫内手术修复的解剖学基础

目的　为单侧性唇腭裂胎儿宫内手术修复提供解剖学基础。 方法 制作和观察21～32周正常和单侧完全性唇腭裂胎儿头颈部血管铸型标本,比较他们唇腭部血供的来源及吻合情况。 结果 ①正常胎儿唇腭部的血供主要由上唇动脉、鼻翼下缘动脉和腭大动脉组成。两侧上唇动脉在中线附近吻合成上唇动脉弓,并在鼻中隔前下部形成浅深两层血管网,且上唇动脉鼻中隔支也与腭大动脉穿支相互吻合;②单侧完全性唇腭裂胎儿唇腭部血供由于患侧裂隙的阻隔,导致左右上唇动脉不能吻合成弓,患侧腭大动脉穿过骨残端与患侧鼻腔内的血管相吻合。 结论 单侧完全性唇腭裂胎儿唇腭部血管非常丰富,尤以上唇动脉和腭大动脉为血供主干。     

Ellis Van Creveld2 is Required for Postnatal Craniofacial Bone Development

Ellis‐van Creveld (EvC) syndrome is a genetic disorder with mutations in either EVC or EVC2 gene. Previous case studies reported that EvC patients underwent orthodontic treatment, suggesting the presence of craniofacial bone phenotypes. To investigate whether a mutation in EVC2 gene causes a craniofacial bone phenotype, Evc2 knockout (KO) mice were generated and cephalometric analysis was performed. The heads of wild type (WT), heterozygous (Het) and homozygous Evc2 KO mice (1‐, 3‐, and 6‐week‐old) were prepared and cephalometric analysis based on the selected reference points on lateral X‐ray radiographs was performed. The linear and angular bone measurements were then calculated, compared between WT, Het and KO and statistically analyzed at each time point. Our data showed that length of craniofacial bones in KO was significantly lowered by ～20% to that of WT and Het, the growth of certain bones, including nasal bone, palatal length, and premaxilla was more affected in KO, and the reduction in these bone length was more significantly enhanced at later postnatal time points (3 and 6 weeks) than early time point (1 week). Furthermore, bone‐to‐bone relationship to cranial base and cranial vault in KO was remarkably changed, i.e. cranial vault and nasal bone were depressed and premaxilla and mandible were developed in a more ventral direction. Our study was the first to show the cause‐effect relationship between Evc2 deficiency and craniofacial defects in EvC syndrome, demonstrating that Evc2 is required for craniofacial bone development and its deficiency leads to specific facial bone growth defect. Anat Rec, 299:1110–1120, 2016. © 2016 Wiley Periodicals, Inc.     

A case of a median occipital suture and development of occipital squama in man

A case of a median suture within the squamous part of the occipital bone is described. This rare variety can be explained by the fact of bilateral anlagen of the supraoccipital and interparietal bones which give rise to the Squama occipitalis. In contrast to previous findings on the unpaired origin of the os supraoccipitale a paired origin of this bone can indeed be demonstrated. The normal development of the Squama occipitalis based on the analysis of 134 human embryos is described in detail.     

Development of the human tensor veli palatini: specimens measuring 13.6-137 mm greatest length; weeks 6-16 of development

The present study seeks to determine the main events that occur in the development of the tensor veli palatini (TVP). A light microscope was used on serial sections of 60 human specimens from weeks 6 to 16 of development. The TVP becomes visible in an embryo of 14.5 mm greatest length (GL; week 6) from a common blastema with the medial pterygoid muscle. In embryos of Carnegie stage 20 (week 7), the TVP is differentiated and relates to the anlage of the pterygoid hamulus. At week 8 of development, when the palatal shelves become horizontal, the presence of the anlage of the palatine aponeurosisis distinguished and is reached by the TPV. In an embryo of 30 mm GL, the chondrification nucleus of the pterygoid hamulus and the synovial bursa of the TVP are identifiable. At week 9, the TVP is continuous with the palatine aponeurosis. At week 13, a connective tissue lamina appears between the TVP and the intramembranous ossification center for the anterior process of the malleus, which we know as the goniale and interpret as an attachment of the muscle to the primary vertebrate jaw or incudomalleal joint. The TVP from its origin, innervation and relation to the goniale appears to be a muscle of mastication that, at the end of the embryonic period, reaches the palatine aponeurosis anlage and the mesenchyme of the auditory tube and specializes in the movements of the soft palate and the auditory tube.     

The neglected maxillary process of the palatine bone.

In most recent anatomy textbooks as well as in the latest anatomical nomenclature, the maxillary process of the palatine bone is not mentioned at all. The maxillary process is, however with rare exceptions, always present as an important part of the closure of the hiatus sinus maxillaris. In our material consisting of 200 disarticulated, macerated skull bones and 25 specimens of maxillary sinus, the maxillary process was missing in only 5 cases (2.2%). This process develops in the second year of life and displays different shapes. It can be long and slender or wide and round shaped. Its upper margin is more or less concave, corresponding to the margin of the hiatus over which it is bent. Its inferior margin can be smooth or irregular. In instances in which maxillary sinus is double, the os palatinum has two maxillary processes, so that both sinuses are partly closed with the maxillary process of the palatine bone.     

翼腭神经节的解剖研究及其临床意义

目的　研究翼腭神经节及毗邻结构的显微外科解剖关系,为临床手术治疗相关疾病提供解剖学依据。 方法　成人尸头标本15例（30侧）,采用手术显微镜及鼻内镜观察翼腭神经节及毗邻结构。 结果　翼腭神经节为翼腭窝内副交感神经节,为翼管神经、上颌神经、腭神经三者交汇处,位于内上方为翼管神经,位于外下方为上颌神经,位于下方为腭神经,腭神经起始于腭骨垂直板与上颌骨后壁的夹角处,腭神经起始处外径为（1.23±0.32）mm,向前内走行,并于腭降动脉的后内侧逐渐紧贴腭骨垂直板下降进入翼腭管。 结论　翼腭神经节与腭神经及翼管神经相邻,先通过腭神经寻找到翼腭神经节,再通过翼腭神经节可定位翼管神经,因此可作为翼管神经切除术中的重要解剖标志。     

Is the pterygopalatomaxillary suture (sutura sphenomaxillaris) a growing suture in the fetus?

The pterygopalatomaxillary suture is considered as having an important role in the posteroanterior growing of the maxilla. To determine whether this suture is a growing suture in the fetus, we performed a histological study of this suture in a fetus aged of 16 weeks of amenorrhea. Serial sections (5 μm) of the pterygopalatomaxillary suture area have been performed. Fibrous sutures are separating four pieces of ossification (maxilla, palatine bone, lateral and medial plates of the pterygoid process). A fibroblastic growing site has been observed on the dorsal aspect of the pterygopalatomaxillary suture, in contact to the anterior border of the lateral plate of the pterygoid process. The posteroanterior growing of maxilla is dependent on a growing suture located on the anterior border of the pterygoid process. The pterygoid process (via its lateral plate) makes the junction between the maxilla and both the cranial base and the condylar mandibular site of growth.     

Dental laminae and teeth of embryonic Ichthyophis glutinosus (L.) (Amphibia: Gymnophiona)

Light microscopic studies of dental lamina anlagen and the form and order of primary teeth were undertaken on embryos of Ichthyophis glutinosus. The palate dental lamina responsible for the dentition of the vomers and the palatine portions of the maxillopalatines develops unpaired on the lingual sides of these bones. Similarly, the upper jaw dental lamina is undivided in the rostro-median; it originates lingual to the premaxillaries. Orally paired and aborally unpaired, the dental laminae of the lower jaw are laid down along the inner sides of their respective bony anlagen. Of these, the orally undivided dental lamina corresponds to the dental portion of the caudally fused lower jaw bones while the aboral pair of dental laminae correspond to the splenial portions. When fully developed, the primary teeth are unbladed-conical and divided. They are labio-marginal, monostichous and pleurally anchored.     

Surgical and radiologic anatomy of a cochleostomy produced via posterior tympanotomy for cochlear implantation based on three-dimensional reconstructed temporal bone CT images

Purpose

In this study, we evaluated the surgical and radiologic anatomy of a cochleostomy produced via posterior tympanotomy for cochlear implantation (CI).

Materials and methods

Twenty computed tomography (CT) images of the temporal bone from patients aged between 20 and 60 years were selected. The inclusion criterion was a radiologically normal temporal bone CT scan. Three-dimensional (3D) reconstructed images were obtained using high-resolution axial temporal bone CT scans. Eight points were used to evaluate the surgical anatomy of the posterior tympanotomy and cochleostomy. The length of lines between the points and the angles between the lines were measured.

Results

The mean length of line AB (superior-inferior length of the posterior tympanotomy for CI) was 6.48 ± 0.26 mm, while line AC (width of the chorda tympani and facial nerves) was 3.60 ± 0.2 mm. The mean angle of ABC (angle at which the chorda tympani nerve branched from the facial nerve) was 18.40° ± 1.05°. The mean length of line AD (distance from the facial ridge to the point of cochleostomy) was 9.58 ± 0.47 mm.

Conclusions

3D imaging of the facial recess and round window can be used to identify the facial recess before surgery. This may help to avoid injury to the chorda tympani nerve during posterior tympanotomy, and make it easier to insert the electrode array during CI by creating a large enough posterior tympanotomy to avoid injury to the facial nerve, which can cause immediate or delayed facial palsy.     

Sagittal craniofacial growth evaluated on children dry skulls using V<Subscript>2</Subscript> and V<Subscript>3</Subscript> canal openings as references

The purpose of this study was to investigate the relationship between standard cephalometric landmarks and lines and those using ovale, rotundum, greater palatine and infra-orbital foramina as references. Thirty-four children dry skulls, 19 males and 15 females aged 0-6 years, were examined by computed tomography scanning. The classical cephalometric dimensions of skull base were measured from middle sagittal plane crossing over basion, nasion and sella turcica. Those of hard palate (maxilla and palatine bone) were measured from axial plane intersecting posterior nasal spine and anterior nasal spine. The dimensions between ovale and rotundum foramina, rotundum and infra-orbital foramina, greater palatine and infra-orbital foramina were determined by using constructed tomographic planes enclosing these different foramina. Biostatistical analysis using partial correlations showed that the linear variables with nerve canal openings as references are strongly related to length of both the skull base and of the hard palate. The results highlight the importance of the nerve canal openings of skull base and bone facial components in normal or pathologic craniofacial growth investigations.     

Osteopoikilosis and multiple exostoses caused by novel mutations in <Emphasis Type="Italic">LEMD3</Emphasis> and <Emphasis Type="Italic">EXT1</Emphasis> genes respectively - coincidence within one family

Background  

Osteopoikilosis is a rare autosomal dominant genetic disorder, characterised by the occurrence of the hyperostotic spots preferentially localized in the epiphyses and metaphyses of the long bones, and in the carpal and tarsal bones [1]. Heterozygous LEMD3 gene mutations were shown to be the primary cause of the disease [2]. Association of the primarily asymptomatic osteopokilosis with connective tissue nevi of the skin is categorized as Buschke-Ollendorff syndrome (BOS) [3]. Additionally, osteopoikilosis can coincide with melorheostosis (MRO), a more severe bone disease characterised by the ectopic bone formation on the periosteal and endosteal surface of the long bones [4–6]. However, not all MRO affected individuals carry germ-line LEMD3 mutations [7]. Thus, the genetic cause of MRO remains unknown. Here we describe a familial case of osteopoikilosis in which a novel heterozygous LEMD3 mutation coincides with a novel mutation in EXT1, a gene involved in aetiology of multiple exostosis syndrome. The patients affected with both LEMD3 and EXT1 gene mutations displayed typical features of the osteopoikilosis. There were no additional skeletal manifestations detected however, various non-skeletal pathologies coincided in this group.     

腭扁桃体血管的应用解剖

在30例已固定的成人尸体头部标本上观察了腭扁桃体的动脉、静脉及其毗邻关系。腭降动脉及腭升动脉腭支主要分布于扁桃体的上极和上部;咽升动脉及腭升动脉主干分布于扁桃体的中部;面动脉主干及舌动脉则主要分布于扁桃体的下部和下极。以上各动脉分支均穿过咽上缩肌直接分带于扁桃体。腭扁桃体静脉先于其被膜下形成静脉网,再汇集成1～5支扁桃体静脉,后分别流入扁桃体旁静脉、咽静脉和舌静脉内。     

The premaxilla: Embryological evidence that it does not exist in man

Many accounts of the human premaxilla describe its ossification centers and time of fusion with the maxilla, but that such a bone even exists in the human has long been questioned. Very few specimens undergoing initial phases of ossification have been reported and no convincing photographs of separate centers have been published. This report is based on 90 serially sectioned human embryos whose ages (Streeter's Horizons XVIII to XXIII) were closely grouped around the age when ossification of the upper jaw begins. There is but one ossification center bilaterally which, although it appears first in the cuspid region, rapidly involves an area extending from the molar to the central incisor region. Not one of the specimens showed an independent center for the “premaxilla” nor an “incisive suture” in the area of ossification. The premaxilla does not exist as an independent bone in man.     

Variations of the prominences of the bony palate and their relationship to complete dentures in Korean skulls.

The osteological and morphological variations of the prominences in the bony palate of 160 Korean skulls were studied. The frequency of the occurrence of the posterior palatine crest, located on the posterior border of the greater palatine foramen, was 13.8%. Palatal ridges were observed commonly in the skulls; however, the smooth type, which has no palatal ridges in the palate, was shown in 14.7% of cases, and palatal spines were observed in 33.8%. The prevalence of palatal tubercles was 11.6%, and all were found in the molar region. The palatine torus was found in 18.8% of cases and the most common type was along the median palatine suture from the incisive foramen to the posterior border of the palatine bone (63.3%). No significant differences between sexes or sides were found in the posterior palatine crest, palatal ridges, and palatal tubercle. However, the sex distribution of the palatine torus was significantly different (P < 0.05). These results would be helpful clinically in fabricating maxillary complete dentures for edentulous patients.