耳内镜下新西兰兔中耳的解剖研究

目的　耳内镜下观察兔中耳解剖结构,探讨兔作为耳内镜解剖训练模型的可行性,为兔中耳相关的其他实验研究提供解剖学依据。 方法　5只（10耳）新西兰兔麻醉处死后,耳内镜下经外耳道入路观察兔鼓膜、中耳鼓室结构,辨别听小骨、上中下鼓室、面神经等。 结果　与人对比,新西兰兔听小骨由锤砧联合体和镫骨组成;上鼓室外侧壁部分骨质缺如,由鼓膜向上延续并覆盖;听泡类似于人的中、下鼓室,包含咽鼓管、面神经、鼓岬、前庭窗、蜗窗以及鼓室神经等结构,乳突为听泡尾侧的板障型骨管;面神经鼓室段水平走行于上鼓室下方骨壁内,后经锥隆起垂直走行于听泡后壁,经茎乳孔出听泡。 结论　新西兰兔中耳结构与人相似,既可作为耳科医生练习耳内镜操作的解剖模型,也可作为耳部三维解剖结构的教学标本。     

Distribution of type I collagen, type II collagen and PNA binding glycoconjugates during chondrogenesis of three distinct embryonic cartilages

Summary Previous studies of chondrogenesis have been focused on limb bud cartilage, whereas little is known about chondrogenic processes of other cartilages with different developmental fates. We hypothesize that cartilages with various developmental fates might show identical characteristics of chondrogenesis. The chondrogenic processes in the nasal septum, the mandible, and the limb bud of the mouse were examined by means of PNA-binding glycoconjugate, and types I and II collagen expression. Swiss-Webster mouse embryos of 11 days (E11) to 14 days (E14) gestation were fixed and processed for imniuno- and lectin histochemistry. The blastema of mesenchymal cell aggregates stained positively with anti-type I collagen, but very weakly with anti-type II collagen in all three models at E12, whereas PNA bound to the blastema in the limb bud but not in nasal septum or mandible. Types I and II collagens coexisted in cartilages at E13. Type II collagen was predominant in E14; type I collagen was confined to the peripheral region. The synchronized transitional expression of the collagen phenotypes in all three embryonic cartilages may be systemically regulated. The presence or absence of the PNA-binding glycoconjugates may be involved in characterizing the nature of the cartilages.     

耳内镜下新西兰兔中耳的解剖研究

目的　耳内镜下观察兔中耳解剖结构,探讨兔作为耳内镜解剖训练模型的可行性,为兔中耳相关的其他实验研究提供解剖学依据。 方法　5只（10耳）新西兰兔麻醉处死后,耳内镜下经外耳道入路观察兔鼓膜、中耳鼓室结构,辨别听小骨、上中下鼓室、面神经等。 结果　与人对比,新西兰兔听小骨由锤砧联合体和镫骨组成;上鼓室外侧壁部分骨质缺如,由鼓膜向上延续并覆盖;听泡类似于人的中、下鼓室,包含咽鼓管、面神经、鼓岬、前庭窗、蜗窗以及鼓室神经等结构,乳突为听泡尾侧的板障型骨管;面神经鼓室段水平走行于上鼓室下方骨壁内,后经锥隆起垂直走行于听泡后壁,经茎乳孔出听泡。 结论　新西兰兔中耳结构与人相似,既可作为耳科医生练习耳内镜操作的解剖模型,也可作为耳部三维解剖结构的教学标本。     

Early development of the malleus and incus in humans

It is widely accepted by developmental biologists that the malleus and incus of the mammalian middle ear are first pharyngeal arch derivatives, a contention based originally on classical embryology that has now been backed up by molecular evidence from rodent models. However, it has been claimed in several studies of human ossicular development that the manubrium of the malleus and long process of the incus are actually derived from the second arch. This ‘dual‐arch’ interpretation is commonly presented in otolaryngology textbooks, and it has been used by clinicians to explain the aetiology of certain congenital abnormalities of the human middle ear. In order to re‐examine the origins of the human malleus and incus, we made three‐dimensional reconstructions of the pharyngeal region of human embryos from 7 to 28 mm crown–rump length, based on serial histological sections from the Boyd Collection. We considered the positions of the developing ossicles relative to the pharyngeal pouches and clefts, and the facial and chorda tympani nerves. Confirming observations from previous studies, the primary union between first pharyngeal pouch and first cleft found in our youngest specimens was later lost, the external meatus developing rostroventral to this position. The mesenchyme of the first and second arches in these early embryos seemed to be continuous, but the boundaries of the developing ossicles proved to be very hard to determine at this stage. When first distinguishable, the indications were that both the manubrium of the malleus and the long process of the incus were emerging within the first pharyngeal arch. We therefore conclude that the histological evidence, on balance, favours the ‘classical’ notion that the human malleus and incus are first‐arch structures. The embryological basis of congenital ossicular abnormalities should be reconsidered in this light.     

The origin of the stapes and relationship to the otic capsule and oval window

Background: The stapes, an ossicle found within the middle ear, is involved in transmitting sound waves to the inner ear by means of the oval window. There are several developmental problems associated with this ossicle and the oval window, which cause hearing loss. The developmental origin of these tissues has not been fully elucidated. Results: Using transgenic reporter mice, we have shown that the stapes is of dual origin with the stapedial footplate being composed of cells of both neural crest and mesodermal origin. Wnt1cre/Dicer mice fail to develop neural crest‐derived cartilages, therefore, have no middle ear ossicles. We have shown in these mice the mesodermal stapedial footplate fails to form and the oval window is induced but underdeveloped. Conclusions: If the neural crest part of the stapes fails to form the mesodermal part does not develop, indicating that the two parts are interdependent. The stapes develops tightly associated with the otic capsule, however, it is not essential for the positioning of the oval window, suggesting that other tissues, perhaps within the inner ear are needed for oval window placement. Developmental Dynamics 241:1396–1404, 2012. © 2012 Wiley Periodicals, Inc.     

Hemifacial microsomia: developmental consequence of perturbation of the auriculofacial cartilage model?

The cause of hemifacial microsomia (HFM) is currently the subject of much investigation. Despite a large body of clinical and experimental data, little is certain other than the heterogeneity of this malformation complex. Here we suggest that some of the cases previously designated as being multifactorial in origin may be interpreted instead as resulting from a single-gene mutation, by applying a stochastic single-gene model. A variety of models of the pathogenesis of HFM have been described, including the proposal that local embryonic haemorrhage is a causal mechanism. More recently, it has been suggested that an interference in chondrogenesis is primarily responsible for the HFM phenotype. In this paper direct experimental evidence, based on surgical interference of mandibular development in the chick embryo, is applied in favour of the latter concept. In particular, asymmetrical perturbation of Meckel's cartilage has been shown to result in asymmetry of the mandible, and it is proposed that, irrespective of cause, the skeletal pathogenesis of HFM primarily involves the auriculofacial cartilage model.     

The incudopetrosal joint of the human middle ear: a transient morphology in fetuses

In spite of the amount of research on fetal development of the human middle ear and ear ossicles, there has been no report showing a joint between the short limb of incus and the otic capsule or petrous part of the temporal bone. According to observations of serial histological sections from 65 embryos and fetuses at 7–17 weeks of development, the incudopetrosal joint exhibited a developmental sequence similar to the other joints of ossicles, with an appearance of an interzone followed by a trilaminar configuration at 7–12 weeks, a joint cavitation at 13–15 weeks and development of intraarticular and capsular ligaments at 16–17 weeks. These processes occurred at the same time or slightly later than any other joint. Thus, the joint development might coordinate with vibrating ossicles in utero. The growing short limb of incus appeared to accelerate an expansion of the epitympanic recess of the tympanic cavity. Additional observations of five late-stage fetuses demonstrated the incudopetrosal joint located in the fossa incudis joint changing to syndesmosis. Consequently, a real joint with a cavity existed transiently between the human neurocranium and the first pharyngeal arch derivative (i.e. incus) in contrast to the tympanostapedial joint or syndesmosis between the neurocranium and the second arch derivative. The newly described joint might have an effect on the widely accepted primary jaw concept: the mammalian jaw should thus have been created within the first pharyngeal arch, although the connection with neurocranium by the stapes is of a different origin.     

Development of the Skull of the Pantropical Spotted Dolphin (Stenella attenuata)

We describe the bony and cartilaginous structures of five fetal skulls of Stenella attenuata (pantropical spotted dolphin) specimens. The specimens represent early fetal life as suggested by the presence of rostral tactile hairs and the beginnings of skin pigmentation. These specimens exhibit the developmental order of ossification of the intramembranous and endochondral elements of the cranium as well as the functional and morphological development of specific cetacean anatomical adaptations. Detailed observations are presented on telescoping, nasal anatomy, and middle ear anatomy. The development of the middle ear ossicles, ectotympanic bone, and median nasal cartilage is of interest because in the adult these structures are morphologically different from those in land mammals. We follow specific cetacean morphological characteristics through fetal development to provide insight into the form and function of the cetacean body plan. Combining these data with fossil evidence, it is possible to overlie ontogenetic patterns and discern evolutionary patterns of the cetacean skull. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

Disconnecting bones within the jaw‐otic network modules underlies mammalian middle ear evolution

The origin of the mammalian middle ear ossicles from the craniomandibular articulation of their synapsid ancestors is a key event in the evolution of vertebrates. The richness of the fossil record and the multitude of developmental studies have provided a stepwise reconstruction of this evolutionary innovation, highlighting the homology between the quadrate, articular, pre‐articular and angular bones of early synapsids with the incus, malleus, gonial and ectotympanic bones of derived mammals, respectively. There are several aspects involved in this functional exaptation: (i) an increase of the masticatory musculature; (ii) the separation of the quadrate bone from the cranium; and (iii) the disconnection of the post‐dentary bones from the dentary. Here, we compared the jaw‐otic complex for 43 synapsid taxa using anatomical network analysis, showing that the disconnection of mandibular bones was a key step in the mammalian middle ear evolution, changing the skull anatomical modularity concomitant to the acquisition of new functions. Furthermore, our analysis allows the identification of three types of anatomical modules evolving through five evolutionary stages during the anatomical transformation of the jawbones into middle ear bones, with the ossification and degradation of Meckel's cartilage in mammals as the key ontogenetic event leading the change of anatomical modularity.     

颞下经下颌入路相关骨性结构解剖及其临床意义

目的研究与颞下经下颌入路相关的骨性结构解剖,为扩大手术暴露提供解剖学参考。方法选用成人尸头10例(20侧),经模拟手术后去除软组织,显露相关骨性结构,进行观察和测量。结果颧弓是暴露中颅底和颞下窝的关键,颧弓长度和下颌关节窝宽度分别为32.9±2.6mm和15.5±1.3mm;下颌孔位于下颌升支内侧面中央略偏后上方,下颌升支的斜行截骨安全且可以获得最佳的纵向暴露;颞下窝,翼腭窝和咽旁间隙骨性结构复杂,腔隙众多且互为交通;茎突是重要的解剖标志,其根部至颈静脉孔后缘仅2.95±0.25mm。结论颞下经下颌入路暴露充分,掌握相关骨性解剖对手术治疗侧颅底区沟通性肿瘤具有重要意义。     

Novel autosomal dominant mandibulofacial dysostosis with ptosis: clinical description and exclusion of TCOF1

Methods: Six affected family members underwent a complete medical genetics physical examination and two affected subjects had skeletal survey. All available medical records were reviewed. Linkage analysis using the markers spanning the TCOF1 locus was performed. One typically affected family member had a high resolution karyotype. Results: Affected subjects had significant craniofacial abnormalities without any significant acral changes and thus had a phenotype consistent with a MFD variant. Distinctive features included hypoplasia of the zygomatic complex, micrognathia with malocclusion, auricular abnormalities with conductive hearing loss, and ptosis. Significantly negative two point lod scores were obtained for markers spanning the TCOF1 locus, excluding the possibility that the disease in our kindred is allelic with TCS. High resolution karyotype was normal. Conclusions: We report a kindred with a novel type of MFD that is not linked to the TCOF1 locus and is also clinically distinct from other types of AD MFD. Identification of additional families will facilitate identification of the gene causing this type of AD MFD and further characterisation of the clinical phenotype.     

Superficial temporal artery: the “C” shape half-buttonhole configuration as it courses over the zygomatic arch

Purpose

To describe the course and configuration of the superficial temporal artery (STA) around the zygomatic arch.

Methods

Volume rendered 3D reconstructions of computed tomography angiography of 25 healthy patients were performed and analyzed at Duke University Hospitals.

Results

The STA coursed over the zygomatic arch or over the condylar process of the mandible in all cases (25/25 pts, 100 %). The STA courses over the posterior zygomatic arch in 23/25 pts (92 %), creating a characteristic “C” shape half-buttonhole configuration as it embraces the arch. When the STA travels posterior to the zygomatic arch, there is no C shape configuration (2/25 pts, 8 %). The STA bifurcates distal to the zygomatic arch in 24/25 pts (96 %).

Conclusions

The “C” shape half-buttonhole configuration is a useful identifying characteristic of the most common course of the STA—over the posterior zygomatic arch before it bifurcates.

     

Development of the Human Incus With Special Reference to the Detachment From the Chondrocranium to be Transferred into the Middle Ear

The mammalian middle ear represents one of the most fundamental features defining this class of vertebrates. However, the origin and the developmental process of the incus in the human remains controversial. The present study seeks to demonstrate all the steps of development and integration of the incus within the middle ear. We examined histological sections of 55 human embryos and fetuses at 6 to 13 weeks of development. At 6 weeks of development (16 Carnegie Stage), the incus anlage was found at the cranial end of the first pharyngeal arch. At this stage, each of the three anlagen of the ossicles in the middle ear were independent in different locations. At Carnegie Stage 17 a homogeneous interzone clearly defined the incus and malleus anlagen. The cranial end of the incus was located very close to the otic capsule. At 7 and 8 weeks was characterized by the short limb of the incus connecting with the otic capsule. At 9 weeks was characterized by an initial disconnection of the incus from the otic capsule. At 13 weeks, a cavity appeared between the otic capsule and incus. Our results provide significant evidence that the human incus developed from the first pharyngeal arch but independently from Meckel's cartilage. Also, during development, the incus was connected with the otic capsule, and then it was detached definitively. The development of the incus in humans provides evidence that this ossicle is homologous to the quadrate. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.     

A population level atlas of Mus musculus craniofacial skeleton and automated image‐based shape analysis

Laboratory mice are staples for evo/devo and genetics studies. Inbred strains provide a uniform genetic background to manipulate and understand gene–environment interactions, while their crosses have been instrumental in studies of genetic architecture, integration and modularity, and mapping of complex biological traits. Recently, there have been multiple large‐scale studies of laboratory mice to further our understanding of the developmental basis, evolution, and genetic control of shape variation in the craniofacial skeleton (i.e. skull and mandible). These experiments typically use micro‐computed tomography (micro‐CT) to capture the craniofacial phenotype in 3D and rely on manually annotated anatomical landmarks to conduct statistical shape analysis. Although the common choice for imaging modality and phenotyping provides the potential for collaborative research for even larger studies with more statistical power, the investigator (or lab‐specific) nature of the data collection hampers these efforts. Investigators are rightly concerned that subtle differences in how anatomical landmarks were recorded will create systematic bias between studies that will eventually influence scientific findings. Even if researchers are willing to repeat landmark annotation on a combined dataset, different lab practices and software choices may create obstacles for standardization beyond the underlying imaging data. Here, we propose a freely available analysis system that could assist in the standardization of micro‐CT studies in the mouse. Our proposal uses best practices developed in biomedical imaging and takes advantage of existing open‐source software and imaging formats. Our first contribution is the creation of a synthetic template for the adult mouse craniofacial skeleton from 25 inbred strains and five F1 crosses that are widely used in biological research. The template contains a fully segmented cranium, left and right hemi‐mandibles, endocranial space, and the first few cervical vertebrae. We have been using this template in our lab to segment and isolate cranial structures in an automated fashion from a mixed population of mice, including craniofacial mutants, aged 4–12.5 weeks. As a secondary contribution, we demonstrate an application of nearly automated shape analysis, using symmetric diffeomorphic image registration. This approach, which we call diGPA, closely approximates the popular generalized Procrustes analysis (GPA) but negates the collection of anatomical landmarks. We achieve our goals by using the open‐source advanced normalization tools (ANT) image quantification library, as well as its associated R library (ANTsR) for statistical image analysis. Finally, we make a plea to investigators to commit to using open imaging standards and software in their labs to the extent possible to increase the potential for data exchange and improve the reproducibility of findings. Future work will incorporate more anatomical detail (such as individual cranial bones, turbinals, dentition, middle ear ossicles) and more diversity into the template.     

The comparative anatomy of the pig middle ear cavity: a model for middle ear inflammation in the human?

This study was undertaken to develop a functional model of otitis media with effusion (OME) in the pig ( Sus scrofa ), with the purpose of investigating the origin of lymphocytes populating the middle ear during the course of an inflammatory process. The relevance of the model to the human condition of OME is to a large extent dependent on the anatomical and physiological similarities between the middle ear cavity and the pharyngeal lymphoid tissue of the pig and man. Anatomical specimens were collected from 7 young Large White pigs to determine the gross anatomy of the middle ear cavity and the histological characteristics of the middle ear mucosa. It was found that the anatomy of the 3 parts of the middle ear cavity in man and in the pig is broadly similar, although some minor differences were observed. The porcine eustachian tube was seen to be cartilaginous throughout its length in contrast to the part osseous, part cartilaginous structure found in man; the porcine ossicles were slightly different in shape to those of man and the air cell system was situated inferior to the tympanic cavity in the pig as opposed to posteriorly in man. This paper describes the structure and morphology of the pig middle ear cavity and compares and contrasts it with that of man. The minor differences observed are of anatomical importance but do not diminish the usefulness of the pig middle ear cleft as a potential model for human middle ear disorders.     

Geometric morphometric analysis of allometric variation in the mandibular morphology of the hominids of Atapuerca, Sima de los Huesos site

Allometry is an important factor of morphological integration that contributes to the organization of the phenotype and its variation. Variation in the allometric shape of the mandible is particularly important in hominid evolution because the mandible carries important taxonomic traits. Some of these traits are known to covary with size, particularly the retromolar space, symphyseal curvature, and position of the mental foramen. The mandible is a well studied system in the context of the evolutionary development of complex morphological structures because it is composed of different developmental units that are integrated within a single bone. In the present study, we investigated the allometric variation of two important developmental units that are separated by the inferior nerve (a branch of CN V3). We tested the null hypothesis that there would be no difference in allometric variation between the two components. Procrustes-based geometric morphometrics of 20 two-dimensional (2D) landmarks were analyzed by multivariate regressions of shape on size in samples from 121 humans, 48 chimpanzees, and 50 gorillas (all recent specimens), eight fossil hominids from Atapuerca, Sima de los Huesos (AT-SH), and 17 Neandertals. The findings show that in all of the examined species, there was significantly greater allometric variation in the supra-nerve unit than in the infra-nerve unit. The formation of the retromolar space exhibited an allometric relationship with the supra-nerve unit in all of the species studied. The formation of the chin-like morphology is an "apodynamic" feature of the infra-nerve unit in the AT-SH hominids. The results of this study support the hypothesis that allometry contributes to the organization of variation in complex morphological structures.     

国人颞中静脉的解剖学研究及意义

目的　研究国人颞中静脉的解剖学特征和标志，为临床应用提供解剖学依据。 方法　26侧（左12侧，右14侧，男性18，女性3）经10%福尔马林灌注固定的人头标本，解剖颞区颞中静脉及属支，观察其走行分布，测量主干到各解剖标志距离及管径，计数属支数目并测量管径。比较左、右侧差异。 结果　所有标本存在颞中静脉，主干管径平均2.91 mm（0.72~5.88 mm），属支0~7支，属支管径平均2.05 mm（0.54~5.30 mm），可有2级属支（3.8%，1例）。主干汇入颞浅静脉的位置不完全一致，汇点高者在颧弓根部（42.3%，11例），低者位于颧弓下缘9.02~21.00 mm处。主干大致有3种分布类型：①经典型53.8%（14例），②分裂聚合型30.8%（8例），③直角型15.4%（4例）。转折处到耳屏内侧缘的垂直距离平均18.69 mm，主干到颧弓中点、眶外缘与颧弓交界处、眼外眦、眉弓外端距离的平均值，左侧分别为：（17.23±7.29）、（18.82±9.00）、（21.14±6.96）、（9.62±8.87）mm，右侧分别为：（17.28±5.74）、（18.34±7.63）、（19.40±6.98）mm、（8.17±5.53）mm；相对应的管径平均值分别为左：（3.75±1.63）、（3.34±1.00）、（3.08±1.18）、（2.81±1.23）mm；右：（4.29±2.93）、（2.90±1.29）、（2.89±1.20）、（2.57±1.21）mm。左、右侧无统计学差异。 结论　对国人颞中静脉的走行分布进行解剖学类型划分，以丰富解剖学资料；掌握颞中静脉的解剖学特征和标志，于颞区手术具有指导意义。