Function and functional groupings of the complex mouth apparatus of the squat lobsters Munida sarsi Huus and M. tenuimana G.O. Sars (Crustacea: Decapoda).

Like all other decapods, the anomuran squat lobsters Munida sarsi and M. tenuimana have a mouth apparatus composed of six pairs of mouthparts plus labrum and paragnaths (upper and lower lips). To study the functional significance of this complexity, we examined the mouthparts with scanning electron microscopy and also observed their function directly, under laboratory conditions, using macro-video equipment. No differences were found between the two species. The movement patterns of the mouthparts are described in detail and illustrated as serial drawings. Proceeding from maxillipeds 3 towards the mandibles, the movement pattern gets increasingly stereotypical, with the mandibles performing but a single movement in a medio-lateral plane. From morphology, the mouthparts are subdivided into 20 parts, but from the functional analyses the 20 parts form 8 functional groups: 1, transporting mouthparts (maxilliped 2 endopod and maxilliped 3 endopod); 2, transporting-aligning mouthparts (maxilliped 1 basis); 3, sorting-aligning mouthparts (maxilla 1 basis and maxilla 2 basis); 4, current-generating mouthparts (flagella of maxilliped 2 and maxilliped 3 exopods); 5, cutting-crushing mouthparts (incisor and molar processes, labium, and mandibular palp); 6, ingesting mouthparts (maxilla 1 coxa, maxilla 2 coxa, and maxilliped 1 coxa); 7, respiratory mouthparts (scaphognathite, maxilliped 1 epipod, and maxilliped 2 and maxilliped 3 exopods); and 8, dorso-ventral mouthparts (maxilla 1 endopod, maxilla 2 endopod, maxilliped 1 endopod, and maxilliped 1 exopod). These groupings apply mostly to the processes of food handling and have little significance with respect to grooming. When comparing our results to the literature on other decapods, we found much resemblance to conditions in other anomurans.     

中华鲎虫外部形态结构的初步观察

中华鲎虫体由头、躯干和尾3部分组成.头部具1对复眼和1个无节幼体眼,复眼后有1个颈感器.第1触角细小、棒状,第2触角退化.口器由上唇、大颚和2对小颚组成,上唇为头部的突起物,大颚和2对小颚为附肢,第2小颚的皮肤皱褶延长扩大形成头胸甲.雌体躯干部由36个体节组成,雄体39个体节,前30节具附肢,共57对.雌体躯干部后6个体节无附肢,雄体躯干部后9个体节无附肢.尾节分叉,细长多节,具刚毛,左右两根尾鞭的分节不对称.     

Role of maxilla 2 and its setae during feeding in the shrimp Palaemon adspersus (Crustacea: Decapoda)

The movements of the basis of maxilla 2 in Palaemon adspersus were examined using macro-video recordings, and the morphology of its setae was examined using both scanning and transmission electron microscopy. The basis of maxilla 2 performs stereotypical movements in the latero-medial plane and gently touches the food with a frequency of 3-5 Hz. The medial rim of the basis of maxilla 2 carries three types of seta. Type 1 is serrate, type 2 and 3 are serrulate, and type 2 has a prominent terminal pore. Type 2 is innervated by 18-25 sensory cells whose cilia protrude through the terminal pore and are in direct contact with the external environment. The structure of type 2 setae indicates that they are mainly gustatory, although still bimodal due to their innervation by presumed chemosensory and mechanosensory neurons. Distally, the three types of setae have a complex arrangement of the cuticle involving water-filled canals, which may serve to improve flexibility. Type 1 and 3 setae have fewer sensory cells (4-9) but probably also have a bimodal sensory function. The function of type 1 setae is probably to protect type 2 setae, while type 3 setae might serve to groom the ventral side of the basis of maxilla 1.     

Feeding mechanics in primitive teleosts and in the halecomorph fish Amia calva

The mechanics of feeding in Salmo gairdneri and Hoplias malabaricus, two generalized predaceous teleosts, was studied using high-speed movies (200 frames per second). In Hoplias, the feeding mechanism is characterized by an extreme anterior swing of the maxilla and rapid depression of the hyoid occurring synchronously with mandibular depression and neurocranial elevation. A similar feeding sequence is observed in Salmo although the movements of the head are neither as extreme nor as rapid.
The anterior swing of the maxilla, usually attributed to mandibular depression, increased when the ligamentous connection of the maxilla to the mandible was severed. A mechanical model of the jaw was constructed to elucidate the functional interrelationships of the neurocranium, maxilla and mandible.
Films of the "holostean" Amia calva feeding show that the feeding mechanism is of a fundamentally different nature than that of primitive teleost fishes. Extreme anterior swinging of the maxilla occurs synchronously with jaw opening but branchiostegal expansion and hyoid depression only reach a maximum well after the jaws have begun to close. The existence of a highly efficient levator operculi—opercular series—mandible coupling is hypothesized on the basis of the rapid initial jaw opening.
This pattern of feeding movements in Amia has necessitated a revision of current theories on the nature and significance of the "holostean"     

The first female maxilla of the hominoid Ouranopithecus macedoniensis from the late Miocene of Macedonia,Greece

A maxilla with both toothrows C-M³ of a late Miocene hominoid is described. It was found at the locality Nikiti 1 (NKT) of Chalkidiki (Macedonia, Greece). The locality has been dated to late Vallesian-earliest Turolian. The morphological characters and the comparison of the new maxilla suggest that it is a female individual of Ouranopithecus macedoniensis. It is the first known female maxilla of the species. Comparison with the other two known male maxillae of Ouranopithecus macedoniensis indicates the following differences: smaller size of maxilla and teeth, smaller mesial groove in the canine, more lingually situated mesial groove in the canine, slightly smaller mesiobuccal projection in P³ and relatively shorter P⁴. There are no significant morphological differences in the molars. Various statistical parameters for the Ouranopithecus teeth have been calculated and compared with those of the extant hominoids. This comparison suggests the presence of a single species in the sample.     

Patterns of prey size and taxonomic composition in larval fish: are there general size-dependent models?

The allometric relationship of maxilla length to larval fish weight approached a slope of 1/3 for 11 species from Conception Bay, Newfoundland. In 10 of these species, mean prey size increased with length of the maxilla but not constantly. In six species, niche breadth increased with length of maxilla. The rate of change in niche breadth was inversely related to the rate of change in mean prey size. Nauplii and copepodites of calanoids were selected positively, and cyclopoids negatively for almost all species of larval fish.     

Stephonyx, a new, widespread genus of lysianassoid Amphipoda

A new genus, Stephonyx , is established for six species of scavenging lysianassoid amphipods currently included in the genus Euonyx. Stephonyx is distinguished from other lysianassoid genera by a combination of characters which include the structure of the mandibular molar, the structure of the spine-teeth on maxilla 1, and a chelate gnathopod 1. Species of Euonyx are considered to be commensals of echinoderms with modified mouthparts in which the mandibular molar is lost, the lacinia mobilis is vestigial and the spine-teeth of maxilla 1 are simple and reduced in size.     

The functional significance of the pterygomaxillary ligament in Xenopus Iaevis (Amphibia: Anura)

A pterygomaxillary ligament, which runs postero-inferiorly from the posterior end of the maxilla to the pterygoid, is described macroscopically and microscopically in the aquatic anuran amphibian Xenopus laevis (Daudin). The quadratojugal is absent in this species, and consequently the short maxilla has no posterior articulation and is potentially mobile. However, the pterygomaxillary ligament limits upward and lateral displacement of the maxilla when pressure is applied upwards during closure of the lower jaw. The ligament absorbs forces applied to the posterior end of the maxilla and permits their dissipation via the pterygoid to the neurocranium.     

Prenatal growth pattern of the human maxilla.

Regarding maxillofacial morphogenesis there has been a long debate on the growth of the maxillary structure. Using 120 normal fetal maxillae of gestational ages from 16 to 41 weeks, palatal radiograms and frontal histologic sections were made. We have observed two pairs of accentuated growth areas in the fetal maxillae and named them primary growth centers to formulate the maxillary trapezoid (MT) by radiologic image. The MT is formed by four primary growth centers that are best demonstrated by palatal radiograms of the fetal maxilla as well as by frontal histologic sections. The dimensional increase in the MT during the fetal period is documented and statistically analyzed. From this series of results, we have suggested that the growth centers which demarcate the MT are the basic structures of the developing human maxilla. It was also found that the four primary growth centers are the most active sites for maxilla formation until 20 weeks of gestation and thereafter the growth of the maxilla is enhanced by the participation of the intramembranous bone formation along the periphery. This was in contrast to the central primary growth centers that have already finished maturation in the early fetal period and remain only as a peripherally radiating arrangement of thick trabecular bones.     

记裂齿鱼属(Perleidus)一新种

本文记述了在安徽和县发现的裂齿鱼属一新种——扬子裂齿鱼(Perleidus yangtzensis,sp.nov.)。根据其形态特征,与相近的种作了对比,认为和马达加斯加早三迭世的皮氏裂齿鱼(P.pivetcaui)最为接近。从而认为含鱼化石地层的时代为三迭纪或可能为早三迭世。     

New approach to the gummy smile

The authors present a multidisciplinary approach to the gingival smile in which its three components are evaluated. These components are the dynamic component of the lip (repose versus smiling) and the two static elements of the gum and maxilla. Once an appropriate diagnosis has been made, the authors act on the gingiva for delayed passive eruption, on the maxilla for long face syndrome, and on the lip with lip-elongation techniques. When delayed passive eruption is associated with hyperfunction of the lip elevators, an intraoral approach with an incision at the level of the upper labial frenulum and dissection from the anterior nasal spine to the anterior maxillary fossae, in addition to gingival remodeling, is recommended to reduce gingival exposure.     

Effects of a denture adhesive in edentulous patients after maxillectomy

doi: 10.1111/j.1741‐2358.2011.00538.x
Effects of a denture adhesive in edentulous patients after maxillectomy Objective: The objective of this study is to evaluate the usefulness of a denture adhesive in edentulous patients after maxillectomy. Background: Maxillectomy patients suffer from functional impairments. Denture adhesives (DAs) are the solution in such patients. However, little is known about DAs in maxillectomy patients. Materials and Methods: Eight edentulous patients who had undergone maxillectomy were included and divided into three groups. Group 1 (half ≤ remaining residual maxilla), Group 2 (quarter < remaining residual maxilla < half) and Group 3 (remaining residual maxilla ≤ quarter). They were evaluated by a speech intelligibility test and a mixing ability test, respectively. A cream‐type DA called New Poligrip^® (GlaxoSmithKline, Tokyo, Japan) was used. Results: Applying the DA, speech intelligibility showed a higher score than the data without DA. Conclusion: The effects of using a DA depend on the amount of the remaining residual maxilla. Our study showed that if the remaining residual maxilla is less than a quarter (Group 3), it is difficult to have confidence in the effectiveness of the DA to improve masticatory function. On the other hand, the use a DA showed improved speech intelligibility test values in all groups.     

Lip-nasal aesthetics following Le Fort I osteotomy

Forty-one patients undergoing Le Fort I osteotomy for superior and/or anterior repositioning of the maxilla were prospectively studied for changes in soft-tissue morphology of the nasomaxillary region. Nasal parameters studied were changes in interalar rim width and nasal tip projection. It was observed that alar rim width increases with anterior and/or superior repositioning of the maxilla, but increases in nasal tip projection occur only when there is an anterior vector of maxillary movement. These nasal changes could not be quantitatively correlated to magnitude of maxillary movement. Lip changes studied were the horizontal displacement at the vermilion border and subnasale versus that of the incisal edge and point A, respectively, when the maxilla is sagittally advanced and the vertical shortening of the lip versus that of the incisal edge when the maxilla is shortened. Using linear regression analysis, horizontal displacement of the upper lip at the vermilion border was 0.82 +/- 0.13 mm for every 1 mm of maxillary advancement at the incisal edge (p less than 0.001) and 0.51 +/- 0.13 at the subnasale for every 1 mm of maxillary advancement at point A (p less than 0.001). Eighty percent of patients undergoing maxillary intrusive procedures had lip shortening ranging from 20 to 50 percent of the vertical maxillary reduction. Surprisingly, no statistically significant correlation could be demonstrated for lip shortening versus extent of vertical maxillary reduction. Previous literature in disagreement with these findings is discussed. Guidelines for treatment planning utilizing these data are suggested.     

Variation in maxillary sinus anatomy among platyrrhine monkeys

Variations in the maxillary sinus anatomy of extant and fossil catarrhine primates have been extensively examined using computed tomography (CT), and have potential utility for phylogenetic analyses. This approach has also been used to demonstrate its anatomical variation in eight of the 16 extant genera of platyrrhines and the absence of the sinus in Saimiri and Cacajao. We used this approach to evaluate the three-dimensional anatomy of the maxillary sinus in all extant platyrrhine genera, and here argue the phylogenic implications of this variation. This study confirms, for the most part, previous CT studies and augments them with the six genera not studied previously: Ateles, Lagothrix, Callithrix, Cebuella, Pithecia and Chiropotes. The entire maxilla is pneumatized by the sinus in the atelines, Cebus, and Callicebus, whereas the sinus pneumatizes only the medial part of the maxilla in the callitrichines and Aotus. Pithecia has a unique conformation in which the maxillary sinus and the expanded inferior meatus pneumatize the posteromedial and anterolateral parts of the entire maxilla, respectively. Chiropotes has no sinus, and the inferior meatus possibly expands into the area between the middle meatus and medial surface of the maxilla to disturb sinus formation, as in the case of its close relative Cacajao. Finally, we argue that the sinus that pneumatizes the entire maxilla is a primitive feature in extant platyrrhines and was probably shared by the last common ancestor of the anthropoids.     

A simple and inexpensive system for monitoring jaw movements in ambulatory humans

A simple and inexpensive method for recording vertical movements of the human mandible relative to the maxilla is presented. Measurements are made from accelerometers and a Hall-effect device temporarily glued to the upper and lower anterior teeth. The accelerometer signals are integrated once to give velocity and a second time to give position. Movements of the mandible relative to the maxilla are obtained by integrating the difference between the two accelerometer signals. The (relative) velocity and position records derived in this way are linear, but subject to drift when the jaw is stationary. Steady mandibular position is obtained from the Hall-effect system, but this signal must be corrected for its inherent non-linearity. This device can record rapid movements of the mandible even when the head is unrestrained, and interferes minimally with normal jaw movements.     

Complex maxillary fractures: role of buttress reconstruction and immediate bone grafts

Between 1978 and 1984, 558 patients with complex facial fractures have been treated. One hundred and seventy-one of these patients have had complex Le Fort fractures of the maxilla. In this group of patients, the importance of direct anatomic reconstruction of the anterior maxillary buttresses has been assessed. Complete exposure of the injured buttresses will facilitate assessment of the exact fracture pattern. Direct fixation of the medial and lateral maxillary buttresses on each side, in combination with immediate bone-graft reinforcement or replacement of comminuted or missing buttresses, will facilitate the reconstruction of even the most severely injured maxilla in one stage. This approach is combined with similar reconstructive techniques in other areas of the craniofacial skeleton. Associated mandibular fractures are managed with rigid internal fixation utilizing A-O techniques. The use of these techniques dramatically facilitates airway management and simplifies the treatment of the edentulous patient, the patient with bilateral condylar neck fractures, and those patients with sagittal splitting of the maxilla and palate. The use of both internal craniofacial suspension wires and external craniofacial suspension devices has become largely unnecessary, and reconstruction of even the most complex injuries in one stage with minimal complications and secondary deformities is made possible.     

云南开远新发现的腊玛古猿化石

本文描述的标本是1980年6月和1982年5月,在云南开远小龙潭晚中新世褐煤层中发现的古猿化石。标本有左下第一至第三臼齿列和一件带十二枚牙齿的上颌骨。从标本反映的形态特征观察,应归为腊玛古猿。     

陕北槽齿类新发现

本文记述了采自陕北府谷县三迭系和尚沟组上部的一槽齿类化石。根据骨髂形态特征认为属于古鳄亚目的原鳄科,与Chasmatosaurus和Elaphrosuchus相近,但上颌骨参与外鼻孔的构成及前上颌骨不呈喙嘴状等却显著不同。为此另建立一新属(Xilousuchus)。考虑其一些进步的构造、新属种的生存时代应稍晚于上述Chasmatosaurus和Elaphrosuchus。     

安徽巢县人类化石地点的新材料

1983年对巢县银山人类化石地点的发掘结果再次表明,该地点的人类化石的地质时代大致相当于北京猿人地点1—4层的或稍晚。发现人类上颌骨化石一块,具有早期智人的特征。     

The skull of an early Late Triassic aetosaur and the evolution of the stagonolepidid archosaurian reptiles

Disarticulated bones of several individuals recovered from the Late Triassic fluvial and lacustrine deposits at Krasiejów, Poland, are here described, allowing the restoration of the skull structure of a new aetosaurian archosaur: Stagonolepis olenkae sp. nov. The Krasiejów deposits probably correspond in age to the Lehrberg Beds (late Carnian) of Baden‐Württemberg, Germany. The stratigraphical position of the new taxon combined with other available evidence is used to propose a model of aetosaurian evolution. The proposed phylogenetic position of Aetosaurus ferratus (Norian, Germany) as the basal aetosaurid is refuted and this species is instead proposed to be the most derived member of the Stagonolepis–Aetosaurus evolutionary lineage. Gradual change in several morphological characters can be observed from Stagonolepis robertsoni, through the new species from Krasiejów, to the stratigraphically youngest Aetosaurus ferratus. These changes include a decrease in the number of teeth and a decrease in the convexity of the ventral profile of the maxilla. The anterior elongation of the maxilla is associated with the expansion of the anterior tip of the maxilla towards the naris. In S. robertsoni and S. olenkae, the maxilla extends to middle of the naris, whereas in Aetosaurus, it reaches the anterior half of the naris. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 860–881.