滇金丝猴、藏酋猴和猕猴咀嚼装置骨学特征的比较

本文对滇金丝猴、藏酋猴和猕猴毛耳亚种中与咀嚼有关的48项骨学特征作了比较,试图探讨它们在功能与形态及行为方面的相关关系。对所得变量进行了多变量统计分析、齿弓对称性分析及咀嚼能力分析。结果表明：滇金丝猴与猕猴属具有不同的下颌形状。前者齿弓对称性比后者好,且具有更强的咀嚼能力;藏酋猴的咀嚼能力远较毛耳猴接近滇金丝猴;咬啐坚果的能力与咀嚼能力大小相反。在下颌发育中有异速生长现象。据此对食性的推测与已有的野外观察资料相符。     

滇金丝猴下颌的生物力学研究

利用生物力学原理,判别分析和异速生长对我国特有的滇金丝猴下颌研究表明,由于雄性比雌性具有相对更长的下颌,导致了整个下颌结构在两性间的差异。在所分析的8个变量中,4个被选为性别鉴别的重要特征,判别式为:D=-27.65-0.729CONM1+0.596MANDL+1.204MANDSYM-1.778MANCORPW。与猕猴和长鼻猴相比,滇金丝猴具有相对短的下颌骨,较宽的下颌髁和较高的下颌体。这些特征保障了下颌齿,特别是颊齿列更有利于叶类食物的咀嚼,即有利于咀嚼过程中消除下颌的疲劳。     

元谋古猿下颌臼齿三维立体特征

采用欧氏距离矩阵分析（EDMA）方法对72枚元谋古猿及作为对比样本的10枚禄丰古猿、现生大猿类和人类下颌臼齿齿冠13个测量标志点三维测量数据的统计分析显示：元谋古猿在下颌臼齿齿冠三维形态测量特征上与禄丰古猿最为接近。与现生大猿类及人类相比,元谋古猿和禄丰古猿均与人类之间呈现出非常显著的差异,而与猿类较为接近。它们两者及生大猿类均与人类之间具有许多共同的差异表现特点。元谋古猿在下颌臼齿三维测量特征方面与三种现生大猿类各自之间的差别表现相似。其中,元谋古猿与猩猩之间的牙齿形态特征上似乎更为接近。但目前对这些特征相似差异的含义尚难以确定。     

下颌LOCATOR种植覆盖义齿咀嚼效率的比较

目的：种植支持的覆盖义齿是针对下颌骨后牙区没有足够骨量的病人的一种适当的治疗方案。LOCATOR是近年来一种新型改良的种植体附着系统。本研究在病人佩戴LOCATOR附着系统支持的下颌种植覆盖义齿后,通过比较不同种植体数量对咀嚼效率的影响,以期用最小的成本达到较好的临床效果。方法：19名下颌无牙颌患者中,10名植入2枚种植体,9名植入3枚种植体。三月后行LOCATOR附着系统支持的种植覆盖义齿修复,并计算咀嚼效率增加量。结果：通过SPSS20．0软件进行统计分析,采用95％可信区间,α=0．05,对两组覆盖义齿咀嚼效率的增加量进行t检验：P〉0．05,两组之间咀嚼效率的增加量无显著性差异。针对下颌LOCATOR种植覆盖义齿,植入两枚种植体和三枚种植体提升的咀嚼效率并无统计学差异。结论：针对LOCATOR系统支持的下颌种植覆盖义齿,两枚种植体既能有效地提高咀嚼效率。     

特定电磁波治疗颞下颌关节功能紊乱

颞下颌关节功能紊乱是一种常见病。临床表现为,开口和咀嚼时关节疼痛,张口受限,关节弹响,咀嚼肌酸胀无力,影响咀嚼。常伴有头痛,头晕,耳鸣等症状,我们采用特定电磁波治疗30例患取得了较好疗效,现小结如下。     

下颌起排法全口排牙临床效果研究

目的:研究通过比较不同的排牙方式制作的全口义齿对咀嚼次数、咀嚼效率以及患者的主观感受的影响。方法:78例无牙颌患者按照牙槽嵴高度分为正常组和低平组,正常组有患者32例,低平组有患者46例,每组分别戴用上颌起排法和下颌起排法制作的全口义齿,比较咀嚼次数、咀嚼效率和满意度的差别。结果:在戴用上颌起排法制作的全口义齿时,正常组的咀嚼次数高于低平组,差异具有统计学意义(t=3.60,P0.05);戴用下颌起排法制作的全口义齿后,低平组的咀嚼次数高于采用上颌起排法的全口义齿,差异具有统计学意义(t=4.41,P0.05);在戴用上颌起排法制作的全口义齿中,正常组的咀嚼效率高于低平组,差异具有统计学意义(t=5.72,P0.05);而在戴用下颌起排法制作的全口义齿后,低平组的咀嚼效率高于采用上颌起排法的全口义齿,差异具有统计学意义(t=7.16,P0.05)。正常组认为使用下颌起排法制作全口义齿咀嚼能力、稳固感好于上颌起排法,差异均具有统计学意义(P0.05);低平组认为使用下颌起排法制作全口义齿咀嚼能力、稳固感和舒适感好于上颌起排法,差异均具有统计学意义(P0.05)。结论:对于牙槽嵴低平无牙颌患者使用下颌起排法制作的全口义齿,能够有效地增强咀嚼效率,提高义齿的稳定性。     

猕猴属种间颅骨差异的探讨

为了研究狒猴属的颅骨差异性,从面探讨种间在形态、功能和系统分化方面联系,测定了１１１个猕猴种类的７７个颅骨变量,用于主成分分析和判别分析。应用巢式分析方法,分析过程包括３个步骤。所有变量根据功能和部位的不同首先分为７个单位：下颌、下颌齿、上颌齿、上面颅、下面颅,、面颅后部和颅腔。第２步根据它们所揭示的相似性（具有相同的种间及种内差异性类型）合并为３个解剖区域：咀嚼器官（下颌、下颌齿、上颌齿）,面颅     

无颌的世界

当你大口地嚼肉、吃着山珍海味的时候,你一定会感谢大自然赐给了你一对强有力的颌(上颌和下颌),使你能够把食物嚼碎,尽情地享受着这人间美味。但你可曾知道,在我们的地球上还有一群无颌的动物,它们没有颌,不能主动地捕食和咀嚼食物,只能过一种寄生或滤食的生活。也许当你在吃肉     

山西绵山植被木本植物优势种群种间关联

采用2×2列联表的χ2检验、Pearson相关系数和Spearman秩相关系数检验,研究了山西绵山植被21个优势种群、210个种对间的种间关联性。结果表明:1)χ2检验有109个种对呈正相关,101个种对呈负相关,正负关联比为1.08;Pearson相关系数检验87个种对正相关,122个种对呈负相关,正负关联比为0.71;Spearman秩相关系数检验99个种对呈正相关,111个种对呈负相关,正负关联比为0.89。2)按照21个优势种对环境的适应方式和主导生态因素,它们被划分为两大生态种组。3)与Pearson相关系数检验相比,Spearman秩相关系数检验具有较高的灵敏度。4)种对间的正关联或正相关,主要是由于它们具有相近的生物学特性,对生境具有相似的生态适应性和相互重叠的生态位所致;而种对间的负关联或负相关,则主要是由于它们具有不同的生物学特性,对生境具有不同的生态适应性和相互分离的生态位所致。     

大熊猫与小熊猫生态习性的比较：食物、体型大小及系统发育的影响

大熊猫和小熊猫是食肉目中尤为引人注目的 两个物种,均特化为以竹类为生,在四川西部的横断山地同域共存.近年来化石和分子生物学等方面的证据表明两者亲缘关系较远,其在诸多形态特征上的相似乃是长期趋同进化的结果.竹子是一类低营养价值的食物,有丰富的储量及相对稳定的营养组成,保障了两种熊猫的长期续存.由于仍保留着食肉动物消化系统的典型特征,大熊猫、小熊猫对食物的消化利用率极低,两者在一些生态习性(如独栖、无冬眠、巢域普遍重叠及具有活动与休息多次交替的昼夜活动模式等)的相似可能反映了这种特殊食物的影响.此外,大熊猫和小熊猫在食性、昼夜活动节律及微生境利用上的差异与其体型大小及系统发育有关,有利于两者在川西横断山地的同域共存.     

Mechanical advantage of area of origin for the external pterygoid muscle in two murid rodents, Apodemus speciosus and Clethrionomys rufocanus

The actions of masticatory muscles in relation to transverse grinding, associated with forward masticatory movement of the mandible, were investigated by using a mechanical model in the two murid rodents, the Japanese field mouse (Apodemus speciosus: subfamily Murinae) and the gray red-backed vole (Clethrionomys rufocanus: subfamily Arvicolinae). Furthermore, statics of the masticatory system on a sagittal plane while chewing is taking place were also analyzed in these rodents. The inward grinding movements of hemimandibles are generated by the posterior temporalis and internal and external pterygoids in both species. In addition to these muscles, the anterior temporalis also moves the hemimandibles lingually in Apodemus speciosus. The area of origin of the external pterygoid seems more advantageous for transverse grinding in A. speciosus than in Clethrionomys rufocanus. On the basis of the static analysis, the anterodorsal area of origin of the external pterygoid to the upper second and third molars in Clethrionomys rufocanus appears to be an adaptive character to prevent the jaw joints from dislocation during occlusion at a posterior point on the elongated row of cheek teeth.     

Biomechanical evaluation of the equine masticatory action: Calculation of the masticatory forces occurring on the cheek tooth battery

The forces generated during equine mastication influence the teeth, as well as the periodontium, the jaw bones, the temporomandibular joints and materials used in dental therapy. Due to the limited accessibility of the cheek teeth located farther caudal in the equine oral cavity the measurement of the masticatory forces on these teeth is virtually impossible. The calculation of such forces is an appropriate, indirect alternative to direct measuring. Hence, a mathematical model, which respects several morphological features of the equine dentition, e.g. the Curve of Spee, is presented. The relevant parameters were measured on laterolateral radiographs of 24 cadaver heads and 6 skulls. Our calculations yielded two major results. (1) The masticatory forces increased from rostral to caudal. This increase was due to distinct anatomical features of the equine dentition, i.e. the Curve of Spee, the position of the teeth, and the length of the mandible. (2) The masticatory forces decreased with age. This decrease was due to the reduced height of the Curve of Spee in older horses. These results are discussed in view of veterinary dental treatment, with special reference to the geriatric horse.     

Pharyngeal mastication and food transport in the carp (Cyprinus carpio L.): A cineradiographic and electromyographic study

Cyprinids constitute the largest fish family and are characterized by their pharyngeal teeth. The masticatory mechanism is still poorly understood. The complex of structures that determine the movements of pharyngeal teeth and chewing pad in the carp (Cyprinus carpio L.) is analyzed. Activities in 16 head muscles of a free-swimming carp were recorded. X-ray cinerecordings, synchronized with electromyograms, were made of the intake, transport, mastication, and deglutition of radiopaque food pellets. Metal markers allowed a detailed movement analysis. Masticatory cycles are bilaterally synchronous and show distinct crushing and grinding patterns. Direct masticatory muscles that suspend and connect the pharyngeal bones steer and stabilize the masticatory movements. Baudelot's ligament, between skull and pectoral girdle, is applied as fulcrum, effects a crucial shift of the rotation axis of the pharyngeal jaw, and transforms crushing into grinding; simultaneous abduction lengthens the grinding stroke. Body muscles supply indirectly the power for mastication; they also appear to be regulated more distantly. The epaxial muscles lift the skull and thereby the levators of the pharyngeal bones, thus transmitting high forces to the teeth. They also stretch the levator of the bone as soon as occlusion is reached and thus optimize its production of forces during grinding. The hypaxial muscles retract the pharyngeal bones indirectly during grinding and power the teeth in sliding. The chewing pad, previously assumed to be motionless, rotates rostroventrad with the skull and intensifies grinding. Respiration and mastication are mutually related. The extensive movements of the pharyngeal bones are permitted only by the simultaneous expansion of the buccopharynx and a slide-coupling in the branchial floor. Muscular pads that line the pharynx are shown to transport food toward the teeth. The constrictor pharyngis effects deglutition. Natural food, intestinal contents, and feces of the carp were analyzed with respect to the capacity for distinct masticatory operations. During the experiments pellets, barley, and worms were fed. The carp is specialized for polyphagy and this appears to be based on the profiles of the heterodont teeth rather than on drastic changes in the two preprogrammed activity patterns. Comparison of the pharyngeal jaw system in the carp and higher teleosts emphasizes the structural design for the application of large forces in this cyprinid.     

The ontogeny of premolar dental wear in Cercocebus albigena (cercopithecidae)

The orientation of striated wear facets on primate teeth serves as a useful guide for reconstructing jaw movements during mastication. Most wear facets on the molars are formed during one of the two well-documented movements, Phase I or Phase II, of the power stroke. Another jaw movement direction, “orthal retraction” (OR) has been proposed to account for a third set of facets occasionally present on the pointed tips of premolars and molars. Evidence advanced here indicates that OR facets on pointed anterior premolars (P₃) of cercopithecoids are actually Phase I facets that have become reoriented as a result of a rotation of this tooth during its eruption. “Orthal retraction” probably does not exist as a discrete masticatory phase.     

Mandibular movement and muscle activity during mastication in the guinea pig (Cavia porcellus)

Optoelectronic analysis of mandibular movement and electromyography (EMG) of masticatory muscles in Cavia porcellus indicate bilateral, unilateral, and gnawing cycles. During bilateral and unilateral cycles, the mandibular tip moves forward, lateral, and down during the lingual phase of the power stroke to bring the teeth into occlusion. EMG activity is generally asymmetric, with the exception of activity of the temporalis muscle during bilateral cycles. During gnawing cycles, the mandible moves in an anteroposterior direction that is opposite that during bilateral and unilateral chew cycles. Bilateral and unilateral cycles of pellets were significantly longer than carrot. With the exception of the width of bilateral cycles, the magnitude of cycle width, length, and height during the mastication of carrots was greater than that during the mastication of pellets. Significant differences exist between EMG durations during mastication of pellets and carrots. The lateral pterygoid displays continuous activity during gnawing cycles. Significant differences also exist in the durations of EMG activity between the working and balancing side during all three cycle types. High level activity of balancing side temporalis and anterior belly of digastric (ABD) during bilateral cycles occurs during rotation and depression of the mandible during the power stroke. The temporalis apparently provides a ?braking”? or compensatory role during closing and power strokes. Differences between Cavia masticatory patterns and those shown by Rattus and Mesocricetus are apparently due to differences in dental morphology, occlusal relationships, and, possibly, the poorly developed temporalis in Cavia. The large number and wide diversity of rodent groups afford students of mammalian mastication an opportunity to investigate and compare different masticatory specializations.     

Arch form,tooth size,and occlusomandibular kinesis in the Ceboidea

Correlations between dental morphology, arch configuration, and jaw movement patterns were quantitatively investigated in 23 ceboid species to elucidate integrative aspects of occlusal functional anatomy in an adaptive and evolutionary context. Differential maxillary-mandibular arch widths are primary in guiding lateral jaw movements. These movements are characterized according to their associated condylar shifts as either predominantly translatory or rotational. Predominantly translatory movements result from peripheral contact relationships between maxillary arches which are considerably wider posteriorly than their opposing mandibular arches. The greatest degree of mandibular movement is in the molar region in functional association with wide “primitive” maxillary molars, narrow mandibular molars, constricted maxillary intercanine widths, and narrow maxillary incisors. In contrast, predominantly rotational masticatory jaw movements result from differential arch widths which are greatest in the maxillary canine and incisor regions. Here most jaw movement is in the anterior segment and this is reflected in small maxillary-mandibular molar width differences, a high degree of premolarization, wide-set maxillary canine teeth, and wide maxillary incisors. Possible selectional factors in the putative evolution of rotational predominance in mastication from the more primitive translatory pattern are discussed.     

A cinefluorographic study of mandibular movement during feeding in the rat (Rattus norvegicus)

The anatomy of the masticatory apparatus, and particularly of the mandibular joints, has led to the view that mandibular movement in the Rodentia is predominantly propalinal, or forwards and backwards in direction. As part of an investigation into the mechanism of function of the mandibular joints in these animals, the feeding behaviour of "August" strain and "Wistar" rats was examined by cinephotography and cinefluorography. The rats were trained to feed on barium sulphate impregnated biscuit and animal cake and to drink radio-opaque liquids. Cinefluorographic recordings of ingestion, mastication, deglutition and of drinking were taken in both the lateral and dorso-ventral projections.
Analysis of the recordings has shown a fundamental separation of ingestive and masticatory activity in the rat, which can be attributed to the morphology of the jaws and particularly to the disparity in the lengths of the mandibular and maxillary diastemas. To bring the incisor teeth into occlusion for ingestion, the mandible is brought forward through the rest position and the condyle into articulation with the anterior part of the fossa. In mastication the condyle is moved backwards to bring the molar teeth into occlusion and the condyle into articulation with the posterior articular facet on the fossa. Once the mandible has been moved into the appropriate position for either ingestion or mastication and deglutition, the movements involved in the separation or chewing of the food are cyclical with combined horizontal and transverse movements as well as the fundamental vertical movement acting to open and close the mouth. The basic movement of ingestion carries the mandibular incisors upwards and forwards across the lingual surfaces of the maxillary incisors, so separating the bite. The grinding stroke of mastication is a horizontal movement carrying the mandibular molars anteriorly across the maxillary.     

Biplanar X-ray motion analysis of the lower jaw movement during incisor interaction and mastication in the beaver (Castor fiber L. 1758)

The first biplanar X-ray motion analysis of mastication and food processing for Castor fiber is presented. While particles are chipped off interaction of incisors involves variable movements of the lower mandible and thus incisors. After jaw opening the tip of the lower incisors can reach different positions anteriorly of the upper incisors. Then the mandible moves upwards and backwards and brings the tips of the incisors into contact. The lower incisors slide along the wear facet of the upper to the ledge when the cheek teeth occlude. The glenoid fossa and lower jaw condyle are in close contact during incisor contact and no transverse movements are observed. Mastication involves interaction of the cheek teeth with no contact of the incisors. When the cheek teeth are in occlusal contact the mandible is moved forward and transverse, or mediolateral. In consecutive power strokes the jaw is moved alternately to the right and left side. When the jaw opens it is brought into a more central but not totally centred position. During mastication the condyles are positioned posteriorly to the glenoid allowing lateral movement of the mandible. The lateral movement is particularly noticeable in the anterior part of the mandible. With the lateral movements of the incisors one glenoid has to move posteriorly, the other anteriorly.     

Tooth Morphology in Fossil and Extant Lagomorpha (Mammalia) Reflects Different Mastication Patterns

The functional interpretation of the cheek teeth and the mastication cycle of Lagomorpha are deduced from various aspects of tooth morphology of fossil and extant species. Mastication is composed of an almost orthal shearing and transverse grinding in a lingual direction. Shearing blades are not only indicated by facets but as well by thickened enamel. A primary shearing blade (PSB) inherited from stem lagomorphs occurs in all examined species. It can be correlated with facets 1 and 5 (sensu Crompton 1971) and occurs in very few mammals; it is conspicuously absent in the sister-taxon Rodentia. A secondary shearing blade (SSB) occurs in derived Ochotonidae and two basal Leporidae (Romerolagus and Pronolagus) as a convergent pattern. In fossil ochotonids from Europe, the “lagicone structure” is gradually reduced in favor of the SSB. Thus, ochotonids strengthen the shearing ability, whereas most leporids favor the grinding function realized by the partial crenulation of the enamel band of the re-entrant folds. For the mastication cycle, the distinct phases were recognized, related to phase I of the tribosphenic model. The first movement (phase Ia) is directed almost orthally, the second (phase Ib) lingually. Only in Lepus europaeus was an additional phase detected, which might correspond to phase II.     

Trends in the Actions of Mammalian Masticatory Muscles

The actions of the masticatory muscles of a variety of mammalsin which feeding behavior and the configuration of the masticatoryapparatus differ have been reported. The most common approachused in these studies involves (1) obtaining a good anatomicalperception of the musculature, (2) deriving a theoretical modelof the actions of these muscles during jaw movement, and (3)testing this model by recording muscle activity and jaw movementssimultaneously. A catalogue of the activity patterns in eleven species of mammalsduring food reduction reveals certain trends in the actionsof the masticatory muscles. Horizontal jaw movements are generatedprimarily by differential activities of the deep temporalis,superficial masseter, and medial pterygoid. Vertical movementsand the maintenance of tooth to food contact apparently areproduced by action of the superficial temporalis, deep masseter,and zygomaticomandibularis. Thus, horizontal movements are seeminglygenerated by muscles having fibers arranged in marked anteroposteriordirection, whereas vertical movements are generated by muscleshaving more or less vertically arranged fibers. The asymmetry of jaw movement and the muscular activity generatingit suggest that mastication involves an interactionbetween anunbalanced and flexible functional unit (muscles) and a balancedand stable structural unit (skull and teeth). Thus, any unbalancingof the structural unit results in a further unbalancing of themasticatory process.