Anatomic contribution to the study on the variety of fibrous formations of the arm in humans

The authors have examined an anatomical preparation of a human upper limb preserved in the Anatomical Museum in Bologna. The specimen was formed by bone, fibrous formations, musculus biceps brachii and musculus coracobrachialis. The soft parts were kept in situ and dried by mummification. The humerus showed abnormalities at its proximal extremity (Fig. 1) and the muscles displayed fibrous varieties: a) a fibrous sheet (Fig. 1, 2) connected the caput brevis of the musculus biceps brachii to the articular capsule of the shoulder joint; b) an aponevrosis (Fig. 1, 3) connected the musculus coracobrachialis to the same articular capsule and the humerus. These observations were discussed from an evolutionary and functional point of view.     

An azhdarchid humerus (Pterosauria,Azhdarchidae) from the Upper Cretaceous of Saratov Region

A proximal humerus fragment referred to as Azhdarchidae indet. from the Rybushka Formation (Upper Cretaceous, Lower Campanian) of the Beloe Ozero locality in Saratov Region is described. The proximal articular surface is not saddle-shaped, has a weakly convex profile in the frontal section. The most posteriorly projecting part of the proximal articular surface is displaced ventrally. A large pneumatic foramen is located on the anterior surface ventral to the base of deltopectoral crest and close to the proximal articular surface. The humeral head is slightly declined from the diaphysis and only slightly overhangs the diaphysis posteriorly. This proximal humerus fragment possibly belongs to Volgadraco bogolubovi Averianov, Arkhangelsky et Pervushov, 2008, described from the Rybushka Formation of the Shirokii Karamysh 2 locality in Saratov Region.     

Caudal vertebral body articular surface morphology correlates with functional tail use in anthropoid primates

Prehensile tails, capable of suspending the entire body weight of an animal, have evolved in parallel in New World monkeys (Platyrrhini): once in the Atelinae (Alouatta, Ateles, Brachyteles, Lagothrix), and once in the Cebinae (Cebus, Sapajus). Structurally, the prehensile tails of atelines and cebines share morphological features that distinguish them from nonprehensile tails, including longer proximal tail regions, well‐developed hemal processes, robust caudal vertebrae resistant to higher torsional and bending stresses, and caudal musculature capable of producing higher contractile forces. The functional significance of shape variation in the articular surfaces of caudal vertebral bodies, however, is relatively less well understood. Given that tail use differs considerably among prehensile and nonprehensile anthropoids, it is reasonable to predict that caudal vertebral body articular surface area and shape will respond to use‐specific patterns of mechanical loading. We examine the potential for intervertebral articular surface contour curvature and relative surface area to discriminate between prehensile‐tailed and nonprehensile‐tailed platyrrhines and cercopithecoids. The proximal and distal intervertebral articular surfaces of the first (Ca1), transitional and longest caudal vertebrae were examined for individuals representing 10 anthropoid taxa with differential patterns of tail‐use. Study results reveal significant morphological differences consistent with the functional demands of unique patterns of tail use for all vertebral elements sampled. Prehensile‐tailed platyrrhines that more frequently use their tails in suspension (atelines) had significantly larger and more convex intervertebral articular surfaces than all nonprehensile‐tailed anthropoids examined here, although the intervertebral articular surface contour curvatures of large, terrestrial cercopithecoids (i.e., Papio sp.) converge on the ateline condition. Prehensile‐tailed platyrrhines that more often use their tails in tripodal bracing postures (cebines) are morphologically intermediate between atelines and nonprehensile tailed anthropoids. J. Morphol. 275:1300–1311, 2014. © 2014 Wiley Periodicals, Inc.     

Shape of articular surface of crocodilian (Archosauria) elbow joints and its relevance to sauropsids

The determination of area and shape of articular surfaces on the limb bones of extinct archosaurs is difficult because of postmortem decomposition of the fibrous tissue and articular cartilages that provide the complex three‐dimensional joint surfaces in vivo. This study aims at describing the shape of the articular cartilages in the elbow joints of six crocodilian specimens; comparing its structure with that of four birds, three testudines, and five squamates; and comparing the shapes of the surfaces of the calcified and the articular cartilages in the elbow joints of an Alligator specimen. The shapes of the articular cartilages of crocodilian elbow joint are shown to resemble those of birds. The humerus possesses an olecranon fossa positioned approximately at the midportion of the distal epiphysis and bordering the margin of the extensor side of the articular surface. The ulna possesses a prominent intercotylar process at approximately the middle of its articular surface, and splits the surface into the radial and ulnar cotylae. This divides the articular cartilage into an articular surface on the flexor portion, and the olecranon on the extensor portion. The intercotylar process fits into the olecranon fossa to restrict elbow joint extension. Dinosaurs and pterosaurs, phylogenetically bracketed by Crocodylia and Aves (birds), may have possessed a similar olecranon fossa and intercotylar process on their articular cartilages. Although these shapes are rarely recognizable on the bones, their impressions on the surfaces of the calcified cartilages provide an important indication of the extensor margin of the articular surfaces. This, in turn, helps to determine the maximum angle of extension of the elbow joint in archosaurs. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

Multiple male morphs in the leaf‐footed bug Mictis longicornis (Hemiptera: Coreidae)

Species within the coreid clade (Hemiptera: Coreidae) can often be observed competing in intrasexual competitions over access to mates and territories. Coreids that partake in these competitions typically possess sexually dimorphic hind legs that are used to strike and squeeze their rivals. In addition to their weaponized legs, some coreid species also possess sexually dimorphic abdominal tubercles, which are assumed to be sexually selected weapons. Still, much remains unknown about the morphology of these structures. Here, using the species Mictis longicornis Westwood, we investigate the frequency distribution and static allometry of abdominal thickness, a measure that includes tubercle length. Furthermore, we also investigate the morphological relationship between abdominal tubercles and weaponized hind legs. We find that male abdominal thickness is best explained by a bimodal distribution, thereby describing the first observed male polymorphism in the coreid clade; a phenomenon typically associated with alternative reproductive tactics. Additionally, we find that major males are characterized primarily by having large weaponized legs and abdominal tubercles, which further suggests that abdominal tubercles are used in male–male competition.     

Scanning electron microscopy and distribution of specialized mechanoreceptors in the texas rat snake,Elaphe obsoleta lindheimeri (Baird and Girard)

Scanning electron microscopy (SEM) of the surface tubercles of a specialized mechanoreceptor found within the head of Elaphe obsoleta lindheimeri indicates that the tubercle consists of a craterlike structure with a peg emerging from its center. After removal of the outer keratinized layers of the epidermis, the SEM discloses a replicate tubercle on the underlying alpha keratin layer. Over 6000 tubercles were found within a single snake. The mechanoreceptors were more densely concentrated on anterior scales, and their number appears to be species specific so that they are more concentrated in snakes with smaller heads than in those with larger ones.     

Morphological and functional aspects of the temporal bone articular tubercle morphology inHomo erectus andHomo sapiens

The morphological variability of the temporal articular tubercle was studied inHomo erectus andHomo sapiens. Five configurations have been defined. There is a high heterogeneity amongHomo erectus. The Neandertal lineage and that leading toHomo sapiens sapiens are more homogenous, each of them exhibits a high frequency of one configuration. This study has also focused on the functional implications of this variation. A theoretical approach to two different configurations of the articular tubercle is considered in the same bony, muscular and ligamentary context. This suggests that the configuration which consists of a transverse concavity is, for the mandible depression, concomitant with a slight functional disadvantage in comparison with the cylindrical configuration. It appears that a midfacial projection allows for a compensation of this disadvantage. It is concluded that this model can be proposed for Neandertals which present a very concave articular tubercle and a typical midfacial projection.     

Structural characterization of the micropatterned egg plastron in the mosquito,Aedes albopictus

Eggs of the Asian tiger mosquito Aedes albopictus are fully covered with an air‐covering plastron network that enables them to stay below the surface of the water. Scanning electron microscopy revealed that the chorionic surface was covered with clusters of globular tubercles of different sizes. Histologically, the eggshell provides a typical water‐repellent microarchitecture consisting of an outer exochorion, a membranous endochorion and an intermediate pillar layer. The eggshell has a distinct chorionic tubercle that increases the surface area for gas exchange to enhance respiration capacity. In particular, the chorionic wall gives rise to a hexagonal pattern with smooth and elevated boundaries. In A. albopictus, a set of micropatterns for each hexagon was specified, and each central tubercle was surrounded by 20 small peripheral tubercles. Our fine structural analysis revealed that the partitioning of the surface into numerous hexagonal chorionic sculptures is associated with the Voronoi partition (tessellation), based on the distance to a point in a specific area of the plane. Therefore, the micropatterned surface of the mosquito eggshell appears to not only resist wetting by hydrostatic pressure but also provide resistance to lysate deposition by the biofouling process.     

MicroCT Analysis of Symphyseal Ontogeny in Archaeolemur

Previous analyses of symphyseal fusion in the extinct Malagasy lemur Archaeolemur identified several functional characteristics of joint morphology that vary postnatally (Ravosa and Simons in American Journal of Physical Anthropology 95:63–76, 1994). To complement that study, we used an imaging technique (microCT) that provides novel data on ontogenetic and local variation in biomineralization along the mandibular symphysis before complete ossification among adult Archaeolemur. Our sample of unfused symphyses comprised juveniles from the 2 earliest postnatal dental ages examined previously. We imaged each specimen (ca.18 μm volume elements) with slices parallel to the coronal plane, i.e., orthogonal to the joint articular surface. In ≤5 labiolingually equidistant joint sites, we collected 40 contiguous slices (18-μm intervals). Each of the 5 joint sites is represented by 1 slice, with biomineralization values sampled at 5 equidistant points along the articular surface and at 3 external cortical bone points. Our analysis of Archaeolemur indicates the presence of ontogenetic increases in bone mineral density accompanying increases in joint size and the number and distribution of symphyseal rugosities. Such postnatal changes are particularly marked for the middle of the joint presumed to lie adjacent to a degrading fibrocartilage pad. In Archaeolemur, labial regions of the symphysis ossify earlier and are likewise more biomineralized. Ontogenetic increases in symphyseal biomineralization, overall size, and fusion are consistent with elevated masticatory stresses owing to the postweaning shift to adult-like feeding behaviors. However, the labiolingual pattern of fusion and biomineralization in Archaeolemur appears related more to constraints on synostosis owing to the lingually located vascular supply characteristic of mammalian symphyses.     

Relationships between geometry and kinematic characteristics in the temporomandibular joint

Motions of the temporomandibular joint (TMJ) involve both translation and rotation; however, there may be substantial variations from one human to another, and these variations present significant difficulties when designing TMJ prostheses. The disc-condyle glides along the temporal bone and the condyle centre describe a curve that depends on the individual morphology. This study analyses disc-condyle rotatory and translatory displacements moving all along the temporal bone facets which are mainly composed of two areas: the articular tubercle slope (ATS) and the preglenoid plane separated by the articular tubercle crest. Displacements were quantified using 3D video analysis, and this technique was computer-assisted. From a population of 32 volunteers, we were able to establish a correlation between the kinematic characteristics of the joint and the disc-condyle trajectories. This study quantifies the geometrical characteristics of the ATS and their inter-individual variations, which are useful in TMJ prosthesis design.     

The morphology and evolutionary history of the glenohumeral joint of hominoids: A review

The glenohumeral joint, the most mobile joint in the body of hominoids, is involved in the locomotion of all extant primates apart from humans. Over the last few decades, our knowledge of how variation in its morphological characteristics relates to different locomotor behaviors within extant primates has greatly improved, including features of the proximal humerus and the glenoid cavity of the scapula, as well as the muscles that function to move the joint (the rotator cuff muscles). The glenohumeral joint is a region with a strong morphofunctional signal, and hence, its study can shed light on the locomotor behaviors of crucial ancestral nodes in the evolutionary history of hominoids (e.g., the last common ancestor between humans and chimpanzees). Hominoids, in particular, are distinct in showing round and relatively big proximal humeri with lowered tubercles and flattened and oval glenoid cavities, morphology suited to engage in a wide range of motions, which enables the use of locomotor behaviors such as suspension. The comparison with extant taxa has enabled more informed functional interpretations of morphology in extinct primates, including hominoids, from the Early Miocene through to the emergence of hominins. Here, I review our current understanding of glenohumeral joint functional morphology and its evolution throughout the Miocene and Pleistocene, as well as highlighting the areas where a deeper study of this joint is still needed.     

New postcranial elements of the Thalassodrominae (Pterodactyloidea,Tapejaridae) from the Romualdo Formation (Aptian–Albian), Santana Group,Araripe Basin,Brazil

Tapejarids are edentate pterosaurs recovered mainly from Early Cretaceous deposits. They are diagnosed by five synapomorphies, among which only one is postcranial: a broad and well‐developed tubercle at the ventroposterior margin of the coracoid. Regarding the clade Thalassodrominae, most phylogenetic studies are based on cranial elements, as postcranial skeletons of these pterosaurs are rare. Here, new postcranial material from the Romualdo Formation (Aptian–Albian) from the Araripe Basin is described. The material comprises the three posteriormost cervical vertebrae, the first seven dorsal vertebrae (fused into a notarium), both scapulocoracoids, a fragment of a sternum, a partial right humerus, a small fragment of a 4th phalanx of the wing finger, a distal extremity of the right femur and the proximal portions of both tibia and fibula. Comparisons with other specimens and morphological features examined in a phylogenetic context, such as the presence of three foramina lateral and dorsal to the neural canal of the cervical vertebrae, the presence of a notarium and a pneumatic foramen on the ventral side of the proximal portion of the humerus, allow the assignment of this specimen as Thalassodrominae indet. Regarding palaeobiogeographical aspects, to date, this clade is exclusively found in the Romualdo Formation. It is the most complete postcranial material assigned to the Thalassodrominae described so far.     

Relationships between geometry and kinematic characteristics in the temporomandibular joint

Motions of the temporomandibular joint (TMJ) involve both translation and rotation; however, there may be substantial variations from one human to another, and these variations present significant difficulties when designing TMJ prostheses. The disc–condyle glides along the temporal bone and the condyle centre describe a curve that depends on the individual morphology.

This study analyses disc–condyle rotatory and translatory displacements moving all along the temporal bone facets which are mainly composed of two areas: the articular tubercle slope (ATS) and the preglenoid plane separated by the articular tubercle crest. Displacements were quantified using 3D video analysis, and this technique was computer-assisted.

From a population of 32 volunteers, we were able to establish a correlation between the kinematic characteristics of the joint and the disc–condyle trajectories. This study quantifies the geometrical characteristics of the ATS and their inter-individual variations, which are useful in TMJ prosthesis design.     

The dorsal tail tubercle of Mertensiella caucasica and M. luschani (Amphibia: Salamandridae)

Males of the two species of Mertensiella (M. caucasica and M. luschani) possess a tubercle projecting from the skin of the dorsal tail base, the single morphological character that defines the genus. The dorsal tail tubercle functions during courtship, and its role is similar in both species. The tubercle is inserted into the cloaca of the female during ventral amplexus, shortly before the male deposits a spermatophore. Histological examination, however, revealed that the dorsal tubercles differ structurally between the two species. In M. caucasica, the tubercle consists primarily of elongate mucous glands, with granular glands occurring only at the base. Both mucous and granular glands of the tubercle are larger than those in typical skin. Unlike typical skin, however, mucous glands are larger than granular glands. In M. luschani, mucous glands and granular glands occur throughout the tubercle, and the granular glands are larger than the mucous glands, although both types are larger than those in typical skin. The dorsal tubercles of M. caucasica and M. luschani may not be homologous structures and may have resulted from convergent evolution. J Morphol 232:93–105, 1997. © 1997 Wiley-Liss, Inc.     

Trabecular architecture and joint loading of the proximal humerus in extant hominoids,Ateles, and Australopithecus africanus

Objectives

Several studies have investigated potential functional signals in the trabecular structure of the primate proximal humerus but with varied success. Here, we apply for the first time a “whole‐epiphyses” approach to analysing trabecular bone in the humeral head with the aim of providing a more holistic interpretation of trabecular variation in relation to habitual locomotor or manipulative behaviors in several extant primates and Australopithecus africanus.

Materials and methods

We use a “whole‐epiphysis” methodology in comparison to the traditional volume of interest (VOI) approach to investigate variation in trabecular structure and joint loading in the proximal humerus of extant hominoids, Ateles and A. africanus (StW 328).

Results

There are important differences in the quantification of trabecular parameters using a “whole‐epiphysis” versus a VOI‐based approach. Variation in trabecular structure across knuckle‐walking African apes, suspensory taxa, and modern humans was generally consistent with predictions of load magnitude and inferred joint posture during habitual behaviors. Higher relative trabecular bone volume and more isotropic trabeculae in StW 328 suggest A. africanus may have still used its forelimbs for arboreal locomotion.

Discussion

A whole‐epiphysis approach to analysing trabecular structure of the proximal humerus can help distinguish functional signals of joint loading across extant primates and can provide novel insight into habitual behaviors of fossil hominins.

     

Role of muscles stabilizing the human shoulder joint

Clinical observations of the surgeon-traumatologist demonstrate the role of the muscles inserting to the greater and smaller tubercles of the humerus for fixating the shoulder joint.     

From E‐MAPs to module maps: dissecting quantitative genetic interactions using physical interactions

Recent technological breakthroughs allow the quantification of hundreds of thousands of genetic interactions (GIs) in Saccharomyces cerevisiae. The interpretation of these data is often difficult, but it can be improved by the joint analysis of GIs along with complementary data types. Here, we describe a novel methodology that integrates genetic and physical interaction data. We use our method to identify a collection of functional modules related to chromosomal biology and to investigate the relations among them. We show how the resulting map of modules provides clues for the elucidation of function both at the level of individual genes and at the level of functional modules.     

Morphological modifications of knee articular cartilage in bullfrogs (Lithobates catesbeianus) (Anura: Ranidae) during postmetamorphic maturation

The organization of knee articular cartilage of the bullfrog (Lithobates catesbeianus) differs in relation to morphofunctional adaptation in many aspects from similar structures in mammals. Thus, we investigated the structural organization and distribution of the extracellular matrix components in three articular cartilage regions in the distal epiphysis of the femur and proximal epiphysis of the tibia in male bullfrogs at 7, 540 and 1,080 days after metamorphosis. Cartilage thickness and cell density decreased in all regions with age. The basophilia differed among cartilage sites during aging. Calcium deposits were detected in growth cartilage of the femur and tibia in older animals. Immunohistochemical staining for chondroitin-6-sulfate was positive in the pericellular and territorial matrix in all samples. Positive immunostaining for type I collagen was observed in the superficial layer at all ages and in ossification centers of older animals. Reactivity to type II collagen was intense and was found throughout the stroma at all ages. Ultrastructural analysis of the epiphyseal region, in young animals, showed that the cytoplasm of chondrocytes was rich in rough endoplasmic reticulum, Golgi complex and mitochondria. In old animals, were observed a reduction in the size and number of mitochondria, disintegration of rough endoplasmic reticulum, and vacuolization of the Golgi complex. The bullfrog articular cartilage presented structural and organizational changes during aging which may contribute to the functional cartilage deterioration in old animals.     

重庆市发现宜章臭蛙

2014年7~8月在重庆市南川区三泉镇采集到5号臭蛙类标本,经形态特征比较和DNA数据比对及遗传距离分析,鉴定为宜章臭蛙(Odorrana yizhangensis),属重庆市新纪录。重庆南川的宜章臭蛙与模式产地标本相比,指关节下瘤雌蛙较雄蛙明显;有外掌突;趾关节下瘤明显,趾间全蹼;后肢前伸贴体时胫跗关节超过吻端。重庆南川区与湖南宜章经度和纬度相距均约5°,为宜章臭蛙已知分布的最西点。宜章臭蛙的形态和遗传分化及分布格局,是否由于我国滇西高山峡谷地区、粤桂湘赣南岭山地和湘渝鄂边境地区特殊地理效应及第四纪冰期气候的反复变化造成的,值得进一步探讨。     

New characters for the functional interpretation of primate scapulae and proximal humeri

The study of muscle function in nonhuman primates through the technique of electromyography (EMG) has facilitated the identification of specific functional roles for muscles in particular behaviors. This has led to a more complete understanding of the biomechanics of certain regions of the musculoskeletal system, and should facilitate our ability to identify morphological features useful in the functional interpretation of fossil material. The current paper represents one such investigation of a new set of morphometric characters of the scapula and proximal humerus suggested by EMG analyses of shoulder muscle function. A set of new metric variables were examined on the scapulae and proximal humeri of 25 species of extant anthropoid primates, as well as on casts of scapulae and humeri of three fossil primate taxa. The variables are primarily related to the line of action and attachments of the rotator cuff muscles. The position of the scapular spine, the degree of lateral expansion of the subscapular fossa, the size and shape of the subscapularis insertion facet on the lesser tubercle, and the orientation of the infraspinatus insertion facet on the greater tubercle all appear to successfully sort the extant taxa into locomotor groups. Their appearance on the fossil specimens generally supports previous functional interpretations of each taxon's locomotor abilities based on a variety of other characters, suggesting that these traits are equally applicable to fossil material. © Wiley-Liss, Inc.