Arrangement Of Muscles Research Articles

Anatomical anomaly of human digastric muscles.

In the submandibular region an anatomical anomaly of muscle arrangement was found. Between the left and right digastric muscles, asymmetric accessory digastric muscles were detected, which all arose from the mandible and were attached to the hyoid bone. Furthermore, the right anterior digastric muscle had an accessory belly. These anomalies of digastric muscles may be anatomical manifestations of a functional support of the mylohyoid muscle.

Re-description of Eubothrium vittevitellatus Mamaev, 1968 (Cestoda: Pseudophyllidea) from sand fish (Trichodon trichodon Tilesius) in Kamchatka Bay with an assessment of its distribution

Eubothrium vittevitellatus is re-described with particular attention being paid to scolex characters seen by scanning electron microscopy in material obtained from the intestines of the sand fish (Trichodon trichodon) from Kamchatka Bay. It is confirmed as a valid species distinguishable from others in the genus by the combined characters of scolex shape, muscle arrangement and position of vitelline follicles. Peculiarities in the distribution and specificity of the species of Eubothrium highlighted by E. vittevitellatus are discussed.

Comparative histology of the scolex and neck region of Glaridacris laruei (Lamont, 1921) Hunter, 1927 and Glaridacris catostomi Cooper, 1920 (Cestoidea: Caryophyllidea)

The histology of the scolex and neck region was examined in adults of the caryophyllidean tapeworms Glaridacris laruei and Glaridacris catostomi, parasites of the white sucker, Catostomus commersoni (Lacépède). Several distinct cell types were identified in the parenchyma including tegumental cells, flame cells, longitudinal muscle cells (myoblasts), transverse and dorsoventral muscle cells, parenchyma cells, epithelioid cells, and cells associated with the calcareous corpuscles. The proliferative zone of germinative cells reported for strobilate tapeworms was not found in these species. Faserzellen, or neck cells, which consisted of a deeply staining mass of cells, were found in the medullary parenchyma of the neck. Histochemical tests revealed that the cytoplasm of the Faserzellen was rich in RNA and protein, but alkaline and acid phosphatase activity were not detected. The arrangement of musculature in the scolex was examined; muscles associated with the attachment organs of G. laruei appear more developed compared with those of G. catostomi. Measurements of the various cells and their characteristic staining properties are presented in tabular form.

The step technique for the reconstruction of lower lip defects after cancer resection. A follow-up study of 165 cases.

One hundred and sixty-five patients with localized cancer of the lower lip were excised and reconstructed over a 25-year period using Bengt Johanson's step technique. Eight-eight percent of the tumors were less than 2 cm in size and 65% were of high histopathological differentiation. Fifty-six percent were reconstructed with bilateral step flaps. Nine local recurrences appeared in 5 patients, none of whom died of lip cancer. Eight patients later developed regional metastases and 3 of these patients died of lip cancer. The 5-year survival rate was 98%. The step technique is recommended for reconstruction of lip defects of up to 2/3 of the lower lip and may, in larger resections, be combined with either a fan flap or an Estlander flap. The outstanding functional results are due to the use of adjacent tissue for the reconstruction which preserves the normal arrangement of muscles, vessels and nerves.

The larval musculature of the barnacle Ibla quadrivalvis Cuvier (Cirripedia, Lepadomorpha)

The lecithotrophic development of Ibla quadrivalvis comprises six naupliar stages and a cypris stage. Despite lecithotrophy, the planktonic nauplius has a complete skeletal musculature, associated in part with a ventral endoskeleton. The naupliar musculature remains unchanged for the first five naupliar stages. Modifications of the musculature begin to occur in stage VI, preliminary to the change at the sixth moult to the musculature of the cyprid. In this transition, some naupliar muscles are histolysed, some cypris muscles arise as new developments and some muscles are transformed from naupliar muscles to cypris muscles. Details are given of these changes. The pattern of muscle development during the change from nauplius to cyprid in I. quadrivalvis is compared with the more extreme histolysis and replacement of the musculature during the nauplius-cyprid moult of Semibalanus balanoides . The cypris muscu­lature is also compared with that of the rhizocephalan Lernaeodiscus porcellanae . In spite of lecithotrophy, I. quadrivalvis retains a relatively generalized arrangement of thoracican naupliar muscles and cypris muscles and a generalized transition from one to the other. The evolution of total muscle replacement at the nauplius-cyprid moult in advanced thoracicans is discussed.

Functional bases of fiber length and angulation in muscle.

The differences in angulation and length observed for the fibers of anatomical muscles may reflect two distinct mechanical requirements: arrangement for pinnation, reflecting an increase in physiological cross-section and arrangement for equivalent placement of sarcomeres, possibly associated with coordination. The observed differences in fiber angulation and length have different effects upon the responses of sarcomeres, specifically on their extent and rate of shortening and on the force they may generate. The basic mechanisms governing these effects and the various arrangements of muscles are reviewed. Fiber length and angulation in the complex M. adductor mandibulae externus 2 of a lizard were measured stereotactically; these values correlate well with the hypothesis that the muscle shows equivalence and demonstrate that angulation for pinnation is less constant. An outline for the study of muscle architecture and function, detailing the kinds of information require to estimate forces and evaluate muscle and fiber placements, is presented.

Thinning of fetal pulmonary arterial wall and postnatal remodelling: ultrastructural studies on the respiratory unit arteries of the pig.

Adaptation to extra-uterine life and postnatal remodelling of intra-acinar arteries was followed in 34 Large White pigs, from birth to adult life, applying morphometry to light and electronmicroscopic studies. After birth, percentage wall thickness decreased rapidly due to a reduction in overlap of adjacent smooth muscle cells and an increase in smooth muscle cell surface area/volume ratio, (p less than 0.01 at 12 h), without a reduction in the volume density of smooth muscle cells. Smooth muscle cells appeared immature at birth and synthetic rather than contractile organelles predominated. Between 3 weeks and 6 months myofilament volume density doubled (p less than 0.0001). At all ages, pericytes, intermediate and smooth muscle cells showed similar volume densities of contractile and synthetic organelles. Thus, the high fetal pulmonary vascular resistance appeared to be due to the shape and arrangement of smooth muscle and other contractile cells within the vessel wall, rather than an excessive contractility of these cells. After birth rapid remodelling of arterial wall structure achieved a reduction in wall thickness by 30 min, continuing during the first week of life. After 3 weeks, remodelling involved an increase in wall thickness, connective tissue deposition with more collagen than elastin (p less than 0.0001), and smooth muscle cell differentiation.

The vestibuloocular reflex of the adult flatfish. I. Oculomotor organization.

The flatfish species constitute a natural paradigm for investigating adaptive changes in the vertebrate central nervous system. During metamorphosis all species of flatfish experience a 90 degree change in orientation between their vestibular and extraocular coordinate axes. As a result, the optic axes of both eyes maintain their orientation with respect to earth horizontal, but the horizontal semicircular canals become oriented vertically. Since the flatfish propels its body with the same swimming movements when referenced to the body as a normal fish, the horizontal canals are exposed to identical accelerations, but in the flatfish these accelerations occur in a vertical plane. The appropriate compensatory eye movements are simultaneous rotations of both eyes forward or backward (i.e., parallel), in contrast to the symmetric eye movements in upright fish (i.e., one eye moves forward, the other backward). Therefore, changes in the extraocular muscle arrangement and/or the neuronal connectivity are required. This study describes the peripheral and central oculomotor organization in the adult winter flounder, Pseudopleuronectes americanus. At the level of the peripheral oculomotor apparatus, the sizes of the horizontal extraocular muscles (lateral and medial rectus) were considerably smaller than those of the vertical eye muscles, as quantified by fiber counts and area measurements of cross sections of individual muscles. However, the spatial orientations and the kinematic characteristics of all six extraocular muscles were not different from those described in comparable lateral-eyed animals. There were no detectable asymmetries between the left and the right eye. Central oculomotor organization was investigated by extracellular horseradish peroxidase injections into individual eye muscles. Commonly described distributions of extraocular motor neurons in the oculomotor, trochlear, and abducens nuclei were found. These motor neuron pools consisted of two contralateral (superior rectus and superior oblique) and four ipsilateral populations (inferior oblique, inferior rectus, medial rectus, and lateral rectus). The labeled cells formed distinct motor neuron populations, which overlapped little. As expected, the numbers of labeled motoneurons differed in horizontal and vertical eye movers. The numerical difference was especially prominent in comparing the abducens nucleus with one of the vertical recti subdivisions. Nevertheless, there was bilateral symmetry between the motoneurons projecting to the left and right eyes.(ABSTRACT TRUNCATED AT 400 WORDS)

Swimming In The Pteropod Mollusc, Clione Limacina: I. Behaviour and Morphology*

ABSTRACT In the pteropod mollusc Clione limacina (Phipps), swimming is accomplished through alternate dorsal and ventral flexions of a pair of strongly muscularized wing-like parapodia (wings). Wing musculature is arranged in seven muscle groups. The two outermost dorsal and ventral groups produce the bending movements of swimming. The three inner muscle groups include longitudinal and transverse wing retractors and dorso-ventral muscles. The overall muscle arrangement is similar to that of the generalized mollusc foot. During hovering locomotion the wings pronate on downstroke and supinate on upstroke to produce a maximal angle of attack of 42° for both phases. Wing tips nearly touch or overlap in the saggital plane at the extreme of each half-cycle. High speed movie analysis of hovering swimming indicates that upstroke and downstroke are nearly symmetrical. It is suggested that wings produce lift in both wing phases. We estimate from wing dimensions and velocity measurements that the Reynolds number of the wings is approximately 200. A novel lift-generating mechanism, similar to the ‘clap-and-fling’ of insects, may be utilized by the Clione wing to generate lift throughout the wing cycle despite the reversal of wing movement in each half-stroke.

Smooth muscle in the hepatic artery, portal vein and hepatic vein within the liver of the raccoon and guinea pig

The amount and arrangement of smooth muscle in the intrahepatic vessels suggests that the guinea pig would be a good animal model for studying mechanisms controlling intrahepatic portal vein blood flow, while the raccoon would be good for studying hepatic vein mechanisms of control.

Morphology of the head of Mydas clavatus drury (Diptera : Mydaidae)

The external and internal morphology of the head capsule and mouthparts of M. clavatus (Diptera : Mydaidae) are described by light and scanning electron microscopy. The face bears a prominent postclypeal region, and a conspicuous anteclypeus. Large air sacs occupy a major portion of the internal head volume. Internally, there is a well-developed tentorium. Paired labellar glands are found within the head capsule. Three major head pumps are present. The mouthparts consist of the labrum, reduced maxillae, and labium. Labellar lobes are well developed and bear rows of pseudotracheae. The fly feeds by extending the mouthparts by means of muscular contractions, and spreading the large furca to expose the pseudotracheae to the substrate. Previous authors assumed that Mydaidae was a predaceous family. The structure of the mouthparts of M. clavatus is indicative of nectar-feeding habits. M. clavatus has a fragile hypopharynx and both labrum and hypopharynx are incapable of being manoeuvred, ruling out the possible role of predation. In the field, flies were observed to feed only on nectar. M. clavatus lacks mandibles in both males and females and has a movable hinged fulcrum similar to the cyclorraphous Diptera. The labella show a different organization than that found in blood-sucking and nectar-feeding Tabanoidea as well as Cyclorrapha. M. clavatus on the other hand has a more primitive arrangement of the labial muscles and sclerites. M. clavatus is unique in having long internal pseudotracheal tubes, an esophageal dilator originating on an air sac, and cibarial protractors that originate on the subgenae.

Some structural aspects of precapillary vessels.

According to the present state of the art, the former Chambers-Zweifach conception is no longer tenable as the ubiquitous module of microvascular organization. Any attempt to define the consecutive segments of precapillary vessels in a random collection of sectioned tissues is impaired by the extreme scatter of variations and the lack of additional criteria necessary for a distinct classification. With these inadequacies in mind, arterioles, terminal arterioles, and their precapillary segments (sphincters?) are identified by applying the following parameters: luminal diameter, composition of the subendothelial space, and thickness as well as completeness of the media. Endothelial components of particular functional significance are different types of cytoplasmic filaments and myoendothelial junctions. The former serve as a cytoskeleton and may provide a mechanism to adapt endothelial tensile strength to variations of shearing forces. The latter appear to be sites of firm intercellular attachment and of electrotonic coupling of the endothelium to the underlying smooth-muscle cells. The former unanimously accepted helicoidal arrangement of vascular smooth muscle (VSM) must be modified according to most recent findings, and the tridimensional shape of VSM and its transition to pericyte-like elements remain to be further elucidated. Future effects, from which solutions to the many open problems may be expected, must therefore aim at combined vital-, light-, and electron-microscopic studies of the methodically accessible microvascular beds. This necessity has already been recognized, and first promising steps have been taken.

A skeleton of physical ideas for the dynamics of complex systems

Abstract We define complex systems, from molecular ensembles and networks to galactic clusters, as fluid-plastic-elastic systems in which bulk/shear viscosity ratios are large, with the consequence that interactions among parts at any level lead to internalization of action (energy × time) and to variable process delays between external inputs and outputs. Living systems are notably complex by this measure. Complex systems can be comprehended dynamically through an extended statistical mechanics, irreversible thermodynamics, and nonlinear mechanics, in the form of an electrohydrodynamic field physics. Chemical reactivity (making, breaking, or exchanging bonds) is subsumed in the generalized mechanics as a diffusive process. In this paper we apply this physical construct to the problems of dynamic regulation and coordination among parts in the forms of life found in the more than 300 families of flowering plants. We choose to use these particular plants rather than vertebrates, mammals, or man, as exemplars of our theory to show how effective “chemical languages” can be, without the obfuscating arrangements of nervous systems and muscles designed to support locomotion.

Anatomy of the tail in the beaver (Castor canadensis)

A detailed description of the caudal muscles and a review of the bones in the tail of the North American beaver (Castor canadensis) are presented as a base for future functional studies. Differences between previous and present findings are noted and discussed. All the differences indicate that the arrangement of muscles and tendons is more complex than previously indicated.

Flexor muscles of the thigh of crab-eating monkeys (Macaca fascicularis)

On the basis of 44 hindlimbs of 14 male and 14 female crab-eating monkeys (Macaca fascicularis), the morphology of the adductor muscles of the thigh was described and some functional indices were calculated. The results obtained from this study agreed generally with those of otherMacaca species reported by various authors. For the classification and nomenclature of the adductors, the criteria proposed byUhlmann (1967, 1968) was well adapted to the crab-eating monkey. The adductors comprise the m. gracilis, m. pectineus, m. adductor longus, pars longa and pars brevis of m. adductor brevis, pars lata and pars minima of m. adductor magnus and m. obturatorius externus. In males, the adductors are generally inserted further down the femur, and the insertions of pars brevis of the m. adductor brevis and pars minima of the m. adductor magnus have longer attachments to the femur than in females. The arrangement of each adductor muscle and of each fasciculus of a thigh muscle may invoke a principle of organization.

Ultrastructural study of guinea pig tracheal smooth muscle and its innervation.

The ultrastructure of guinea pig tracheal smooth muscle and its innervation was studied by transmission electron microscopy. Smooth muscle cells were arranged into bundles separated by collagen and connective tissue cells. Gap junctions were found only rarely between adjacent smooth muscle cells. Bundles of axons (predominantly unmyelinated) were seen on the periphery of the muscle bundles. Some penetrated deep into the bundles and a few made close neuromuscular contacts (less than 20 nm). Such a spatial arrangement of nerves and smooth muscle suggests a potential for nervous control and limited myogenic activity. Axon profiles containing small agranular vesicles characteristic of cholinergic nerves and small granular vesicles characteristic of adrenergic nerves were seen in close association with airway smooth muscle and with one another. Some large granular vesicles were associated with varicosities of both nerve types. Quantitative studies demonstrated a preponderance of cholinergic over adrenergic nerve profiles in both upper and lower segments. Varicosities, characteristic of adrenergic nerves, were observed more frequently in upper compared with lower segments; however, observed differences were not significant. The morphological findings are consistent with the control functions exerted by cholinergic and adrenergic nerves but provide no basis for control by nonadrenergic inhibitory nerves.

Paradoxical relaxation of arterial strips induced by vasoconstrictive agents.

Longitudinal strips isolated from canine distributing muscular arteries were relaxed by noradrenaline and contracted by papaverine. This paradoxical relaxation and contraction may be due to a helical and circular arrangement of smooth muscle in the wall which is incompressible. Various vasoconstrictive agents, including noradrenaline, produced a circumferential contraction and longitudinal relaxation in muscular arteries. Vasodilator agents produced the opposite effect. The direction and magnitude of response of a helical strip to a vasoactive substance depended upon its sectioning angle from the transverse axis of the vessel.

Familial study of hypertrophic cardiomyopathy and congenital aortic valve disease

A woman with coexisting calcific aortic valve disease and hypertrophic obstructive cardiomyopathy was studied before homograft replacement of the aortic valve and in the second and fourth postoperative years. Postoperative hemodynamic findings, in studies performed with and without pharmacologic agents, were similar to those of patients with hypertrophic cardiomyopathy. Echocardiographic studies 9 years after operation revealed asymmetric septal hypertrophy and systolic anterior motion of the mitral valve leaflet echoes. The patient eventually died from carcinoma of the bronchus 9 years after aortic valve replacement. At autopsy the heart showed the features of hypertrophie obstructive cardiomyopathy. In addition, in the aorta the arrangement of the smooth muscle and elastic fibers was disordered. Subsequently, 10 asymptomatic relatives from four generations of this family were studied clinically and with echocardiography. Unsuspected asymmetric septal hypertrophy was found in four, and the pattern of the aortic valve echoes was compatible with a bicuspid valve in three. Three relatives had coexisting asymmetric septal hypertrophy and a bicuspid aortic valve. This family study shows that hypertrophie cardiomyopathy and bicuspid aortic valve may coexist and may be inherited as a dominant characteristic with variable manifestations.

The ultrastructure, development and mode of operation of the ventrogenital complex ofCryptocotyle lingua(Creplin) (Digenea: Heterophyidae)

Cryptocotyle lingua, in common with other Heterophyidae, has no cirrussac or cirrus. To ensure that cross fertilization occurs, an elaborate ventrogenital complex has developed to enable two individuals to remain firmly attached while mutual exchange of sperms takes place. The ventrogenital complex consists of a ventral invagination, the ventrogenital sac, which contains a protrusible gonotyl in the apex of which is embedded the modified ventral sucker. An anterior pocket opens into the ventrogenital sac anteriorly, and the male and female genital pores posteriorly, dorsal to the root of the gonotyl. During copulation two individuals face in opposite directions, their ventral surfaces being closely applied and the gonotyl of one consequently now lying opposite the anterior pocket of the other. The arrangement of muscles suggests the mode of operation, namely, the gonotyl (and ventral sucker) of one enters the anterior pocket of the other, simultaneously, so that the two individuals are pulled closely together and held firmly. The protrusion of the gonotyl brings the genital pores of both individuals into close proximity, the male pore of one being opposite the female pore of the other as they face in opposite directions. An arrangement of grooves in the adjacent surfaces of the gonotyls ensures a mutual flow of sperms from the male pore of one to the female pore of the other, the flow being initiated by contraction of the circular muscles around the ductus ejaculatorius in each. The ventrogenital complex developes in the encysted metacercaria in the fish second intermediate host. At 38 days old, the stage infective to the bird, all essential parts of the ventrogenital complex are present.

External anatomy and muscle morphology of the walking legs of the scorpion Hadrurus arizonensis

1. 1. The relationships between total leg length, leg segment length and body size for different sized scorpions ( Hadrurus arizonensis) are described. Ipsilateral walking legs are differentially oriented (Fig. 1). Leg length increases in progressively more posterior legs (Fig. 2). 2. 2. Unlike the situation in insects and crustaceans, in the scorpion the joint between the body and the coxa is relatively immobile. The coxa-trochanter (C-T) joint is monocondylic, permitting relatively complex movements, while the remaining leg joints are dicondylic, planar joints (Fig. 5). 3. 3. The C-T joint musculature is relatively complicated reflecting the complexity of joint movement (Fig. 3). The more distal joints are controlled by simpler antagonistic muscle arrangements (Fig. 4).