Morphologico-functional study of the locomotor system of penguins as a principle of the general motor model of "underwater flight." III

Based on some ideas about the evolution of the underwater flight of penguins (part I) and morphological data obtained by dissection of 26 individuals (part II), a survey is developed about the cooperation and interaction of the components of the muscle apparatus and some ethological peculiarities of Penguins are explained by their anatomical basis. The knowledge of the mechanics of the shoulder joint will be useful for comparative anatomical studies of specimens of recent and fossil birds.     

Dynamic structural characteristics of the m. triceps surae in human subjects of various physiques

At examination of 305 boys and girls Russian, Kazakh in Alma-Ata strength of the m. triceps surae (strength of the foot flexion) has been estimated, anatomical diameter of this muscle and strength per 1 sm2 of the anatomical diameter (specific strength) has been calculated. Somatotyping after V. N. Shevkunenko has been performed. At dolichomorphy the specific strength is higher than at brachymorphy. In 24 corpses of 18-38-year-old men typical peculiarities of construction and structure of the m. triceps surae is studied. Correlation of the m. triceps surae parts and degree of its pinnateness do not reveal any definite differences in connection with the complexion. As demonstrate the data of light microscopy and mathematical treatment of the results by means of mixtures method statistically reliable predominance of the connective tissue component in the m. triceps surae and more often occurrence of thick muscle fibers in the m. soleus at dolichomorphy is stated. According to the electron microscopy data, better development of the connective tissue carcass of the m. triceps surae is proved in persons of dolichomorphic complexion.     

Investigation of development, structure and function of the phrenicocolic and duodenal suspensory ligaments

The development and structure of the duodenal suspensory ligament and the phrenicocolic ligament were studied in the human fetus, newborn and adult. The observations presented show that the superior retention band is transformed into the suspensory ligament of the duodenum. Within this ligament the muscle of Treitz develops. The inferior retention band atrophies. A new ligament, the phrenicocolic ligament, is formed in the fetal period of life. In this ligament, smooth muscle cells develop. The possible functions of the suspensory ligament of the duodenum and the phrenicocolic ligament are discussed.     

Comparative anatomical study of the gracilis and coracobrachialis muscles: implications for facial reanimation

Since the introduction of cross-facial nerve grafting and free vascularized muscle transfer for the treatment of longstanding facial paralysis, substantial progress has been made toward restoration of facial expression that is as normal as possible. Much of the focus has remained on the gracilis as a donor muscle. However, its inherent anatomical characteristics may preclude it from ever being more than simply a mass of contractile tissue in the face. The coracobrachialis muscle, which is the analogue in the arm of the lower limb adductor mass, was proposed as an alternative donor muscle because it was thought that certain features would allow it to improve on the overall results that are currently possible with the gracilis. A comparative anatomical study was conducted to gauge this potential. A total of 133 muscles were analyzed, including 96 dissected specimens, 16 arterial and 14 venous study specimens, and seven neurovascular study specimens. Anatomical parameters were recorded for each muscle and later tabulated. Histological analysis of the nerves to 10 gracilis and 10 coracobrachialis muscles was performed, and the findings were confirmed with intraneural dissection of an additional 20 nerves under an operating microscope. The coracobrachialis was observed to be a practical alternative to the gracilis. Indeed, it has many of the attributes that initially drew attention to the gracilis as a possible donor muscle, including a reliable neurovascular supply, minimal donor-site morbidity, and the option of having two teams operate simultaneously. In addition, it has a size, shape, and form that make it an excellent choice for transfer to the face. It could be easily attached in the face to provide static support as well as animation, because of its long proximal tendon, the thick intermuscular septum along its lateral surface, and, when present, the ligament of Struthers.     

The eye of the magellanic penguin (Spheniscus magellanicus): structure of the anterior segment

We undertook a light and scanning electron microscopic study of the eye in the Magellanic penguin (Spheniscus magellanicus). The anatomical peculiarities of the eyeball shape in Sphenisciformes have been previously described by others; here, we show that they are accompanied by several modifications in the organization of the anterior segment of the eye. The main change was found in the portion of opaque sclera extending from the cornea to the anterior border of the scleral ossicles, which was much broader than in other avian eyes. This scleral region was made of a very dense fibrous tissue and was as difficult to cut as the ossicles. The corneo-scleral boundary was also different from that of other birds, since the aqueous humor channel and the pectinate ligament were located 1.0-1.5 mm posterior to the cornea. The osseous ring was formed by 13 bones, including three pairs of over- and underplates. There was a single ciliary muscle, with meridionally oriented striated fibers. They were inserted on a circumference along the boundary between the fibrous sclera and the ossicles, far away from the wall of the aqueous humor channel. On their posterior end, the muscle fibers formed a tendinous structure attached to the inner surface of the sclera and to the outer surface of the ciliary body. Only short zonular fibrils were observed. These anatomical features are probably relevant for the adaptation of penguin eyes to vision on land and in the aquatic environment.     

The role of Treitz' ligament in regulating the evacuation of solid food from the duodenum

In the chronic experiments on dogs by means of modified method of multiple drainage of the intestinal fistulas, the effect of the Treitz ligament transection on dynamics of solid carbohydrate food evacuation from the duodenum was studied. It was established that in the norm, evacuation from the duodenum was submitted to exponential law and depended on absolute quantity of food evacuated from the stomach. After the Treitz ligament transection, the evacuation through intestine had a non-exponential character. The operation led to disturbance in co-ordination between evacuatory function of the stomach and that of duodenum, and also had the depressive effect on intestinal emptying. The conclusion is made of the functional role of the Treitz ligament as active regulator of solid food evacuation from the duodenum.     

Ultrastructural features of skeletal muscle in mice after physical exercise: its relation to the pathogenesis of leucocyte invasion

This study was designed to elucidate which factor(s) trigger off the enhanced macrophage activity after strenuous physical exercise. For an understanding of the cause of this phenomenon we extended the study of the ultrastructural features of skeletal muscle after physical exercise to its possible relation to the pathogenesis of leucocyte invasion. Ultrastructural investigations revealed muscle damage after a strenuous physical exercise. The pathogenesis of the detected autolytic alterations could be related to a local accumulation of lactate, to the ischemic compression syndrome, to an insufficient oxygen supply or to anatomical peculiarities. The greatest functional claim was that fibrillolytic degeneration was capable of being triggered off in the skeletal muscular structure, thereby initiating the release of filament fragments, whose peptides were capable of being depicted as chemotactic signals for leucocytes. The appearance of leucocytes in the muscular tissue suggests that the basic humoral immunity reactions control the cellular cooperation in the muscular tissue.     

Polarizing analysis of the crimped collagen ligament of the maxillary barbel in Parauchenipterus galeatus, and the functional implications

A polarizing analysis of the crimped collagen ligament in the maxillary barbel of the catfish Parauchenipterus galeatus showed clearly that the maxillo-mandibular ligament of this species is formed by two types of collagen fibres. The first is composed of uncrimped, and the second of crimped collagen fibres. An anatomical examination of the muscular and osteological components which act in the movement of the barbel revealed that abduction of the barbel is performed by the extensor tentaculi muscle and the mechanism of adduction by muscular relaxation of the extensor tentaculi combined with release of the stored elastic energy of the maxillo-mandibular ligament. This ligament has rubber properties and because of this can store energy during abduction (first stage of the cycle of barbel movement). The stored energy is released when the action of the extensor tentaculi muscle ceases. The second half of the locomotory cycle is to return the maxilla to its original position by the antagonistic action of the ligament. The crimping of the ligament permits the take up of slack, allowing greater extension, with less chance of snapping. The connective tissue between the hyomandibular and the maxilla may assist the adduction of the barbel.     

3D Topography of the Young Adult Anal Sphincter Complex Reconstructed from Undeformed Serial Anatomical Sections

Background

Pelvic-floor anatomy is usually studied by artifact-prone dissection or imaging, which requires prior anatomical knowledge. We used the serial-section approach to settle contentious issues and an interactive 3D-pdf to make the results widely accessible.

Method

3D reconstructions of undeformed thin serial anatomical sections of 4 females and 2 males (21–35y) of the Chinese Visible Human database.

Findings

Based on tendinous septa and muscle-fiber orientation as segmentation guides, the anal-sphincter complex (ASC) comprised the subcutaneous external anal sphincter (EAS) and the U-shaped puborectal muscle, a part of the levator ani muscle (LAM). The anococcygeal ligament fixed the EAS to the coccygeal bone. The puborectal-muscle loops, which define the levator hiatus, passed around the anorectal junction and inserted anteriorly on the perineal body and pubic bone. The LAM had a common anterior attachment to the pubic bone, but separated posteriorly into puborectal and “pubovisceral” muscles. This pubovisceral muscle was bilayered: its internal layer attached to the conjoint longitudinal muscle of the rectum and the rectococcygeal fascia, while its outer, patchy layer reinforced the inner layer. ASC contraction makes the ano-rectal bend more acute and lifts the pelvic floor. Extensions of the rectal longitudinal smooth muscle to the coccygeal bone (rectococcygeal muscle), perineal body (rectoperineal muscle), and endopelvic fascia (conjoint longitudinal and pubovisceral muscles) formed a “diaphragm” at the inferior boundary of the mesorectum that suspended the anorectal junction. Its contraction should straighten the anorectal bend.

Conclusion

The serial-section approach settled contentious topographic issues of the pelvic floor. We propose that the ASC is involved in continence and the rectal diaphragm in defecation.     

Anatomo-anthropological typology of the jaws in man

Basing on the morphological signs selected in the morphologically contrast samples of the facial skeleton, 27 variants of the upper and lower jaws have been obtained for each, characterizing interconnection and interdependence of several morphological signs. Into each of these variants people of various races and sex, with massive or gracile masticatory apparatus can get. However, the reduction degree, directness, temps and successiveness of reorganizations together with exogenic influence within the limits of the normal reaction in various parts of the masticatory apparatus of the individuals, that belong to the same variant, is identical. Thus, an anatomo-anthropological typology of the dento-maxillary apparatus is obtained, owing to which it is possible to study and compare: 1--individual morphological peculiarities, 2--regional and ethnic norms in morphology of the jaws, 3--within the 27 variants of the structure selected it is possible to study functional, biochemical and other factors. The results demonstrate, that 27 morphological variants of the jaw structure can serve as anatomical marker for distinguishing 27 risk groups for caries.     

Properties of the celiac trunk--anatomical study

Although anatomical properties and vessel variations of the celiac trunk are well explored in the literature, there is not so much information on the arterial diameters, and this data is important for surgical procedures and angiographic examinations. The aim of this study was to investigate properties of the celiac trunk in humans by using anatomical dissection. Ninety cadavers were dissected for the celiac trunk identification and arterial diameter measurements. The results of anatomical examination showed that in 72% of all cases the celiac trunk divides into the splenic artery and the common hepatic artery, while the left gastric artery arises as a first branch and had origin between aorta, all over the celiac trunk up to a bifurcation. From the 90 cadavers, 4 presented anatomical variations. Where normal anatomy was present, the mean length of the celiac trunk was 1.9 +/- 0.08 cm and its mean arterial diameter was 0.78 +/- 0.08 cm. The splenic artery had the largest diameter (0.61 +/- 0.05 cm) and the left gastric artery had the smallest diameter (0.38 +/- 0.03 cm). Our data represent original results about anatomical variations and arterial diameter of the celiac trunk and its main branches provided by anatomical dissection.     

Anatomy of the external anal sphincter in man

The anatomy of the external anal sphincter was studied in 20 adult human cadavers of both sexes by dissection and histological examination. The external anal sphincter is not naturally divided into layers or laminae. The lowermost muscle bundles differ from the main part in being completely surrounded by thick fibrous tissue septa derived form the longitudinal anal coat. The perineal branch of S4 supplies the posterior third, the inferior haemorrhoidal nerves supply the anterior two thirds. All fibres of the sphincter retain their skeletal attachment to the anococcygeal ligament to the coccyx. Some fibres cross the median plane to be continuous with the transversus perinei of the opposite side. A cleft was displayed separating the lower border of the levator ani muscle from the upper border of the external anal sphincter. The muscle bundles of the sphincter are arranged circumferentially in one continuous circle and not in loops. Fibres from the anterior border of the levator ani muscle extend to cover and blend with the outer surface of the external sphincter in their way to the anococcygeal ligament.     

Simulation of muscle and adipose tissue deformation in the passive human pharynx

Quantifying the contribution of passive mechanical deformation in the human pharynx to upper airway collapse is fundamental to understanding the competing biomechanical processes that maintain airway patency. This study uses finite element analysis to examine deformation in the passive human pharynx using an intricate 3D anatomical model based on computed tomography scan images. Linear elastic properties are assigned to bone, cartilage, ligament, tendon, and membrane structures based on a survey of values reported in the literature. Velopharyngeal and oropharyngeal cross-sectional area versus airway pressure slopes are determined as functions of Young's moduli of muscle and adipose tissue. In vivo pharyngeal mechanics for small deformations near atmospheric pressure are matched by altering Young's moduli of muscle and adipose tissue. The results indicate that Young's moduli ranging from 0.33 to 14 kPa for muscle and adipose tissue matched the in vivo range of area versus pressure slopes. The developed anatomical model and determined Young's moduli range are expected to be useful as a starting point for more complex simulations of human upper airway collapse and obstructive sleep apnea therapy.     

The failure response of the human cervical facet capsular ligament during facet joint retraction

Studies implicate the cervical facet joint and its capsule as a primary anatomical site of injury during whiplash exposures to the neck. Although the facet joint is known to undergo stretch as the superior vertebra is retracted relative to the inferior vertebra during the whiplash kinematic, the response of the facet capsular ligament and its microstructure during failure in joint retraction is unknown. Polarized light imaging and vector correlation analysis were used to measure the collagen fiber alignment in the human capsular ligament, together with traditional mechanical metrics, during joint retraction sufficient to induce ligament failure. Anomalous fiber realignment occurs at 2.95±1.66mm of displacement, which is not different from the displacement when the ligament first yields (2.77±1.55mm), but is significantly lower (p=0.016) than the displacement at tissue failure (5.40±1.65mm). The maximum principal strain at the first detection of anomalous fiber realignment (0.66±0.39) also is significantly lower (p=0.046) than the strain at failure (1.39±0.64), but is not different from the strains at yield or partial failure. The onset of collagen fiber realignment determined in this study corresponds to the ligament's yielding and supports assertions that the facet capsule can undergo tissue injury during joint retraction. Further, such microstructural responses may indicate tissue damage in the absence of rupture.     

Effects of tendon and muscle belly dissection on muscular force transmission following tendon transfer in the rat

The aim of the present study was to quantify to what extent the scar tissue formation following the transfer of flexor carpi ulnaris (FCU) to the distal tendon of extensor carpi radialis (ECR) affects the force transmission from transferred FCU in the rat. Five weeks after recovery from surgery (tendon transfer group) and in a control group, isometric length-force characteristics of FCU were assessed for progressive stages of dissection: (i) with minimally disrupted connective tissues, (ii) after full dissection of FCU distal tendon exclusively, and (iii) after additional partial dissection of FCU muscle belly. Total and passive length-force characteristics of transferred and control FCU changed significantly by progressive stages of dissection. In both groups, tendon dissection decreased passive FCU force exerted at the distal tendon, as well as the slope of the length-force curve. However, force and slope changes were more pronounced for transferred FCU compared to controls. No additional changes occurred after muscle belly dissection. In contrast, total force increased in transferred FCU following both tendon and muscle belly dissection at all lengths studied, while dissection decreased total force of control FCU. In addition, after tendon and muscle belly dissection, we found decreased muscle belly lengths at equal muscle-tendon complex lengths of transferred FCU. We conclude that scar tissue limits the force transmission from transferred FCU muscle via the tendon of insertion to the skeleton, but that some myofascial connectivity of the muscle should be classified as physiological.     

The role of the duodenojejunal junction in regulating the evacuatory function of the duodenum

Chronic experiment on dogs was performed to study the effect of duodenojejunal junction exclusion from the evacuatory process on dynamics of gastric and duodenal emptying of the carbohydrate and fatty food. It is established that in the case of exclusion of the duodenojejunal junction, the degree of coordination of gastric and duodenal emptying decreases, dynamics of chyme evacuation from the duodenum considerably changes. It is concluded that the duodenum is not a mere transporter of food coming from the stomach, but has its own regulation mechanisms represented by the duodenojejunal junction and the Treitz ligament.     

Hemomicrocirculatory bed of the muscles of the shoulder and forearm

By means of classical anatomical techniques: injection of contrast masses into the vascular network, macro-microscopic preparation, translucency, roentgenography, and some histological techniques, peculiarities of the hemomicrocirculatory bed in muscles of the human arm and forearm have been revealed. Small arteries of the 3d-4th order run along the muscle fiber fasciculi. In the center of the 2d order muscle fasciculus, in its internal perimysium, arteriole and venule (or 2 venules) run; from them into the 1st order fasciculus, precapillary arterioles and postcapillary venules, connected by means of capillaries, run. The arteriole and the venule, accompanying it, together with the precapillary arterioles and postcapillary venules, branching off them, form a unit of the microcirculatory bed of the arm and forearm muscles (module). Well developed intramuscular arterial anastomoses, presence of isolated structural-functional units of the hemomicrocirculatory bed ensure functional prosperity of the human muscles.     

Biochemical investigation of tissue growth: towards definition of "standard" tissue samples

This paper presents an animal model [the kangaroo], a quantitative anatomical dissection procedure, and a mathematical model [two-phase linear regression] which illustrate that body tissues grow at varying rates relative to each other. An argument is developed that biochemists interested in tissue chemical activity need to be able to sample tissue of known [predicted] growth rate. It is assumed that the ability to select, say muscle tissue samples, from any one animal at a stage of its growth where the individual selected pieces of tissue have known [predicted] low, average and high growth rates would allow comparisons to be made between the sampled tissues that may elucidate the underlying biochemical mechanisms involved in the growth process. It is asserted that to establish standards for tissue samples used in biochemical growth studies, the growth rate of the sampled tissue should be one of the criteria incorporated into the definition of what is "standard" for a tissue sample.     

Anatomical variant of the meniscus related to posterior junction: a case report

Background

There are several reports on anatomical differences of the meniscus. However, there are only a few reports on abnormalities in both menisci and anatomical differences in anterior cruciate ligament insertions.

Case presentation

This is a case report of a 36-year-old Hispanic man presenting symptoms, including knee pain, locking, and effusion, with an anatomical abnormality of the menisci corresponding to the fusion of the posterior horns of the menisci in tandem with the insertion of the posterior meniscus fibers in the anterior cruciate ligament.

Conclusions

This is the first study describing a meniscus anatomical variant with isolated posterior junction of the posterior horn with an anomalous insertion to the anterior cruciate ligament. The recognition of meniscus variants is important as they can be misinterpreted for more significant pathology on magnetic resonance images.