Three-dimensional architecture and moment arms of human rotator cuff muscles in vivo: Interindividual, intermuscular, and intramuscular variations

The human rotator cuff consists of four muscles, each with a complex, multipennate architecture. Despite the functional and clinical importance, the architecture of the human rotator cuff has yet to be clearly described in humans in vivo. The purpose of this study was to investigate the intramuscular, intermuscular, and interindividual variations in architecture and moment arms of the human rotator cuff. Muscle volumes, fascicle lengths, physiological cross-sectional areas (PCSAs), pennation angles, and moment arms of all four rotator cuff muscles were measured from mDixon and diffusion tensor imaging (DTI) scans of the right shoulders of 20 young adults. In accordance with the most detailed dissections available to date, we found substantial intramuscular variation in fascicle length (coefficients of variation (CVs) ranged from 26% to 40%) and pennation angles (CVs ranged from 56% to 62%) in all rotator cuff muscles. We also found substantial intermuscular and interindividual variations in muscle volumes, but relatively consistent mean fascicle lengths, pennation angles, and moment arms (CVs for all ≤17%). Moreover, when expressed as a proportion of total rotator cuff muscle volume, the volumes of individual rotator cuff muscles were highly consistent between individuals and sexes (CVs ≤16%), suggesting that rotator cuff muscle volumes scale uniformly, at least in a younger population without musculoskeletal problems. Together, these data indicate limited interindividual and intermuscular variability in architecture, which may simplify scaling routines for musculoskeletal models. However, the substantial intramuscular variation in architecture questions the validity of previously reported mean architectural parameters to adequately describe rotator cuff function.

Magnetic resonance imaging provides new insights into the characterization of adipose and lean tissue distribution

Magnetic resonance imaging (MRI) represents a major advance in the study of human body composition and nutritional status. Measurement of whole body and regional adipose tissue (AT) distribution, quantification of lean tissue (LT) and its principal constituent skeletal muscle, and the assessment of visceral AT are among the advantages made possible by MRI. Indeed, the ability to quantify visceral AT has provided the researcher with significant insight into the complex relationships between body composition and health risk. Because there are no known health risks associated with MRI, this methodology is well suited for studying the effects of various nutritional perturbations on both AT and LT, in particular visceral AT and skeletal muscle. An overview of the historical development and current status of MRI within the context of body composition research is provided. Validation studies are reviewed, and new insights into the nature of AT and LT distribution in both sexes and the effects of weight loss on these same parameters are presented. Finally, directions for future MRI research are suggested.

[Practical aspects of knee anatomy]

The anatomy of the knee provides a standardised description of articular surfaces, ligament and tendinous insertions in order to understand the combined action of the femoro-tibial and femoro-patellar compartments, as well as their stabilisation mechanisms. Nevertheless, the isolated vision of the articulation is insufficient; one also needs to study the global action of the limb by integrating the rotation of the whole skeletal body and its positions in the sagittal and frontal plans.

Comparative study of sensitive and vegetative innervation of external and internal anal sphincter muscles in different mammals

Proprioceptive innervation of the external anal sphincter muscle and the organization of the vegetative and sensitive nerve components of the internal and sphincter muscle have been studied in different mammals. The findings of typical muscle spindles in the external anal sphincter muscle were constant in the pig, frequent in the goat and cow, rare in the sheep and horse and absent in the roe and rabbit. In the pig, muscle spindles were observed in the entire extension of the muscle, while in the sheep, goat, cow and horse, the receptors were found only in the cranial portion of the muscle. In all the species studied, the internal anal sphincter muscle had numerous ganglion cells, isolated or grouped, and rare Pacinian, Pacinian-like, and Golgi-Mazzoni corpuscles. Their functional role has been hypothesized.

Transposition of flexor pollicis brevis muscle for reconstruction of thumb opposition. Anatomical study and clinical application

OBJECTIVE

Based on the anatomical study and clinical trial of transposition of the flexor pollicis brevis muscle (M. f. p.b.) for the reconstruction of thumb opposition, we suggested a new method for the treatment of irreparable median nerve injury which causes paralysis of the opponens pollicis and the abductor pollicis brevis muscles (M.a.p.b) and leads to loss of thumb opposition.

MATERIAL AND METHODS

Anatomical study and biomechanic analysis were performed on 20 cadaveric hands and 8 patients who had been treated and followed up on an average for 12 months.

RESULTS

The M.f.p.b. overlaps the M.a.p.b. for about half of its width at the muscle origins and the overlapping reduced to about 1/3 of the width at the muscle belley level. The M.f.p.b. chiefly inserted on the palmar aspect of the base of proximal phalanx. The M.a.p.b. primarily was inserted on the radial side of the first metacarpophalangeal(MP) joint, and the M.f.p.b. was entirely innervated by the deep branch of the ulnar nerve. In an attempt to increase the angle between longitudinal force lines of these two muscles for 7 degrees-9 degrees, we transferred the insertion of the M.f.p.b. to the radial side of the MP joint, so that it gives this muscle the function of opposition. Eight patients were treated and followed up on an average for 12 months. All had fine functional results.

CONCLUSIONS

This method is effective, and least traumatic, and does not need transposition of another tendon.

[Effects of strength and endurance training on skeletal muscles in the elderly. New muscles for old!]

A well-known effect of increasing age is the gradual reduction of muscle function, and thus of performance in the activity of daily living. Recent research has shown that, even among the very elderly, exercise can improve not only strength and endurance, but also balance and mobility, thus reducing the risk of falls. The possibility of counteracting some of the age-related muscle changes has also been demonstrated. The article reviews current knowledge of strength and endurance training in the elderly, the importance of exercise to improve physical performance, and how lifelong exercise can counteract the effects associated with the ageing of the neuromuscular system.

The fibre type composition of the rabbit latissimus dorsi muscle

The fibre type distribution has been mapped in the latissimus dorsi muscle of the Dutch rabbit. Using the myosin ATPase stain, a distinct border was found to run in a cranial to caudal direction, which effectively divided the muscle into 2 segments of different fibre type proportions. Although both segments contained mostly fast twitch fibres, the medial areas were found to contain approximately 10-20% slow (i.e. type I) fibres while the lateral portions contained very few, if any, slow fibres. Significantly fewer type IIa fibres were also found in the lateral areas of the muscle. These histochemical findings were confirmed by the use of the reverse transcriptase polymerase chain reaction, which demonstrated that more messenger RNA of the slow myosin heavy chain was found in the medial regions compared with the lateral segment. These results demonstrate the importance of choosing well defined sampling sites when evaluating regimes designed to transform this heterogeneous muscle for use in subsequent myoplasty procedures.

[Anatomical study of the distal tendon of the brachial biceps muscle. Application to biceps-triceps transfer in tetraplegic patients]

In some cases of biceps-to-triceps transfer the muscle fibres of the biceps are inserted very distally, preventing correct setting of the transfer. A knowledge of the anatomy of the intramuscular part of the distal tendon of the biceps is useful to lengthen this tendon proximally. A study of 40 specimens showed that the intramuscular part of the distal tendon of the biceps is a large flattened lozenge-shaped aponeurosis located in a frontal plane. It receives muscle fibre insertions on both aspects. The length of the invisible part of the tendon can be estimated by a simple formula: 0.55 a + 4 cm, where "a" represents the length of the tendon between the most proximal tendinous point visible, and the most distal muscle point visible.

[The reinnervation of skeletal muscles]

Experiments were conducted to study different methods of reinnervation of predenervated muscle, for which purpose three groups of animals were used. The first group (reinnervation as to Brunelli) served as a kind of control. In the second group, side notches were cut in the nerve-neurotizator before inserting it into the muscle, in the third group, endomysium and perimysium were defibered at the site of insertion into the muscle of the nerve-neurotizator. The obtained results showed that in the second and third groups processes of reinnervation proceed faster by far and in a more efficient way. This is because the nerve-neurotizator has side cuttings in it, which fact promotes the ingrowth into the muscle tissue of a great many of nerve conductors, and because the skeletal muscle neurotropism gets enhanced at the expense of the connective tissue being formed in sites of defiberation of endomysium and perimysium. The secured results permit recommending the proposed ways and means for reinnervation of denervated muscles in a clinical setting as more efficacious than that by Brunelli.

Blood pressure in Jamaican children: relationship to body size and composition

Blood pressure levels in adults and children are related to body size and composition, but some of these relationships are unclear and they have been incompletely described in the Jamaican population. In a cross-sectional survey of 2,332 school children (6-16 years old; 1,046 boys, 1,286 girls), we measured systolic and diastolic blood pressure and pulse rate, and explored their relationship to weight, height, and waist, hip and mid-upper arm circumferences. The effect of these and other derived measures of body composition on blood pressure was explored in univariate and multivariate analysis. Blood pressure increased with age in both boys and girls, although the increase was greater for systolic than for diastolic blood pressure. The increase of systolic blood pressure among boys continued after age 11 years, but that for girls levelled off. Height and weight were the major predictors of blood pressure, but were highly correlated with each other and with all measures of body composition. Age, height and height-sex interaction explained 11.4% of systolic blood pressure variation, and the largest incremental contribution to this model was provided by the addition of body mass index or hip circumference, each explaining an additional 2.6% of the variance. Lean body mass made a larger contribution to blood pressure than percent fatness. Blood pressure in Jamaican children rises with age and this rise may be steeper in boys than girls. Blood pressure variation is significantly related to several measures of body composition including measures of fatness and fat free mass.

An anatomical variant of the extensor carpi radialis brevis muscle

BACKGROUND

Variations in musculature are of interest not only to the anatomist but also to the surgeon, insofar as they can be a source of error in both diagnosis and treatment. Muscular anomalies in the lower arm and in the hand have frequently been described in the literature; some of the lesions they can be confused with are ganglia and other soft tissue tumors.

CASE REPORT

In the course of preparation of a small, fine-jointed right upper extremity, an accessory muscle was discovered in the forearm and hand region; it branched off from the extensor carpi radialis brevis (ECRB) muscle. Its tendon crossed over the extensor retinaculum and attached to the dorsal digital expansion of the index finger. Both muscles were innervated by a branch of the deep branch of the radial nerve. The observations made here supplement our knowledge of variations in the antebrachial and dorsal regions of the arm and hand, which should be quite useful in hand surgery.

Adipose tissue, the immune system and exercise fatigue: how activated lymphocytes compete for lipids

Adipose depots that contain lymph nodes, and probably intermuscular fat in skeletal and cardiac muscle, are specialized to provision adjacent tissue in a paracrine mode. Perinodal adipocytes respond selectively to various cytokines and incorporate proportionately more polyunsaturated fatty acids. Lipolysis in the adipocytes of node-containing depots can be stimulated via inflammation of the enclosed lymph nodes. Repeated immune stimulation elicits properties characteristic of perinodal adipocytes in those elsewhere in the same depot, and hours later in other node-containing depots, but not in nodeless depots. Such site-specific properties of adipose tissue enable partitioning of dietary and metabolic supplies of fatty acids between competing tissues. Local interactions emancipate the peripheral immune system from competing with other tissues for lipids during immune responses, and may be especially important during periods of high demand, such as strenuous exercise. Biopsies of subcutaneous adipose tissue from sites remote from lymph nodes do not adequately represent the composition of fatty acids available to the immune system in situ, and perhaps that supplied to other tissues. Intermuscular fat in skeletal and cardiac muscle may also indicate paracrine relationships between adipocytes and "end-user" tissues. The concept of paracrine interactions between certain adipocytes and "user" tissue may account for the widespread contiguity between these tissues in vivo.

[Significance of features of the projection of the cervical part of the thoracic duct onto the left sternocleidomastoid muscle for performing operations involving video support]

To work out practical recommendations for using videosupport projection of cervical part of the thoracic duct on sternoclaidomastoid muscle was determined in 158 corpses of adults. Surgical access to the thoracic duct is available using common macrosurgical equipment until the moment of visualization of major lymphatic corrector, although it is reasonable to involve videosupport at following stage with the camera of videoendosurgical kit adjusted in inferior margin of the wound. This allows to perform all the necessary actions to expose cervical part of the thoracic duct and to correct them according to video information on the monitor.

[The effect of deep branches of cervical nerve on motorial function of trapezius muscle]

OBJECTIVE

The aim of this study was to examine the effects of deep branches of cervical plexus on trapezius muscle.

METHODS

The evoked electromyography of 32 trapezius of 16 SD rats was examined in different time and results obtained were processed by statistical methods.

RESULTS

After cutting the accessory nerves, stimulating the deep branches of cervical plexus evoked the myoelectricity, the myoelectricity results varied according to different time.

CONCLUSION

The deep branches of cervical plexus are another important motorial supply to trapezius muscles. After cutting the accessory nerves, if the branches were undamaged, the shoulder's function would be greatly preserved.

[Structure and functions of muscle allotransplants developing in adrenals and the alloplasty area after long-term exposure]

The cross allotransplantation of right gastrocnemius muscles was carried out between intact rats and rats in which adrenals and right shins were subjected to low-energy He-Ne laser radiation (10 procedures for 2 weeks, the exposure duration 5 min; total dose for each rat 15-18 J/cm2). By conditions of experiment, the rats in each series were both donors and recipients, and hence the heterogeneity of rats in each series was the same. It was shown that the laser radiation in the dose studied and the regimes of exposure of rat adrenals and shin (area of the planned allotransplantation) influenced the muscle alloplasty. In rats with irradiated adrenals and shin, the disintegration and resorption of muscle allografts occurred more actively. In intact rats, muscle allografts were more viable. The allogenic muscle tissue and a weak contractile reaction of allografts were revealed in most of them. The allografts showed a moderate lymphocytic infiltration. The data obtained indirectly evidence that the transplant immune reaction increased in rats with irradiated adrenals and shin. In intact rats, the transplant immune reaction to irradiated m.gastrocnemius from irradiated shin decreased.

Aspects on muscle properties and use in competitive Alpine skiing

This brief report describes the physiological demands in competitive Alpine skiing as well as the physiological profile of elite skiers. Maximal heart rate is typically attained by the end of either of the four Alpine ski disciplines. The giant slalom probably calls for the largest reliance upon aerobic energy metabolism and oxygen uptake may increase to 75%-100% of maximal aerobic power. Although high caliber skiers typically show increased maximal aerobic power, it is unlikely that this is an important factor determining success in skiing. Also, anaerobic energy provision accounts for more than half of the total energy yield. Accordingly, plasma and muscle lactate accumulation is substantial after a single race. Similarly, during skiing there is a high rate of glycogen utilization that eventually may result in depletion of muscle glycogen stores by the end of a day of intense skiing. Muscles of Alpine skiers do not possess a distinct fiber type composition and, if anything, skiers tend to show a preponderance of slow twitch fibers. This concords with the recruitment of both muscle fiber types during slalom or giant slalom. Elite skiers show increased knee extensor strength. This seems warranted because there is great reliance upon slow and forceful eccentric muscle actions when performing turns in the giant slalom or slalom.

Magnetic resonance imaging of the foot and ankle

This article describes the application of MR imaging to musculoskeletal imaging, specifically, imaging of the foot and ankle. The instrumentation, safety, and imaging techniques are discussed with specific attention to fat suppression, three-dimensional Fourier transform images, dynamic imaging, magnetization transfer contrast, and MR angiography. Normal and abnormal osseous, ligamentous, and tendonous anatomy is discussed and illustrated.

The anatomic features of the normal tarsus of the live horse as perceived by the sense of sight

A description is given of 75 features present in the normal tarsus of the standing horse which are apparent due to visible skin contours overlying them. Depending on whether or not the pelvic limb is supporting full weight or resting, some contours alter their configuration. Therefore the contour of each underlying feature is described separately for each stance of the limb. It is considered that visual inspection and identification of the apparent superficial features of the normal equine tarsus form the basis of orientation and clinical inspection. Furthermore, these features provide reference points for procedures associated with surgery, arthroscopy, intraarticular treatment and anesthesia of a horse's tarsus suspected of being injured or infected.

Histochemical and morphometric study of fiber types in ten skeletal muscles of healthy young adult cats

A histochemical and morphometric study of fiber types in a variety of skeletal muscles of healthy young adult cats was undertaken to provide normative data not available previously. Using a standardized system of nomenclature, fiber types 1, 2A, 2B, and 2C were identified in most cat muscles on the basis of myosin ATPase staining at pH 4.45. Type-2M fibers were present in temporalis (TEM) and masseter (MAS) muscles. Type-1 fibers predominated in medial head of triceps (MHT) and soleus muscles. Type-2B fibers were dominant in biceps femoris, lateral head of gastrocnemius cranial tibial, long head of triceps, and superficial digital flexor muscles; type-2A fibers were dominant in buccinator muscle samples; and type-2M fibers were dominant in TEM and MAS muscles. Numbers of type-2C fibers did not exceed 2 to 3% of the myofiber population in any muscle. In CT and LHT muscles, a gradient of fiber type distribution was observed, with significant (P < 0.05) increase in numbers of type-1 and type-2A fibers in deeper regions of the muscles. The distribution of fiber types was compartmentalized in MHT and MAS specimens. Diameter of type-2B fibers was significantly (P < 0.05) larger than that of type-1 and type-2A fibers in biceps femoris, lateral head of gastrocnemius, cranial tibial, long head of triceps, and superficial MHT muscles. Diameter of type-2M fibers was significantly (P < 0.05) larger than that of type-1 fibers in TEM and MAS muscles. The soleus type-1 muscle fibers were the largest fibers encountered in any muscle.(ABSTRACT TRUNCATED AT 250 WORDS)