Noninvasive MRI thermometry with the proton resonance frequency (PRF) method: in vivo results in human muscle

The noninvasive thermometry method is based on the temperature dependence of the proton resonance frequency (PRF). High-quality temperature images can be obtained from phase information of standard gradient-echo sequences with an accuracy of 0.2 degrees C in phantoms. This work was focused on the in vivo capabilities of this method. An experimental setup was designed that allows a qualitative in vivo verification. The lower-leg muscles of a volunteer were cooled and afterwards reheated with an external water bolus. The temperature of the bolus water varied between 17 degrees C and 37 degrees C. The in vivo temperature images can be used to extract the temperature in muscle tissue. The data in the fat tissue are difficult to interpret because of the predominance of susceptibility effects. The results confirm the method's potential for hyperthermia control.

Ragged red fibers in normal aging and inflammatory myopathy

Ragged red fibers are an important marker for mitochondrial disease. To evaluate the hypothesis that mitochondrial dysfunction may play a role in the pathogenesis of aging and inclusion body myositis, we studied the frequency of ragged red fibers in muscle biopsy specimens from 15 young and 13 old normal adults, and from 27 patients with inclusion body myositis, polymyositis, or dermatomyositis. Serial transverse cryostat sections were stained with modified Gomori trichrome, modified succinic dehydrogenase, and cytochrome c oxidase. The frequency of ragged red fibers, determined by measuring the percent number of succinic dehydrogenase-positive ragged red fiber equivalents, was significantly higher in old compared to young normal subjects (0.33 vs. 0.02%, p < 0.0001). With the exception of a single polymyositis biopsy specimen showing a large number of ragged red fibers, the frequency of ragged red fibers in patients with polymyositis or dermatomyositis was similar to that of age-matched normal control subjects. The frequency of ragged red fibers was more than 1% in 7 of 8 patients with inclusion body myositis (maximum, 15%). The modified succinic dehydrogenase stain was more sensitive than the modified Gomori trichrome in detecting accumulation of mitochondria in muscle fibers. Cytochrome c oxidase activity was deficient in most ragged red fibers. We conclude that the number of ragged red fibers increases with normal aging and may reflect an age-related decline in muscle mitochondrial oxidative metabolism. The frequent occurrence of ragged red fibers in inclusion body myositis suggests that mitochondrial function may be impaired in this disease.

Effects of clenbuterol and salbutamol on tissue rubidium uptake in vivo

In anesthetized rats, injection of the beta 2-adrenoceptor (beta 2-AR) agonist clenbuterol (0.45 mumol/kg) caused a marked stimulation of 86RbCl (Rb) uptake by skeletal muscle, but had no effect on other tissues; soleus muscle showed the largest (144% increase) response. Injection of another beta 2-AR agonist (salbutamol 0.45 mumol/kg) had no effect on Rb uptake by any tissue except soleus muscle (83%). Both agonists increased body (colonic) temperature to the same extent. A 3-day treatment with salbutamol as a dietary admixture had no effect on body weight, muscle mass, or tissue Rb uptake, whereas the same treatment using clenbuterol produced significant increases in body weight and muscle mass and significant decreases in Rb uptake in three of the four muscle groups studied; Rb uptake in soleus was not affected. In another experiment, the short-term effect of clenbuterol injection on muscle Rb uptake was found to be resistant to a high dose (20 mg/kg) of the selective beta 2-AR antagonist ICI 118551. It was concluded that the selective effects of short-term administration of clenbuterol on muscle Rb uptake, coupled with its effects over 3 days on Rb uptake and muscle hypertrophy, implicate beta-AR modulation of cation transport (possibly via Na,K-adenosine triphosphatase [ATPase] activity) in the anabolic effects of clenbuterol on muscle protein deposition. Since the stimulation of Rb uptake by clenbuterol was resistant to high doses of a selective beta 2-AR antagonist and since salbutamol had little or no effect on muscle hypertrophy or Rb uptake, it is suggested that clenbuterol may exert its effects via an atypical beta-AR.

Changes in Na+, K(+)-adenosinetriphosphatase, citrate synthase and K+ in sheep skeletal muscle during immobilization and remobilization

The K+ balance and muscle activity seem to interact in a complex way with regard to regulating the muscle density of Na(+)-K+ pumps. The effect of immobilization was examined in ten sheep that had low muscle K+ content. Three additional sheep served as untreated controls. After being brought from pasture to sheep stalls one hindlimb was immobilized in a plaster splint for 9 weeks, and in five of the animals remobilization was carried out for a further 9 weeks. The weight bearing of the leg in plaster was recorded by a force plate. Open muscle biopsies from the vastus lateralis muscle were obtained before the study, after 9 weeks of immobilization, and after another 9 weeks of remobilization. The Na(+)-K+ pump density was measured as [3H]-ouabain binding to intact tissue, and citrate synthase activity was measured in tissue homogenate. The tissue content of K+ was measured in fat-free dried tissue. Muscle K+ content increased linearly by almost 70% through the 18-week period independent of intervention. Immobilization reduced thigh circumference by 8% (P < 0.05). A slight decrease in the area of type I fibres at 9 weeks and a slight increase at 18-weeks was found. The [3H]-ouabain binding was reduced by 39% and 22% in the immobilized and control legs, respectively, whereas citrate synthase activity was reduced by about 30% in both legs after 9 weeks of immobilization. During remobilization both the [3H]-ouabain binding and the citrate synthase activity increased to the same level as in the control animals. The plaster cast significantly reduced mass bearing of the immobilized leg, and a corresponding reduction in muscle activity must be assumed to have occurred in both legs as judged from citrate synthase activity. We concluded from this study that the reduction in the [3H]-ouabain binding during immobilization independent of an increase in muscle K+ content points to muscle activity as a strong stimulus for control of Na(+)-K+ pump density.

Neomyogenesis in neonatally de-efferented and postnatally denervated rat muscle spindles

The ultrastructure of muscle spindles de-efferented by the extirpation of the lumbosacral spinal cord at the age of 2 days and subsequently deprived of their sensory innervation by the section of the sciatic nerve at 3-4 weeks of age was studied in serial sections of 2-month-old rat hindlimb muscles. De-efferentation leaves the primary sensory neurons and their peripheral axons intact and capable of inducing the muscle spindle morphogenesis during the critical period of their development. In de-efferented and subsequently denervated muscle spindles, new supernumerary intrafusal muscle profiles (SIPs) appeared in the muscle spindle A region. They were formed in intimate spatial relation with the original intrafusal muscle fibres (IMFs) predominantly from activated satellite cells derived from both nuclear bag (larger diameter) and nuclear chain fibres. SIPs, however, lacked the typical nuclear accumulations, as well as other ultrastructural distinctions present in control IMFs. The majority of differentiated SIPs separated from original IMFs, whereas the less differentiated SIPs were usually closely apposed to the surface of the parent IMFs and both were covered by the common basal lamina. In some spindles, the original IMFs and/or new SIPs at different stages of their differentiation were found together and they formed clusters of variable shape and composition. In the majority of clusters, all profiles seemed to be isolated along their entire length, although in few clusters, occasional cytoplasmic connections of variable length between intrafusal profiles were found. This result is important for the interpretation of the forthcoming study of expression of muscle spindle-specific myosin heavy chain isoforms in denervated SIPs in rat muscle spindles gradually deprived of their motor and sensory innervation.

Skeletal muscle buffer value, fibre type distribution and high intensity exercise performance in man

Interrelationships between quadriceps femoris muscle buffer value (beta), fibre type distribution, and lactate concentration and pH following short-term high intensity exercise were examined in eighteen young healthy human volunteers. Muscle biopsy samples were taken from the lateral portion of the quadriceps femoris muscle at rest and after fatiguing dynamic or isometric exercise. Isometric exercise required the maintenance of 60% quadriceps maximum voluntary contraction, and dynamic exercise, the performance of a modified Wingate Test. The muscle buffer value displayed a positive, but non-significant correlation with the relative area of the muscle occupied by type II fibres (r = 0.42, P = 0.09). An elevated beta was associated with a lesser decrement in muscle pH during intensive exercise but did not permit the accumulation of a higher muscle lactate concentration or allow for an enhanced dynamic or isometric exercise performance. A superior performance during dynamic exercise was associated with a high concentration of muscle lactate and a low muscle pH post-exercise; in turn, each of these factors was positively dependent on the relative area of the muscle occupied by type II fibres. The converse was found for isometric exercise, where there was a tendency for an enhanced performance to be associated with a low muscle lactate and high muscle pH post-exercise. No significant relationship between the relative type II fibre area and isometric performance capacity could be established. It was concluded that the muscle buffer value is not a major limiting factor to the performance of high intensity exercise, suggesting that the involvement of intramuscular acidosis in the development of fatigue may be indirect. The most important determinant of high intensity exercise capacity appears to be the proportional area of the muscle occupied by type II fibres, where a high value provides for a superior dynamic but inferior isometric exercise performance.

The hand as a concept: digital differences and their importance

Digits of the hand vary from each other with respect to bone and joint architecture, muscles, tendons, and degree of functional independence. The hand may be conceived as having a central rigid framework moved at the wrist by flexors, extensors, abductors, and adductors. But on each side of this central structure lies a mobile (hinged) segment necessary for pinch and to increase the strength of grasp. At the distal end of this triplex framework lie multijointed appendages essential for any type of pinch or grasp more sophisticated than that of a lobster claw. The thumb has a highly mobile carpometacarpal joint but lacks a middle phalanx. Therefore, it has no proximal interphalangeal (PIP) joint and consequently no mechanical need for a lumbrical. Since the thumb has excellent coordination without a lumbrical, the lumbrical's function as a sense organ cannot be simply to coordinate finger movement. Mechanically the lumbrical is a deflexor of the PIP joint. Because lumbricals are richly endowed with muscle spindles, their passive stretch by contraction of the flexor digitorum profundus might both inhibit finger extensors and facilitate wrist extensors. Since each digit is unique, accurate mathematical and computer modelling of the hand must take into consideration this uniqueness.

Training-induced changes in muscle architecture and specific tension

Five men underwent unilateral resistance training of elbow extensor (triceps brachii) muscles for 16 weeks. Before and after training, muscle layer thickness and fascicle angles of the long head of the triceps muscle were measured in vivo using B-mode ultrasound, and fascicle lengths were estimated. Series anatomical cross-sectional areas (ACSA) of the triceps brachii muscle were measured by magnetic resonance imaging, from which muscle volume (Vm) was determined and physiological cross-sectional area (PCSA) was calculated. Elbow extension strength (isometric; concentric and eccentric at 30, 90 and 180 degrees.s-1) was measured using an isokinetic dynamometer to determine specific tension. Muscle volumes, ACSA, PCSA, muscle layer thickness and fascicle angles increased after training and their relative changes were similar, while muscle and fascicle length did not change. Muscle strength increased at all velocities; however, specific tension decreased after training. Increase in fascicle angles, which would be the result of increased Vm and PCSA, would seem to imply the occurrence of changes in muscle architecture. This might have given a negative effect on the force-generating properties of the muscles.

Hypertrophy and proliferation of skeletal muscle fibers from aged quail

The purpose of this study was to determined whether fibers in the anterior latissimus dorsi (ALD) muscle from aged Japanese quail have decreased hypertrophic or proliferative responses to 30 days of stretch overload compared with fibers from adult birds. Two groups of quail were studied, 12-wk-old quail (adult; n = 16) and 90-wk-old quail (aged; n = 16). The left wing of each bird was overloaded with a weight corresponding to 10% of the bird's body weight, and the right wing served as the intra-animal control. Quails were killed after 30 days of stretch overload. Total fiber number was quantified by counting all the fibers in a transverse section from the midbelly of the ALD muscle. ALD muscles in aged quails retained the capacity to increase their muscle mass (145%), total fiber number (49%), and fiber cross-sectional area (54%) in response to stretch overload. The ALD muscle in aged quail had a significantly lower increase in muscle mass (33%) and mass corrected for nonmuscle tissue (36%) compared with the ALD from young adult birds. Age had no effect on fiber type distribution shifts with stretch. These results suggest that although muscles in old birds have a substantial ability to adapt to enlarge, stretch-induced hypertrophy is attenuated in muscles from old quail.

Muscle length alters geometry of arterioles and venules in hamster retractor

We investigated how changes in muscle length (Lm) would alter the geometry of arterioles and venules and whether such an effect would depend on the orientation of microvessels to muscle fibers. The parallel-fibered retractor muscle of anesthetized (pentobarbital sodium, 65 mg/kg) male hamsters (n = 20, 105 +/- 4 g) was exposed and irrigated with physiological saline solution (pH 7.4; 35 degrees C). Sarcomere length (Ls) was measured at x2,400 magnification after topical application (3 min, 10(-5) M) of a fluorescent dye [4-(4-diethylaminostyryl)-N-methylpyridinium iodide]. In vivo Ls at resting Lm (i.e., at Lm = 100%) was 3.00 +/- 0.02 microns. The origin and insertion of the retractor were cut, and the muscle was reflected dorsally while the circulation arising from the ventral surface was preserved. Polystyrene "tendons" were glued to each end of the muscle to control Lm, which was varied in 10% increments from 80 to 130% of in situ Lm; Ls increased linearly (r2 = 0.82) from 2.58 +/- 0.03 to 3.89 +/- 0.07 microns, respectively. Arteriole and venule branches and the centerline of "Y" bifurcations were classified based on orientation angles (theta) with respect to muscle fibers at Lm = 100%; three categories were defined using trigonometry (detailed in the APPENDIX) based on microvessel behavior during changes in Lm: parallel (P), 0 degree < or = theta < or = 32.6 degrees; intermediate (I), 32.6 degrees < theta < 59.4 degrees; and normal (N), 59.4 degrees < or = theta < or = 90 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

Dynamic echo planar imaging of exercised muscle

Echo planar imaging was used to record dynamic changes in tissue transverse relaxation rates (delta R2) in the anterior tibialis muscle during dorsi-flexion exercise and recovery. Using a single spin-echo technique to calculate the change in relaxation rate produced by the exercise a time resolution of 4 s was achieved for each measurement of delta R2. For a fixed workload of 70% of maximum voluntary contraction (MVC), the duration of dorsi-flexion exercise was varied and measurements of delta R2 were obtained throughout exercise and for at lease 5 min of recovery. Comparisons were made between the single echo results and those obtained using multiple echo measurements of T2 with much lower time resolution, to verify that the two techniques gave the same results. We found on average that delta R2 decreased by an average of 8.7 s-1 within the tibialis with an average rate of decrease during exercise of delta R2/ delta t(ex) = -0.061 s-2. For the high time resolution studies we consistently observed that there was a continued decrease in the measured value of delta R2 after the exercise, reaching a minimum value about a minute after the exercise ceased. This average rate of undershoot during the postexercise period was given by delta R2/ delta t(us) = -0.035 s-2. This effect has not been noted previously in MR imaging studies and may be attributed to increased flow within the tissue as contracting muscle fibers relax following exercise. The results can be interpreted using simple fast exchange or slow exchange models for tissue water relaxation. For the case of rapid exchange the changes in delta R2 may be indicative of an increase in the net water volume within the muscles, whereas in the case of slow exchange delta R2 is primarily a measure of intracellular volume increases.

On the agonistic display of the Siamese fighting fish. I. The frontal display apparatus

The agonistic behavior of the Siamese fighting fish has long been a popular subject for ethologists. While this behavior is well documented, its physiological basis is still poorly understood. One of the most important components of this behavior is the frontal display, in which a fish faces its opponent directly with tonically extended gill covers. As a first step towards establishing this display as a model for behavioral physiology, the musculoskeletal structure of the frontal display apparatus is examined. The opercular bones and the opercular abductor, the opercular dilator muscle, appear to have undergone adaptive modifications that facilitate the display. The opercular bone rotates around the hyomandibular bone through a ball-and-socket joint. Due partly to a reduction of its articulation with the preopercular bone, the operculum can rotate as much as 90 degrees around this joint. The opercular dilator muscle consists of three parts: a deep belly--DO alpha, and two superficial bellies--DO beta and DO gamma. The three portions have different origins, but all three insert on the lateral surface of the opercular bone just dorsal to the spheroidal joint. In comparison, the opercular dilator muscle of the sunfish and the goldfish lacks the superficial bellies. Innervation of this muscle is derived from the maxillary division of the trigeminal nerve, all three portions are innervated by axons from the same fascicle, suggesting that they are embryologically related. The superficial bellies consist of uniform, large muscle fibers. The deep belly consists of an external group of large fibers around a central tendon, and an internal group of small fibers. Enzyme histochemistry shows that the external group of fibers consists mostly of fast-twitch fibers, whereas the internal group consists of slow, oxidative fibers. Direct stimulation demonstrates that all bellies can mediate opercular extension. The architectural and biochemical differences among the three portions suggest that they are functionally not equivalent. The fast-fatiguing muscles may mediate the initiation, while the large fibers of the superficial bellies and the small oxidative fibers of the deep belly may be involved in the maintenance of the display.

Recent advancements in functional movement analysis

The purpose of this paper is to describe the concept of Functional Movement Analysis (FMA) and review the recent advancements pertaining to the clinical application of FMA. After a brief introduction to the concept of FMA, the role computers have played in FMA development is presented. A generalized movement measurement technique is introduced along with the resulting benefits associated with the implementation of body segment based coordinate systems. Finally, the role of mechanical power estimates and movement synthesis techniques in the future maturation of FMA is considered.

Skeletal muscle metabolism and body fat content in men and women

The purpose of the present study was to verify the relationships between indicators of body fat content and specific characteristics of skeletal muscle in a large sample of men and women. Six skinfold thicknesses (sigma 6S) and maximal oxygen uptake (VO2 max) were measured in 348 Caucasian subjects (149 women and 199 men). Fiber type proportions (type I, type IIA, and type IIB) and activity levels of marker enzymes for the Krebs cycle (malate dehydrogenase, MDH) and for the fatty acid oxidation (3-hydroxyacyl CoA dehydrogenase, HADH) pathways were determined in vastus lateralis muscle samples. No significant correlation was found between fiber type proportions and sigma 6S. Significant and negative correlations were, however, obtained in both genders between the sigma 6S and MDH enzyme activity (r = -0.23; p < 0.01), but not between the sigma 6S and HADH enzyme activity. When individuals with low and high amount of subcutaneous fat but paired for VO2max were compared, vastus lateralis of fat men exhibited the same proportion of type I fiber (38.6 +/- 10.3 vs 38.5 +/- 13.4%) and HADH activity level (3.43 +/- 1.05 vs. 3.34 +/- 0.81 U/g), but had about 20% less MDH enzyme activity than vastus lateralis of leaner men (158 +/- 35 vs. 198 +/- 43 U/g;p < 0.05). No difference was found in any of these muscle phenotypes when comparisons were made between women with low and high amount of subcutaneous fat but also paired for VO2max. Moreover, no relations were observed between skeletal muscle fiber type proportion or metabolic markers with relative subcutaneous fat distribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of freeze/thaw conditioning on the tensile properties and failure mode of bone-muscle-bone units: a biomechanical and histological study in dogs

Eight pairs of canine supraspinatus bone-muscle-bone units were mechanically tested to failure in tension. One side was tested immediately post mortem, and the other side was tested after exposure to a standard freeze/thaw process (-60 degrees C). The failure site was analyzed histologically. Fresh specimens had greater values for ultimate strength (p < 0.001), stiffness (p < 0.001), and energy to failure (p < 0.001). All specimens failed in the muscle close to the musculotendinous junction. The length of muscles subjected to the freezing process was reduced (9.3%). In addition, the load-displacement curves for the fresh and frozen specimens showed marked differences in shape. The loss of tensile strength in muscle tissue is due to damage of the intracellular contractile elements caused by postmortem autolysis; this type of damage is increased as a result of the freeze/thaw process. The freeze/thaw process significantly altered the tensile properties of normal muscle tissue, no matter how carefully it was done. One cannot expect to receive representative data if muscle is frozen and thawed.

Effects of strength and endurance training on thigh and leg muscle mass and composition in elderly women

The effects of 18 wk of intensive strength and endurance training on knee extensor, knee flexor, and lower leg muscle mass and composition were studied in 76- to 78-yr-old women. Muscle cross-sectional area (CSA), lean tissue CSA, and relative proportion of fat were determined using computed tomography. The strength-trained women increased their total muscle lean tissue CSA of the thigh (1.5%; P = 0.035), quadriceps CSA (4.5%; P = 0.021), quadriceps lean tissue CSA (5.8%, P = 0.009), and mean Hounsfield unit of the lower leg muscles (11.2%; P = 0.035) compared with the changes that occurred in the control group during the experiment. The change in quadriceps lean tissue CSA because of the strength training was also significant compared with that in the endurance group. The relative proportion of fat within the quadriceps muscle decreased due to the strength training compared with the changes that occurred in the endurance group. The results show that intensive strength training can induce skeletal muscle hypertrophy in elderly women and thereby also reduce the relative amount of intramuscular fat, whereas the effects of endurance training are negligible.

Knee extension torque and intramuscular pressure of the vastus lateralis muscle during eccentric and concentric activities

The objectives of this study were to determine whether the occurrence of delayed onset muscle soreness (DOMS) for the vastus lateralis muscle was associated with elevated intramuscular pressure (IMP); and to assess, whether high eccentric forces occurred at an increased muscle length (as determined by joint angle). Therefore, peak knee extension torque, peak IMP of the vastus lateralis muscle, and the joint angle at which peak torque (JAPT) occurred were determined in eight male subjects during repetitive eccentric and concentric activities until fatigue occurred. Peak torque was significantly higher for eccentric compared to concentric activity (P < 0.01) and declined significantly for both activities (P < 0.01) throughout the protocols. When comparing the start (prior to fatigue) to the end (fatigue state), mean torque for eccentric activity declined from 191 to 147 (N.m) and for concentric activity declined from 166 to 104 (N.m). In contrast, peak IMP was not significantly different between the types of activity and did not change significantly with time. At the start and the end, the mean IMP remained constant for eccentric activity at 54 mmHg (7.2 kPa) but for concentric activity was 78 mmHg (10.4 kPa) and 96 mmHg (12.8 kPa), respectively. All the subjects, however, experienced DOMS of the vastus lateralis muscle exclusively for the eccentric activity leg. The JAPT was not different between activity types and did not change significantly with time; however, a significant interaction between activity type and time was observed (P = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Anatomy of the hyoid apparatus in Odontoceti (toothed whales): specializations of their skeleton and musculature compared with those of terrestrial mammals

BACKGROUND

The hyoid apparatus of odontocetes (toothed whales) serves as a major attachment point for many of the muscles and ligaments subserving breathing, swallowing, and sound production.

METHODS

This study examines the hyoid apparatus in 48 specimens of ten odontocete genera (Phocoena, Lagenorhynchus, Stenella, Delphinus, Tursiops, Grampus, Globicephala, Mesoplodon, Physeter, and Kogia) collected post mortem from beach strandings.

RESULTS

The odontocete hyoid apparatus, as that of their closest terrestrial relatives, the artiodactyls, is divisible into a basal portion (basihyal, paired thyrohyals) and a suspensory portion (paired ceratohyals, epihyals, stylohyals, and tympanohyals) connecting the basal portion to the skull base. Unlike other terrestrial mammals, the basal portion lies inferior to the laryngeal aditus, is flattened dorso-ventrally, and is relatively large, thus providing a broad surface area for muscle attachments. The suspensory elements are not as flattened and are joined by synovial joints (except for epihyal-stylohyal fusion). Muscular specializations include enlargement of those which retract the hyoid apparatus (e.g., sternohyoid) or control the tongue (e.g., styloglossus, hyoglossus). These muscles may be particularly important in a specialized prey capture behavior called suction feeding. In addition, the hyoid apparatus has a tilted placement, which allows asymmetrical enlargement of the piriform sinuses. Asymmetry is also seen in the muscular attachments between the larynx and the hyoid apparatus. The most pronounced differences from the basic pattern are observed in two families: Physeteridae and Ziphiidae.

CONCLUSIONS

The derived position and shape of the odontocete hyoid apparatus may have evolved to subserve several specialized upper respiratory/digestive tract functions, such as simultaneous feeding (suction and swallowing) and sound production.

Differences in physical characteristics in collegiate baseball players. A descriptive position by position analysis

Physical characteristics including height, weight, body composition, and somatotype of NCAA Division II baseball players were evaluated to determine if differences in physical profiles exist by position at this level of competition. Differences in height, weight, lean body weight and somatoplots were found among various players. Pitchers were found to be taller that infielders and outfielders and displayed more endomorphy and less mesomorphy than the outfielders. Among the infielders, first basemen were taller than second basemen and third basemen while shortstops were found to be taller than second basemen. With respect to weight, first basemen and catchers were found to be heavier than second basemen. The second basemen had less lean body mass than all other infield groups. The data reveal more than a general description is warranted when describing the physical characteristics of baseball players at this level of play.

[Anatomical studies on the thumb muscles of the human hand]

The thenar muscles in 34 cases of 25 human adults were dissected using a stereoscopic microscope. The main supplying branch of the median nerve is often called the recurrent branch because of its characteristic recurrent course, and it enters the muscles between the abductor pollicis brevis and the superficial head of the flexor pollicis brevis. The other branch of the median nerve enters the latter muscle directly close to the tendon of the flexor pollicis longus laterally. This is called the direct branch, and was observed in 32 cases. Of these 32, it passed medial to the tendon in 7 cases. The deep terminal branch of the ulnar nerve supplies the transverse and the oblique heads of the adductor pollicis. One of the branches passes laterally piercing through the latter, and connects with the direct branch of the median nerve under the tendon of the flexor pollicis longus. The anastomosis between the two nerves was observed in 31 cases (91%). The obtained results concerning the nerve supply of the thenar muscles are summarized in Table 1. As seen in this table, the boundary of the supplying area between the median and ulnar nerves almost coincides with the position of the tendon of the flexor pollicis longus. In the other three cases in which a thick anastomosis, about 1 mm in thickness, existed between the median and ulnar nerves in the forearm (Martin-Gruber anastomosis), remarkable expansion of the supplying area of the ulnar nerve within the thenar muscles was observed, as seen in Table 2. According to the descriptions from clinical fields, the opponens pollicis and even the abductor pollicis brevis are sometimes supplied by the ulnar nerve. Such an extreme case may be explained by the existance of the anastomosis described above. The palmar interosseous muscle of the thumb has been described in textbooks. In this study, it is identified as the muscle fascicle of the adductor pollicis dorsal to the princeps pollicis artery, and was observed in 22 cases (65%). The macaca fuscata was also examined in 5 cases. In contrast to humans, all the thenar muscles can be identified without difficulty because no fusions are observed among them and because the nerve supply for each muscle is fairly constant.

Distribution of different fibre types of M. extensor carpi radialis longus of the rat

As revealed by the NADH-diaphorase and myosine ATPase, the M. extensor carpi radialis longus of the rat possesses at least 3 main kinds of fibres, with different distribution on the superficial and deep portions of the muscle. The superficial portion revealed that 67.68% are FG (fast-twitch-glycolytic) fibres, 14.72% are FOG (fast-twitch-oxidative) fibres and 17.60% are SO (slow-twitch-glycolytic) fibres. Already the deep portion revealed that 71.29% are SO (slow-twitch-glycolytic) fibres, 17.46% are FOG (fast-twitch-oxidative-glycolytic) fibres and 11.25% are FG (fast-twitch-glycolytic) fibres. The miosine ATPase reaction was used to demonstrate contracting characteristics. These findings suggest that the movements of fast contraction of the M. extensor carpi radialis longus are predominant.

Statistical analysis of compositional data in anatomy

BACKGROUND

Variables which describe the composition, or relative size of components, of an organism need to be analysed in an appropriate manner.

METHODS

A few of the appropriate descriptive and inferential techniques have been described and applied to a number of anatomical data sets.

RESULTS

When applied to data on the composition of the vastus medialis in adults, a small but significant difference in average muscle fibre type distribution was demonstrated between males and females. There was little evidence for a relationship between fibre type distribution and age over the range considered.

CONCLUSIONS

Graphical displays via ternary diagrams are a simple way of illustrating compositional data simultaneously between and within groups. Numerical analysis is likely to involve transformation of original variables before standard univariate or multivariate statistical techniques can be used.

Arthroscopic anatomy of the lateral elbow: a comparison of three portals

Ten fresh cadaveric elbows were used to evaluate the proximity of the radial nerve and its branches to three anterolateral portals. A proximal anterolateral portal used routinely at our institution and located 2 cm proximal and 1 cm anterior to the lateral epicondyle was compared with the distal anterolateral portal described by Andrews and with a mid-anterolateral portal. The three portals were initially established without joint distention while the elbows were flexed 90 degrees. Measurements were then obtained with and without joint distention at flexion angles of 0 degrees and 90 degrees. The radial nerve was found to be an average distance of 3.8 mm at extension and 7.2 mm at 90 degrees of flexion from the distal anterolateral portal, located 3 cm distal and 1 cm anterior to the lateral epicondyle. Conversely, the distance between the proximal anterolateral portal cannula and the nerve was statistically greater (p < 0.05), averaging 7.9 mm in extension and 13.7 mm in flexion. The remaining anterolateral portal, located 1 cm directly anterior to the lateral epicondyle, was found to be at a statistically greater average distance from the nerve than was the distal anterolateral portal but statistically closer than was the more proximal portal. The ability to visualize the joint arthroscopically was assessed using the three portals, and although the ulnohumeral joint could be adequately seen using all portals, radiohumeral joint visualization was most complete and technically easiest using the most proximal portal.(ABSTRACT TRUNCATED AT 250 WORDS)

[Histochemical and morphometric characteristics of some extraocular muscles of the dog]

This investigation was carried out on retractor bulbi, lateral and medial rectus muscles of six adult dogs. Tissues were collected from near the center of individual muscle bellies. These were stained for m-ATPase at varying pHs during preincubation, NADH-TR, Alpha-GPDH, Modified Mason trichrome and Hematoxyline and Eosin. Muscle fibers were classified as type I and type II, based on their reaction for m-ATPase. The retractor bulbi muscle was composed entirely of type II, oxidative, muscle fibers, with no glycolytic fibers. The rectus muscles presented a stratified composition, with superficial muscle fiber bundles containing a mixture of type II fibers oxidative and glycolytic, and central bundles of type I, mixed with type II. It was observed that there was less interstitial tissue in the center of the muscle bellies. Large diameter nerve fibers were also observed in the central layers.