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At least 55 records · Page 3Linked to original sources
PubMed2006

[A histological innovative study of Balb/c mouse tooth germ transplanted to nude mouse in vivo].

PURPOSE: To observed the changes of the developed mouse's dental germs after transplanting into nude mouse and find some theoretical foundation for establishing an innovative experimental model. METHODS: Eight tooth germs from four 5th day postnatal Balb/c mice were transplanted to the back muscles of the adult nude mice. At seventh and fourteenth day after grafting, the germs were collected, fixed, demineralized, dehydrated, and embedded in wax. Serial sections of 5 microm thick were made following the routine methods, stained with haematoxylin-eosin dying solution, and observed under a light microscope. The mandibular first molars were taken out from the 12th and 19th day postnatal mouse. Serial sections of 5 microm thick were made following the routine methods, then compared with the germs after graft. RESULTS: All implantations were located in the superficial muscles with abundant capillary vessels. The dental germs could further developed after grafting under the microscope, but slower than dental germs self-development. The layer of dentin was thin, plenty of dentin with disorganized dentin tubule formed after grafting. Although the location of Hertwig's epithelial root sheath hardly moved, the roots developed further. The floor of pulp chamber could form and the pulp chambers were shrinking. The degree of calcification in the area of root increased very clearly. The inflammatory reaction was found at 7th day while hardly noted at 14th day after grafting. CONCLUSIONS: It suggests that late development of mouse tooth germs could further develop after heterotopic transplantation within the superficial muscles of the nude mouse. This model is useful for study of tooth root development in short time.

Animals↗
PubMed2003

[The transplantation of latissimus dorsi flap of the base of T shape artery with the pedicle of the thoracodorsal artery].

OBJECTIVE: To explore the possibility that the free latissimus dorsi musculo-cutaneous flap to repair the forearm leg wound. METHODS: To design latissimus dorsi musculo-cutaneous flap which is foundation on T form thoracodorsal artery stalk. To set the short arm into the receiver artery break and anastomos them. It is not only reassure the blood of free musculo-cutaneous flap, but also reconstruct the continuation of the receiver main artery. RESULTS: In 16 patients, 15 patients success completely, 1 patient main success. The blood supply of receiver is adequate. CONCLUSIONS: The free T form thoracodorsal artery stalk musculo-cutaneous flap free grafting is a good method to repair the skin and soft tissues defection of forearm and leg.

Anastomosis, Surgical↗
PubMed2006

Altered patterns of superficial trunk muscle activation during sitting in nonspecific chronic low back pain patients: importance of subclassification.

STUDY DESIGN: A cross-sectional comparative study between healthy controls and two subgroups of nonspecific chronic low back pain (LBP) patients. OBJECTIVES: To determine differences in trunk muscle activation during usual unsupported sitting. SUMMARY OF BACKGROUND DATA: Patients with LBP commonly report exacerbation of pain on sitting. Little evidence exists to confirm that subgroups of patients with nonspecific chronic LBP patients use different motor patterns in sitting than pain-free controls. METHODS: A total of 34 pain-free and 33 nonspecific chronic LBP subjects were recruited. Two blinded clinicians classified nonspecific chronic LBP patients into two subgroups (active extension pattern and flexion pattern). Surface electromyography (sEMG) was recorded from five trunk muscles during subjects' unsupported "usual" and "slumped" sitting. RESULTS: No differences in trunk muscle activity were observed between healthy controls and nonspecific chronic LBP groups for usual sitting. When the classification system was applied, differences were identified. Compared with no-LBP controls, the active extension pattern group presented with higher levels of cocontraction of superficial fibers of lumbar multifidus (12%), iliocostalis lumborum pars thoracis (36%) and transverse fibers of internal oblique (43%). while the flexion pattern group showed a trend toward lower activation patterns (lumbar multifidus, -7%; iliocostalis lumborum pars thoracis, -6%, and transverse fibers of internal oblique, -5%). The flexion relaxation ratio of the back muscles was lower for nonspecific chronic LBP (superficial lumbar multifidus: t = 4.5; P < 0.001 and iliocostalis lumborum pars thoracis:t = 2.7; P < 0.001), suggesting a lack of flexion relaxation for the nonspecific chronic LBP. CONCLUSION: Subclassifying nonspecific chronic LBP patients revealed clear differences in sEMG activity during sitting between pain-free subjects and subgroups of nonspecific chronic LBP patients.

Abdominal Muscles↗
PubMed1996

[The courses and the segmental origins of the cutaneous branches of the thoracic dorsal rami].

It is described in many textbooks that the medial cutaneous branches (RCM) from the medial branches of the upper six thoracic dorsal rami supply the upper half of the back of the body, the lateral cutaneous branches (RCL) from the lateral branches of the lower six thoracic dorsal rami supply the lower half of it, and the area supplied by both branches is limited to a few segments. Unlike those descriptions, we had frequently observed RCL from the second or the third thoracic dorsal ramus penetrating the rhomboideus muscle during previous research concerning the double innervation of the superficial muscles of the back by both the ventral and the dorsal rami (Kumaki et al., 1984). To make clear the origin of the discrepancy between the description in the textbooks and our observations, we examined the segmental origins, the courses, and the distributions of both the medial and the lateral branches of the thoracic dorsal rami on 20 sides of 11 bodies dissected in the years 1986 and 1989. Consequently, RCL from the second thoracic dorsal ramus (Th 2) was observed in 25% of the cases and RCL from Th 3 and Th 4 were observed in 50% and in 70%, respectively. The highest segment of RCL was Th 2 in 25%, Th 3 in 25%, Th 4 in 35%, Th 6 in 10%, or Th 8 in 5%, and the mean was Th 3.65 +/- 1.53. On the other hand, the lowest segment of RCM was Th 6 (15%), Th 7 (35%), Th 8 (25%), Th 9 (15%), or Th 10 (10%), and the mean was Th 7.70 +/- 1.19. The mean number of the segments at which the dorsal ramus of the thoracic nerve sent both RCM and RCL was 4.55 +/- 1.50 (Max: 9 segments). Thus, we made clear that RCL from the upper thoracic nerves were commonly observed and that the number of segments sending both RCM and RCL was larger than hitherto described. The course of the upper RCL was bent at the points where the RCL penetrated the superficial muscles of the back forming a "Z"-shape, i.e., RCL changed its course from an infero-lateral to an infero-medial direction at the point of penetrating the rhomboid muscle and from an infero-medial to a lateral direction at the point of penetrating the trapezius muscle or the latissimus dorsi muscle. These directions might be associated with the development of the muscles. Sometimes RCL was sharply pulled in a medial direction by the trapezius muscle to penetrate the muscle near the median plane and appeared as RCM. Therefore, we supposed that the main reason why the upper RCL had been overlooked was because the complicated zigzag course of the RCL was damaged by the inadequate dissection or RCL was mistaken for the RCM. While the points where the cutaneous branches penetrated the superficial muscles were variable, the points where they penetrated the thoraco-lumbar fascia were relatively stable. This point of the RCM was generally near the tip of the spinal process of the same segmental number of the nerve, and the same point of RCL was generally at the gap between the longissimus and the iliocostal muscles in the intercostal space one segment lower than the segment of the RCL. The RCL from the last thoracic to the third lumbar dorsal rami communicated with one another to form a nerve plexus under the lumbo-dorsal aponeurosis, then penetrated that aponeurosis forming several nerve bundles, crossed over the iliac crest and supplied the hip skin as the superior cluneal nerves. Therefore, each bundle was not equivalent to each segment, but was composed of two or more segments.

Humans↗
PubMed2001

Variability in the control of head movements in seated humans: a link with whiplash injuries?

The aim of this study was to determine how context and on-line sensory information are combined to control posture in seated subjects submitted to high-jerk, passive linear accelerations. Subjects were seated with eyes closed on a servo-controlled linear sled. They were asked to relax and received brief accelerations either sideways or in the fore-aft direction. The stimuli had an abrupt onset, comparable to the jerk experienced during a minor car collision. Rotation and translation of the head and body were measured using an Optotrak system. In some of the subjects, surface electromyographic (EMG) responses of selected neck and/or back muscles were recorded simultaneously. For each subject, responses were highly stereotyped from the first trial, and showed little sign of habituation or sensitisation. Comparable results were obtained with sideways and fore-aft accelerations. During each impulse, the head lagged behind the trunk for several tens of milliseconds. The subjects' head movement responses were distributed as a continuum in between two extreme categories. The 'stiff' subjects showed little rotation or translation of the head relative to the trunk for the whole duration of the impulse. In contrast, the 'floppy' subjects showed a large roll or pitch of the head relative to the trunk in the direction opposite to the sled movement. This response appeared as an exaggerated 'inertial' response to the impulse. Surface EMG recordings showed that most of the stiff subjects were not contracting their superficial neck or back muscles. We think they relied on bilateral contractions of their deep, axial musculature to keep the head-neck ensemble in line with the trunk during the movement. About half of the floppy subjects displayed reflex activation of the neck muscles on the side opposite to the direction of acceleration, which occurred before or during the head movement and tended to exaggerate it. The other floppy subjects seemed to rely on only the passive biomechanical properties of their head-neck ensemble to compensate for the perturbation. In our study, proprioception was the sole source of sensory information as long as the head did not move. We therefore presume that the EMG responses and head movements we observed were mainly triggered by the activation of stretch receptors in the hips, trunk and/or neck. The visualisation of an imaginary reference in space during sideways impulses significantly reduced the head roll exhibited by floppy subjects. This suggests that the adoption by the central nervous system of an extrinsic, 'allocentric' frame of reference instead of an intrinsic, 'egocentric' one may be instrumental for the selection of the stiff strategy. The response of floppy subjects appeared to be maladaptive and likely to increase the risk of whiplash injury during motor vehicle accidents. Evolution of postural control may not have taken into account the implications of passive, high-acceleration perturbations affecting seated subjects.

Acceleration↗
PubMed2004

Does anticipation of back pain predispose to back trouble?

Limb movement imparts a perturbation to the body. The impact of that perturbation is limited via anticipatory postural adjustments. The strategy by which the CNS controls anticipatory postural adjustments of the trunk muscles during limb movement is altered during acute back pain and in people with recurrent back pain, even when they are pain free. The altered postural strategy probably serves to protect the spine in the short term, but it is associated with a cost and is thought to predispose spinal structures to injury in the long term. It is not known why this protective strategy might occur even when people are pain free, but one possibility is that it is caused by the anticipation of back pain. In eight healthy subjects, recordings of intramuscular EMG were made from the trunk muscles during single and repetitive arm movements. Anticipation of experimental back pain and anticipation of experimental elbow pain were elicited by the threat of painful cutaneous stimulation. There was no effect of anticipated experimental elbow pain on postural adjustments. During anticipated experimental back pain, for single arm movements there was delayed activation of the deep trunk muscles and augmentation of at least one superficial trunk muscle. For repetitive arm movements, there was decreased activity and a shift from biphasic to monophasic activation of the deep trunk muscles and increased activity of superficial trunk muscles during anticipation of back pain. In both instances, the changes were consistent with adoption of an altered strategy for postural control and were similar to those observed in patients with recurrent back pain. We conclude that anticipation of experimental back pain evokes a protective postural strategy that stiffens the spine. This protective strategy is associated with compressive cost and is thought to predispose to spinal injury if maintained long term.

Adult↗
PubMed2002

The effect of back squat depth on the EMG activity of 4 superficial hip and thigh muscles.

The purpose of this study was to measure the relative contributions of 4 hip and thigh muscles while performing squats at 3 depths. Ten experienced lifters performed randomized trials of squats at partial, parallel, and full depths, using 100-125% of body weight as resistance. Electromyographic (EMG) surface electrodes were placed on the vastus medialis (VMO), the vastus lateralis, (VL), the biceps femoris (BF), and the gluteus maximus (GM). EMG data were quantified by integration and expressed as a percentage of the total electrical activity of the 4 muscles. Analysis of variance (ANOVA) and Tukey post hoc tests indicated a significant difference (p < 0.001*, p = 0.056**) in the relative contribution of the GM during the concentric phases among the partial- (16.9%*), parallel- (28.0%**), and full-depth (35.4%*) squats. There were no significant differences between the relative contributions of the BF, the VMO, and the VL at different squatting depths during this phase. The results suggest that the GM, rather than the BF, the VMO, or the VL, becomes more active in concentric contraction as squat depth increases.

Electromyography↗