Skeletal muscle possesses a remarkable ability for its regeneration and injured tissue repair. This ability depends on the activity and contributions of muscle satellite cells. Proliferating satellite cells, termed myogenic precursor cells or myoblasts, are activated and driven out of their quiescent state upon muscle injury. In this summary, we present a review to summarize the molecular regulation in skeletal satellite cells to light on the satellite cells' self-renewal mechanism.
Cell Proliferation ; Humans ; Muscle, Skeletal ; Regeneration ; Satellite Cells, Skeletal Muscle ; cytology ; Soft Tissue Injuries

The tibialis anterior tendon functions as a major dorsiflexor of the ankle. A rupture in this tendon can cause serious problems in the ambulatory function. A closed traumatic rupture without open wound or an atraumatic rupture can delay diagnosis and treatment. There are not enough guidelines for an effective surgical treatment on this chronic condition. Herein, we report two cases of chronic tibialis anterior disruption successfully treated by semitendinosus autograft.
Ankle ; Autografts* ; Diagnosis ; Muscle, Skeletal ; Rupture* ; Tendons* ; Wounds and Injuries

OBJECTIVE: To study the percentages of polymorphonuclear leukocytes (PMN), mononuclear cells (MNC) and fibroblastic cells (FBC) in different post-traumatic intervals after skeletal muscle mechanical injury in rats. METHODS: The rat model of skeletal muscle mechanical injury was established. The rats were divided into injured groups (6 h, 12 h, 1 d, 3 d, 7 d, 10 d and 14 d after injury) and control group. The percentages of PMN, MNC and FBC in different post-traumatic intervals after skeletal muscle mechanical injury were assessed with HE staining and image analysis. RESULTS: At post-injury 6-12h, the percentages of PMN and MNC infiltration appeared in injured sites and that of PMN reached peak. At 1 d, the percentage of MNC infiltration appeared and reached peak, while that of PMN decreased. At 3-7 d, the percentage of FBC gradually increased, while that of PMN and MNC decreased. At 10-14d, the percentage of FBC reached peak. CONCLUSION The percentages of PMN, MNC and FBC in injured zones showed time-dependent changes, which might be used as reference index for determination of age of skeletal muscle injury.
Animals ; Fibroblasts ; Muscle, Skeletal/injuries* ; Neutrophils ; Rats ; Time Factors

As the technologic sophistication of generation and distribution of electrical energy has grown, so has the general concern about the effects of electric fields on human health. There can be no doubt that the significance of electrical trauma will continue to grow with our increasing use of power. It is apparent that our understanding of the various forms of electric trauma must increase, while we continue to promote safety near electrical hazards and develop effective medical therapies. Tissue damage as a result of electrical injury occurs by two mechanisms which are summative in action and have a variable degree of contribute to the ultimate damage produced. Thermal tissue damage occurs as a result of heat generated within the tissue (which offer an electrical resistance) secondary to the passage of the electrical current. High temperatures can also lead to cell membrane components, e.g., phospholipids, to dissolve. Electroportation damage is the tissue damage induced secondary to the strong electric field. Transmembrane potentials caused by electrical current result in the formation of pore in the phospholipid component of the cell membrane resulting in loss of function of the cell membrane with consequent cell death.
Animals ; Electric Injuries/physiopathology* ; Heart Injuries/physiopathology* ; Hemodynamics ; Humans ; Muscle, Skeletal/injuries*

OBJECTIVES: To explore the changes of elbow flexor muscle strength after musculocutaneous nerve injury and its correlation with needle electromyography (nEMG) parameters. METHODS: Thirty cases of elbow flexor weakness caused by unilateral brachial plexus injury (involving musculocutaneous nerve) were collected. The elbow flexor muscle strength was evaluated by manual muscle test (MMT) based on Lovett Scale. All subjects were divided into Group A (grade 1 and grade 2, 16 cases) and Group B (grade 3 and grade 4, 14 cases) according to their elbow flexor muscle strength of injured side. The biceps brachii of the injured side and the healthy side were examined by nEMG. The latency and amplitude of the compound muscle action potential (CMAP) were recorded. The type of recruitment response, the mean number of turns and the mean amplitude of recruitment potential were recorded when the subjects performed maximal voluntary contraction. The quantitative elbow flexor muscle strength was measured by portable microFET 2 Manual Muscle Tester. The percentage of residual elbow flexor muscle strength (the ratio of quantitative muscle strength of the injured side to the healthy side) was calculated. The differences of nEMG parameters, quantitative muscle strength and residual elbow flexor muscle strength between the two groups and between the injured side and the healthy side were compared. The correlation between elbow flexor manual muscle strength classification, quantitative muscle strength and nEMG parameters was analyzed. RESULTS: After musculocutaneous nerve injury, the percentage of residual elbow flexor muscle strength in Group B was 23.43% and that in Group A was 4.13%. Elbow flexor manual muscle strength classification was significantly correlated with the type of recruitment response, and the correlation coefficient was 0.886 (P<0.05). The quantitative elbow flexor muscle strength was correlated with the latency and amplitude of CMAP, the mean number of turns and the mean amplitude of recruitment potential, and the correlation coefficients were -0.528, 0.588, 0.465 and 0.426 (P<0.05), respectively. CONCLUSIONS The percentage of residual elbow flexor muscle strength can be used as the basis of muscle strength classification, and the comprehensive application of nEMG parameters can be used to infer quantitative elbow flexor muscle strength.
Humans ; Elbow ; Electromyography ; Musculocutaneous Nerve ; Elbow Joint/physiology* ; Muscle, Skeletal ; Muscle Strength ; Peripheral Nerve Injuries

OBJECTIVETo explore the blood supply of the reverse arterial arch at the superior border of the hallucal abductor island flap and provide an anatomical basis for repairing fore foot skin defect using this flap.

METHODSThe constitution, course, distribution, and external diameter of the arterial arch at the superior border of the hallucal abductor, and the concomitant veins and nerves were observed on 12 sides of formaldehyde-fixed and 12 fresh adult foot specimens perfused with red latex. The surgical approach using the arterial arch at the superior border of the hallucal abductor for repairing fore foot skin defect were designed.

RESULTSThe arterial arch at the superior border of the hallucal abductor, constituted by the branch of the medial tarsal artery or the branch of the anterior medial malleolus artery anastomosed with the superficial branch of the medial basal hallucal artery or the branch of the superficial branch of the medial plantar artery or the all the four branches, functioned as the axis of the medial tarsal, the medialis pedis and the medial plantar. The external diameters of the anterior medial malleolus artery, the medial tarsal artery, the branch of the superficial branch of the medial plantar artery, and the distal arterial arch at the superior border of the hallucal abductor were 1.02∓0.03 mm, 0.73∓0.04 mm, 0.56∓0.02 mm, and 0.53∓0.14 mm, respectively. Most of the arteries (91.67%) had one concomitant vein with the external diameters of 1.01∓0.03 mm, 0.81∓0.04 mm, 0.57∓0.01 mm, and 0.61∓0.02, respectively, and only a small fraction of them (8.33%) had two concomitant veins.

CONCLUSIONSThe fore foot skin defect can be repaired using this flap supplied by the branch of the anterior medial malleolus artery and the medial tarsal artery, the superficial branch of the medial plantar artery, or all the three. The pivot point formed by the neck of the first metatarsal or metatarsophalangeal joint allows for long vessel pedicles and larger flap areas to increase the flexibility of surgery.

Foot Injuries ; surgery ; Humans ; Muscle, Skeletal ; anatomy & histology ; blood supply ; Skin ; injuries ; Soft Tissue Injuries ; surgery ; Surgical Flaps ; blood supply

PURPOSE: This study was designed to measure time-dependent changes in muscle excursion and collagen content after tenotomy, and to analyze the correlation between muscle excursion and collagen content in a rabbit model. MATERIALS AND METHODS: Twenty-four rabbits underwent tenotomy of the second extensor digitorum longus (EDL) muscles on the right legs and were randomly assigned to three groups based on the period of time after tenotomy (2, 4, and 6 weeks). The second EDL muscles on left legs were used as controls. At each time after tenotomy, passive muscle excursion and collagen content, determined by hydroxyproline content, were measured bilaterally, and the ratio of each value to the normal one was used. RESULTS: The mean ratio of muscle excursion after tenotomy to the value of the control decreased in a time-dependent fashion: 92.5% at 2 weeks, 78.6% at 4 weeks, and 55.1% at 6 weeks. The mean ratio of hydroxyproline content in muscle to the value of the control increased in a time-dependent fashion: 119.5% at 2 weeks, 157.3% at 4 weeks, and 166.6% at 6 weeks. There was a significant negative correlation between the ratio of hydroxyproline content in muscle after tenotomy to the control values and the ratio of muscle excursion after tenotomy to the control values (r=-0.602, p=0.002). CONCLUSION: The decrease in muscle excursion seems to correlate with the increase in collagen content in the muscle in a time-dependent fashion following tenotomy.
Animals ; Collagen/*metabolism ; Hydroxyproline/metabolism ; Muscle, Skeletal/*metabolism ; Rabbits ; Tendon Injuries/*metabolism ; Tendons ; Tenotomy ; Time Factors

PURPOSE: To determine the time of magnetic resonance(MR) signal intensity changes in denervated skeletal muscle and to compare MR imaging with electromyography(EMG) in the evaluation of peripheral nerve injury. MATERIALS AND METHODS: We evaluated MR imagings of denervated muscles after experimental transection of the sciatic nerve in five rabbits using 1.0T MR unit. MR imaging and EMG were performed 3 days and 1, 2 and 3 weeks after denervation. T1-weighted images(T1-WI), T2-WI and Short Tau Inversion Recovery(STIR) images were obtained. The signal intensity (SI) of muscles in the denervated and normal sides were visually and quantitatively compared. After measuring the SI of the normal and abnormal areas, the time of SI change was determined when there was significant difference (P<0.05) of SI between the normal and denervated sides. RESULTS: On STIR images, two of the five rabbits showed significant SI changes at the third day(P<0.05) and all showed significant changes(P<0.05)at the first week. On T2-WI, one rabbit showed significant SI changes at the third day, and all showed significant SI changes at the first week. On T1-WI, significant SI changes were seen in one rabbit at the second week and in one at the third. One week after denervation, all showed denervation potential on EMG. CONCLUSION: This study suggests that MR imaging using STIR images is a useful method in the evaluation of denervated muscle, and that MR signal changes of denervated muscle may precede EMG changes after denervation. To localize and to determine the severity of the peripheral nerve injury, future analysis of the distribution of abnormal MR SI in denervated muscles would be helpful.
Denervation ; Magnetic Resonance Imaging* ; Muscle, Skeletal* ; Muscles ; Peripheral Nerve Injuries ; Rabbits* ; Sciatic Nerve

Acupuncture Therapy ; methods ; Adolescent ; Adult ; Female ; Humans ; Male ; Middle Aged ; Muscle, Skeletal ; injuries

Adult ; Cross-Sectional Studies ; Humans ; Male ; Muscle, Skeletal ; injuries ; Musculoskeletal Diseases ; epidemiology ; Occupational Diseases ; epidemiology ; Welding