家兔趾长伸肌肌内神经、运动终板和肌梭的分布

目的：探究家兔趾长伸肌肌内神经、运动终板与肌梭的分布。方法：改良Sihler’s染色法、乙酰胆碱酯酶染色法及HE染色法。结果：趾长伸肌是短肌束构成的长肌,肌束起点高的,止点相应亦较高。连于第2趾的肌纤维占据了肌腹上1／3,止于其余3趾的肌纤维位于下2／3。趾长伸肌的神经来自2条肌外神经干,上支及其分支支配第2趾的肌纤维,下支司其余3趾。运动终板分布除冠状切面上为弥漫的黑色颗粒外,其余各切面均为一条连续的运动终板带。各部的肌梭密度分别是：起端33.95个／g、肌腹中部44.76个／g、止端为零。结论：家兔趾长伸肌内,肌梭分布不均匀。肌内神经分支密集的部位,运动终板集聚、肌梭密度亦高。家兔趾长伸肌具有划分亚部的特征。     

Demonstration of glutamate-like immunoreactivity at rat neuromuscular junctions by quantitative electron microscopic immunocytochemistry

Motor nerve terminals and adjacent structures in the extensor digitorum longus and soleus muscles of young adult rats were examined for their content of glutamate by means of quantitative, electron microscopic immunocytochemistry employing colloidal gold particles as markers. The level of glutamate immunoreactivity was stronger in the extensor digitorum longus terminals than in the soleus terminals. In both muscles the glutamate immunolabelling was stronger in the nerve terminals than in the synaptic clefts and the postsynaptic tissue separating the secondary clefts, but the differences were larger in the extensor digitorum longus than in the soleus muscle. The myofibrils of the soleus muscle were more densely labelled than those in the extensor digitorum longus muscle: The level of immunoreactivity was high in the Schwann cells of both muscles. By comparing the labelling intensity of motor nerve terminals with that of muscle fibres and hippocampal mossy fibres (compartments that have been analysed previously with respect to their glutamate content), the mean concentration of fixed glutamate in the extensor digitorum terminals was estimated to be in the range of 10–20 mmol/l. An association of glutamate immunoreactivity with synaptic vesicles was demonstrated in the most strongly labelled terminals. Whether these epitopes were localized in the interior of the vesicles or at their external surface could not be resolved with the present technique. These data indicate that motor nerve terminals contain glutamate, and that the enrichment of this amino acid is more pronounced in the terminals of the extensor digitorum longus muscle (a fast muscle) than in those of the soleus muscle (a slow muscle). A possible modulatory or trophic role of glutamate in the mammalian neuromuscular junction should be considered.     

Effect of thyroid hormones on acetylcholinesterase mRNA levels in the slow soleus and fast extensor digitorum longus muscles of the rat

In the rat, the level of acetylcholinesterase messenger RNA in the typical slow soleus muscles is only about 20-30% of that in the fast extensor digitorum longus muscles. The expression of contractile proteins in muscles is influenced by thyroid hormones and hyperthyroidism makes the slow soleus muscle faster. The influence of thyroid hormones on the levels of acetylcholinesterase messenger RNA level in the slow soleus and fast extensor digitorum longus muscle of the rat was studied in order to examine the effect of thyroid hormones on muscle acetylcholinesterase expression. Hyperthyroidism was induced in rats by daily thyroid hormone injection or thyroid hormone releasing tablet implantation. Hind-limb suspension was applied to produce muscle unloading. Muscle denervation or reinnervation was achieved by sciatic nerve transection or crush. Acetylcholinesterase messenger RNA levels were analyzed by Northern blots and evaluated densitometrically. Hyperthyroidism increased the levels of acetylcholinesterase messenger RNA in the slow soleus muscles close to the levels in the fast extensor digitorum longus. The effect was the same in the unloaded soleus muscles. Acetylcholinesterase expression increased also in the absence of innervation (denervation), in the presence of changed nerve activation pattern (reinnervation), and under enhanced tonic neural activation of the soleus muscle (electrical stimulation). However, the changes were substantially smaller than those observed in the control soleus muscles. Enhancement of acetylcholinesterase expression in the soleus muscles by the thyroid hormones is, therefore, at last in part due to hormonal effect on the muscle itself. On the contrary, increased level of the thyroid hormones had no influence on acetylcholinesterase expression in the normal fast extensor digitorum longus muscles. However, some enhancing influence was apparent whenever the total number of nerve-induced muscle activations per day in the extensor digitorum longus muscle was increased. Thyroid hormones seem to be an independent extrinsic factor of acetylcholinesterase regulation in the slow soleus muscle.     

Repeated stimuli for axonal growth causes motoneuron death in adult rats: the effect of botulinum toxin followed by partial denervation

Axons of motoneurons to tibialis anterior and extensor digitorum longus muscles of adult rats were induced to sprout by injecting botulinum toxin into them, by partial denervation or by a combination of the two procedures. Ten weeks later, the number of motoneurons innervating the control and operated tibialis anterior and extensor digitorum longus muscles was established by retrograde labelling with horseradish peroxidase. In the same preparations, the motoneurons were also stained with a Nissl stain (gallocyanin) to reveal motoneurons in the sciatic pool. Examination of the spinal cords from animals treated with botulinum toxin showed that the number of retrogradely labelled cells and those stained with gallocyanin in the ventral horn on the treated compared to the control side was unchanged. In rats that had their L4 spinal nerve sectioned on one side, the number of retrogradely labelled cells on the operated side was 48+/-3% (n = 5) of that present in the control unoperated ventral horn. Thus, just over half the innervation was removed by cutting the L4 spinal nerve. Counts made from gallocyanin-stained sections showed that 94+/-4% (n = 5) of motoneurons were present in the ventral horn on the operated side. Thus, section of the L4 spinal nerve did not lead to any death of motoneurons. In rats that had their muscles injected with botulinum toxin three weeks prior to partial denervation, the number of retrogradely labelled cells was reduced from 48+/-3% (n = 5) to 35+/-4% (n = 5). Moreover, only 67+/-5% (n = 5) of motoneurons stained with gallocyanin, suggesting that a proportion of motoneurons died after this combined procedure. This result was supported by experiments in which motor unit numbers in extensor digitorum longus muscles were determined by measurements of stepwise increments of force in response to stimulation of the motor nerve with increasing stimulus intensity. In partially denervated extensor digitorum longus muscles, 16.6+/-0.7 (n = 5) motor units could be identified, and in animals treated with botulinum toxin prior to partial denervation only 13.3+/-0.9 (n = 3) motor units were present. Taken together, these results show that treatment with botulinum toxin followed by partial denervation causes motoneuron death in adult rats.     

Ultraterminal sprouting in innervated and partially denervated adult and aged rat muscle

End plates from the extensor digitorum longus, soleus and diaphragm muscles of adult (10-month-old) and aged (25-month-old) rats were examined to determine whether aging affects the frequency of occurrence of ultraterminal sprouting, a form of terminal sprouting commonly associated with muscle denervation. There was a significant increase in the fraction of end plates exhibiting ultraterminal sprouts in the extensor digitorum longus muscle only; the number increased from 5.5% in 10-month-old animals to 23.0% in 25-month-old animals. To see whether age also influences the sprouting response to denervation, extensor digitorum longus muscles from 10-and 25-month-old animals were partially denervated by severing spinal nerve L5, and end plates were examined 4-7 and 10-14 days following denervation. Denervation induced a more profound increase in the percentage of end plates exhibiting ultraterminal sprouting in the 10- compared with 25-month-old animals. However, sprouting remained significantly greater in the 25- compared with the 10-month-old animals. Furthermore, following denervation the average ultraterminal sprout length was significantly greater in the 25- compared with the 10-month-old animals. There was no correlation between the extent of muscle denervation and the percentage of end plates exhibiting ultraterminal sprouts. End plates with ultraterminal sprouts had larger areas and contained fewer nerve terminal branches than end plates without these sprouts. It is suggested that the limited response to partial denervation in the 25-month-old extensor digitorum longus muscles may indicate that the aged extensor digitorum longus has already approached the maximum capacity for sprouting.     

Different effects of physical training on the morphology of motor nerve terminals in the rat extensor digitorum longus and soleus muscles

Summary The morphology of nerve terminals in the rat extensor digitorum longus and soleus muscles was studied with light microscopy in 13-week-old male animals after 6 weeks of treadmill running and compared with data from untrained controls. The terminals were stained with methylene blue. Physical training tended to increase the area and length of the nerve terminals in relation to the corresponding muscle fiber diameter, and to reduce the density of nerve terminal varicosities, but significant differences between the trained group and the control group were obtained only in the extensor digitorum longus muscle. The different degrees of effect on the nerve terminals in the two muscles may be due to different abilities to respond to the training, but may also be due to differences in work load caused by the training. The effect of training on extensor digitorum longus junctions may reflect some transformation from fast to slow morphological characteristics.     

Adaptive range of myosin heavy chain expression in regenerating soleus is broader than in mature muscle

Summary In adult rat muscles experimentally exposed to various patterns of activation, expression of myosin heavy chain isoforms changes, but only within a certain adaptive range. It is characteristic and different in fast or slow muscles. This may be due either to different intrinsic properties of the myogenic cells of the two types of muscles or to extrinsic factors. To test these assumptions, either rat soleus or extensor digitorum longus muscles were injured and transplanted to the bed of the extensor digitorum longus muscle. They regenerated and were reinnervated by the extensor digitorum longus nerve. Expression of myosin heavy chain isoforms was demonstrated immunohistochemically and by in situ hybridization, and analysed by SDS-gel electrophoresis. Three months after cross-transplantation, regenerated soleus expressed all adult myosin heavy chain isoforms, including the myosin heavy chain-2B. The latter was detected in about 50% of muscle fibres and contributed about 10–20% of all myosin heavy chains. The same percentage of myosin heavy chain-2B was found in regenerated extensor digitorum longus. In this regard therefore, the adaptive range of the regenerated soleus muscle was not significantly different from that of the extensor digitorum longus regenerating under the same conditions. This indicates that restriction of the adaptive range in a mature soleus muscle is not due to intrinsic properties of its myogenic cells. It is probably imposed by an extrinsic factor leading to irreversible shut-down of individual myosin heavy chain genes. On the other hand, myosin heavy chain-1 expression was significantly greater in the regenerated soleus than in the extensor digitorum longus innervated by the same nerve. Myosin heavy chain-1 and myosin heavy chain-2B were co-expressed in some regenerated soleus muscle fibres.     

Treatment of the neuromuscular junction with 4-aminopyridine results in improved reinnervation following nerve injury in neonatal rats

During early postnatal development, nerve injury results in the death of a large proportion of motoneurones and poor recovery of muscle function. Our previous results have shown that premature enhancement of transmitter release from nerve terminals prevents the death of motoneurones following neonatal nerve injury. Whether this increase in motoneurone survival is reflected in an improvement in the reinnervation of muscle was studied here. The muscles in one hindlimb of newborn rats were treated with 4-aminopyridine. Three days later, the sciatic nerve was crushed in the treated leg. When the animals were seven, 14 and 21days of age, the soleus and extensor digitorum longus muscles were removed and processed for GAP-43 (a 43-kDa growth-associated protein) and synaptophysin immunocytochemistry. Both GAP-43 and synaptophysin were expressed in normal soleus and extensor digitorum longus muscles at seven days. Synaptophysin was still expressed at 14 days, but GAP-43 expression had declined. Following nerve injury at three days of age, there was no GAP-43 or synaptophysin immunoreactivity in nerve terminals at seven days. By 21 days, there were 17.3+/-2.1 GAP-43-positive terminals per section in the soleus and 17.7+/-1.4 in the extensor digitorum longus, with mean terminal areas of 47.5+/-3.3 and 49.8+/-2.6 microm(2), respectively. In animals in which nerve crush was preceded by 4-aminopyridine treatment, at 21 days there were 32.9+/-2.6 GAP-43-immunoreactive terminals in the soleus and 44.9+/-2.3 in the extensor digitorum longus, with a mean area of 122.7+/-6.6 microm(2) in the soleus and 136.2+/-9.7 microm(2) in the extensor digitorum longus. These results indicate that in muscles pretreated with 4-aminopyridine, prior to nerve crush at three days, there are significantly more terminals, which occupy a larger area than in untreated muscles. Thus, increasing transmitter release prior to nerve injury significantly improved the ability of axons to reinnervate muscle.     

Differential synaptic effects on physiological flexor hindlimb motoneurons from cutaneous nerve inputs in spinal cat.

1. We previously demonstrated in the spinal cat that superficial peroneal cutaneous nerve stimulation produced strong reflex contraction in tibialis anterior (TA) and semitendinosus (St) muscles but unexpectedly produced mixed effects in another physiological flexor muscle, extensor digitorum longus (EDL). The goal of the present study was to further characterize the organization of ipsilateral cutaneous reflexes by examining the postsynaptic potentials (PSPs) produced in St, TA, and EDL motoneurons by superficial peroneal and saphenous nerve stimulation in decerebrate, spinal cats. 2. In TA and St motoneurons, low-intensity cutaneous nerve stimulation that activated only large (A alpha) fibers [i.e., approximately 2-3 times threshold (T)], typically produced biphasic PSPs consisting of an initial excitatory phase and subsequent inhibitory phase (EPSP, IPSP). Increasing the stimulus intensity to activate both large (A alpha) and small (A delta) myelinated cutaneous fibers supramaximally (15-45 T) tended to enhance later excitatory components in TA and St motoneurons. 3. In EDL motoneurons, 2-3 T stimulation of the superficial peroneal nerve evoked initial inhibition (of variable magnitude) in 7/10 EDL motoneurons tested, with either excitation (n = 2) or mixed effects (n = 1) observed in the remaining EDL motoneurons. Saphenous nerve stimuli produced excitation either alone, or preceded by an inhibitory phase in EDL. Increasing the stimulus intensity enhanced later inhibitory influences from superficial peroneal and excitatory influences both from superficial peroneal and saphenous nerve inputs in EDL motoneurons. 4. Short-latency (less than 1.8 ms) EPSPs were observed in a few motoneurons in all reflex pathways examined, except for EPSPs in EDL motoneurons evoked by saphenous stimulation. IPSPs with central latencies less than 1.8 ms were also produced by both saphenous (TA, n = 1; EDL, n = 2) and superficial peroneal (EDL, n = 4) nerve stimulation. 5. The results, in comparison with other reports employing spinal and nonspinal preparations, suggest that removal of influences from higher centers reveals inhibitory circuits from the superficial peroneal and saphenous nerves to EDL motoneurons in the spinal preparation. The inhibitory inputs observed are thought to reflect the activation of "specialized" reflex pathways. Additionally, the demonstration of short-latency EPSPs and IPSPs suggest that the minimal linkage in both the excitatory and inhibitory cutaneous reflex pathways examined is disynaptic. The results are discussed in relation to previous studies on classically conditioned flexion reflex facilitation in spinal cat.     

Changes of ribosomal capacity for protein synthesis,contraction and histochemical properties of muscle after implantation of fast nerve into denervated and into self-reinnervated slow soleus muscle of the rat

The ribosomal capacity for protein synthesis in the fast extensor digitorum longus muscle of the rat is markedly higher than in the slow soleus muscle. Implantation of the "fast" peroneal nerve into the denervated or into the self-reinnervated soleus muscle results in transformation (increase) of capacity of isolated ribosomes for protein synthesis into that of the fast muscle type. The degree of transformation is higher after implantation into the self-reinnervated than into the denervated soleus muscle. A high degree of recovery of weight and tetanic tension output is recorded after the "fast" nerve implantation. The effect of transformation with respect to contraction properties is considerably more marked in the case of heteroinnervation of the denervated muscle and persists even after 5 months of heteroinnervation. Transformation of the histochemical muscle fibre pattern is also more pronounced after heteroinnervation of the denervated than self-reinnervated soleus muscle; the muscle acquires the fibre pattern of the fast extensor digitorum longus muscle. The acquisition of the reciprocal pattern of oxidative and glycolytic enzymes suggests that the activation of protein synthesis induced by the foreign "fast" nerve supply is coupled with the operation of specific RNA species.     

Postnatal development of rat motor nerve terminals

Summary The nerve terminals of neuromuscular junctions in the rat diaphragm, extensor digitorum longus muscle and soleus muscle have been studied in animals between 3 weeks and 2.5 years of age using methylene blue stain and light microscopy. Dimensions, structure and organization of the nerve terminals were shown to change during life at various rates in different muscles and postnatal periods. The area and length of the terminals increase in all three muscles until young adult age. Later these dimensions continue to increase in the extensor digitorum longus and soleus muscles. In the diaphragm only the length increases, and this occurs late in adult life. The area also increases in relation to the diameter of the corresponding muscle fiber. Adult soleus terminals are more elongated than terminals in the diaphragm and extensor digitorum longus muscle. During adult life the extension of nerve terminals in relation to muscle fiber length increases in the extensor digitorum longus and soleus muscles, but is almost unchanged in the diaphragm. The nerve terminal branches are mainly coarse and irregular in young animals, but possess varying numbers of varicosities in adult animals. The number of varicosities is high in the extensor digitorum longus muscle and low in the diaphragm. In old animals the number of varicosities tends to be reduced. With increasing age the nerve terminal branches become organized in distinct groups with increasing distance between the groups. This is prominent in the soleus.     

长伸肌瓣的解剖学基础

在30个成人下肢标本上观察了长伸肌的形态、血供和神经支配。测得肌长23.1cm。该肌由7-17支胫前动脉横向分支供应,肌下份有腓动脉穿支发出补充,动脉主要从肌的内侧入肌。腓深神经约发出2支分支分布该肌,也是从肌内侧进入肌内。根据观察结果我们认为长仲肌瓣倒置治疗小腿中下份慢性骨髓炎及开放性胫骨骨折,似为较理想的供肌。     

Anterior tarsal tunnel syndrome

Three hundred twenty patients complaining of pain and/or numbness of their feet were evaluated in our Clinical Neurophysiology Laboratory. Nerve conduction studies of deep peroneal, superficial peroneal, sural and posterior tibial nerves were studied bilaterally. Needle electromyography (EMG) of anterior tibial, long peroneal, abductor hallucis longus, extensor hallucis longus, gastrocnemius and extensor digitorum brevis muscles were examined bilaterally. Nerve conduction studies of 25 healthy volunteer subjects (16 female, 9 male, age range 36-70, mean age 52.82 +/- 8.8) with no complaint composed the control group. Fourteen of these patients (8 female, 6 male, age range 40-70, mean age 55.73 +/- 12.04) were found to have anterior tarsal tunnel syndrome (anterior TTS) bilaterally or unilaterally. In the patients with anterior TTS, the nerve conduction studies revealed deep peroneal nerve distal latency as 6.5 +/- 1.9 msec; the amplitude as 1.8 +/- 1.3 mV at the ankle level; and the conduction velocity as 41.5 +/- 5.9 m/sec in the distal segment. When these values were compared with the control group statistically, results were found highly significant (p < 0.005). Needle EMG findings in the anterior TTS group showed only in the extensor digitorum brevis muscle. Other nerves and muscles were normal. All patients with anterior TTS were performing Namaz for years, and none of them had the predisposing factor which may cause entrapment neuropathy. So, we suggest that chronic prolonged stretching of the deep peroneal nerve on the dorsum of the foot during Namaz may cause anterior TTS.     

Accessory peroneal nerves in the human

The Nervus peroneus profundus accessorius was described by Ruge (1878) in the lower mammals and for the first time identified by Bryce (1897) in man. It is an accessory terminal branch of the superficial peroneal (musculocutaneous) nerve which winds round the lateral malleolus beneath the tendons of the peronei muscles and reaches the dorsum of the foot; there it often supplies the lateral portion of the extensor digitorum brevis muscle. In further investigations this nerve has been traced in 21.2% of subjects resp. in 13.5% of legs. This nerve, however, is not the only accessory branch of the common peroneal nerve: In 14 out of 140 subjects (10%) resp. in 22 out of 280 legs (7.9%) a Nervus peroneus superficialis accessorius has been found. This nerve pierces the anterior crural intermuscular septum either in common with deep peroneal (anterior tibial) nerve or at a lower point. Then it descends in front of the septum rarely giving off muscular branches to the extensor digitorum longus and peroneus tertius muscles; in the lower half of the leg it pierces the crural fascia, passes in front of the ankle joint and becomes the medial cutaneous nerve of the dorsum of the foot. This accessory superficial peroneal nerve may be of importance in surgery of the leg and foot.     

An unique variation of the peroneus tertius muscle

Peroneus tertius (fibularis tertius) is a muscle unique to humans. It often appears to be a part of extensor digitorum longus, and might be described as its "fifth tendon". Although its insertion variation has been reported by many authors, variations of its origin points are not common. A variation of the peroneus tertius muscle was found during routine dissection of a 75-year-old male cadaver. The muscle originated from the extensor hallucis longus. The muscle belly of the extensor hallucis longus arose from the middle two-fourths of the medial surface of the fibula, medial to the extensor digitorum longus, and anterior surface of the interosseous membrane. It lay under the extensor digitorum longus, and lateral to the tibialis anterior muscle. The muscle belly of the extensor hallucis longus divided into medial and lateral parts 17 cm below its origin point. The lateral part, named as peroneus tertius, continued downward to reach the medial part of the dorsal surface of the base of the fifth metatarsal bone. The medial part ran also downward and divided into two tendons reaching the dorsal surface of the base of the distal phalanx of the great toe. This kind of variation may be important during foot or leg surgery.     

Species specific morphology of mammalian motor nerve terminals

Summary Motor nerve terminals in the diaphragm, extensor digitorum longus and soleus muscles of young and adult rat, hamster and guinea pig were studied with the light microscope after staining with methylene blue. In adult animals the nerve terminals are smaller in the diaphragm than in the two other muscles. In the rat and hamster the extensor digitorum longus and soleus terminals are of similar area, but the terminals in extensor digitorum longus are shorter. In the guinea pig the terminals are smaller and shorter in soleus than in extensor digitorum longus. The density of nerve terminal varicosities is lowest in the diaphragm in all three species. In the rat and hamster the density is higher in extensor digitorum longus than in soleus. In the guinea pig the converse is found. In all three muscles the density of varicosities is higher in the rat than in the hamster and guinea pig. The nerve terminal branches in the diaphragm are mostly organized in one group. In the rat and hamster the soleus terminal branches are more separated in groups than the extensor digitorum longus terminal branches. In the guinea pig the number of groups is almost the same in the two muscles. These muscle and species-specific differences appear already in very young animals.     

Targeting functional subtypes of spinal motoneurons and skeletal muscle fibers in vivo by intramuscular injection of adenoviral and adeno-associated viral vectors

We report that functional subtypes of spinal motoneurons and skeletal muscle fibers can be selectively transduced using replication-defective adenoviral (ADV) or adeno-associated (AAV) viral vectors. After intramuscular injection in adult rodents, ADV vectors transduced both fast-twitch and slow-twitch skeletal muscle fibers. Intramuscular injection of ADV vectors also caused transduction of spinal motoneurons and dorsal root ganglion cells. However, only neurons innervating the injected muscle were transduced, as shown by co-injection of a retrograde axonal tracer. In adult male rats it is therefore possible to transduce fast or slow spinal motoneurons and muscle fibers selectively since in these animals, the extensor digitorum longus and soleus muscles contain almost exclusively fast or slow motor units, respectively. In rats, AAV vectors transduced muscle fibers in the predominantly fast extensor digitorum longus but not in the predominantly slow soleus muscle. We did not observe any transduction of spinal motoneurons following intramuscular injection of AAV vectors. These results show that physiologically and clinically important subpopulations of cells in the neuromuscular system can be selectively transduced by viral vectors.     

Repeated stimuli for axonal growth causes motoneuron death in adult rats: the effect of botulinum toxin followed by partial denervation

Axons of motoneurons to tibialis anterior and extensor digitorum longus muscles of adult rats were induced to sprout by injecting botulinum toxin into them, by partial denervation or by a combination of the two procedures. Ten weeks later, the number of motoneurons innervating the control and operated tibialis anterior and extensor digitorum longus muscles was established by retrograde labelling with horseradish peroxidase. In the same preparations, the motoneurons were also stained with a Nissl stain (gallocyanin) to reveal motoneurons in the sciatic pool. Examination of the spinal cords from animals treated with botulinum toxin showed that the number of retrogradely labelled cells and those stained with gallocyanin in the ventral horn on the treated compared to the control side was unchanged. In rats that had their L4 spinal nerve sectioned on one side, the number of retrogradely labelled cells on the operated side was 48±3% (n=5) of that present in the control unoperated ventral horn. Thus, just over half the innervation was removed by cutting the L4 spinal nerve. Counts made from gallocyanin-stained sections showed that 94±4% (n=5) of motoneurons were present in the ventral horn on the operated side. Thus, section of the L4 spinal nerve did not lead to any death of motoneurons. In rats that had their muscles injected with botulinum toxin three weeks prior to partial denervation, the number of retrogradely labelled cells was reduced from 48±3% (n=5) to 35±4% (n=5). Moreover, only 67±5% (n=5) of motoneurons stained with gallocyanin, suggesting that a proportion of motoneurons died after this combined procedure. This result was supported by experiments in which motor unit numbers in extensor digitorum longus muscles were determined by measurements of stepwise increments of force in response to stimulation of the motor nerve with increasing stimulus intensity. In partially denervated extensor digitorum longus muscles, 16.6±0.7 (n=5) motor units could be identified, and in animals treated with botulinum toxin prior to partial denervation only 13.3±0.9 (n=3) motor units were present.Taken together, these results show that treatment with botulinum toxin followed by partial denervation causes motoneuron death in adult rats.     

Dimensions of the anterior tarsal tunnel and features of the deep peroneal nerve in relation to clinical application

Background The aim of this study was to demonstrate anatomical features of the anterior tarsal tunnel and the deep peroneal nerve and to discuss the importance of these structures for the anterior tarsal tunnel syndrome and some other surgical approaches to minimize the injury risk. Methods Lower limbs of 18 formalin fixed cadavers were examined. The limbs showed no evidence of pathology or trauma. Results The lateral length of the tunnel was 21.7 ± 4.3 mm and the medial length of the tunnel was 55.0 ± 9.0 mm. The width of the tunnel at the inferior border between the extensor hallucis longus and extensor digitorum longus tendons was 12.6 ± 2.1 mm. The location of the deep peroneal nerve bifurcation was in the anterior tarsal tunnel in 31 specimens (86.1%) and distal to the tunnel in two specimens (5.6%). In three specimens (8.3%) there was no bifurcation because of the absence of the medial terminal branch of the deep peroneal nerve. In these three specimens, the superficial peroneal nerve distributed to the adjacent sides of the great and second toes. Bifurcation above the tunnel was not observed in our specimens. There was connection between the deep peroneal nerve and the superficial peroneal nerve in 10 specimens (27.8%) in the first interdigital space. During the observations, the presence of a fibrous band over the nerve and vessel was noted in 22 specimens (61.1%). Conclusions We believe that a detailed anatomic knowledge of the anterior tarsal tunnel and the deep peroneal nerve will be of help during surgical approaches to this area and the diagnosis of the problems related to the peripheral nerves on the dorsum of the foot. This study was presented on the 4th Asian-Pacific International Congress of Anatomists (APICA 2005) in Kusadasi, Turkey on 7-10 September 2005.     

Multielectrode intrafascicular and extraneural stimulation

The relationship between nerve stimulation, pulse amplitude and isometric muscle force was measured to investigate recruitment of motor units. Force addition experiments were performed to obtain insight in the intersection of motor unit groups recruited by different electrodes. Intrafascicular and extraneural multielectrode configurations were used for nerve stimulation. Experiments were performed on rats. The common peroneal nerve was stimulated and the forces of the tibial anterior and extensor digitorum longus muscles were measured isometrically. Recruitment was more stable for intrafascicular electrodes than for extraneural electrodes. Especially for intrafascicular electrodes no strict inverse recruitment was observed. Force addition experiments indicated that small overlap of recruited motor unit groups occurred more often for intrafascicular than for extraneural electrodes.