Depressor Muscles Research Articles

보톡스를 이용한 외상 후 하순 비대칭 교정

Botulinum toxin type A (BTX-A) inhibits muscle contraction, which leads to reversible muscle atrophy and paralysis. Therefore, BTX-A injection can be an effective treatment of facial asymmetry that originated from the uncoordinated muscle movement. A 52-year-old patient was referred from another hospital for the correction of post-traumatic sequelae. The patient had prominent scar in the mandibular symphysis area with asymmetric lower lip movement. The reason for this asymmetric lower lip movement was due to damage in the lower lip depressor muscle. After the injection of BTX-A on the lower lip depressors, asymmetric lip movement has been improved.

Bilateral flight muscle activity predicts wing kinematics and 3-dimensional body orientation of locusts responding to looming objects

We placed locusts in a wind tunnel using a loose tether design that allowed for motion in all three rotational degrees of freedom during presentation of a computer-generated looming disc. High-speed video allowed us to extract wing kinematics, abdomen position and 3-dimensional body orientation. Concurrent electromyographic (EMG) recordings monitored bilateral activity from the first basalar depressor muscles (m97) of the forewings, which are implicated in flight steering. Behavioural responses to a looming disc included cessation of flight (wings folded over the body), glides and active steering during sustained flight in addition to a decrease and increase in wingbeat frequency prior to and during, respectively, an evasive turn. Active steering involved shifts in bilateral m97 timing, wing asymmetries and whole-body rotations in the yaw (ψ), pitch (χ) and roll (η) planes. Changes in abdomen position and hindwing asymmetries occurred after turns were initiated. Forewing asymmetry and changes in η were most highly correlated with m97 spike latency. Correlations also increased as the disc approached, peaking prior to collision. On the inside of a turn, m97 spikes occurred earlier relative to forewing stroke reversal and bilateral timing corresponded to forewing asymmetry as well as changes in whole-body rotation. Double spikes in each m97 occurred most frequently at or immediately prior to the time the locusts turned, suggesting a behavioural significance. These data provide information on mechanisms underlying 3-dimensional flight manoeuvres and will be used to drive a closed loop flight simulator to study responses of motion-sensitive visual neurons during production of realistic behaviours.

The role of ventral and preventral organs as attachment sites for segmental limb muscles in Onychophora

BackgroundThe so-called ventral organs are amongst the most enigmatic structures in Onychophora (velvet worms). They were described as segmental, ectodermal thickenings in the onychophoran embryo, but the same term has also been applied to mid-ventral, cuticular structures in adults, although the relationship between the embryonic and adult ventral organs is controversial. In the embryo, these structures have been regarded as anlagen of segmental ganglia, but recent studies suggest that they are not associated with neural development. Hence, their function remains obscure. Moreover, their relationship to the anteriorly located preventral organs, described from several onychophoran species, is also unclear. To clarify these issues, we studied the anatomy and development of the ventral and preventral organs in several species of Onychophora.ResultsOur anatomical data, based on histology, and light, confocal and scanning electron microscopy in five species of Peripatidae and three species of Peripatopsidae, revealed that the ventral and preventral organs are present in all species studied. These structures are covered externally with cuticle that forms an internal, longitudinal, apodeme-like ridge. Moreover, phalloidin-rhodamine labelling for f-actin revealed that the anterior and posterior limb depressor muscles in each trunk and the slime papilla segment attach to the preventral and ventral organs, respectively. During embryonic development, the ventral and preventral organs arise as large segmental, paired ectodermal thickenings that decrease in size and are subdivided into the smaller, anterior anlagen of the preventral organs and the larger, posterior anlagen of the ventral organs, both of which persist as paired, medially-fused structures in adults. Our expression data of the genes Delta and Notch from embryos of Euperipatoides rowelli revealed that these genes are expressed in two, paired domains in each body segment, corresponding in number, position and size with the anlagen of the ventral and preventral organs.ConclusionsOur findings suggest that the ventral and preventral organs are a common feature of onychophorans that serve as attachment sites for segmental limb depressor muscles. The origin of these structures can be traced back in the embryo as latero-ventral segmental, ectodermal thickenings, previously suggested to be associated with the development of the nervous system.

An N-Myristoylated Globin with a Redox-Sensing Function That Regulates the Defecation Cycle in Caenorhabditis elegans

Globins occur in all kingdoms of life where they fulfill a wide variety of functions. In the past they used to be primarily characterized as oxygen transport/storage proteins, but since the discovery of new members of the globin family like neuroglobin and cytoglobin, more diverse and complex functions have been assigned to this heterogeneous family. Here we propose a function for a membrane-bound globin of C. elegans, GLB-26. This globin was predicted to be myristoylated at its N-terminus, a post-translational modification only recently described in the globin family. In vivo, this globin is found in the membrane of the head mesodermal cell and in the tail stomato-intestinal and anal depressor muscle cells. Since GLB-26 is almost directly oxidized when exposed to oxygen, we postulate a possible function as electron transfer protein. Phenotypical studies show that GLB-26 takes part in regulating the length of the defecation cycle in C. elegans under oxidative stress conditions.

Adjunctive techniques in facial paralysis

Facial paralysis continues to represent a challenging clinical problem without a single solution or approach. Multiple areas of cosmetic and functional deficits complicate a paralyzed face, and each requires a targeted approach for optimal rehabilitation. When prioritizing care in patients with facial paralysis, ocular protection, and oral competence remain the primary areas of concern. However, other accompanying problems, such nasal obstruction, lower lip asymmetry, and facial drooping also prominently contribute to the morbidity of patients with facial paralysis. This article addresses these commonly overlooked problems in facial paralysis and focuses on the surgical management of incompetent nasal valve, depressor muscle asymmetry, and facial ptosis.

Force encoding in stick insect legs delineates a reference frame for motor control

The regulation of forces is integral to motor control. However, it is unclear how information from sense organs that detect forces at individual muscles or joints is incorporated into a frame of reference for motor control. Campaniform sensilla are receptors that monitor forces by cuticular strains. We studied how loads and muscle forces are encoded by trochanteral campaniform sensilla in stick insects. Forces were applied to the middle leg to emulate loading and/or muscle contractions. Selective sensory ablations limited activities recorded in the main leg nerve to specific receptor groups. The trochanteral campaniform sensilla consist of four discrete groups. We found that the dorsal groups (Groups 3 and 4) encoded force increases and decreases in the plane of movement of the coxo-trochanteral joint. Group 3 receptors discharged to increases in dorsal loading and decreases in ventral load. Group 4 showed the reverse directional sensitivities. Vigorous, directional responses also occurred to contractions of the trochanteral depressor muscle and to forces applied at the muscle insertion. All sensory discharges encoded the amplitude and rate of loading or muscle force. Stimulation of the receptors produced reflex effects in the depressor motoneurons that could reverse in sign during active movements. These data, in conjunction with findings of previous studies, support a model in which the trochanteral receptors function as an array that can detect forces in all directions relative to the intrinsic plane of leg movement. The array could provide requisite information about forces and simplify the control and adaptation of posture and walking.

Electromyographic responses to emotional facial expressions in 6–7 year olds: A feasibility study

Preliminary studies have demonstrated that school-aged children (average age 9–10years) show mimicry responses to happy and angry facial expressions. The aim of the present study was to assess the feasibility of using facial electromyography (EMG) as a method to study facial mimicry responses in younger children aged 6–7years to emotional facial expressions of other children. Facial EMG activity to the presentation of dynamic emotional faces was recorded from the corrugator, zygomaticus, frontalis and depressor muscle in sixty-one healthy participants aged 6–7years. Results showed that the presentation of angry faces was associated with corrugator activation and zygomaticus relaxation, happy faces with an increase in zygomaticus and a decrease in corrugator activation, fearful faces with frontalis activation, and sad faces with a combination of corrugator and frontalis activation. This study demonstrates the feasibility of measuring facial EMG response to emotional facial expressions in 6–7year old children.

Role of wing pronation in evasive steering of locusts

Evasive steering is crucial for flying in a crowded environment such as a locust swarm. We investigated how flying locusts alter wing-flapping symmetry in response to a looming object approaching from the side. Desert locusts (Schistocerca gregaria) were tethered to a rotatable shaft that allowed them to initiate a banked turn. A visual stimulus of an expending disk on one side of the locust was used to evoke steering while recording the change in wingbeat kinematics and electromyography (EMG) of metathoracic wing depressors. Locusts responded to the looming object by rolling to the contralateral direction. During turning, EMG of hindwing depressors showed an omission of one action potential in the subalar depressor (M129) of the hindwing inside the turn. This omission was associated with increased pronation of the same wing, reducing its angle-of-attack during the downstroke. The link between spike-omission in M129 and wing pronation was verified by stimulating the hindwing depressor muscles with an artificial motor pattern that included the misfire of M129. These results suggest that hindwing pronation is instrumental in rotating the body to the side opposite of the approaching threat. Turning away from the threat would be highly adaptive for collision avoidance when flying in dense swarms.

Neural Circuit Reconfiguration by Social Status

The social rank of an animal is distinguished by its behavior relative to others in its community. Although social-status-dependent differences in behavior must arise because of differences in neural function, status-dependent differences in the underlying neural circuitry have only begun to be described. We report that dominant and subordinate crayfish differ in their behavioral orienting response to an unexpected unilateral touch, and that these differences correlate with functional differences in local neural circuits that mediate the responses. The behavioral differences correlate with simultaneously recorded differences in leg depressor muscle EMGs and with differences in the responses of depressor motor neurons recorded in reduced, in vitro preparations from the same animals. The responses of local serotonergic interneurons to unilateral stimuli displayed the same status-dependent differences as the depressor motor neurons. These results indicate that the circuits and their intrinsic serotonergic modulatory components are configured differently according to social status, and that these differences do not depend on a continuous descending signal from higher centers.

A model of the levator-depressor neuro-mechanical system of the stick insect leg

It has been established in experiments that, in the stick insect, antagonistic muscle pairs of each leg joint are associated with their own central pattern generator (CPG) which is, in essence, responsible for driving the motoneurones (MNs) that innervate the muscles of the antagonistic muscle pair [1]. This arrangement ensures large flexibility of the leg movements in these animals. It is therefore of paramount interest to study the function of the CPG-MN-muscle systems at the different joints of the leg. Modelling can be a useful integrative tool in this study and in understanding the interactions between the elements (CPG, MN and muscles) of the neuro-mechanical system in question. In this paper, we report on the results of our modelling work of the levator-depressor neuro-mechanical system. The model includes all three elements of the system: the CPG, the MNs and the levator and depressor muscles. The CPG consists of two mutually inhibitory neurones which form a relaxation oscillator [2], and which control the MN activity via inhibitory interneurones like in [3]. However, additional interneurones convey the afferent information from the campaniform sensilla (CS) to the CPG. The core of the mechanical model is the mechanical equation of motion of the femur. The muscles are modelled as nonlinear springs with variable elasticity moduli and with viscous damping parallel to the springs. Finally, the coupling between the neuronal and the muscle system is done by using a simple, linear, 1st order synapse model [4]. The synaptic activity, as it varied in time, depending on the activity of the MNs, set the actual value of the elasticity moduli of the muscles (springs). The model successfully reproduced the electrical activity of the CPG neurones and MNs, as well as the angular movement of the femur as seen during normal straightforward locomotion. In this case, the activity of the MNs was fully controlled by that of the CPG. However, additional modulation of the synaptic input to the MNs changed this picture and the angular motion of the femur could be modified to have either the depression or the levation as the dominating state, e.g. mimicking backward or curve walking. We could also simulate the experimental conditions after partial removal of the femoral CS. In this case, the original dominance of the depression was overturned, and the levator MN was continuously active because the corresponding CPG neurone showed tonic activity. However, the depressor MN and muscle could be activated in the model by stimulation of the CS. The balance between contraction of the levator and depressor muscle could again be shifted by separately modulating the synaptic input to the MNs. In conclusion, we showed that the model could successfully mimic the behaviour of its biological counterpart. The above simulations provided strong evidence for a high behavioural flexibility of the model under various peripheral (CS stimuli) or central (modulatory signals) influences. Some of these behavioural modes also hint at corresponding processes that might take place in the stick insect during locomotion in a changing environment.

Jumping mechanisms and performance of snow fleas (Mecoptera, Boreidae)

Flightless snow fleas (snow scorpion flies, Mecoptera, Boreidae) live as adults during northern hemisphere winters, often jumping and walking on the surface of snow. Their jumping mechanisms and performance were analysed with high speed imaging. Jumps were propelled by simultaneous movements of both the middle and hind pairs of legs, as judged by the 0.2 ms resolution afforded by image rates of 5000 frames s(-1). The middle legs of males represent 140% and the hindlegs 187% of the body length (3.4 mm), and the ratio of leg lengths is 1:1.3:1.7 (front:middle:hind). In preparation for a jump the middle legs and hindlegs were rotated forwards at their coxal joints with the fused mesothorax and metathorax. The first propulsive movement of a jump was the rotation of the trochantera about the coxae, powered by large depressor muscles within the thorax. The acceleration time was 6.6 ms. The fastest jump by a male had a take-off velocity of 1 m s(-1), which required 1.1 μJ of energy and a power output of 0.18 mW, and exerted a force about 16 times its body weight. Jump distances of about 100 mm were unaffected by temperature. This, and the power per mass of muscle requirement of 740 W kg(-1), suggests that a catapult mechanism is used. The elastic protein resilin was revealed in four pads at the articulation of the wing hinge with the dorsal head of the pleural ridge of each middle leg and hindleg. By contrast, fleas, which use just their hindlegs for jumping, have only two pads of resilin. This, therefore, provides a functional reference point for considerations about the phylogenetic relationships between snow fleas and true fleas.

To Determine the Influence of the Complete Denture Prosthesis on Masticatory Muscle Activity in Elderly Patients: An in vivo Study

ABSTRACT Introduction Mastication is a highly coordinated neuromuscular function involving fast effective movements of the jaw and continuous modulation of force. In older subjects these mechanisms act with marked differences. They have a reduced capacity in various functions of stomatognathic system. Objectives To evaluate the elevator and depressor muscle activity with and without complete denture prosthesis. Materials and methods For the purpose of the study 12 patients between the age of 40 and 70 years were selected. Surface electrodes from the electromyographic unit were placed in the region of right and left anterior temporal muscles, Masseter muscle and depressor muscle at the region of anterior belly of digastric and the electromyographic activity was recorded. Results and discussion The obtained values were subjected to statistical analysis. A paired t- test was performed to determine the difference between the subjects with and without denture prosthesis. Conclusion The elevator muscles showed higher activity in subjects wearing the denture prosthesis when compared to those without denture prosthesis. No significant change in muscle activity was seen on maximal opening of the depressor muscle between the subjects with and without denture prosthesis.

α-Catulin CTN-1 is required for BK channel subcellular localization in C. elegans body-wall muscle cells

The BK channel, a voltage- and Ca(2+)-gated large-conductance potassium channel with many important functions, is often localized at specific subcellular domains. Although proper subcellular localization is likely a prerequisite for the channel to perform its physiological functions, little is known about the molecular basis of localization. Here, we show that CTN-1, a homologue of mammalian α-catulin, is required for subcellular localization of SLO-1, the Caenorhabditis elegans BK channel α-subunit, in body-wall muscle cells. CTN-1 was identified in a genetic screen for mutants that suppressed a lethargic phenotype caused by expressing a gain-of-function (gf) isoform of SLO-1. In body-wall muscle cells, CTN-1 coclusters with SLO-1 at regions of dense bodies, which are Z-disk analogs of mammalian skeletal muscle. In ctn-1 loss-of-function (lf) mutants, SLO-1 was mislocalized in body-wall muscle but its transcription and protein level were unchanged. Targeted rescue of ctn-1(lf) in muscle was sufficient to reinstate the lethargic phenotype in slo-1(gf);ctn-1(lf). These results suggest that CTN-1 plays an important role in BK channel function by mediating channel subcellular localization.

Activity Patterns and Timing of Muscle Activity in the Forward Walking and Backward Walking Stick InsectCarausius morosus

Understanding how animals control locomotion in different behaviors requires understanding both the kinematics of leg movements and the neural activity underlying these movements. Stick insect leg kinematics differ in forward and backward walking. Describing leg muscle activity in these behaviors is a first step toward understanding the neuronal basis for these differences. We report here the phasing of EMG activities and latencies of first spikes relative to precise electrical measurements of middle leg tarsus touchdown and liftoff of three pairs (protractor/retractor coxae, levator/depressor trochanteris, extensor/flexor tibiae) of stick insect middle leg antagonistic muscles that play central roles in generating leg movements during forward and backward straight walking. Forward walking stance phase muscle (depressor, flexor, and retractor) activities were tightly coupled to touchdown, beginning on average 93 ms prior to and 9 and 35 ms after touchdown, respectively. Forward walking swing phase muscle (levator, extensor, and protractor) activities were less tightly coupled to liftoff, beginning on average 100, 67, and 37 ms before liftoff, respectively. In backward walking the protractor/retractor muscles reversed their phasing compared with forward walking, with the retractor being active during swing and the protractor during stance. Comparison of intact animal and reduced two- and one-middle-leg preparations during forward straight walking showed only small alterations in overall EMG activity but changes in first spike latencies in most muscles. Changing body height, most likely due to changes in leg joint loading, altered the intensity, but not the timing, of depressor muscle activity.

Radiofrequency (GFX™) Ablation for the Reduction of Glabellar Frowning

A new minimally invasive procedure is described for the reduction of glabellar frowning. Glabellar furrow relaxation or GFX (TM) utilizes bipolar radiofrequency energy targeted at peripheral motor nerve fibers to the depressor muscles of the forehead. This procedure is a useful adjunct in forehead rejuvenation when performed concomitantly with blepharoplasty or forehead lifting in a surgical setting. With proper training the procedure can be performed under local anesthesia in the office setting to produce very natural results. The relevant anatomy and technique is described here in detail because this represents new knowledge in facial plastic surgery. A cohort of patients has been studied for over 12 months demonstrating the efficacy of the relaxation that can be achieved with the procedure. The GFX procedure offers the patients and surgeons an alternative treatment to botulinum toxin A when longer lasting relaxation of the forehead depressor muscles is desired.

Neurogenic temporomandibular joint dislocation treated with botulinum toxin: report of 4 cases

Many patients suffer recurrent episodes of temporomandibular joint (TMJ) dislocation due to an excess of muscle contraction or spasticity in the depressor muscles of the jaw. The manual repositioning using the Nelaton maneuver is the first treatment. Occasionally, it may be necessary to use sedation or general anesthesia to achieve the desired muscle relaxation. In case of recurrence, surgical treatment is indicated. One nonsurgical method of treatment is the local infiltration of botulinum toxin type A. We present 4 cases of recurrent TMJ dislocation in patients suffering from conditions of neurologic origin, with considerable motor deterioration, treated with local infiltration of botulinum toxin type A. In conclusion, the injection of botulinum toxin type A is an effective method in cases of neurogenic TMJ dislocation, with low morbididty and side effects, improving patients' quality of life.

Actions of motor neurons and leg muscles in jumping by planthopper insects (hemiptera, issidae)

To understand the catapult mechanism that propels jumping in a planthopper insect, the innervation and action of key muscles were analyzed. The large trochanteral depressor muscle, M133b,c, is innervated by two motor neurons and by two dorsal unpaired median (DUM) neurons, all with axons in N3C. A smaller depressor muscle, M133a, is innervated by two neurons, one with a large-diameter cell body, a large, blind-ending dendrite, and a giant ovoid, axon measuring 50 microm by 30 microm in nerve N5A. The trochanteral levator muscles (M132) and (M131) are innervated by N4 and N3B, respectively. The actions of these muscles in a restrained jump were divisible into a three-phase pattern. First, both hind legs were moved into a cocked position by high-frequency bursts of spikes in the levator muscles lasting about 0.5 seconds. Second, and once both legs were cocked, M133b,c received a long continuous sequence of motor spikes, but the two levators spiked only sporadically. The spikes in the two motor neurons to M133b,c on one side were closely coupled to each other and to the spikes on the other side. If one hind leg was cocked then the spikes only occurred in motor neurons to that side. The final phase was the jump movement itself, which occurred when the depressor spikes ceased and which lasted 1 ms. Muscles 133b,c activated synchronously on both sides, are responsible for generating the power, and M133a and its giant neuron may play a role in triggering the release of a jump.

Energy storage and synchronisation of hind leg movements during jumping in planthopper insects (Hemiptera, Issidae)

The hind legs of Issus (Hemiptera, Issidae) move in the same plane underneath the body, an arrangement that means they must also move synchronously to power jumping. Moreover, they move so quickly that energy must be stored before a jump and then released suddenly. High speed imaging and analysis of the mechanics of the proximal joints of the hind legs show that mechanical mechanisms ensure both synchrony of movements and energy storage. The hind trochantera move first in jumping and are synchronised to within 30 micros. Synchrony is achieved by mechanical interactions between small protrusions from each trochantera which fluoresce bright blue under specific wavelengths of ultra-violet light and which touch at the midline when the legs are cocked before a jump. In dead Issus, a depression force applied to a cocked hind leg, or to the tendon of its trochanteral depressor muscle causes a simultaneous depression of both hind legs. The protrusion of the hind leg that moves first nudges the other hind leg so that both move synchronously. Contractions of the trochanteral depressor muscles that precede a jump bend the metathoracic pleural arches of the internal skeleton. Large areas of these bow-shaped structures fluoresce bright blue in ultraviolet light, and the intensity of this fluorescence depends on the pH of the bathing saline. These are key signatures of the rubber-like protein resilin. The remainder of a pleural arch consists of stiff cuticle. Bending these composite structures stores energy and their recoil powers jumping.

Anatomical Dissection and Modified Sihler Stain of the Lower Branches of the Facial Nerve

The cervical branch of the facial nerve and the muscles it supplies play a role in perioral function and neck aesthetics. Paralysis of the cervical branch in some patients may result in lip depressor deficiency and an asymmetric smile. It is unclear whether this is the result of platysmal weakness alone, or attributable to coinnervation of the lip depressor muscles by the cervical and marginal mandibular branches of the facial nerve. The purpose of this study was to provide a detailed description of the anatomy and function of the cervical branch to assist surgeons operating in the face and neck. Anatomical dissection of the marginal mandibular and cervical branches was performed in 20 hemifacial human cadaver specimens. The modified Sihler stain was used to stain the extramuscular and intramuscular nerve branches in eight specimens. The course, branching patterns, and neuromuscular relationships of the cervical and marginal mandibular branches were examined. Multiple cervical branches were identified in 85 percent of specimens, and an anastomosis with the transverse cervical cutaneous nerve was documented consistently. A communication between the marginal mandibular and cervical branches was identified in seven specimens, and coinnervation of the depressor anguli oris by intramuscular cervical branch ramifications was seen in one. A detailed description of the anatomy of the cervical branch is provided. Coinnervation of the lower lip depressors by the cervical branch remains a plausible explanation for the lower lip deformity attributed to cervical branch paralysis in some patients.

Vertical and horizontal eye movement responses to unilateral and bilateral bone conducted vibration to the mastoid

Bone-conducted vibration (BCV) delivered to the skull causes linear acceleration of the mastoids and results in small potentials (oVEMPs) from the extraocular muscles in humans. Very small eye movements to both air- and bone-conducted sound with latencies of around 9 ms and amplitudes up to 16.5 mdeg have also been reported (where mdeg = millidegrees =0.001 degree). To clarify the otolith-ocular responses we investigated the effect of unilateral and bilateral BCV (500 Hz of the mastoid) on eye movements in human subjects, and the effect of gaze position on these movements using a video-based eye-movement recording system. We found very small, short-latency eye-movement responses similar to those previously reported, but these were followed by larger (up to 0.57 degrees) prolonged responses peaking at around 120 ms post-stimulus. For unilateral stimulation the eyes moved downwards when directed away from the stimulated mastoid and upwards when directed towards stimulation. Horizontal movements were towards the stimulated mastoid with little effect of gaze position. Bilateral stimulation enhanced the downward responses, suggesting that the depressor muscles are preferentially activated by BCV. Bilateral stimulation either eliminated the horizontal response or produced convergence of the eyes: the convergence suggests that the eye-movement response is probably primarily driven by the contralateral mastoid.