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At least 379 records · Page 21Linked to original sources
PubMed2006

Effects of anterior cruciate ligament (ACL) injury on postural control and muscle activity of head, neck and trunk muscles.

The aim of the study was to evaluate the effects that an anterior cruciate ligament injury of the knee has on postural control and activity of neck, head and trunk muscles to investigate the existence of connections between the masticatory system and body posture. Surface electromyographic activity of the muscles at mandibular rest position, and during maximal voluntary clenching and posturometric and stabilometric measurements of 25 adult patients having pathology on the left knee were compared with a control non-pathological group. At rest, the patients showed a higher muscular activity of anterior temporalis, masseter, sternocleidomastoid and lower trapezius, compared with the control subjects (P < 0.05). At maximal voluntary clenching, the patients showed a lower muscular activity of the right anterior temporalis and masseter and a higher muscular activity of the lower trapezius, compared with the control subjects. For the stabilometric measurements, all the subjects showed a significant reduction in the postural centre of pressure path length during the test with eyes open and cotton rolls, compared with the test with eyes closed and mandibular rest position (P < 0.05). In addition, the patients showed a significant displacement of the postural centre of pressure in a forward direction (P < 0.05) and into the right side (P < 0.05), compared with the control subjects. Anterior cruciate ligament injury appears to be associated to a change in the activity of head, neck and trunk muscles and to a change in the position of the postural centre of pressure. Cotton rolls seem to improve the stability of the subject.

Adult↗
PubMedDate not supplied

Influence of knee pathology on body posture and muscle activity of head, neck and trunk muscles.

AIM: The aim of the study was to evaluate the effects that an anterior cruciate ligament (ACL) injury of the knee has on postural control and activity of neck, head and trunk muscles in order to investigate the existence of connections between the masticatory system and body posture. METHODS: Surface electromyographic (sEMG) activity of the muscles and their asymmetry index, at mandibular rest position, and during maximal voluntary clenching (MVC), and posturometric and stabilometric measurements of 25 patients (mean age 28+/-9 years) having undergone ACL injury of the left knee were compared with a control non-pathologic group. RESULTS: At rest, the patients showed a higher sEMG activity of the anterior temporalis, masseter, sternocleidomastoid and lower trapezius, compared with the control subjects (P<0.05). At MVC, the patients showed a lower sEMG activity of the right anterior temporalis and masseter and a higher sEMG activity of the lower trapezius, compared with the control subjects. For the stabilometric measurements, all the subjects showed a significant reduction in the Center of Pressure (CoP) path length during the test with eyes open and cotton rolls, compared with the test with eyes closed and mandibular rest position (P<0.05). In addition, the patients showed a significant displacement of the CoP in a forward direction (P<0.05) and to the righ side (P<0.05), compared with the control-subjects during each test. CONCLUSIONS: ACL injury appears to be associated to a change in the sEMG activity of head, neck and trunk muscles and to a change in the position of the CoP of the body. Cotton rolls seem to improve the stability of the subject.

Adult↗
PubMed2004

Design and implementation of a hands-free electrolarynx device controlled by neck strap muscle electromyographic activity.

The electrolarynx (EL) voice prosthesis is widely used, but suffers from the inconvenience of requiring manual control. Therefore, a hands-free EL triggered by neck muscle electromyographic (EMG) activity was developed (EMG-EL). Signal processing circuitry in a belt-mounted control unit transforms EMG activity into control signals for initiation and termination of voicing. These control signals are then fed to an EL held against the neck by an inconspicuous brace. Performance of the EMG-EL was evaluated by comparison to normal voice, manual EL voice, and tracheo-esophageal (TE) voice in a series of reaction time experiments in seven normal subjects and one laryngectomy patient. The normal subjects produced voice initiation with the EMG-EL that was as fast as both normal voice and the manual EL. The laryngectomy subject produced voice initiation that was slower than with the manual EL, but faster than with TE voice. Voice termination with the EMG-EL was slower than normal voice for the normal subjects, but not significantly different than with the manual EL. The laryngectomy subject produced voice termination with the EMG-EL that was slower than with TE or manual EL. The EMG-EL threshold was set at 10% of the range of vocal-related EMG activity above baseline. Simulations of EMG-EL behavior showed that the 10% threshold was not significantly different from the optimum threshold produced through the process of error minimization. The EMG-EL voice reaction time appears to be adequate for use in a day-to-day conversation.

Adult↗
PubMed1992

Identification and categorization of the vascular patterns to muscles of the thoracic limb, thorax, and neck of dogs.

Vascular patterns to thoracic limbs, thorax, and neck muscles were studied in 10 dogs (20 limbs) to identify muscles most suitable for transposition in the treatment of large wounds. Gross dissection of injected specimens and angiography were used to identify vascular pedicles. Size and location of pedicles were generally consistent, and any variations would not interfere with most muscle transfers. The cutaneous trunci, latissimus dorsi, sternothyroideus, sternohyoideus, deep pectoral, anconeus, ulnaris lateralis, and ulnar head of flexor carpi ulnaris muscles were identified as suitable for transfer. The cranial trapezius, caudal omotransversarius, cleidobrachialis, and caudal sternocephalicus muscles also had potential for use. Other muscles, because of inaccessibility or unfavorable vascular pattern, were not suitable candidates for transfer.

Animals↗
PubMed1993

Interaction between the muscles of the neck and the extraocular muscles of the myopic eye. An electromyographic study.

The functional relationships between the extraocular muscles of the myopic eye and the muscles of the neck were studied by means of electromyography, with the aim of demonstrating a possible alteration of the posture of the head due to abnormal tonus of the trapezius and sternocleidomastoid mm. in subjects with defective vision. The study was conducted in a group of 10 subjects with normal vision and a group of 10 myopic subjects, between the ages of 20 and 40 years. Electromyographic recordings of the relevant muscles were made during varied eye movements. Analysis of the results demonstrated a marked difference in tonic activity of the named muscles between the myopic and the normal groups. The findings suggest that, in the correction of visual defects, attention should be paid to postural adjustment of the neck by means of a series of programmed exercises directed towards the trapezius and sternocleidomastoid mm.

Adult↗
PubMed1980

Importance of microstereoencephalotomy for tremor alleviation.

Application of the microelectrode technique in human stereotactic surgery, which is especially important for tremor control, is now routine for the procedure in our surgical theater. Neurons responsible for tremor generation can very delicately and exactly be identified within the ventralis intermedius nucleus (Vim) of the thalamus, which automatically determines the location of the minimum required thermocoagulation lesion to abolish tremor. Neurons with rhythmic burst discharges, which are synchronus in phase to the peripheral tremor, are organized in delicate somatotopic fashion within the Vim. Electrical stimulation of the neuron area through this microelectrode usually inhibits tremor of the corresponding area and a small thermocoagulation lesion, usually 3 mm in diameter, permanently abolishes tremor. These three findings, i.e., existence of rhythmic bursts, effect of the stimulation and surgical lesion, are the same in parkinsonian tremor, postural tremor and intention tremor. Physiological interpretation of different types of tremor will be proposed. In the cases of idiopathic neck tremor, a single Vim neuron corresponded to four neck muscles, i.e., bilateral sternocleidomastoid muscle (SCM) and bilateral posterior neck muscles, and most markedly to the controlateral posterior neck muscle and the ipsilateral SCM. Instrumentation of microstereoencephalotomy is also explained.

Aged↗
PubMed1994

Contribution of the rib cage inspiratory muscles to breathing in baboons.

We have measured the electromyograms of the rib cage inspiratory muscles, including the neck muscles, in five lightly anesthetized baboons breathing at rest in the supine and head-up postures. When supine, the animals did not have any activity in the scalene (three heads) or sternomastoid muscles. In contrast, a phasic inspiratory electrical activity was invariably recorded from the parasternal intercostals, external intercostals, and levator costae. Measurements of the changes in length of the parasternal intercostals indicated that these muscles also shortened during inspiration, and they further showed that this inspiratory shortening was eliminated after selective muscle denervation. Similar observations were made in the head-up posture, although the inspiratory shortening of the parasternal intercostals was smaller in this posture. These observations thus indicate that: (1) the inspiratory expansion of the rib cage in baboons results entirely from the actions of the inspiratory intercostal muscles and mostly from the action of the parasternal intercostals; and (2) the load imposed on these muscles is greater in the head-up posture, presumably because of the action of gravity on the chest wall.

Animals↗
PubMed1989

Physiological properties of tandem muscle spindles in neck and hind-limb muscles.

Although tandem muscle spindle complexes are found in small but significant numbers in most muscles, experimental investigation of their properties has been problematic because of the difficulty of distinguishing their afferents from those of "normal" single spindles. Of particular interest are the afferents from b2c capsules of tandem spindles, which unlike normal spindles contain only a static b2 nuclear bag fibre and some nuclear chain fibres. The absence of a dynamic b1 nuclear bag fibre from b2c spindles has engendered much speculation as to their response properties and their possible role in motor control. We have recently developed a method for the identification of afferents from b2c spindles in electrophysiological experiments, using infusion or topical application of succinylcholine (SCh). SCh causes the contraction of the dynamic b1 and static b2 nuclear bag intrafusal fibres, and paralyses the nuclear chain fibres. Afferents from b2c spindles are characterized by a strong "biasing" of their discharge rate to about 100 impulses per second (i.p.s.) when activated by SCh (reflecting the contraction of the static b2 fibre), while primary afferents from normal b1b2c spindles show a large increase in dynamic sensitivity as well as "biasing" (reflecting the contraction of both dynamic b1 and static b2 bag fibres). Histological examination of tenuissimus spindles activated by SCh has confirmed this relationship between the pattern of activation by SCh and the number of intrafusal nuclear bag fibres in the spindle. In this paper we review the value of SCh as a means of testing spindle afferents for functional inputs from sensory terminals on the nuclear bag fibres, and discuss the properties of b2c afferents from tandem spindles in the context of their possible function.

Animals↗
PubMed2004

Botulinum toxin A in the prophylactic treatment of migraine--a randomized, double-blind, placebo-controlled study.

Botulinum toxin A has been suggested to be effective in the prophylactic treatment of migraine. However, only very few randomized, double-blind, placebo-controlled studies are available. We designed such a study with a specific focus on different injection sites. Sixty patients with a migraine according to the criteria of the International Headache Society were randomly assigned to receive either placebo in the frontal and neck muscles, or to receive 16 U botulinum toxin A in the frontal muscles and placebo in the neck muscles, or to receive in total 100 U botulinum toxin A in the frontal and neck muscles. The observation period was 3 months. In both treatment groups, 30% of patients showed a reduction of migraine frequency in month 3 by at least 50% compared with baseline, in the placebo group 25% of the patients showed such a reduction (P = 0.921). There were no significant differences between the three study groups with respect to reduction of migraine frequency, number of days with migraine, and the number of total single doses to treat a migraine attack. In the post hoc analysis, the reduction of all accompanying symptoms was significantly higher in the 16 U treatment group compared with the placebo group. In the 100 U treatment group significantly more adverse events occurred compared with the placebo group. All adverse events were mild and transient. Our study did not show any efficacy of botulinum toxin A in the prophylactic treatment of migraine. Only accompanying symptoms were significantly reduced in the 16 U but not in the 100 U treatment group. Future studies should focus on the efficacy of botulinum toxin A in specific subgroups of patients, on the efficacy of repetitive injections, and on other injection sites.

Adult↗
PubMed2006

Sports exercise effect on shortening of saccadic reaction time associated with neck extensor muscle activity.

We investigated sports exercise effect on shortening of saccadic reaction time associated with neck extensor muscle activity. Saccadic reaction time was measured in neck rest position, 20 degrees neck flexion, and 30 % muscle contraction of the shoulder girdle elevators for two groups. These groups were an untrained group that has never belonged to any sports club (UT group) and a group that has belonged to high-speed ball sports clubs (HS group). In the neck flexion and 30 % muscle contraction conditions, there was a significant shortening of the reaction time for the HS group. For the UT group, no significant shortening was found in those conditions, and the reaction time in the 30 % contraction was rather significantly longer than that in the rest position. Sports experience pursuing a high-speed ball will be effective in the shortening of the saccadic reaction time associated with the activity of neck extensors.

Adult↗
PubMed2002

Transmission through the dorsal spinocerebellar and spinoreticular tracts: wakefulness versus thiopental anesthesia.

BACKGROUND: Most of what is known regarding the actions of injectable barbiturate anesthetics on the activity of lumbar sensory neurons arises from experiments performed in acute animal preparations that are exposed to invasive surgery and neural depression caused by coadministered inhalational anesthetics. Other parameters such as cortical synchronization and motor ouflow are typically not monitored, and, therefore, anesthetic actions on multiple cellular systems have not been quantitatively compared. METHODS: The activities of antidromically identified dorsal spinocerebellar and spinoreticular tract neurons, neck motoneurons, and cortical neurons were monitored extracellularly before, during, and following recovery from the anesthetic state induced by thiopental in intact, chronically instrumented animal preparations. RESULTS: Intravenous administration of 15 mg/kg, but not 5 mg/kg, of thiopental to awake cats induced general anesthesia that was characterized by 5-10 min of cortical synchronization, reflected as large-amplitude slow-wave events and neck muscle atonia. However, even though the animal behaviorally began to reemerge from the anesthetic state after this 5-10-min period, neck muscle (neck motoneuron) activity recovered more slowly and remained significantly suppressed for up to 23 min after thiopental administration. The spontaneous activity of both dorsal spinocerebellar and spinoreticular tract neurons was maximally suppressed 5 min after administration but remained significantly attenuated for up to 17 min after injection. Peripheral nerve and glutamate-evoked responses of dorsal spinocerebellar and spinoreticular tract neurons were particularly sensitive to thiopental administration and remained suppressed for up to 20 min after injection. CONCLUSIONS: These results demonstrate that thiopental administration is associated with a prolonged blockade of motoneuron output and sensory transmission through the dorsal spinocerebellar and spinoreticular tracts that exceeds the duration of general anesthesia. Further, the blockade of glutamate-evoked neuronal responses indicates that these effects are due, in part, to a local action of the drug in the spinal cord. The authors suggest that this combination of lumbar sensory and motoneuron inhibition underlies the prolonged impairment of reflex coordination observed when thiopental is used clinically.

Afferent Pathways↗
PubMed2006

Head immobilization can impair jaw function.

Findings that jaw-opening/-closing relies on both mandibular and head movements suggest that jaw and neck muscles are jointly activated in jaw function. This study tested the hypothesis that rhythmic jaw activities involve an active repositioning of the head, and that head fixation can impair jaw function. Concomitant mandibular and head-neck movements were recorded during rhythmic jaw activities in 12 healthy adults, with and without fixation of the head. In four participants, the movement recording was combined with simultaneous registration of myoelectric activity in jaw and neck muscles. The results showed neck muscle activity during jaw opening with and without head fixation. Notably, head fixation led to reduced mandibular movements and shorter duration of jaw-opening/-closing cycles. The findings suggest recruitment of neck muscles in jaw activities, and that head fixation can impair jaw function. The results underline the jaw and neck neuromuscular relationship in jaw function.

Adult↗
PubMed1985

Characteristics of male fallow deer muscle at a time of sex-related muscle growth.

Muscle characteristics of male fallow deer undergoing neck muscle enlargement as the mating season (rut) approached were studied. Five commercially-raised males were slaughtered prerut and five were slaughtered 11 weeks later, just before the rut began. During this period, increases in individual muscle weight were not the same: two of the three neck muscles studied grew more rapidly than the average, whereas the back and two hind leg muscles grew more slowly. The splenius, the neck muscle that grew the most apparently in response to a rise in plasma testosterone, was studied. Cryosections were cut and stained for myofibrillar ATPase so that the muscle fiber classes--slow oxidative (type I), fast oxidative-glycolytic (type IIA) and fast glycolytic (type IIB)--could be distinguished. The IIB class was absent from the splenius and the occurrence of I and IIA fibers did not change during the period of splenius growth. However, the splenius of fallow deer increased in activity of NADH-tetrazolium oxidoreductase at the fiber peripheries as the rut approached. Further, fiber areas increased markedly during the period of growth, with type I fibers doubling in area and type IIA nearly trebling. Thus, the endocrinal and/or neural changes associated with the rut differentially affected these fiber types, and since type IIA fibers outnumbered type I by nearly 2 to 1, muscle enlargement is clearly dominated by the former class. Fiber areas were normally distributed for both fiber types, prerut and at the start of the rut, and coefficients of variation were similar. These results suggest that all fibers within a type are equally liable to grow during the growth period.

Acclimatization↗
PubMed1991

Effect of proprioceptor stimulation on postural stability in patients with peripheral or central vestibular lesion.

Body sway in upright stance at rest and after inducing proprioceptor stimulation, elicited by vibration applied to the calf or neck muscles, was studied in 11 patients with peripheral lesion and in 17 patients with central vestibular lesion. The responses were compared with those of 20 normal subjects. Vibratory stimulus was applied at five different frequencies, ranging from 32 to 150 Hz, and at a constant amplitude of 2.1 mm. Postural stability was measured with a force platform in terms of average deviation of body position (ADBP) analyzed in relation to the individual maximum support distance in the anterio-posterior direction. In patients with peripheral vestibular lesion ADBP was moderately increased, compared to normal subjects, when the calf muscles were exposed to vibration under eyes closed conditions (i.e. no visual information available); stimulation of neck muscles both under eyes open and eyes closed conditions and stimulation of calf muscles with open eyes produced an ADBP of the same magnitude as in controls. In patients with central vestibular lesion, proprioceptor stimulation of calf and neck muscles caused increased ADBP whether with eyes open or closed. The ADBP induced by stimulation of neck muscles was significantly greater in patients with a central lesion than in those with a peripheral vestibular lesion. The results indicate that patients with peripheral lesion differ from those with central vestibular lesion in their reaction to proprioceptor stimulus; and that in patients with central vestibular lesion proprioceptor stimulation of the neck muscles produces disproportionately powerful cervico-collic reflexes.

Brain Stem↗
PubMed2002

Glossopharyngeal and neck accessory muscle breathing in a young adult with C2 complete tetraplegia resulting in ventilator dependency.

BACKGROUND AND PURPOSE: This case report describes the use of glossopharyngeal breathing (GPB) and neck accessory muscle breathing (NAMB) in the treatment of an individual who was dependent on a ventilator secondary to a spinal cord injury. CASE DESCRIPTION: The patient was a 19-year-old man with C2 complete tetraplegia. He received a 5-week inpatient program of GPB training 3 to 4 times per week. A 4-week NAMB training program followed. OUTCOME: Following GPB training, forced vital capacity increased 35-fold, time off the ventilator improved from 0 to 30 minutes, and a nonfunctional cough became a weak functional cough. After NAMB training, the patient was able to be off the ventilator for 2 minutes. DISCUSSION: Increased ventilatory capability has the potential to affect patients' quality of life by improving cough function and decreasing dependence on a ventilator in the event of accidental disconnection.

Adult↗
PubMed2004

Impaired trunk muscle function in sub-acute neck pain: etiologic in the subsequent development of low back pain?

Low back pain (LBP) and neck pain are associated with dysfunction of the trunk and neck muscles, respectively, and may involve common or similar mechanisms. In both cases, dysfunction may compromise spinal control. Anecdotally, neck pain patients commonly develop LBP. This study investigated the possibility that trunk muscle function is compromised in neck pain patients and that compromised trunk muscle function is associated with increased risk of LBP. Fifty-four neck pain patients and 52 controls were assessed on an abdominal drawing-in task (ADIT) and on self-report tests. Performance on the ADIT was able to detect neck pain patients with 85% sensitivity and 73% specificity. Catastrophizing and McGill pain questionnaire (affective) scores were higher in patients with an abnormal task response than in patients with an uncertain or normal response, although the self-report data did not predict task performance. Fifty subjects from each group were contactable by telephone at 2 years. They were asked whether they had experienced persistent or recurrent LBP since the assessment. Subjects (patients and controls) who obtained an abnormal response on the ADIT were 3 to 6 times more likely to develop persistent or recurrent LBP than those who obtained an uncertain or normal response. ADIT performance was the main predictor of development of LBP in patients. The results suggest that reduced voluntary trunk muscle control in neck pain patients is associated with an increased risk of developing LBP.

Abdominal Muscles↗
PubMed2006

Interaction between acoustic startle and habituated neck postural responses in seated subjects.

Postural and startle responses rapidly habituate with repeated exposures to the same stimulus, and the first exposure to a seated forward acceleration elicits a startle response in the neck muscles. Our goal was to examine how the acoustic startle response is integrated with the habituated neck postural response elicited by forward accelerations of seated subjects. In experiment 1, 14 subjects underwent 11 sequential forward accelerations followed by 5 additional sled accelerations combined with a startling tone (124-dB sound pressure level) initiated 18 ms after sled acceleration onset. During the acceleration-only trials, changes consistent with habituation occurred in the root-mean-square amplitude of the neck muscles and in the peak amplitude of five head and torso kinematic variables. The subsequent addition of the startling tone restored the amplitude of the neck muscles and four of the five kinematic variables but shortened onset of muscle activity by 9-12 ms. These shortened onset times were further explored in experiment 2, wherein 16 subjects underwent 11 acceleration-only trials followed by 15 combined acceleration-tone trials with interstimulus delays of 0, 13, 18, 23, and 28 ms. Onset times shortened further for the 0- and 13-ms delays but did not lengthen for the 23- and 28-ms delays. These temporal and spatial changes in EMG can be explained by a summation of the excitatory drive converging at or before the neck muscle motoneurons. The present observations suggest that habituation to repeated sled accelerations involves extinguishing the startle response and tuning the postural response to the whole body disturbance.

Acceleration↗