Sternocleidomastoid Activity Research Articles

Effects of chin tuck exercise using neckline slimmer device on suprahyoid and sternocleidomastoid muscle activation in healthy adults.

[Purpose] This study investigated the effect of chin tuck exercise (CTE) using a neckline slimmer device on suprahyoid (SH) and sternocleidomastoid (SCM) muscle activation in healthy adults. [Subjects and Methods] We measured activation of the SH and SCM muscles using surface electromyography in 20 healthy adults during head lift exercise (HLE) and CTE using a neckline slimmer device. The order of exercises was randomized and the mean and peak values of each muscle’s activation were assessed. [Results] During the CTE using a neckline slimmer device, SH activation was significantly greater and SCM activation was significantly lower than during the HLE. [Conclusion] This study suggest that chin-tuck exercise using a neckline slimmer device may be more helpful than HLE for swallowing training.

Effect of a cervical support pillow on sternocleidomastoid activity and satisfaction in asymptomatic participants.

[Purpose] The aim of this study was to examine the changes in sternocleidomastoid muscle (SCM) activity when using a cervical support pillow (CSP) and to determine the pillow’s effect on satisfaction in asymptomatic participants. [Subjects and Methods] This study followed a cross-over design and the order of the measurements was counterbalanced. Twenty asymptomatic participants were positioned supine for 5 minutes by using either a CSP or a general pillow (GP) while the activity of the SCM was measured using surface electromyography. [Results] The CSP significantly decreased the activity of the SCM compared with the GP, and satisfaction after use of the CSP was significantly greater than that after use of the GP. [Conclusion] This study suggests that the CSP may be effective in preventing unnecessary neck muscle activation during sleep in asymptomatic people.

Effect of Different Cervical Spine Joint Mobilizations on Craniocervical Flexion Exercise: Analysis of Sternocleidomastoid Muscle Activity and Thickness and Longus Colli Muscle Thickness

Effect of Different Cervical Spine Joint Mobilizations on Craniocervical Flexion Exercise: Analysis of Sternocleidomastoid Muscle Activity and Thickness and Longus Colli Muscle Thickness

Effect of ageing on the myosin heavy chain composition of the human sternocleidomastoid muscle

The myosin heavy chain (MyHC) composition of ageing limb muscles is transformed into a slower phenotype and expresses fast-twitch fibre type atrophy, presumably due to age-related motor unit remodelling and a change in the patterns of physical activity. It is not known if ageing affects the sternocleidomastoid muscle (SCM) in a similar way. The goal of the study was to analyze the MyHC composition and the size of muscle fibres in the ageing SCM by immunohistochemical methods and quantitative analysis and stereology using our own software for morphometry. We hypothesize that with ageing the MyHC composition of SCM transforms similarly as in ageing limb muscles, but the size of the muscle fibres is less effected as in limb muscles. The study was performed on the autopsy samples of the SCM in 12 older males. The results were compared with those published in our previous study on 15 young adult males.An ageing SCM transforms into a slower MyHC profile: the percentage of slow-twitch fibres is enhanced (numerical proportion 44.6 vs. 31.5%, P<0.05; area proportion 57.2 vs. 38.4%, P<0.05). The share of hybrid 2a/2x fibres is diminished (numerical proportion 14.1 vs. 26.8%, P<0.05), the area proportion of all fast-twitch fibres expressing MyHC-2a and 2x is smaller (50.6 vs. 63.5%, P<0.05), and the area proportion of fibres expressing the fastest myosin isoform MyHC-2x is smaller too (19.0 vs. 34.5%, P<0.05).The slower phenotype with the preferential reduction of the fibres expressing the fastest MyHC-2x provide circumstantial evidence for: (i) more fast-twitch than slow-twitch motor units being lost; and (ii) reinnervation by the surviving motor units. There appears to be no significant influence on muscle fibre size, which is congruent with relatively unchanged SCM activity during life.

Mechanisms of head stability during gait initiation in young and older women: A neuro-mechanical analysis

Decreased head stability has been reported in older women during locomotor transitions such as the initiation of gait. The aim of the study was to investigate the neuro-mechanical mechanisms underpinning head stabilisation in young and older women during gait initiation. Eleven young (23.1 ± 1.1 yrs) and 12 older (73.9 ± 2.4 yrs) women initiated walking at comfortable speed while focussing on a fixed visual target at eye level. A stereophotogrammetric system was used to assess variability of angular displacement and RMS acceleration of the pelvis, trunk and head, and dynamic stability in the anteroposterior and mediolateral directions. Latency of muscle activation in the sternocleidomastoid, and upper and lower trunk muscles were determined by surface electromyography. Older displayed higher variability of head angular displacement, and a decreased ability to attenuate accelerations from trunk to head, compared to young in the anteroposterior but not mediolateral direction. Moreover, older displayed a delayed onset of sternocleidomastoid activation than young. In conclusion, the age-related decrease in head stability could be attributed to an impaired ability to attenuate accelerations from trunk to head along with delayed onset of neck muscles activation.

Mechanical perturbations can elicit triggered reactions in the absence of a startle response.

Perturbations delivered to the upper limbs elicit reflexive responses in stretched muscle at short- (M1: 25-50ms) and long- (M2: 50-100ms) latencies. When presented in a simple reaction time (RT) task, the perturbation can also elicit a preprogrammed voluntary response at a latency (< 100ms) that overlaps the M2 response. This early appearance of the voluntary response following a proprioceptive stimulus causing muscle stretch is called a triggered reaction. Recent work has demonstrated that a perturbation also elicits activity in sternocleidomastoid (SCM) over a time-course consistent with the startle response and it was, therefore, proposed that the StartReact effect underlies triggered reactions (Ravichandran et al., Exp Brain Res 230:59-69, 2013). The present work investigated whether perturbation-evoked SCM activity results from startle or postural control and whether triggered reactions can also occur in the absence of startle. In Experiment 1, participants "compensated" against a wrist extension perturbation. A prepulse inhibition (PPI) stimulus (known to attenuate startle) was randomly presented before the perturbation. Rather than attenuating SCM activity, the responses in SCM were advanced by the PPI stimulus. In Experiment 2, participants "assisted" a wrist extension perturbation. The perturbation did not reliably elicit startle but despite this, two-thirds of trials had RTs of less than 100ms and the earliest responses began at ~ 70ms. These findings suggest that SCM activity following a perturbation is the result of postural control and is not related to startle. Moreover, an overt startle response is not a prerequisite for the elicitation of a triggered reaction.

Effect of neck flexor muscle activation on impact velocity of the head during backward falls in young adults

Falls are a common cause of traumatic brain injuries (TBI) across the lifespan. A proposed but untested hypothesis is that neck muscle activation influences impact severity and risk for TBI during a fall. We conducted backward falling experiments to test whether activation of the neck flexor muscles facilitates the avoidance of head impact, and reduces impact velocity if the head contacts the ground. Young adults (n=8) fell from standing onto a 30cm thick gymnastics mat while wearing a helmet. Participants were instructed to fall backward and (a) prevent their head from impacting the mat (“no head impact” trials); (b) allow their head to impact the mat, but with minimal impact severity (“soft impact” trials); and (c) allow their head to impact the mat, while inhibiting efforts to reduce impact severity (“hard impact” trials).Trial type associated with peak magnitude of electromyographic activity of the sternocleidomastoid (SCM) muscles (p<0.017), and with the vertical and horizontal velocity of the head at impact (p<0.001). Peak SCM activations, expressed as percent maximal voluntary isometric contraction (%MVIC), averaged 75.3, 67.5, and 44.5%MVIC in “no head impact”, “soft impact”, and “hard impact” trials, respectively. When compared to “soft impact” trials, vertical impact velocities in “hard impact” trials averaged 87% greater (3.23 versus 1.73m/s) and horizontal velocities averaged 83% greater (2.74 versus 1.50m/s). For every 10% increase in SCM %MVIC, vertical impact velocity decreased 0.24m/s and horizontal velocity decreased 0.22m/s.We conclude that SCM activation contributes to the prevention and modulation of head impact severity during backward falls.

Correlation between forward head posture, respiratory functions, and respiratory accessory muscles in young adults.

Forward head posture (FHP) causes changes in the strengths and rigidities of cervical muscles. The aim of this study was to investigate correlations between FHP and respiratory functions and the muscle activities of respiratory accessory muscles in young adults in their 20s. A volunteer sample of 33 healthy young adults participated in this study. Craniovertebral angle (CVA), cranial rotational angle (CRA), vital capacity (VC), forced vital capacity (FVC), forced expiratory volume at 1 second (FEV1), peak expiratory flow (PEF), maximal voluntary ventilation (MVV), and sternocleidomastoid (SCM) and upper trapezius activity ratios were measured. Significant positive correlations were found between CVA and VC, FVC, FEV1, PEF, and MVV, and a significant negative correlation was found between CVA and SCM activity ratio. Significant negative correlations existed between CRA and VC and FVC, and significant positive correlations between CRA and SCM and upper trapezius activity ratios. FHP may act to lower respiratory functions, and thus, the maintenance of correct head posture is required to prevent such functional reductions.

An electromyographic study on the sequential recruitment of bilateral sternocleidomastoid and masseter muscle activity during gum chewing.

Mandibular functions are associated with electromyographic activity of the jaw muscles and also the sternocleidomastoid muscle (SCM). The precise spatiotemporal relation of SCM and masticatory muscles activities during chewing is worthy of investigation. To analyse the sequential recruitment of SCM and masseter activities during chewing as indicated by the spatiotemporal locations of their activity peaks. Jaw movements and bilateral surface electromyographic activity of SCM and masseter were recorded during gum chewing in 20 healthy subjects. The timing order was decided by comparing the length of time from the time when the opening started to the time when the surface electromyographic activity reached its peak value. Spatial order was analysed by locating the peak electromyographic activity onto a standard chewing cycle which was created based on 15 unilateral chewing cycles. Paired t-test, one-way ANOVA and Student-Newman-Keuls post-test were used for comparisons. Although the Time to Peak for the balancing side SCM appeared shorter than for the other three tested muscles, most often it did not reach a level of significance. However, the location of the balancing side SCM's peak activity was further from the terminal chewing position (TCP) than the working side SCM and bilateral masseters (P<0·05). The balancing side SCM activity reached its peak significantly further away from TCP than the other three tested muscles during chewing. Further studies with spatiotemporal variables included should be helpful to understand the roles of the head, neck and jaw muscles in orofacial and cervical dysfunctional problems.

Noninvasive assessment of respiratory muscle strength and activity in Myotonic dystrophy.

ObjectiveTo evaluate sensitivity/specificity of the maximum relaxation rate (MRR) of inspiratory muscles, amplitude of electromyographic activity of the sternocleidomastoid (SCM), scalene (SCA), parasternal (2ndIS) and rectus abdominis (RA) muscles; lung function and respiratory muscle strength in subjects with Myotonic dystrophy type 1 (DM1) compared with healthy subjects.Design and methodsQuasi-experimental observational study with control group. MRR of inspiratory muscles, lung function and amplitude of the electromyographic activity of SCM, SCA, 2ndIS and RA muscles during maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax) and sniff nasal inspiratory pressure (SNIP) tests were assessed in eighteen DM1 subjects and eleven healthy.ResultsMRR was lower in DM1 group compared to healthy (P = 0.001) and was considered sensitive and specific to identify disease in DM1 and discard it in controls, as well as SNIP% (P = 0.0026), PImax% (P = 0.0077) and PEmax% (P = 0.0002). Contraction time of SCM and SCA was higher in DM1 compared to controls, respectively, during PImax (P = 0.023 and P = 0.017) and SNIP (P = 0.015 and P = .0004). The DM1 group showed lower PImax (P = .0006), PEmax (P = 0.0002), SNIP (P = 0.0014), and higher electromyographic activity of the SCM (P = 0.002) and SCA (P = 0.004) at rest; of 2ndIS (P = 0.003) during PEmax and of SCM (P = 0.02) and SCA (P = 0.03) during SNIP test.ConclusionsMD1 subjects presented restrictive pattern, reduced respiratory muscle strength, muscular electrical activity and MRR when compared to higher compared to controls. In addition, the lower MRR found in MD1 subjects showed to be reliable to sensitivity and specificity in identifying the delayed relaxation of respiratory muscles.

The clinical and EMG assessment of the effects of stabilization exercise on nonspecific chronic neck pain: A randomized controlled trial.

Neck pain is an important cause of disability. In spite of its high prevalence rate, treatment of the disorder is a challenging topic. Stabilization exercise has been the topic of many studies. To compare the effects of stabilization and routine exercises on chronic neck pain. Forty patients were randomly assigned into either stabilization or routine exercise groups and undertook a 10-week training program. Electromyographic (EMG) activity was recorded from Sternocleidomastoid (SCM), Anterior Scalene (AS) and Splenius Capitis (SC) muscles bilaterally. Endurance time of deep flexor muscles was measured by chronometer.Pain and disability were measured using Visual Analogue Scale (VAS) and neck disability index (NDI) questionnaire, respectively before and after training period. Findings revealed significant decreased pain and disability in both groups after intervention (P< 0/001). Flexor muscles endurance of stabilization group was significantly increased compared with that of routine (P< 0/001). Also EMG activity of SCM, AS and SC muscles were significantly decreased in stabilization group compared with routine (P< 0/001). Increased deep flexor endurance and decreased EMG activity of SCM, AS and SC muscles suggest an important role for stabilizing exercises on reducing the activity of superficial muscles in chronic neck pain.

Neck posture during lifting and its effect on trunk muscle activation and lumbar spine posture

Neck and head posture have been found to have a significant influence on the posture of the lower spine region during lifting and both an extended/upward gaze and a flexed/downward gaze have been hypothesized to lead to increased pain and/or overuse of the neck musculature. As a result, strength training recommendations have turned to the use of a retracted neck posture as being the safer posture to assume during lifting. This study examined trunk and neck muscle activity and lumbar spine posture in seven participants while performing moderate load lifts using a retracted neck posture (chin drawn in posteriorly; recently gaining popularity among coaches, trainers, and physical therapists to reduce neck pain during lifting, and freestyle neck posture (no instructions given). The retracted neck resulted in less lumbar spine flexion and increased lumbar erector spinae, external oblique, and sternocleidomastoid activity. The retracted posture also resulted in decreased activity in the thoracic erector spinae and dorsal neck musculature. The increased trunk and sternocleidomastoid activity and decreased spine flexion observed in the seven participants of this study when lifting with a retracted neck may have the potential to help lower the risk of spine pain/injury.

Positional plagiocephaly is associated with sternocleidomastoid muscle activation in healthy term infants.

To explore the relationship between sternocleidomastoid activation and positional plagiocephaly in healthy full term infants. Participants were 82 infants from a regionally based-longitudinal study of infant development. Sternocleidomastoid (SCM) activation was assessed using active head-righting responses of body-on-head with and against gravity and head-on-body against gravity at 3, 6 and 9weeks. Plagiocephaly was assessed using the Modified Cranial Vault Asymmetry Index (mCVAI) at 9weeks. More severe plagiocephaly was associated with more severe asymmetry in active head-righting responses at all ages (p<0.001). Greater right-sided occipital flatness was related to stronger contralateral/left SCM activation at 3 and at 9weeks (p=0.008). Greater left-sided occipital flatness was related to stronger contralateral/right SCM activation at 3weeks (p=0.004). In infants with any right-sided occipital flatness, the mCVAI was greater in infants with asymmetrical gravity assisted body-on-head responses at 3weeks (mCVAI=4.31 (2.01)%, 95% CI 2.87-5.75) compared to those with symmetrical responses (mCVAI=2.64 (1.66)%, 95% CI 2.06-3.22) (p=0.011). Sternocleidomastoid activation asymmetry is a significant contributor to plagiocephaly development by 9weeks of age due to stronger contralateral SCM activation. Active head-righting responses are appropriate to assess sternocleidomastoid activation in infants under 2months of age.

Changes in neck and upper trunk muscle activities according to the angle of movement of the neck in subjects with forward head posture.

[Purpose] This study investigated changes in neck and upper trunk muscle activities according to the angle of movement of the neck in subjects with Forward Head Posture. [Subjects and Methods] Twenty subjects with forward head postures were recruited. The activities of the sternocleidomastoid muscle, splenius capitis and splenius cervicis muscles, upper trapezius muscle, and middle trapezius muscle during flexion and extension were assessed. [Results] The activity of the sternocleidomastoid muscle showed significant differences between the 30° flexed position and the full range of motion position, and between the neutral position and the full ROM position. The activity of the middle trapezius muscle showed a significant reduction in the 30° extended position and the full ROM position as compared to the neutral position. [Conclusion] In the full flexed position, sternocleidomastoid muscle activity increased significantly, and during extension position, the middle trapezius muscle reduced its activities.

Comparison of Jaw Opening Exercise and Chin Tuck Aganist Resistance Exercise of Suprahyoid, Sternocleidomastoid Muscles Activation

The aim of this study was to compare the effect of two swallowing rehabilitation exercise on suprahyoid, sternocleidomastoid muscle activity of healthy subjects. Twelve healthy subjects(mean age, 25.58±2.46) participated in our study. Subjects were performed to jaw opening exercise(JOE) and chin tuck against resistance exercise(CTARE), and repeated each five trials with isometric exercise during ten seconds. Order of two exercises was counterbalanced. During wo exercises, the activity suprahyoid and sternocleidomastoid muscle measured using surface electromyography. Paired t test was used for statistical analysis of suprahyoid, sternocleidomastoid muscle activity, and for comparison of gender measured by Mann-whitney U test. During two exercises, mean and peak of suprahyoid, mean of sternocleidomastoid revealed no significant difference(p>.05), but peak value of sternocleidomastoid during JOE showed lower activation better than CTARE(p .05). Based on results of this study, Two swallowing rehabilitation exercise may be a evidence data that can be appropriately used in the treatment of swallowing disorders.

Experimentally induced masseter-pain changes masseter but not sternocleidomastoid muscle-related activity during mastication

The aim of this study was to verify the effects of induced masseter-muscle pain on the amplitude of muscle activation, symmetry and coactivation of jaw- and neck-muscles during mastication. Twenty-eight male volunteers, mean age±SD 20.6±2.0years, participated in this study. Surface electromyography of the masseter and sternocleidomastoid (SCM) muscles was performed bilaterally during mastication of a gummy candy before and after injections of monosodium glutamate solution and isotonic saline solution. As a result, we observed a decrease in the amplitude of activation of the masseter muscle on the working side (p=0.009; d=0.34) and a reduction in the asymmetry between the working and the balancing side during mastication (p=0.007; d=0.38). No changes were observed either on the craniocervical electromyographic variables. In conclusion, experimentally induced pain reduced the masseter muscle activation on the working side, thereby reducing the physiological masseters’ recruitment asymmetry between the two sides during mastication. No effects on SCM activity were detected. These results may partly explain the initial maladaptative changes underlying TMD conditions.

Comparison of Chin Tuck Against Resistance and Shaker Exercise on Suprahyoid and Sternocleidomastoid Muscle Activity in Stroke Older Patients with Dysphagia

저항성 고개 숙이기 운동과 shaker 운동은 목뿔위근의 강화를 사용되는 중재법이다. 이전의 연구들에서는 삼킴 장애가 있는 환자들 대상으로 두 운동을 비교하지 않았다. 본 연구는 삼킴장애를 가진 뇌졸중 노인 환자에게 저항성 고개 숙이기 운동과 shaker 운동이 목뿔위근, 목빗근에 미치는 효과를 알아보고자 하였다. 10명의 삼킴 장애가 있는 뇌졸중 노인...

The Effect of Exhalation Breathing Exercise on Respiratory Synergist Muscle Activity and Pulmonary Functions in Patients with Forward Head Posture

Purpose: The aim of this study is to suggest an intervention method for clinical use in the future by analyzing the effect of breathing exercise on activity of sternocleidomastoid muscle and scalenus anterior muscle, which are respiratory synergist muscles, and pulmonary functions in patients with forward head posture. Methods: Prior to the experiment, 12 patients (experimental group) performed feedback exhalation exercise along with conventional deep neck exercise, and 11 subjects (control group) performed feedback deep neck exercise along with conventional deep neck exercise. The intervention programs were performed for 40 minutes once a day (three times a week for four weeks). Results: Before intervention, %RMS was measured for surface electromyography (sEMG), and FVC, FEV1, and FEV1/FVC were measured using a spirometer. After four weeks, these items were re-measured under the same condition and analyzed. In within-group comparison of the experimental group, activity of sternocleidomastoid muscle and scalenus anterior muscle showed a significant decrease (p<0.05) (p<0.001), and forced vital capacity (FVC) showed a significant increase (p<0.05). In within-group comparison of the control group, activity of sternocleidomastoid muscle and scalenus anterior muscle showed a significant decrease (p<0.05), and in between-group comparison, there were significant differences in activity of sternocleidomastoid muscle and FVC (p<0.05). Conclusion: Long-term forward head posture restrains exercise performance of the neck and leads to exercise avoidance of the neck during daily activities, thus restraint factors might be created even while breathing. To cut off this link, a constant effort is required and diversified research on the correlation between neck functions and breathing should be conducted.

Natural mediotrusive contact: does it affect the masticatory and neck EMG activity during tooth grinding?

Objectives: There is scarce knowledge regarding the influence of a natural mediotrusive contact on mandibular and cervical muscular activity. The purpose of this study was to analyze the EMG activity of the anterior temporalis (AT) and sternocleidomastoid (SCM) muscles during awake grinding in healthy subjects with or without a natural mediotrusive occlusal contact.Method: Fifteen subjects with natural mediotrusive occlusal contact (Group 1) and 15 subjects without natural mediotrusive occlusal contact (Group 2) participated. Bilateral surface EMG activity of AT and SCM muscles was recorded during unilateral eccentric or concentric tooth grinding tasks. EMG activity was normalized against the activity recorded during maximal voluntary clenching in intercuspal position (IP) for AT muscles and during maximal intentional isometric head-neck rotation to each side, for SCM muscles.Results: EMG activity of AT and SCM muscles showed no statistical difference between groups. EMG activity of AT muscle was higher in the working side (WS) than in the non-WS (NWS) in Group 1 during concentric grinding (0.492 vs 0.331, p = 0.047), whereas no difference was observed in Group 2. EMG activity of SCM was similar between working and NWSs in both groups and tasks. Asymmetry indexes (AIs) were not significantly different between groups.Discussion: These findings in healthy subjects support the assumption that during awake tooth grinding, central nerve control predominates over peripheral inputs, and reinforce the idea of a functional link between the motor-neuron pools that control jaw and neck muscles.

Effects of breathing type on electromyographic activity of respiratory muscles at different body positions

Aim: To compare the effect of breathing type on the activity of respiratory muscles at different body positions.Methodology: Two groups of 20 subjects each, one with upper costal and the other with costodiaphragmatic breathing, were studied. Electromyographic activity of sternocleidomastoid (SCM), diaphragm (DIA), external intercostal (EIC), and latissimus dorsi (LAT) muscles was recorded at standing and lateral decubitus positions during swallowing and maximal voluntary clenching.Results: All muscles showed higher activity during standing in upper costal breathing subjects except the SCM muscle. EIC activity was higher during standing in the costodiaphragmatic breathing group. Subjects with upper costal breathing showed higher DIA activity than subjects with costodiaphragmatic breathing at both body positions and higher SCM activity at lateral decubitus position, whereas, EIC activity was only higher during swallowing.Conclusions: Subjects with upper costal breathing presented higher respiratory effort than subjects with costodiaphragmatic breathing, being most prominent at the lateral decubitus position.