Upper Trapezius Muscle (upper + trapeziu_muscle)

Distribution by Scientific Domains

Selected Abstracts

On functional motor adaptations: from the quantification of motor strategies to the prevention of musculoskeletal disorders in the neck,shoulder region

P. Madeleine
Abstract Background:, Occupations characterized by a static low load and by repetitive actions show a high prevalence of work-related musculoskeletal disorders (WMSD) in the neck,shoulder region. Moreover, muscle fatigue and discomfort are reported to play a relevant initiating role in WMSD. Aims: To investigate relationships between altered sensory information, i.e. localized muscle fatigue, discomfort and pain and their associations to changes in motor control patterns. Materials & Methods:, In total 101 subjects participated. Questionnaires, subjective assessments of perceived exertion and pain intensity as well as surface electromyography (SEMG), mechanomyography (MMG), force and kinematics recordings were performed. Results:, Multi-channel SEMG and MMG revealed that the degree of heterogeneity of the trapezius muscle activation increased with fatigue. Further, the spatial organization of trapezius muscle activity changed in a dynamic manner during sustained contraction with acute experimental pain. A graduation of the motor changes in relation to the pain stage (acute, subchronic and chronic) and work experience were also found. The duration of the work task was shorter in presence of acute and chronic pain. Acute pain resulted in decreased activity of the painful muscle while in subchronic and chronic pain, a more static muscle activation was found. Posture and movement changed in the presence of neck,shoulder pain. Larger and smaller sizes of arm and trunk movement variability were respectively found in acute pain and subchronic/chronic pain. The size and structure of kinematics variability decreased also in the region of discomfort. Motor variability was higher in workers with high experience. Moreover, the pattern of activation of the upper trapezius muscle changed when receiving SEMG/MMG biofeedback during computer work. Discussion:, SEMG and MMG changes underlie functional mechanisms for the maintenance of force during fatiguing contraction and acute pain that may lead to the widespread pain seen in WMSD. A lack of harmonious muscle recruitment/derecruitment may play a role in pain transition. Motor behavior changed in shoulder pain conditions underlining that motor variability may play a role in the WMSD development as corroborated by the changes in kinematics variability seen with discomfort. This prognostic hypothesis was further, supported by the increased motor variability among workers with high experience. Conclusion:, Quantitative assessments of the functional motor adaptations can be a way to benchmark the pain status and help to indentify signs indicating WMSD development. Motor variability is an important characteristic in ergonomic situations. Future studies will investigate the potential benefit of inducing motor variability in occupational settings. [source]

Motor units in cranial and caudal regions of the upper trapezius muscle have different discharge rates during brief static contractions

Roberto Merletti
No abstract is available for this article. [source]

Motor units in cranial and caudal regions of the upper trapezius muscle have different discharge rates during brief static contractions

D. Falla
Abstract Aim:, To compare the discharge patterns of motor unit populations from different locations within the upper trapezius muscle during brief submaximal constant-force contractions. Methods:, Intramuscular and surface electromyographic (EMG) signals were collected from three sites of the right upper trapezius muscle distributed along the cranial-caudal direction in 11 volunteers during 10 s shoulder abduction at 25% of the maximum voluntary force. Results:, A total of 38 motor units were identified at the cranial location, 36 from the middle location and 17 from the caudal location. Initial discharge rate was greatest at the caudal location (P < 0.05; mean ± SD, cranial: 16.7 ± 3.6 pps, middle: 16.9 ± 4.0 pps, caudal: 19.2 ± 3.3 pps). Discharge rate decreased during the contraction for the most caudal location only (P < 0.05). Initial estimates of surface EMG root mean square values were highest at the most caudal location (P < 0.05; cranial: 32.3 ± 20.9 ,V, middle: 41.3 ± 21.0 ,V, caudal: 51.6 ± 23.6 ,V). Conclusion:, This study demonstrates non-uniformity of motor unit discharge within the upper trapezius muscle during a brief submaximal constant-force contraction. Location-dependent modulation of discharge rate may reflect spatial dependency in the control of motor units necessary for the development and maintenance of force output. [source]

Shoulder Disability After Different Selective Neck Dissections (Levels II,IV Versus Levels II,V): A Comparative Study

Johnny Cappiello MD
Abstract Objectives/Hypothesis: The objective was to compare the results of clinical and electrophysiological investigations of shoulder function in patients affected by head and neck carcinoma treated with concomitant surgery on the primary and the neck with different selective neck dissections. Study Design: Retrospective study of 40 patients managed at the Department of Otolaryngology, University of Brescia (Brescia, Italy) between January 1999 and December 2001. Methods: Two groups of 20 patients each matched for gender and age were selected according to the type of neck dissection received: patients in group A had selective neck dissection involving clearance of levels II,IV, and patients in group B had clearance of levels II,V. The inclusion criteria were as follows: no preoperative signs of myopathy or neuropathy, no postoperative radiotherapy, and absence of locoregional recurrence. At least 1 year after surgery, patients underwent evaluation of shoulder function by means of a questionnaire, clinical inspection, strength and motion tests, electromyography of the upper trapezius and sternocleidomastoid muscles, and electroneurography of the spinal accessory nerve. Statistical comparisons of the clinical data were obtained using the contingency tables with Fisher's Exact test. Electrophysiological data were analyzed by means of Fisher's Exact test, and electromyography results by Kruskal-Wallis test. Results: A slight strength impairment of the upper limb, slight motor deficit of the shoulder, and shoulder pain were observed in 0%, 5%, and 15% of patients in group A and in 20%, 15%, and 15% of patients in group B, respectively. On inspection, in group B, shoulder droop, shoulder protraction, and scapular flaring were present in 30%, 15%, and 5% of patients, respectively. One patient (5%) in group A showed shoulder droop as the only significant finding. In group B, muscle strength and arm movement impairment were found in 25% of patients, 25% showed limited shoulder flexion, and 50% had abnormalities of shoulder abduction with contralateral head rotation. In contrast, only one patient (5%) in group A presented slight arm abduction impairment. Electromyographic abnormalities were less frequently found in group A than in group B (40% vs. 85% [P = .003]), and the distribution of abnormalities recorded in the upper trapezius muscle and sternocleidomastoid muscle was quite different: 20% and 40% in group A versus 85% and 45% in group B, respectively. Only one case of total upper trapezius muscle denervation was observed in group B. In both groups, electroneurographic data from the side of the neck treated showed a statistically significant increase in latency (P = .001) and decrease in amplitude (P = .008) compared with the contralateral side. There was no significant difference in electroneurographic data from the side with and the side without dissection in either group. Even though a high number of abnormalities was found on electrophysiological testing, only a limited number of patients, mostly in group B, displayed shoulder function disability affecting daily activities. Conclusion: The study data confirm that clearance of the posterior triangle of the neck increases shoulder morbidity. However, subclinical nerve impairment can be observed even after selective neck dissection (levels II,IV) if the submuscular recess is routinely dissected. [source]

Myofascial Trigger Points, Neck Mobility, and Forward Head Posture in Episodic Tension-Type Headache

HEADACHE, Issue 5 2007
César Fernández-de-las-Peñas PT
Objective.,To assess the differences in the presence of trigger points (TrPs) in head and neck muscles, forward head posture (FHP) and neck mobility between episodic tension-type headache (ETTH) subjects and healthy controls. In addition, we assess the relationship between these muscle TrPs, FHP, neck mobility, and several clinical variables concerning the intensity and the temporal profile of headache. Background.,TTH is a headache in which musculoskeletal disorders of the craniocervical region might play an important role in its pathogenesis. Design.,A blinded, controlled pilot study. Methods.,Fifteen ETTH subjects and 15 matched controls without headache were studied. TrPs in both upper trapezius, both sternocleidomastoids, and both temporalis muscles were identified according to Simons and Gerwin diagnostic criteria (tenderness in a hypersensible spot within a palpable taut band, local twitch response elicited by snapping palpation, and elicited referred pain with palpation). Side-view pictures of each subject were taken in both sitting and standing positions, in order to assess FHP by measuring the craniovertebral angle. A cervical goniometer was employed to measure neck mobility. All measures were taken by a blinded assessor. A headache diary was kept for 4 weeks in order to assess headache intensity, frequency, and duration. Results.,The mean number of TrPs for each ETTH subject was 3.7 (SD: 1.3), of which 1.9 (SD: 0.9) were active, and 1.8 (SD: 0.9) were latent. Control subjects only had latent TrPs (mean: 1.5; SD: 1). TrP occurrence between the 2 groups was significantly different for active TrPs (P < .001), but not for latent TrPs (P > .05). Differences in the distribution of TrPs were significant for the right upper trapezius muscles (P= .04), the left sternocleidomastoid (P= .03), and both temporalis muscles (P < .001). Within the ETTH group, headache intensity, frequency, and duration outcomes did not differ depending on TrP activity, whether the TrP was active or latent. The craniovertebral angle was smaller, ie, there was a greater FHP, in ETTH patients than in healthy controls for both sitting and standing positions (P < .05). ETTH subjects with active TrPs in the analyzed muscles had a greater FHP than those with latent TrPs in both sitting and standing positions, though differences were only significant for certain muscles. Finally, ETTH patients also showed lesser neck mobility than healthy controls in the total range of motion as well as in half-cycles (except for cervical extension), although neck mobility did not seem to influence headache parameters. Conclusions.,Active TrPs in the upper trapezius, sternocleidomastoid, and temporalis muscles were more common in ETTH subjects than in healthy controls, although TrP activity was not related to any clinical variable concerning the intensity and the temporal profile of headache. ETTH patients showed greater FHP and lesser neck mobility than healthy controls, although both disorders were not correlated with headache parameters. [source]