Biomechanical evaluation of neck muscles has important significance in the diagnosis and treatment for cervical spondylosis, the neck muscle strength and soft tissue stiffness test is two aspects of biomechanical testing. Isometric muscle testing operation is relatively simple, the cost is lower, which can evaluate the muscle force below grade 3. However, isokinetic muscle strength testing can assess the muscle strength of joint motion in any position. It is hard to distinguish stiffness difference in different soft tissues when the load-displacement curve is used to evaluate the local soft tissue stiffness. Elasticity imaging technique can not only show the elastic differences of different tissues by images, but also quantify the elastic modulus of subcutaneous tissues and muscles respectively. Nevertheless, it is difficult to observe the flexibility of the cervical spine by means of the analysis of the whole neck stiffness. In a word, a variety of test method will conduce not only the biomechanical evaluation of neck muscles, but also making an effective biomechanics mathematical model of neck muscles. Besides, isokinetic muscle testing and the elasticity imaging technology still need further validation and optimization before they are better applied to neck muscles biomechanical testing.
Biomechanical Phenomena ; Humans ; Muscle Strength ; Neck Muscles ; physiology

OBJECTIVETo investigate the activities of head, neck and upper trunk muscles with mandibular movement in normal adults.

METHODSThe integral data of surface electromyography (EMG) had been recorded to analyze the activities of anterior temporal (Ta), posterior temporal (Tp), sternocleidomastoid (SCM) and trapezius (TRAP) muscles with mandibular movement in ten normal adults.

RESULTSThe former mentioned muscles acted constantly when the mandible was in the rest position. The activities of Ta, Tp and SCM muscles increased with protrusion of mandible, mouth opening, tapping, maximum clenching, and chewing movements. The amplitudes of the increased activity of these muscles were correlated significantly with each other. When the activities of Ta and Tp muscles increased to 56 times and 25 times respectively, the activity of SCM muscle increased to 5 - 6 times. The activity of trapezius muscle increased with protrusion of mandible and opening movement, but tended to stop with the maximum clenching and chewing movement. The correlations of left and right sides of the same muscles had been found.

CONCLUSIONSThe muscles of head, neck and upper trunk can act as contributors to keep the mandibular positions and take part in the mandibular movements.

Adult ; Electromyography ; Female ; Head Movements ; physiology ; Humans ; Male ; Mandible ; physiology ; Mastication ; physiology ; Movement ; Muscle, Skeletal ; physiology ; Neck Muscles ; physiology ; Range of Motion, Articular ; Shoulder ; physiology ; Temporomandibular Joint ; physiology

OBJECTIVETo observe the histologic changes of the cervical muscles and intervertebral discs caused by dynamic dysequilibrium of frontally cervical muscles in rabbits.

METHODSThirty healthy rabbits with an average age of two years, half males and half females, the mean of weight in (2.75 +/- 0.25) kg, were divided randomly into model group and the sham operation group with fifteen rabbits in each group. The hibateral sternocleidomastoid muscles of rabbits in the model group were shortened by medical pipe to estabish the new animal model (the model was cervical dynamic dysequilibrium); and in the sham operative group, only exposed hibateral sternocleidomastoid muscles by operation. At the same time after two months, the histologic changes of the cervical muscles and intervertebral discs in all rabbits were observed, meanwhile, the myofibrillar amount and its cross section area were compared between two groups.

RESULTSAfter operation, the cervical muscles and intervertebral discs had significant change in model group, but no obvious change in sham operative group. The myofibrillar amount of frontal cervical muscles and back cervical muscles in model group was obviously lower than that of sham operative group (P < 0.05); likewise, the myofibrillar cross section area in model group was obviously lower than that of sham operative group (P < 0.05); the frontal cervical muscles was obviously change than the back cervical muscles.

CONCLUSIONThe cervical dynamic dysequilibrium caused by crispation of frontal cervical muscles can lead to pathologic degeneration of cervical muscles and intervertebral discs. The study may provide experimental proof for early cervical spondylopathy.

Animals ; Female ; Intervertebral Disc ; pathology ; Male ; Neck Muscles ; pathology ; physiology ; Rabbits ; Spasm ; pathology ; physiopathology

Objective: To expore the correlation between neck disability, neck pain and muscle strength in cervical pondylosis of office worker, and to provide scientific basis for the prevention and treatment of cervical spondylosis. Methods: In April 2021 ,234 patients with cervical spondylotic myelopathy treated in the Subsidiary Rehabilitation Hospital of Fujian University of Traditional Chinese Medicine from April 2015 to April 2017 were selected, the correlation between Neck Disability Index (NDI) score, neck pain and muscle strength was analyzed using the Spearman rank correlation method. Mann-Whitney U test was used to compare the difference of maximum muscle strength of isometric contraction. Results: NDI score was negatively correlated with neck flexion, extension, and muscle strength in the left and right flexion directions (r(s)=-0.164, -0.169, -0.222, -0.176, P=0.012, 0.010, 0.001 , 0.007). In mild and moderate functional disorder patients, the muscle strength in flexion, extension and left and right flexion direction was greater, the difference was statistically significant (P <0.01). Conclusion: There is a negative correlation between cervical functional disorder and cervical muscle strength in office workers, suggesting that strengthening cervical muscle strength may be a way to improve cervical spine function.
Cervical Vertebrae ; Humans ; Muscle Strength/physiology* ; Neck Muscles/physiology* ; Neck Pain/physiopathology* ; Occupational Diseases/physiopathology* ; Range of Motion, Articular/physiology* ; Spondylosis/physiopathology*

BACKGROUNDWork-related musculoskeletal disorders (WMSDs) have high prevalence in sewing machine operators employed in the garment industry. Long work duration, sustained low level work and precise hand work are the main risk factors of neck-shoulder disorders for sewing machine operators. Surface electromyogram (sEMG) offers a valuable tool to determine muscle activity (internal exposure) and quantify muscular load (external exposure). During sustained and/or repetitive muscle contractions, typical changes of muscle fatigue in sEMG, as an increase in amplitude or a decrease as a shift in spectrum towards lower frequencies, can be observed. In this paper, we measured and quantified the muscle load and muscular activity patterns of neck-shoulder muscles in female sewing machine operators during sustained sewing machine operating tasks using sEMG.

METHODSA total of 18 healthy women sewing machine operators volunteered to participate in this study. Before their daily sewing machine operating task, we measured the maximal voluntary contractions (MVC) and 20%MVC of bilateral cervical erector spinae (CES) and upper trapezius (UT) respectively, then the sEMG signals of bilateral UT and CES were monitored and recorded continuously during 200 minutes of sustained sewing machine operating simultaneously which equals to 20 time windows with 10 minutes as one time window. After 200 minutes' work, we retest 20%MVC of four neck-shoulder muscles and recorded the sEMG signals. Linear analysis, including amplitude probability distribution frequency (APDF), amplitude analysis parameters such as roof mean square (RMS) and spectrum analysis parameter as median frequency (MF), were used to calculate and indicate muscle load and muscular activity of bilateral CES and UT.

RESULTSDuring 200 minutes of sewing machine operating, the median load for the left cervical erector spinae (LCES), right cervical erector spinae (RCES), left upper trapezius (LUT) and right upper trapezius (RUT) were 6.78%MVE, 6.94%MVE, 6.47%MVE and 5.68%MVE, respectively. Work load of right muscles are significantly higher than that of the left muscles (P < 0.05); sEMG signal analysis of isometric contractions indicated that the amplitude value before operating was significantly higher than that of after work (P < 0.01), and the spectrum value of bilateral CES and UT were significantly lower than those of after work (P < 0.01); according to the sEMG signal data of 20 time windows, with operating time pass by, the muscle activity patterns of bilateral CES and UT showed dynamic changes, the maximal amplitude of LCES, RCES, LUT occurred at the 20th time window, RUT at 16th time window, spectrum analysis showed that the lower value happened at 7th, 16th, 20th time windows.

CONCLUSIONSFemale sewing machine operators were exposed to high sustained static load on bilateral neck-shoulder muscles; left neck and shoulder muscles were held in more static positions; the 7th, 16th, and 20th time windows were muscle fatigue period that ergonomics intervention can protocol at these periods.

Adult ; Electromyography ; methods ; Female ; Humans ; Muscle Fatigue ; physiology ; Muscle, Skeletal ; physiology ; Neck Muscles ; physiology ; Shoulder ; physiology ; Textile Industry ; Workload ; Young Adult

Pain in the cervical region of air force pilots, who are exposed to high G-forces, is a specifically occupational health problem. To minimize neck problems, the cervical muscles need specific strength exercise. It is important that the training for the neck must be carried out with optimal resistance in exercises. The model NSE-1 neck training machine for pilots was designed for neck strengthening exercises under safe and effective conditions. In order to realize the functions of changeable velocity and resistant (CVR) training and neck isometric contractive exercises, the techniques of adaptive hydraulics, sensor, optic and auditory biological feedback, and signal processing were applied to this machine. The training system mainly consists of mechanical parts (including the chair of flexion and extension, the chair of right and left lateral flexion, the components of hydraulics and torque transformer, etc.), and the software of signal processing and biological feedback. Eleven volunteers were selected for the experiments of neck isometric contractive exercises, three times a week for 6 weeks, where CVR training (flexion, extension, right, left lateral flexion) one time a week. The increase in relative strength of the neck (flexion, extension, left and right lateral flexion) was 70.8%, 83.7%, 78.6% and 75.2%, respectively after training. Results show that the strength of the neck can be increased safely, effectively and rapidly with NSE-1 neck training machine to perform neck training.
Aerospace Medicine ; Aircraft ; Equipment Design ; Exercise ; physiology ; Humans ; Military Personnel ; Neck Muscles ; injuries ; physiology ; Neck Pain ; etiology ; prevention & control ; Physical Education and Training ; Posture

OBJECTIVEThe aim of this study was to examine the effects of deep branches of cervical plexus on trapezius muscle.

METHODSThe evoked electromyography of 32 trapezius of 16 SD rats was examined in different time and results obtained were processed by statistical methods.

RESULTSAfter cutting the accessory nerves, stimulating the deep branches of cervical plexus evoked the myoelectricity, the myoelectricity results varied according to different time.

CONCLUSIONThe deep branches of cervical plexus are another important motorial supply to trapezius muscles. After cutting the accessory nerves, if the branches were undamaged, the shoulder's function would be greatly preserved.

Accessory Nerve ; physiology ; Animals ; Cervical Plexus ; physiology ; Electromyography ; Male ; Muscle, Skeletal ; anatomy & histology ; innervation ; physiology ; Neck Dissection ; adverse effects ; Neck Muscles ; anatomy & histology ; injuries ; physiology ; Rats ; Rats, Sprague-Dawley ; Shoulder ; innervation

BACKGROUND AND OBJECTIVES: The observation about the movements of laryngopharyngeal or surrounding structures is very important to understand the physiology of phonation or swallowing and to diagnose the disease. Many investigating methods were used but most of them were ineffective because those were invasive or indirect methods. Ultrasonographical examination of larynx can be applied, but the shortcomings of mechanics limits the usage of ultrasonographical study of larynx. Recently, the revolution of computer and videosystem made ultrasonographical study to be applied to the larynx. In this study, authors wanted to find out the availability of the ultrasonographical study of larynx. MATERIALS AND METHODS: 3.5 and 7.5 MHz probes were applied to anterior neck and the ultrasonographical findings were observed according to the various phonation types. RESULTS: In the axial plane, the movements of bilateral vocal folds were observed. Unilateral movement of vocal cord alone was seen in the case of unilateral vocal cord paralysis. In the parasagittal plane, the movements of whole laryngopharyngeal structures were observed simultaneously. A specific tongue shape was seen on each vowel phonation. On phonation with high pitch, hyoid bone and thyroid cartilage were elevated. And thyroid cartilage was elevated and laid upon the hyoid bone moving medially. On phonation with high pitch extremely, the hyoid bone went down. On phonation loudly, echogenicity of surrounding muscles was increased. CONCLUSION: Authors think that the ultrasonographical study can be applied to the physiologic study of phonation as well as diagnostic tools or therapeutic tools.
Deglutition ; Hyoid Bone ; Larynx* ; Mechanics ; Muscles ; Neck ; Phonation ; Physiology ; Thyroid Cartilage ; Tongue ; Ultrasonography ; Vocal Cord Paralysis ; Vocal Cords