The Anatomical And Clinical Study On Myofascial Pain Of Sternocleidomastoid Muscle

Headache is one of clinical common symptom, has many classifications and particularly complex cause of disease. Sternocleidomastoid muscle trigger point exist is headache an important factor. However, concept of the headache caused by myofascial pain, we know, is difference with cervicogenic headache. Myofascial pain does not implicate the bone structure of cervical vertebra and interverbebral disc, is only with the muscle and fascia of neck. Therefore, for patient with headache, myofascial pain of neck, especially sternocleidomastoid myofascia trigger point should be examined carefully, not neglect.Part Ⅰ and ⅡEpidemiology study of sternocleidomastoid myofascial trigger painMaterial and methodChoose 37 middle-aged and healthy people, the aged between 50 to 84 years old, average 64. And choose 35 healthy university students as the contrastive group, the age of which between 19 to 30 years old, average 23. Examining the Trigger points of the Sternocleidomastoid muscle at different age of the man and women by measurable pressure using the right thumb, and assess the pain degree by method of VAS. ResultsThe score of old men by VAS was 5.226±0.331, and the ole women's was 5.531±0.379; there was no significant differences between two groups (P>0.05); The score of young men by VASwas 2.940±0.331, and the young women s was 3.982±0.405; and there was no significant differences between two groups (P>0.05);The score of In middle age or old men by VAS was 5.358±2.309,and the young men s was 3.357±1.956; There was a significant difference between the two groups (P<0.05).The differences of the pain is significant between the groups of mastoid processus anterior region and midial region, such as between the groups of mastoid process midial region and posterior region(P<0.05); while the differences of the pain was not significant between the groups of anterior and posterior region of the Mastoid processus (P>0.05).Part fflClinical anatomic study of sternocleidomastoid muscleMaterial and methodl.The gross anatomy, such as structure of sternocleidomastoid muscle and distribution of nerves and vessels nearly were observed and measured bilaterally on 8 fresh adult's cadaveric head samples (7 male and 1 female).2.The types of muscular fiber at mastoid process were examined by immunohistochemical methods on 3 cases (bilaterally). The directions and histological characteristic of muscle fiber were observed by HE dye. Resultsl.The length of anterior edge of sternocleidomastoid muscle was 15.78 ± 1.09 mm, posterior edge was 13.39 ±1.27 mm, The total wide at origin (including head of clavicle and sternum) was 4.81 ± 0.94 mm, the wide in middle of sternocleidomastoid muscle was 2.95 ± 0.37 mm, the wide in insertion was 3.76 ± 5.2 mm. During the course to dominating their tissues, great auricular nerve penetrating out of the sternocleidomastoid muscle located at the middle point of posterior edge, then cross walking to upper-anterior on the surface.JThe confluence of posterior auricular vein and retromandibular vein forms external jugular vein located at angle mandible below mastoid process, cross walking to downwards-interior on the surface of sternocleidomastoid muscle.The depth between surface of sternocleidomastoid muscle at Mastoid process and arterial sheath was 35.52 ±6.31 mm, The distance between tip of mastoid process and posterior edge of angle mandible was 7.58 ±3.43 mm,and it was 5.48 ±1.63 mm to get posterior auricular vein, to stylomastoid foramen was 20.85±2.53 mm. Occipital artery originated from posterior wall of external carotid artery with the same point of facial artery. The course of occipital artery located at groove of occipital artery, which situated at interior surface of tip of mastoid process, arrived and supplied to occipital area.The great auricular nerve lies behind posterior external jugular Vein, the distance between them was 8.9 ±0.64 mm.2. According to immunohistochemical methods, muscular fibers ofstemocleidomastoid muscle can be divided into two types, I type was dyed shallowly and II types brown. Cross section of the fiber showed clearly about their contours, as shape of multiple-angle or semi-round, most of them distributed as mosaic structure.Part IVEvaluation and its clinical significance of the surface ECG of stemocleidomastoid muscleMaterial and methodThe isometric contraction and flexion-extension fatigue of sternocleido- mastoid muscle were examined by ME6000-T8 surface ECG (Finland) on 4 cases of normal health adults (men 3 and woman 1), the age was from 20 to 30 years. Median frequency (MF) and mean power frequency (MPF) of the subject were observed and measured on the postures of natural neutrality, flexion, extension, deep inspiration (shrugged shoulder movement), rotatory head (left and right) and flexion extremely. Surface ECG of stemocleidomastoid muscle of right side was measured in all of postures. ResultsMF and MPF were 33±2.1 and 51±4.3 respectively in posture of natural neutrality.In flexion, keeped the posture for 60s, MF and MPF were 28.5±1.5 and 58±3.1 respectively. The MF and MPF were 23±1.3 and 45.3±6.2 during the extension.Asked to shrug shoulder movement, to make a deep inspiration, the MF was 21±1.7 and MPF was 41±3.5. Rotatory posture (1) During the turning head to left side exetrmely, MF and MPF were 46±3.4 and 56±2.7 respectively. (2) During the turning head to right side exetrmely, MF and MPF were 59±2.5 and 71±4.6 respectively. Asked subject to keep the flexion extremely for 5 min, the MF and MPF in first and last one mintues were recorded and measured, they were 43 ± 4.2 and 95±4.6, 19±3.7 and 48±4.2 respectively. The unite is Hz-sec-1.Part VSetting-up and analysis of the three-dimensional finite element model of stemocleidomastoid muscleMaterial and methodThe digital cross section pictures of neck, a serial number 7800-8400 and interval 0.2 mm were received from the first of Digital Virtual Chinese Human I, which including total length of stemocleidomastoid muscle. Getting 1 of every interval 10 from the serial number to build model of stemocleidomastoid muscle according the acquired of 3D and the height of slide was 0.2mm * 10=2 mm. The manner of picture was keep for BMP. Using Ansys 8.0 soft system in our study: (1) 100N wasloaded axial on one pair of the muscle at mastoid process and the direction of pulling force was upward in order to simulating extension of head. (2) A force of 100N was loaded on mastoid level forward in one side and also at same time, a force of 100N was loaded backward in another side, to simulate head rotatory. ResultsThe 3D finite element models of sternocleidomastoid muscle at difference angles were established with the digital cross section pictures of neck and head of Digital Virtual Chinese Human I and Ansys 8.0 soft system, which including lateral and bilateral sides of sternocleidomastoid muscle. (l)When 100N was loaded axial on one pair of the muscle at mastoid process and the direction of pulling force was upward in order to simulating extension of head, the stress loaded on the muscle was fair well-distributed and acting point concentrated on the muscle at the level of mastoid process.(2)When simulating head rotatory, the results showed that high stress area and acting point concentrated on muscles at the level of mastoid process and middle-inferior belly of muscle in contrast side.Main Conclusionl.The tenderness of trigger points of sternocleidomastoid myofascia attack symptoms at the age of 20-70 yrs, and the our study suggested that there were the active trigger point and potential trigger point in sternocleidomastoid muscle. Limited tenderness pain was found when a fixed pressed on the potential trigger point of sternocleidomastoid myofascia. The potential trigger point was irritated by some pathological factors and turned into active trigger, then the referred pain and other local symptoms were happened.2.The study have discovered that there are no obviously significance difference (P>0.05) among the sex on the trigger point of sternocleidomastoid myofascia, however finding that tenderness pain on trigger point of sternocleidomastoid myofascia on female was more serious than man in clinical appratice. The causes may be women have more sensitive sense organ, and different understanding to pain, social and psychological pressure, the experience of pain as before, different emotion to pain and so on.3.The results showed that the incidence and pain degree of the muscle at level of anterior and posterior of the mastoid process were obviously serious than the mastoid process inferior. The causes that may be the fibers bundle of anterior and posterior suffered at level of mastoid press more stress and results in a unbalance of stress during movements.4.Through VAS on the ration measure to trigger points of sternocleidomastoid muscle, the study suggested that the incidence/degree of trigger points pain ofsternocleidomastoid muscle at level of mastoid process was closely relation with ages, the middle-aged and aging group's VAS tenderness grades and the degree of pain on pressure were obviously higher and serious than young people's group (p<0.001). The reasons might related to degeneration, muscle fatigue and decreasing physiological function in aging people. In addition, old people have poor sleep and different on experience to pain on pressure and emotion may be a another important reasons.5.The course of lesser occipital nerve was from under sternocleidomastoid muscle to posterior-superior direction and distributing on the skin of occipital, around auricular pinna from rear, upward and anterior.Body surface projection of great auricular nerve equivalent to the line of posterior edge middle-point of sternocleidomastoid muscle to auricular lobule root roughly, coming out of sternocleidomastoid muscle at middle-upper 1/4 of ranges of the posterior edge, passed through middle 1/3 of the places between jaw angle and mastoid process to direction of anterior-upward, then dividing into three branch behind-inferior part of auricular lobule, distributing over skin of auricular front, auricular lobule, auricular posterior and mastoid process. The branches of occipital artery distributed the subcutaneous part of occipital area passed through groove of occipital artery, which situated at interior surface of tip of mastoid process, then through deep fascia of occipital region at lateral border of obliquus capitis superior muscle. The course of internal jugular vein passed the anterior border of sternocleidomastoid muscle. The depth was 35.52±6.31mm from surface to carotid sheath. In clinical, treatment the myofascia pain at the level of mastoid process with the method of injection, the angle of needle stem with skin was 90 degrees with the depth approximately 20.00mm to insertion. The structures at level of mastoid process, such as great auricular nerve, carotid artery sheath and external jugular vein and so on can not be injured by the way of insertion. The local injection at the area of mastoid process is necessary, blind insertion should be avoided. Injecting can be done after the clinician indenting the penetrative depth safely. That was in order to avoid pricking the vein and artery, result in the medical accident.6.The result of study of histology suggested that the proportions of muscle fiber of Model II (fast muscle) and muscle fiber of Model I (slow muscle) in the sternocleidomastoid muscle was about 2:1. The Model I fibre contains higher oxidase, relatively the less ATP enzyme of enzyme, it shrinks slowly, but with lasting endurance, is suitable for doing balancing, posture keeping and fine movements; The Model II fibre includes higher ATP enzyme and lower oxidase, it is fast to shrink, but easy to be tired, suited to moving or speeding. Model II fibre participate in fast effective activity mainly, so they might become thick because of exercising and need, or become thin because of not moving, fewer move, it is easily adaptable of move than the type I. This kind of composition indicates that sternocleidomastoid muscle is suitable for intermittent load and the unsuitable lasting shrink for a long time.7.The surface electromyogram of stemocleidomastoid muscle was studied in order to determine the changes of electromyogram under different movement states of head, the results suggested that there was different about the MF/MPF of normal person's stemocleidomastoid muscle in different head postures, there was obvious dependence with the body posture (PO.05), this may be closely related with posture, structure characteristic and function of stemocleidomastoid muscle. The results also suggested that acute injuries or chronic strain of stemocleidomastoid muscle can be formed causing by some unsuitable postures.8.Finite element research on stemocleidomastoid muscle found that stress evenly distributed on pairs of side stemocleidomastoid muscle each part when flexion and extension movement of head, this situation can not cause acute injury or chronic strain of stemocleidomastoid muscle. But while rotating, the stress mainly concentrated on belly and part at the level of mastoid process of contrast side. These results conformed to clinical observation basically. Because of work demand or habit, one keep in a posture of making a rum one's head for a long time can lead to chronic damage of muscular fiber at mastoid process and belly of stemocleidomastoid muscle in contrast side. To the patients with chronic damage of stemocleidomastoid muscle, guiding them that should avoid frequently turning head and neck or keep in the posture of rotatory head for a long time, reducing excessive stress acting on pathological muscle fibre, in order to give a recovery of the damaged muscle fibre as soon as possible.