Category Archives: Trigger points

Myofascial trigger points and innervation zone locations in upper trapezius muscles

Myofascial trigger points (MTrPs) are hyperirritable spots located in taut bands of muscle fibres. Electrophysiological studies indicate that abnormal electrical activity is detectable near MTrPs. This phenomenon has been described as endplate noise and it has been purported to be associated MTrP pathophysiology. Thus, it is suggested that MTrPs will be overlap the innervation zone (IZ). The purpose of this work was to describe the location of MTrPs and the IZ in the right upper trapezius.
We screened 71 individuals and eventually enrolled 24 subjects with neck pain and active MTrPs and 24 neck pain-free subjects with latent MTrPs. Surface electromyography (sEMG) signals were detected using an electrode matrix during isometric contraction of the upper trapezius. A physiotherapist subsequently examined the subject’s trapezius to confirm the presence of MTrPs and establish their location. IZ locations were identified by visual analysis of sEMG signals. IZ and MTrPs locations were described using an anatomical coordinate system (ACS), with the skin area covered by the matrix divided into four quadrants.
No significant difference was observed between active and latent MTrPs locations (P = 0.6). Forty-five MTrPs were in the third quadrant of the ACS, and 3 were included in second quadrant. IZs were located approximately midway between the seventh cervical vertebrae and the acromial angle in a limited area in the second and third quadrants. The mean distance between MTrP and IZ was 10.4 ± 5.8 mm.
According to the acquired results, we conclude that IZ and MTrPs are located in well-defined areas in upper trapezius muscle. Moreover, MTrPs in upper trapezius are proximally located to the IZ but not overlapped.

BMC Musculoskelet Disord. 2013 Jun 8;14:179. doi: 10.1186/1471-2474-14-179.
Myofascial trigger points and innervation zone locations in upper trapezius muscles.
Barbero M, Cescon C, Tettamanti A, Leggero V, Macmillan F, Coutts F, Gatti R.

Trigger points in head and neck-shoulder muscles

J Headache Pain. 2011 Feb;12(1):35-43. Epub 2011 Feb 27.
Referred pain from myofascial trigger points in head and neck-shoulder muscles reproduces head pain features in children with chronic tension type headache.
Fernández-de-Las-Peñas C, Fernández-Mayoralas DM, Ortega-Santiago R, Ambite-Quesada S, Palacios-Ceña D, Pareja JA.

Department of Physical Therapy, Occupational Therapy, Rehabilitation and Physical Medicine, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Avenida de Atenas s/n, 28922, Alcorcón, Madrid, Spain,

Our aim was to describe the referred pain pattern and areas from trigger points (TrPs) in head, neck, and shoulder muscles in children with chronic tension type headache (CTTH). Fifty children (14 boys, 36 girls, mean age: 8 ± 2) with CTTH and 50 age- and sex- matched children participated. Bilateral temporalis, masseter, superior oblique, upper trapezius, sternocleidomastoid, suboccipital, and levator scapula muscles were examined for TrPs by an assessor blinded to the children’s condition. TrPs were identified with palpation and considered active when local and referred pains reproduce headache pain attacks. The referred pain areas were drawn on anatomical maps, digitalized, and also measured. The total number of TrPs was significantly greater in children with CTTH as compared to healthy children (P < 0.001). Active TrPs were only present in children with CTTH (P < 0.001). Within children with CTTH, a significant positive association between the number of active TrPs and headache duration (r (s) = 0.315; P = 0.026) was observed: the greater the number of active TrPs, the longer the duration of headache attack. Significant differences in referred pain areas between groups (P < 0.001) and muscles (P < 0.001) were found: the referred pain areas were larger in CTTH children (P < 0.001), and the referred pain area elicited by suboccipital TrPs was larger than the referred pain from the remaining TrPs (P < 0.001). Significant positive correlations between some headache clinical parameters and the size of the referred pain area were found. Our results showed that the local and referred pains elicited from active TrPs in head, neck and shoulder shared similar pain pattern as spontaneous CTTH in children, supporting a relevant role of active TrPs in CTTH in children.

Trigger points and shoulder injury

Researchers of the University of Granada, Spain, conducted a research on chronic impingement syndrome. The study revealed that excessive activation of specific neck and shoulder muscles during daily life or while playing sports –as swimming– is the cause of a high number of injury and shoulder.

The pattern of the pain originated in these muscles –sometimes in regions far from the shoulder– coincides with most of the symptoms suffered by patients attending health care centers for this type of problem. 25 out of 1,000 visits to the family doctor are related to shoulder pain, and the causes of this problem are several. The chronic impingement syndrome is considered the main cause for shoulder pain and disability.

The study was designed to find the differences in the presence of trigger points (TrPs) in the shoulder muscles and to investigate the presence of mechanical hypersensitivity in patients with unilateral shoulder impingement and healthy controls. Twelve patients with strictly unilateral shoulder impingement and 10 matched controls were recruited. TrPs in the levator scapula, supraspinatus, infraspinatus, subscapularis, pectoralis major, and biceps brachii muscles were explored. TrPs were considered active if the local and referred pain reproduced the pain symptoms and the patient recognized the pain as a familiar pain. Pressure pain thresholds (PPT) were assessed over the levator scapulae, supraspinatus, infraspinatus, pectoralis major, biceps brachii, and tibialis anterior muscles. Both explorations were randomly done by an assessor blinded to the subjects’ condition.

Patients with shoulder impingement have a greater number of active and latent TrPs when compared to controls. Active TrPs in the supraspinatus (67%), infraspinatus (42%), and subscapularis (42%) muscles were the most prevalent in the patient group.
Patients showed a significant lower PPT in all muscles when compared to controls. Within the patient group a significant positive correlation between the number of TrPs and pain intensity. Active TrPs in some muscles were associated to greater pain intensity and lower PPTs when compared to those with latent TrPs in the same muscles.
Patients with shoulder impingement showed widespread pressure hypersensitivity and active TrPs in the shoulder muscles, which reproduce their clinical pain symptoms. Our results suggest both peripheral and central sensitisation mechanisms in patients with shoulder impingement syndrome.


Hidalgo-Lozano A, Fernández-de-Las-Peñas C, Alonso-Blanco C, Ge HY, Arendt-Nielsen L, Arroyo-Morales M. Muscle trigger points and pressure pain hyperalgesia in the shoulder muscles in patients with unilateral shoulder impingement: a blinded, controlled study. Experiment Brain Research 2010 Feb 26.

Capsaicin-Induced Central Sensitization Evokes Segmental Increases in Trigger Point Sensitivity in Humans

Capsaicin-Induced Central Sensitization Evokes Segmental Increases in Trigger Point Sensitivity in Humans
Srbely, J.Z., Dickey, J.P., Bent, L.R., Lee, D., Lowerison, M. 2010 Journal of Pain 11 (7), pp. 636-643 0

This study investigated whether inducing central sensitization evokes segmental increases in trigger point pressure sensitivity. We evoked central sensitization at the C5 segment and validated its presence via mechanical cutaneous sensitivity (brush allodynia) testing. Trigger point pressure sensitivity was quantified using the pain pressure threshold (PPT) value.

A 50 cm2 area of the C5 dermatome at the right lateral elbow was pretreated with 45° heat for 10 minutes. Test subjects (n = 20) then received topical capsaicin cream (0.075%; Medicis, Toronto, Canada) to the C5 dermatome, whereas control subjects (n = 20) received a topical placebo cream (Biotherm Massage, Montreal, Canada). PPT readings were recorded from the infraspinatus (C5,6) and gluteus medius (L4,5S1) trigger points at zero (pre-intervention), 10, 20, and 30 minutes after intervention; all PPT readings were normalized to pre-intervention (baseline) values. T

he difference between the PPT readings at the 2 trigger point sites represents the direct influence of segmental mechanisms on the trigger point sensitivity at the infraspinatus site (PPTseg). Test subjects demonstrated statistically significant increases in Total Allodynia scores and significant decreases in PPTseg at 10, 20, and 30 minutes after application, when compared with control subjects. These results demonstrate that increases in central sensitization evoke increases in trigger point pressure sensitivity in segmentally related muscles.

Perspective: Myofascial pain is the most common form of musculoskeletal pain. Myofascial trigger points play an important role in the clinical manifestation of myofascial pain syndrome. Elucidating the role of central sensitization in the pathophysiology of trigger points is fundamental to developing optimal strategies in the management of myofascial pain syndrome.

David G. Simons (1922 – 2010)

David G. Simons (1922 – 2010) the authority to the study of myofascial pain, and the co-author of the famous Red Book :The Trigger Point Manual, the first definitive textbook on the diagnosis and management of trigger point, passed away on Easter Monday 5 April 2010.

Dr. Simons has an early career as the United States Air Force Flight Surgeon, and was chief scientist for Project Manhigh in the 1950s and piloted the program’s second flight to a record-setting altitude of 102,400 feet above sea level. Dr Simons met Dr. Janet Travell when she lectured about trigger points and myofascial pain at the Air Force’s School of Aerospace Medicine. Simons was so intrigued by Travell’s work that he eventually retired from the Air Force in 1965 and began a long informal apprenticeship under her wing.
His research in the diagnosis and treatment of myofascial pain led him to author more than 200 publications about trigger points and chronic pain management and became an internationally recognized authority on the subject.

Travell & Simon's Myofascial Pain and Dysfunction SetIn his paper in 1996, “Clinical and Etiological Update of Myofascial Pain from Trigger Points”, he concluded that: “Myofascial TrPs are a common cause of musculoskeletal pain.”

Dr. Simons never fully retired. At the time of his death, he was living in Covington, Georgia, USA, and was a Professor at Emory University and an Adjunct Professor at the University of Saint Augustine. He was also fully engaged in the latest revision of The Trigger Point Manual.

Based From:

Myofascial Referred-Pain Data Provide Physiologic Evidence of Acupuncture Meridians

Myofascial Referred-Pain Data Provide Physiologic Evidence of Acupuncture Meridians
Dorsher, P.T. 2009 Journal of Pain 10 (7), pp. 723-731

Recently published data suggest substantial anatomic, clinical, and physiologic (referred pain to meridian) overlap of myofascial trigger points and acupuncture points, particularly in the treatment of pain disorders. This qualitative study examines whether myofascial referred-pain data from the Trigger Point Manual can provide independent physiologic evidence of acupuncture meridians. Trigger point regions were subdivided from prior, validated trigger point region-classical acupuncture point correspondence results into subsets according to the 12 acupuncture Organs of their anatomically corresponding acupuncture points (Bladder, Gallbladder, Heart, Kidney, Large Intestine, Liver, Lung, Pericardium, Small Intestine, Spleen, Stomach, and Triple Energizer). The referred-pain patterns for each subset of trigger point regions were graphically applied to a virtual human model along with the subset’s corresponding acupuncture Principal meridian. All 12 meridian distributions were compared qualitatively with the summed referred-pain distributions of their anatomically corresponding trigger point regions. For all 12 subsets of trigger point regions, their summed referred-pain patterns accurately predicted the distributions of their corresponding acupuncture meridians, particularly in the extremities. The myofascial referred-pain data from the Trigger Point Manual provides independent physiologic evidence of acupuncture meridians. Understanding these meridians may enhance treatment of both pain and non-pain conditions.

Perspective: This article demonstrates that myofascial referred-pain data provide independent physiologic evidence of acupuncture meridians. The acupuncture tradition provides pain practitioners with millennia of accumulated clinical experience treating pain (and visceral) disorders and offers the potential for novel pain treatment approaches and understanding of pain neurophysiology.

A Massage Therapist’s Guide to Treating Headaches and Neck Pain

The massage therapist’s guide to treating headaches and neck pain is a practical guide for the massage therapist to assist them in identifying appropriate massage treatment for those experiencing headaches and neck pain. Available from:

The book describes the most common headache types and causes for neck pain that can be effectively addressed with therapeutic massage and associated methods easily incorporated into massage. Assessment procedures are provided both to identify appropriate treatment and to alert the massage therapist to more serious conditions that could be responsible for the symptoms and require a referral for further diagnosis and treatment. Protocols for treatment using massage and other soft tissue methods are provided. The text is written in a practical way that is user friendly.

Incorporates a DVD demonstrating the palpation and treatment methods.

224 pages 183 ills, plus DVD-ROM. Available from:

Central modulation of pain evoked from myofascial trigger point.

OBJECTIVES: Low-intensity low-frequency electrostimulation delivered within a myofascial trigger point (MTP) has been used as intervention to deactivate MTPs. The therapeutic effect has been suggested to be due to peripheral mechanisms. However, nonpainful stimuli are also known to reduce simultaneous pain through central effects. The primary objective of the present study was to assess if central pain modulation occurs after intervention with low-intensity electrostimulation within an MTP. We hypothesized that intervention induces pain inhibition via the periaqueductal gray (PAG).

METHODS: Twenty-four patients with myofascial pain syndrome participated in the study. During functional magnetic resonance scanning, painful (high-intensity) intramuscular electrostimulation was delivered at random intervals (mean interstimulus interval=10.2 s) within an MTP of the upper left trapezius muscle. In-between scanning sessions, intervention (intramuscular electrostimulation, low-intensity, interstimulus interval=0.5 s) was applied to the same area. Patients were divided into responders and nonresponders according to their change in pressure pain thresholds relative to intervention. In addition to a whole brain search, a region of interest approach was also implemented to test the effect of intervention on PAG signal change.

RESULTS: The main findings were:
(1) intervention modulated PAG activity to painful stimuli more in responders than in nonresponders,
(2) change in PAG activity from the whole patient population correlated with change in pressure pain threshold, and
(3) a network known to regulate affective qualities of the pain experience was (subsignificantly) engaged more in responders than in nonresponders.

DISCUSSION: The applied intervention most likely involves supraspinal pain control mechanisms related to both antinociception and regulation of pain affect.

The Clinical Journal of Pain: June 2007 – Volume 23 – Issue 5 – pp 440-448
Niddam, David M. PhD; Chan, Rai-Chi MD; Lee, Si-Huei MD; Yeh, Tzu-Chen MD, PhD; Hsieh, Jen-Chuen MD, PhD

Excessive yawning induced by stimulation of myofascial trigger point

Excessive yawning induced by stimulation of myofascial trigger point – case report
C.-C. Chang and S.-T. Chang
Department of Physical Medicine and Rehabilitation, Tri-Service General Hospital, School of Medicine, National Defense Medical Center, Taipei, Taiwan

We describe a 44-year-old female patient with unusually severe muscle tightness in upper trapezius, levator scapulae, scalenes and the suboccipital extensors pain, which are ascribable to subcutaneous posterior cervical and thoracic trigger points. She was referred to our department for further rehabilitation therapy because of the muscle pain, which was in accordance with marked hyperesthesia, but without referred (distant) pain. She had no history of hypertension, diabetes mellitus, dyslipidemia or cardiac arrhythmia. There were no specific illnesses in her family background. Results of all laboratory tests were within normal limits. A possible contribution might come from the preexisting degenerative change of cervical spine found on the plain films. Maneuver of self-myofascial release (SMR) together with stretching exercise learned from our therapist was used to improve myofascial restrictions and to restore soft-tissue extensibility. Interestingly, several days later, excessive yawning developed whenever she was performing SMR in our physiotherapy room .

Myofascial pain syndrome (MPS), a kind of non-articular musculoskeletal problem, is a painful condition associated with regional pain and muscle tenderness depicted by the presence of myofascial trigger points (MTPs) with hypersensitive nodules. The signs and symptoms associated with MPS include taut muscular bands, palpable nodules, pain are exacerbated by stress and referred pain patterns [1]. There has been no consensus to diagnose the criteria of MPS, but it is commonly agreed that pain is a significant manifestation arising from MTPs [2]. MTPs are manifested as focal muscle contracture on which pressure induces pain and twitching responses [1].
With regard to the treatment of MTPs, the therapeutic effect on the muscle contractions has been suggested to be due to stretch and relaxation of the involved deep muscle fibers possibly resolving the local ischemia postulated as underlying cause of the pain [3]. Considering another treatment, the SMR is a technique used to mitigate myofascial restrictions and restore the extensible structure of soft-tissue [4]. Niddam et al. have recently provided evidence that the intervention of MTP at least partially involves supraspinal pain control via midbrain periaquaduct gray (PAG) [5]. In addition, van der Plas et al. suggested the PAG involving in the hypotensive pathway can be activated by the electrical stimulation of hypothalamic areas [6].
The above points of view imply that the central modulation of pain evoked from MTP might be connected to excessive yawning via spinothalamic tract, PAG and hypothalamus. Regarding the relationship between excessive yawning and thermoregulation [7], excessive yawning has been noted as a symptom of abnormal thermoregulation influenced by hypothalamus [8]. However, further research should be performed to identify the possible connection between specific thermal responsiveness of ventromedial hypothalamic neurons and yawning induced by the stimulation of MTPs in addition to the nonthermal-related excessive yawning [9].

European Journal of Neurology
Volume 16, Issue 6, Pages e118-e119

Occurrence of myofascial pain in patients with possible carpal tunnel syndrome

Occurrence of myofascial pain in patients with possible carpal tunnel syndrome – A single-blinded study
Qerama, E., Kasch, H., Fuglsang-Frederiksen, A.     2008     European Journal of Pain

Background: There exits some similarity between symptoms of carpal tunnel syndrome (CTS) and myofascial pain related to trigger points (TPs) in the infraspinatus muscle.

Aim: The aim was to examine what proportion of patients referred with a clinical suspicion of CTS had myofascial pain in the infraspinatus muscles and how their occurrence was related to the outcome of nerve conduction studies (NCS). Methods: We examined the occurrence of CTS and of TPs in infraspinatus muscles in a cohort of patients suspected for CTS and referred to the Department of Clinical Neurophysiology, Aarhus University Hospital from October 2003 to February 2004. Patients underwent electrodiagnostic studies of the median and ulnar nerves. Additional tests were performed if necessary. Patients were examined for TPs by a blinded examiner immediately after NCS.

Results: We included 335 patients (202 females; 133 males, mean age 46). Two hundred one patients (60%) had abnormal NCS indicating CTS. Fifteen patients (4%) had other electrodiagnostic abnormalities. One hundred nineteen patients (36%) had normal NCS. Forty nine percent (58 out of 119) of the subjects with normal NCS had TPs in the infraspinatus muscles whereas only 26% (53 out of 201) of the patients with abnormal NCS indicating CTS had TPs. Likewise, 26% (4 out of 15) of the patients with other electrodiagnostic abnormalities had TPs.

Conclusions: Approximately one third of patients referred with a clinical suspicion of CTS had TPs in the infraspinatus muscles. This occurrence was higher in the group with normal NCS than in the group with abnormal NCS indicating CTS. When CTS is suspected clinically, physicians must be aware of TPs in the infraspinatus muscles as a possible cause of the symptoms; thus, NCS are important in these patients.