This detailed manual extensively catalogs myofascial trigger points in the muscles of the lower extremities and pelvis, describing their anatomy, referred pain patterns, and clinical examination. The text provides diagnostic information and treatment approaches, including injection techniques, stretching exercises, and corrective actions for various muscle groups such as the quadratus lumborum, hamstrings, and intrinsic foot muscles. Furthermore, it addresses perpetuating factors like postural imbalances and leg length discrepancies, distinguishing myofascial pain from other conditions like nerve entrapment and fibromyalgia. The manual serves as a comprehensive guide for understanding and managing myofascial pain syndromes in the lower body.
Trigger point pain originates from myofascial trigger points (TrPs), which are hyperirritable spots within a taut band of skeletal muscle or in the muscle's fascia. These spots are painful on compression and can give rise to characteristic referred pain, tenderness, and autonomic phenomena. Myofascial trigger points are distinct from cutaneous, ligamentous, periosteal, and nonmuscular fascial trigger points.
A key characteristic of trigger point pain is that it is referred, meaning the pain arises in the trigger point but is felt at a distance, often entirely remote from its source. The pattern of referred pain is reproducibly related to its site of origin. For example:
Trigger points in the quadratus lumborum muscle can refer pain to the sacroiliac (SI) joint, lower buttock, and sometimes even to the front of the thigh.
TrPs in the gluteus minimus muscle can refer pain over the lower lateral buttock, down the lateral aspect of the thigh, knee, and leg to the ankle, mimicking sciatica.
Failure to recognize that the painful area is usually the pain reference zone, not the location of the TrP, can lead to misdiagnosis.
The sources distinguish between active and latent myofascial trigger points.
An active myofascial trigger point is symptomatic with respect to pain; it causes a pattern of referred pain at rest and/or on motion that is specific for that muscle. It is also tender, prevents full lengthening of the muscle, weakens the muscle, usually refers pain on direct compression, mediates a local twitch response, causes tenderness in the pain reference zone, and often produces specific referred autonomic phenomena.
A latent myofascial trigger point is not explicitly defined in this excerpt but is mentioned as something to be distinguished from an active one. It can be inferred that latent TrPs are not currently causing pain but have the potential to become active. Shortening activation can turn latent myofascial trigger points active due to unaccustomed sudden shortening of the muscle during stretch therapy of its antagonist, leading to increased tension and referred pain.
Trigger point pain is a central component of myofascial pain syndrome, which is characterized by pain, tenderness, and autonomic phenomena referred from active myofascial trigger points, along with associated dysfunction. This syndrome is often a significant component of somatic dysfunction.
The experience of trigger point pain can vary. It can be described as a deep ache, though TrPs in the sartorius muscle might be described as sharp or tingling. The intensity can range from a mild discomfort to intolerably persistent and excruciatingly severe, as can be the case with pain referred from gluteus minimus TrPs. Palpation of an active TrP often elicits a jump sign, which is a general involuntary pain response of the patient. It can also evoke a local twitch response of the taut muscle fibers.
Trigger points in different muscles of the lower extremities cause specific patterns of referred pain. For example:
Iliopsoas muscle TrPs refer pain in a vertical pattern along the lumbar spine, down to the sacroiliac region, and into the groin and upper anteromedial thigh.
Gluteus maximus muscle TrPs refer pain locally in the buttock region and sometimes to the sacroiliac joint and upper posterior thigh.
Tensor fasciae latae muscle TrPs refer pain and tenderness to the anterolateral thigh over the greater trochanter and down toward the knee.
Hamstring muscles TrPs refer pain to the gluteal fold and the back of the knee, sometimes extending into the calf and posterior thigh.
Tibialis anterior muscle TrPs refer pain and tenderness primarily to the anteromedial aspect of the ankle and over the dorsal and medial surfaces of the great toe.
Soleus muscle TrPs commonly refer pain and tenderness to the heel.
Understanding the concept of referred pain and being familiar with muscle anatomy and trigger point characteristics are crucial for health professionals to become proficient in identifying and treating myofascial pain. Effective management often involves inactivating the trigger points through techniques like ischemic compression, injection, and stretch, along with addressing any mechanical or systemic perpetuating factors.
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