08/11/2026
The composition of skeletal muscle is many individual fibers bundled together into a muscle spindle; this gives the skeletal muscle a striated appearance. A single muscle fiber is composed mostly of actin and myosin fibers covered by a cell membrane (sarcolemma). These fibers are the functional unit of the organ, leading to contraction and relaxation.
The cells of smooth muscle are also composed of actin and myosin fibers; however, they are arranged in sheets rather than spindles which give this type of muscle a smooth appearance. These cells are present in the walls of many organs such as the lungs, gastrointestinal tract, reproductive organs, blood vessels, and even in the skin.
A myofascial trigger point is defined as a hyperirritable locus within a taut band of skeletal muscle that is located in muscular tissue or in its associated fascia or tendon. Because of the complex nature of the myofascial trigger points and their common presence in acute and chronic muscle dysfunction, an understanding of their clinical features is necessary. According to Travell and Simons, there are seven clinical features:
•Local tenderness over the trigger point
•Referred pain, tenderness, and autonomic phenomena
•Palpable taut band associated with the trigger points
•A local twitch response of a trigger point is usually present in a palpable taut band
•Perpetuation of trigger points
•A therapeutic effect when stretching a muscle with trigger points
•Weakness and fatigability of muscles afflicted with trigger points
Smooth muscle does not develop myofascial trigger points because trigger points rely on the specific structure, innervation, and contraction mechanics of skeletal muscle.
Skeletal muscle is striated and organized into repeating units called sarcomeres that can lock into a hyper-contracted state, forming the palpable “taut bands” characteristic of trigger points. Smooth muscle cells are spindle-shaped and lack this distinct sarcomere striation and linear banding.
