Other Types of Muscular Dystrophy
FSHD is inherited in an autosomal dominant (AD) fashion with nearly complete penetrance and variable expressivity, with mild and severe cases seen in the same family. It is due to…
Dystrophinopathies: Duchenne Muscular Dystrophy
MANIFESTING DMD/BMD CARRIER FEMALES The vast majority of DMD/BMD carriers, 76% and 81%, respectively, are usually free of symptoms. Mild calf hypertrophy may be seen. However, approximately 8% to 19%…
Dystrophinopathies: Molecular Genetic Testing
TREATMENT Goals of therapy in DMD/BMD are to maintain function, prevent contractures, and provide psychologic support. Physical therapy utilizes passive stretching exercises to prevent contractures of the iliotibial band, the…
Dystrophinopathies: Duchenne Muscular Dystrophy—Gower’s Maneuver
Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy (incidence is 1 in 3917 live male births [Norway] to 1 in 4700 [Nova Scotia]). Becker muscular dystrophy…
Overview of Myopathies: Clinical Approach
The history provides clinical clues. In most myopathies, weakness is proximal, affecting movements of the hips, thighs, shoulders, and upper arms. Typically, these patients have difficulty climbing stairs, arising from…
Muscle Fiber Types
Type I fibers are adept at utilizing the aerobic oxidative pathway for long periods of time. As shown by electron microscopy, they contain large numbers of mitochondria, which confer a…
Metabolism of Muscle Cell
CARBOHYDRATE METABOLISM Blood glucose enters the muscle fiber through a specialized muscle-specific glucose transporter. It is then phosphorylated to glucose-6-phosphate and undergoes glycolysis. Glucose-6-phosphate is also derived from degradative phosphorylation…
Muscle Response to Nerve Stimulation
Measurement of the effects of stimulation frequency is possible under similar conditions of isometric contraction. Given that there is all-or-nothing activation and contraction of fibers within a motor unit after…
Muscle Membrane, T Tubules, and Sarcoplasmic Reticulum
T tubules are specialized invaginations of the sarcolemma, with which it is continuous at multiple points. T tubules run transverse to the muscle fibers themselves and the sarcolemma and encircle…
Muscle Fiber Anatomy: Biochemical Mechanics of Contraction
Troponin molecules also run the course of the thin filament but occur as complexes bound at regular intervals. Three components comprise troponin: TnI, TnT, and TnC. TnI is an inhibitory…
