Related Experiment Video
Updated: Aug 6, 2026

10:00
Physiological Recordings of High and Low Output NMJs on the Crayfish Leg Extensor Muscle
Published on: November 17, 2010
Muscle cramps
1Division of General Internal Medicine, University of Washington, Seattle.
Archives of Internal Medicine
|March 1, 1990
Summary
Muscle cramps, painful involuntary contractions, can be diagnosed through patient history and physical exams. Stretching and quinine show the best evidence for treating ordinary cramps.
Area of Science:
- Neurology
- Clinical Medicine
Background:
- Muscle cramps are frequent patient complaints.
- Cramps can manifest as true cramp, tetany, contracture, or dystonia.
Purpose of the Study:
- To describe the pathophysiology and clinical features of different types of muscle cramps.
- To outline an effective diagnostic and therapeutic approach for patients experiencing cramps.
Main Methods:
- Emphasis on detailed patient history and physical examination.
- Inclusion of minimal routine laboratory data when diagnosis is uncertain.
Main Results:
- Stretching exercises and quinine are supported by the best evidence for treating ordinary cramps.
- Pathophysiologic and clinical distinctions between cramp types are detailed.
Conclusions:
- A systematic approach focusing on history and physical exam is crucial for diagnosing muscle cramps.
- Further research is needed to explore this common symptom.
Related Concept Videos
Muscle Contraction
Cross-bridge Cycle
As muscle contracts, the overlap between the thin and thick filaments increases, decreasing the length of the sarcomere—the contractile unit of the muscle—using energy in the form of ATP. At the molecular level, this is a cyclic, multistep process that involves binding and hydrolysis of ATP, and movement of actin by myosin.
Muscle Contraction
In skeletal muscles, acetylcholine is released by nerve terminals at the motor endplate—the point of synaptic communication between motor neurons and muscle fibers. The binding of acetylcholine to its receptors on the sarcolemma allows entry of sodium ions into the cell and triggers an action potential in the muscle cell. Thus, electrical signals from the brain are transmitted to the muscle. Subsequently, the enzyme acetylcholinesterase breaks down acetylcholine to prevent excessive muscle...
Skeletal Muscle Relaxants: Adverse Effects
Skeletal muscle relaxants are widely used for muscle paralysis and relieving pain following any muscle injury or stiffness. However, depending on the drug type, they can have adverse effects that range from mild to severe. Usually, nondepolarizing neuromuscular blockers have minimal side effects. For example, drugs like d-tubocurarine, cisatracurium, and rocuronium cause hypotension, whereas drugs like baclofen, when stopped abruptly, can lead to the recurrence of spastic conditions.
Unlike...
Unlike...
Muscle Recovery and Fatigue
Muscle fatigue refers to the decline in a muscle's ability to maintain the force of contraction after prolonged activity. It primarily stems from changes within muscle fibers. Even before experiencing muscle fatigue, one may feel tired and have the urge to stop the activity. This response, known as central fatigue, occurs due to changes in the central nervous system, namely the brain and spinal cord. While there is no single mechanism that induces fatigue, it may serve as a protective response...
Disorders of the Skeletal Muscle
The clinical conditions affecting the skeletal muscle tissue are broadly categorized as musculoskeletal and neuromuscular disorders.
Musculoskeletal disorders
Musculoskeletal disorders involve injuries and conditions affecting the skeletal muscles and associated connective tissues. These disorders can arise from acute biomechanical stresses or chronic overuse and can occur across different age groups. Common injuries include sprains, fractures, and muscular strains, often resulting from...
Musculoskeletal disorders
Musculoskeletal disorders involve injuries and conditions affecting the skeletal muscles and associated connective tissues. These disorders can arise from acute biomechanical stresses or chronic overuse and can occur across different age groups. Common injuries include sprains, fractures, and muscular strains, often resulting from...

