A muscle relaxant is a drug which affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therapeutic groups: neuromuscular blockers and spasmolytics. Neuromuscular blockers act by interfering with transmission at the neuromuscular end plate and have no central nervous system (CNS) activity. They are often used during surgical procedures and in intensive care and emergency medicine to cause temporary paralysis. Spasmolytics, also known as "centrally acting" muscle relaxants, are used to alleviate musculoskeletal pain and spasms and to reduce spasticity in a variety of neurological conditions. While both neuromuscular blockers and spasmolytics are often grouped together as muscle relaxants, the term is commonly used to refer to spasmolytics only.
The earliest known use of muscle relaxant drugs dates back to the 16th century, when European explorers encountered natives of the Amazon Basin in South America using poison-tipped arrows that produced death by skeletal muscle paralysis. This poison, known today as curare, led to some of the earliest scientific studies in pharmacology. Its active ingredient, tubocurarine, as well as many synthetic derivatives, played a significant role in scientific experiments to determine the function of acetylcholine in neuromuscular transmission. By 1943, neuromuscular blocking drugs became established as muscle relaxants in the practice of anesthesia and surgery.
Organic chemistry is a chemistry subdiscipline involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms. Study of structure includes using spectroscopy and other physical and chemical methods to determine the chemical composition and constitution of organic compounds and materials. Study of properties includes both physical properties and chemical properties, and uses similar methods as well as methods to evaluate chemical reactivity, with the aim to understand the behavior of the organic matter in its pure form (when possible), but also in solutions, mixtures, and fabricated forms. The study of organic reactions includes both their preparation—by synthesis or by other means—as well as their subsequent reactivities, both in the laboratory and via theoretical (in silico) study.
The range of chemicals studied in organic chemistry include hydrocarbons, compounds containing only carbon and hydrogen, as well as compositions based on carbon but containing other elements. Organic chemistry overlaps with many areas including medicinal chemistry, biochemistry, organometallic chemistry, and polymer chemistry, as well as many aspects of materials science.