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MUSCLE: Introduction & Overview

The power of locomotion is that which contracts and relaxes the muscles whereby the members and joints are moved, extended or flexed. This power reaches the limbs by way of the nerves and there are as many forms of power as there are of movement. Each muscle has its own peculiar purpose and it obeys the decree of the composite sense.

MUSCLE: Introduction & Overview

"The power of locomotion is that which contracts and relaxes the muscles whereby the members and joints are moved, extended or flexed. This power reaches the limbs by way of the nerves and there are as many forms of power as there are of movement. Each muscle has its own peculiar purpose and it obeys the decree of the composite sense."  -- Ibn Sina, early 11th century.

Human body, a magnificent engineering marvel at its best. With all that we know, data is in tons and still evolving very minute of the day. The more we search the more we get, i still believe their is so much more we can/will discover in future. What is it, train them or not too, why and how. Hold on to this muscle boat, its a good read… you may learn few things or refresh your memory for sure….

Muscles and nerve fibers allow us to move our bodies. They enable our internal organs to function. The human body has over 600 muscles, which make up around 40 percent of our bodyweight. Around 206 bone by adulthood. Nerve impulses sent from the brain move at a speed of 274 km/h.

What are the 7 ways muscles are named

  1. Location eg. Rectus Abdominis
  2. Action eg. Extensor Digitorum Longus
  3. Direction of Fibers. eg. External Oblique
  4. Shapr eg. Deltoid
  5. Number of Origins eg. Triceps Brochii
  6. Origin/Insertion eg. Sternocleidomastoid
  7. Relative Size eg. Adductor Magnus

The term muscle is derived from the Latin musculus meaning "little mouse" perhaps because of the shape of certain muscles or because contracting muscles look like mice moving under the skin.

Muscle is a soft tissue, Muscle cells contain protein filaments of actin and myosin that slide past one another, producing a contraction that changes both the length and the shape of the cell. Muscles function to produce force and motion. They are primarily responsible for maintaining and changing posture, locomotion, as well as movement of internal organs, such as the contraction of the heart and the movement of food through the digestive system via peristalsis.

Muscle tissues are derived from the mesodermal layer of embryonic germ cells in a process known as myogenesis. There are three types of muscle, skeletal or striated, cardiac, and smooth. Muscle action can be classified as being either voluntary or involuntary. Cardiac and smooth muscles contract without conscious thought and are termed involuntary, whereas the skeletal muscles contract upon command. Skeletal muscles in turn can be divided into fast and slow twitch fibers.

Muscles are predominantly powered by the oxidation of fats and carbohydrates, but anaerobic chemical reactions are also used, particularly by fast twitch fibers. These chemical reactions produce adenosine triphosphate (ATP) molecules that are used to power the movement of the myosin heads.

There are three types of muscle tissue:

1) Skeletal muscle or "voluntary muscle" is anchored by tendons (or by aponeuroses at a few places) to bone and is used to effect skeletal movement such as locomotion and in maintaining posture. Though this postural control is generally maintained as an unconscious reflex, the muscles responsible react to conscious control like non-postural muscles. An average adult male is made up of 42% of skeletal muscle and an average adult female is made up of 36% (as a percentage of body mass).

2) Smooth muscle or "involuntary muscle" is found within the walls of organs and structures such as the esophagus, stomach, intestines, bronchi, uterus, urethra, bladder, blood vessels, and the arrectorpili in the skin (in which it controls erection of body hair). Unlike skeletal muscle, smooth muscle is not under conscious control.

3) Cardiac muscle (myocardium), is also  an "involuntary muscle" but is more akin in structure to skeletal muscle, and is found only in the heart.

The body contains three types of muscle tissue: (a) skeletal muscle, (b) smooth muscle, and (c) cardiac muscle. (Same magnification)

Cardiac and skeletal muscles are "striated" in that they contain sarcomeres that are packed into highly regular arrangements of bundles; the myofibrils of smooth muscle cells are not arranged in sarcomeres and so are not striated. While the sarcomeres in skeletal muscles are arranged in regular, parallel bundles, cardiac muscle sarcomeres connect at branching, irregular angles (called intercalated discs). Striated muscle contracts and relaxes in short, intense bursts, whereas smooth muscle sustains longer or even near-permanent contractions.

  smooth muscle cardiac muscle skeletal muscle
Neuromuscular junction none none present
Fibers fusiform, short (<0.4 mm) branching cylindrical, long (<15 cm)
Mitochondria few numerous many to few (by type)
Nuclei 1 1 >1
Sarcomeres none present, max. length 2.6 µm present, max. length 3.7 µm
Syncytium none (independent cells) none (but functional as such) present
Sarcoplasmic reticulum little elaborated

moderately elaborated

highly elaborated


moderate abundant
Self-regulation spontaneous action (slow) yes (rapid) none (requires nerve stimulus)
Response to stimulus unresponsive "all-or-nothing" "all-or-nothing"
Action potential yes yes yes
Workspace Force/length curve is variable the increase in the force/length curve at the peak of the force/length curve
Response to stimulus

This article series is dedicated to: Ibn Sīnā( also Avicenna Ibn Sīnā or Abu Ali Sina; Persian: ابنسینا; c.980 – June 1037) was a Persianpolymath who is regarded as one of the most significant physicians, astronomers, thinkers and writers of the Islamic Golden Age. He has been described as the father of early modern medicine. Of the 450 works he is known to have written, around 240 have survived, including 150 on philosophy and 40 on medicine.


  1. Mackenzie, Colin (1918). The Action of Muscles: Including Muscle Rest and Muscle Re-education. England: Paul B. Hoeber. p. 1. Retrieved 18 April 2015.
  2. Brainard, Jean; Gray-Wilson, Niamh; Harwood, Jessica; Karasov, Corliss; Kraus, Dors; Willan, Jane (2011). CK-12 Life Science Honors for Middle School. CK-12 Foundation. p. 451. Retrieved 18 April 2015.
  3. Alfred Carey Carpenter (2007). "Muscle". Anatomy Words. Retrieved 3 October 2012.
  4. Douglas Harper (2012). "Muscle". Online Etymology Dictionary. Retrieved 3 October 2012.
  5. Marieb, EN; Hoehn, Katja (2010). Human Anatomy & Physiology (8th ed.). San Francisco: Benjamin Cummings. p. ISBN978-0-8053-9569-3.
  6. McCloud, Aaron (30 November 2011). "Build Fast Twitch Muscle Fibers". Complete Strength Training. Retrieved 30 November 2011.
  7. Larsson, L; Edström, L; Lindegren, B; Gorza, L; Schiaffino, S (July 1991). "MHC composition and enzyme-histochemical and physiological properties of a novel fast-twitch motor unit type". The American Journal of Physiology. 261 (1 pt 1): C93–101. PMID1858863. Retrieved 2006-06-11.

About The Author

Muhammed Javed

Muhammed Javed Subbah completed degree in physical therapy from India and then concentrated on working in hospitals for orthopaedic, sports rehabilitation. Constant learning and.. Read More..


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