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Question:

    What is the strongest muscle in the human body?

Answer:    

    There is no one answer for this question since there are different ways to measure strength. There is absolute strength (maximum force),
dynamic strength (repeated motions), elastic strength (exert force quickly), and strength endurance (withstand fatigue).

There are three types of muscles in the human body: cardiac, smooth and skeletal.

Cardiac muscle makes up the wall of the heart and is responsible for the forceful contraction of the heart. Smooth muscles make up the walls of the intestine, the uterus, blood vessels, and internal muscles of the eye. Skeletal muscles are attached to the bones and in some areas the skin (muscles in our face). Contraction of the skeletal muscles helps limbs and other body parts move.

Most sources state that there are over 650 named skeletal muscles in the human body, although some figures go up to as many as 840. The dissension comes from those that count the muscles within a complex muscle. For example the biceps brachii is a complex muscle that has two heads and two different origins however, they insert on the radial tuberosity. Do you count this as one muscle or two?

Although most individuals have the same general set of muscles, there is some variability from one person to another. Generally, smooth muscles are not included with this total since most of these muscles are at cellular level and number in the billions. In terms of a cardiac muscle, we only have one of those- the heart.

Muscles are given Latin names according to location, relative size, shape, action, origin/insertion, and/or number of origins. For example the flexor hallicis longus muscle is the long muscle that bends the big toe:

  • Flexor = A muscle that flexes a joint
  • Hallicis = great toe
  • Longus = Long

The following are muscles that have been deemed the strongest based on various definitions of strength (listed in alphabetical order):

External Muscles of the Eye
The muscles of the eye are constantly moving to readjust the positions of the eye. When the head is in motion, the external muscles are constantly adjusting the position of the eye to maintain a steady fixation point. However, the external muscles of the eye are subject to fatigue. In an hour of reading a book the eyes make nearly 10,000 coordinated movements.

Gluteus Maximus
The gluteus maximus is the largest muscle in the human body. It is large and powerful because it has the job of keeping the trunk of the body in an erect posture. It is the chief antigravity muscle that aids in walking up stairs.

Heart
The hardest working muscle is the heart. It pumps out 2 ounces (71 grams) of blood at every heartbeat. Daily the heart pumps at least 2,500 gallons (9,450 liters) of blood. The heart has the ability to beat over 3 billion times in a person’s life.

Masseter
The strongest muscle based on its weight is the masseter. With all muscles of the jaw working together it can close the teeth with a force as great as 55 pounds (25 kilograms) on the incisors or 200 pounds (90.7 kilograms) on the molars.

Muscles of the Uterus
The uterus sits in the lower pelvic region. Its muscles are deemed strong because they contract to push a baby through the birth canal. The pituitary gland secretes the hormone oxytocin, which stimulates the contractions.

Soleus
The muscle that can pull with the greatest force is the soleus. It is found below the gastrocnemius (calf muscle). The soleus is very important for walking, running, and dancing. It is considered a very powerful muscle along with calf muscles because it pulls against the force of gravity to keep the body upright.

Tongue
The tongue is a tough worker. It is made up of groups of muscles and like the heart it is always working. It helps in the mixing process of foods. It binds and contorts itself to form letters. The tongue contains linguinal tonsils that filter out germs. Even when a person sleeps, the tongue is constantly pushing saliva down the throat.

Standard DisclaimerRelated Web Sites

Library of Congress Web SiteFurther Reading
  • Biel, Andrew. Trail guide to the body: how to locate muscles, bones and more. Boulder, CO, Andrew Biel, c1997. 297 p.
  • Llamas, Andreu. Muscles and bones. Milwaukee, Gareth Stevens Publications, 1998. 32 p. (Juvenile).
  • Nigg, Benno M., and Walter Herzog editors. Biomechanics of the musculo-skeletal system. 3rd edition. New Jersey, John Wiley and Sons, 2007. 672 p.
  • Oatis, Carol A. Kinesiology: the mechanics and pathomechanics of human movement. Philadelphia, Lippincott, Williams, and Wilkins, c2004. 899 p.
  • The Skeletal system / the muscular system. Chicago, World Book, c2007. 48 p (Juvenile).
  • Van de graff, Kent. Human anatomy. 6th edition. Boston, McGraw Hill, 2002. 840 p.
  • World of anatomy and physiology. K. Lee Lerner and Brenda Wilmoth Lerner editors. Detroit, Thomas/Gale, c2002. 2v.

SearchFor more print resources...
Search on "Biomechanics," "Human anatomy," "Kinesiology," "Muscles," or "Musculoskeletal system" in the Library of Congress Online Catalog.

Photo: Muscular man posing in a leopard-printed outfit.
Strong man, 1895. Prints and Photographs Division, Library of Congress.

Photo: magnified heart cell.
Magnified, a heart muscle cell contracts. Billions of these cells contracting in synchronization produce a heart beat. National Institute on Aging, NIH Web site.

Photo: man pulling on an instrument, possibly to measure arm strength.
Strength training. From Images from the History of Medicine, National Library of Medicine Web site.

Drawing of major human muscles, from front of body.
Superficial anterior muscles. From the MedlinePlus Web site.

Illustration showing a human arm and an artificial arm wrestling.
A challenge - artificial arm vs. human arm?
From the NASA Web site.

Drawing of lower leg muscles.
Lower leg muscles. MedlinePlus Web site.

Diagram of the inside of a muscle.
Structure of a skeletal muscle. From the U.S. National Cancer Institute's Surveillance, Epidemiology and End Results Program.

Photo: magnified and colorized cell, with purple and yellow on green background.
Genetically engineered smooth muscle cells. From the NIST Web site.

Drawing of a male figure's muscles.
Musculature of the human body.
Geminus, Thomas, d. 1562.

From Images from the History of Medicine, National Library of Medicine Web site.

Photo:  man in a small chamber, connected  to monitors.
A Spacelab 1 payload specialist exercises while instruments measure his heart's operation in microgravity. From the NASA Web site.

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  December 28, 2012
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