Over 600 muscles
The body has more than 600 skeletal muscles, and in an adult man they make up about 40 percent of body weight. They range from the gluteus maximus of the buttock, the heaviest, to the stapedius in the middle ear, a few millimetres long. Almost all of them come in pairs, one on each side.
The major muscles of the body from the front and the back, with the superficial layer on the body's right side and a deeper layer on its left, OpenStax Anatomy and PhysiologyWikimedia Commons, OpenStax, CC BY 4.0 (1105 Anterior and Posterior Views of Muscles.jpg)
Skeletal muscles do more than move the limbs. They hold the body upright against gravity, move air in and out of the lungs, close the eyelids and lips, and make heat. When the body is cold, shivering can raise the heat it makes four to five times.
This model holds most of the larger muscles in three layers, from the skin inward. The pages that follow peel them away region by region, from the face to the feet.
Sources
- Susan Standring (ed.), Gray's Anatomy, 42nd ed. (2020), chapter on the functional anatomy of the musculoskeletal system.
- Arthur Guyton and John Hall, Textbook of Medical Physiology, 13th ed. (2016), ch. 6.
Next: Three kinds of muscle