Muscle Anatomy & Physiology


Welcome to the "Muscle Anatomy" section.  In this portion of my blog I will be going to describe the basic anatomy of muscle and how muscle develops and grows, beneficial nutrients for muscle and the age related changes in muscle, specifically sarcopenia.


There are three types of muscle, skeletal, cardiac and smooth. Each one of these muscle play an important role in our ability to properly move and function properly to our internal and external environments. 



  • Skeletal Muscle - Skeletal muscles move and support the skeleton. They make up fifty percent of your body weight.
  • Cardiac Muscle - Cardiac muscles are the muscles of the heart. They are self-contracting, autonomically regulated and must continue to contract in rythmic fashion for the whole life of the organism.

  • Smooth Muscle - Smooth muscle is responsible for the contractility of hollow organs, such as blood vessels, the gastrointestinal tract, the bladder, or the uterus.

To get a better understand of the muscle and their functions it is best to review some of the more common terms and definitions associated with basic muscle structure and anatomy:
Muscle - a band or bundle of fibrous tissue in a human or animal body that has ability to contract, producing movement in or maintaining the position of parts of the body.
Fascicles - a bundle of structures, such as nerve or muscle fibers
Muscle Fibers - one of the structural cells of a muscle

Myofibril - basic rod like unit that contains long chains of sarcomeres 
Myofilaments - filaments within the myofibrils; there are two types, thick filaments myosin and thin filaments called actin.

Sarcomeres - a structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band.
Actin - a protein that forms (together with myosin) the contractile filaments of muscle cells, and is also involved in motion in other types of cells.
Myosin - a fibrous protein that forms (together with actin) the contractile filaments of muscle cells and is also involved in motion in other types of cells.
Muscle Development in an Embryo:

Muscle growth begins when a child is still in a mothers womb, while the baby is still an embryo, it begins to grow muscles using a combination of different layers of cells. Muscle grows by increasing in size also called hypertrophy.  Muscles grows in size and in length due new sarcomeres forming which are then added to the ends of the growing muscle fibers. The myofibrils begin to thicken and eventually split, forming new sarcomeres, these new sarcomeres are then attached to the ends of the muscle which ends in the lengthening of the muscle fiber.  Muscle hypertrophy involves an increase in size of skeletal muscle through an increase in the size of its component cells. Increasing in fiber number is known as hyperplasia.  The enlargement of an organ or tissue caused by an increase in the reproduction rate of its cells.  Example of embyro development shown in pictures below.




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Muscle LifeStyle Changes

As we get into our older year we tend to run into more issues related to our health.  Even the most fit elderly people will have eventually run into problems.  As we get older we begin to lose muscle mass and function, a condition known as age-related sarcopenia or sarcopenia with aging.   

Sarcopenia typically accelerates around age 75, although it may happen in people around ages 65 or 80 and is a contributing factor to frail bones and the likelihood of falls and fractures in older adults.  I find it particularly important in our elder adults to know the signs of sarcopenia and the best ways to help prevent this from becoming an issue.  


Researchers also believe the following factors play a role:
  • Age-related reduction in nerve cells responsible for sending signals from the brain to the muscles to initiate movement
  • A decrease in the concentrations of some hormones, including growth hormone, testosterone, and insulin-like growth factor
  • A decrease in the body's ability to synthesize protein
  • Inadequate intake of calories

Existing evidence indicates the potential importance of diets, to ensure sufficient intakes of protein, vitamin D, and antioxidant nutrients. Other potentially benificial efforts to prevent sarcopenia also include the recognition and potential effectiveness of interventions early on in life.  Staying hydrated throughout the day as well as meeting daily recommended values for micronutrients are highly suggested to prevent muscle related health issues.


Focusing on optimising diet and nutrition throughout life, may be key to preventing sarcopenia and promoting physical capability in older age. Another primary treatment for sarcopenia is resistance or strength training exercises, these are exercises that increases muscle strength and endurance with weights or resistance bands. Example shown in video:





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