Muscles of the Human Body


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 upstairs.
Muscles and Joints
How many muscles are there in the human body?
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.

They do everything from pumping blood throughout the body to helping us lift something heavy. 

Different types of muscle

Skeletal muscles
Skeletal muscles

The three main types of muscle include:

  • Skeletal muscle – the specialized tissue that is attached to bones and allows movement. Together, skeletal muscles and bones are called the musculoskeletal system (also known as the locomotor system). Generally speaking, skeletal muscle is grouped into opposing pairs such as the biceps and triceps on the front and back of the upper arm. Skeletal muscles are under our conscious control, which is why they are also known as voluntary muscles. Another term is striated muscles since the tissue looks striped when viewed under a microscope.
  • Smooth muscle – located in various internal structures including the digestive tract, uterus, and blood vessels such as arteries. Smooth muscle is arranged in layered sheets that contract in waves along the length of the structure. Another common term is an involuntary muscle since the motion of smooth muscle happens without our conscious awareness.
  • Cardiac muscle – The muscle-specific to the heart. The heart contracts and relaxes without our conscious awareness.
Skeletal muscles
Skeletal muscles
Skeletal muscles
Skeletal muscles

Make-up of muscle

Skeletal, smooth, and cardiac muscles have very different functions, but they share the same basic composition. A muscle is made up of thousands of elastic fibers bundled tightly together. Each bundle is wrapped in a thin transparent membrane called a perimysium….the sheath of connective tissue surrounding a bundle of muscle fibers.

the sheath of connective tissue surrounding a bundle of muscle fibers.

An individual muscle fiber is made up of blocks of proteins called myofibrils, which contain a specialized protein (myoglobin) and molecules to provide the oxygen and energy required for muscle contraction. Each myofibril contains filaments that fold together when given the signal to contract. This shortens the length of the muscle fibers which, in turn, shortens the entire muscle if enough fibers are stimulated at the same time.

The Neuromuscular System

neuromuscular system

The brain, nerves, and skeletal muscles work together to cause movement. This is collectively known as the neuromuscular system. A typical muscle is serviced by anywhere between 50 and 200 (or more) branches of specialized nerve cells called motor neurons. This plugs directly into the skeletal muscle. The tip of each branch is called a presynaptic terminal. The point of contact between the presynaptic terminal and the muscle is called the neuromuscular junction.

To move a particular body part:

  • The brain sends a message to the motor neurons.
  • This triggers the release of the chemical acetylcholine from the presynaptic terminals.
  • The muscle responds to acetylcholine by contracting.

Shapes of skeletal muscle

Shapes of skeletal muscle
Shapes of skeletal muscle

Generally speaking, skeletal muscles come in four main shapes, including:

  • Spindle – wide through the middle and tapering at both ends, such as the biceps on the front of the upper arm.
  • Flat – like a sheet, such as a diaphragm that separates the chest from the abdominal cavity.
  • Triangular – wider at the bottom, tapered at the top, such as the deltoid muscles of the shoulder.
  • Circular – a ring shape like a doughnut, such as the muscles that surround the mouth, the pupils, and the anus. These are also known as sphincters

Muscle disorders

How many muscle diseases are there?
There are 9 types of muscular dystrophy, with each type involving an eventual loss of strength, increasing disability, and possible deformity. The most well-known of the muscular dystrophies is Duchenne muscular dystrophy (DMD), followed by Becker muscular dystrophy (BMD).
Types of neuromuscular disorders include:
  • Amyotrophic lateral sclerosis (ALS)
  • Charcot-Marie-Tooth disease.
  • Multiple sclerosis.
  • Muscular dystrophy.
  • Myasthenia gravis.
  • Myopathy.
  • Myositis, including polymyositis and dermatomyositis.
  • Peripheral neuropathy.
Muscle disorders
Muscle disorders

Muscle disorders may cause weakness, pain, loss of movement, and even paralysis. The range of problems that affect muscles is collectively known as myopathy. Common muscle problems include:

 Anatomy Muscle Links


PRO Massage by Nicola. LMT
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