The Human Muscular System

The human musculoskeletal system consists of muscles and joints. There are over 640 muscles in the human body. The muscle tissues tighten and release to make movements possible. Muscles account for approximately one half of a person’s body weight.


The diagram above shows 30 of the major muscles in the human body. There are three types of muscles. The three types of muscles are striatedsmooth, and cardiac.

Striated muscles are also called skeletal or voluntary muscles. These are the muscles that move the bones as well as control the face and eyes. Striated muscles can be consciously controlled.

Smooth muscles are also known as visceral, involuntary, or unstriated muscles. The body has no control over these muscles, which move the internal organs. Blood vessels and secretory ducts also contain smooth muscles.

Cardiac muscles are a combination of the striated and smooth muscles. These muscles are striated in appearance but movement cannot be controlled. Branching fibers from the cardiac muscles form most of the wall of the heart and control the heartbeat.

In preparing this lesson we were faced with the overwhelming reality that there are an estimated 642 muscles in the human body. We decided to create individual lessons for each of the major muscle groups. Before proceeding to the major muscle groups, we’ll list the important root words and suffixes related to muscles.

Root Words For the Muscular System
Duct/o To draw
Fasci/o Band of tissue surround muscle
Flex/o Bend
Leiomy/o Smooth visceral muscle
My/o Muscle
Myocari/o Heart muscle
Myos/o Muscle
Pronati/o Backward or facing down
Rhabdomy/o Skeletal or striated muscle
Sarc/o Soft, fleshy or connective tissue
Supinato/o Forward or facing up
Tens/o Stretch

The chart below shows the suffixes related to the muscular system.

Suffixes Related to the Muscular System
-algia Pain in fibrous tissue
-desis Surgical fixation
-ectomy Removal or excision by surgery
-gram Record
-graphy The process of recording
-itis Inflammation
-ology The study of
-oma Mass or tumor
-otomy To cut into
-pathy Disease
-rrhapy Suture repair

The glossary below includes some of the more common medical terms you’ll encounter related to the musculoskeletal system and related medical conditions.

Abduction Drawing away from the center of the body.
Adduction Drawing toward the center of the body.
ALS Amyotrophic Lateral Sclerosis. Muscle disorder or atrophy with degeneration of nerves in the spinal cord and lower region of the brain.
Articulation Joint
Atrophy Weakening of a muscle due to lack of use.
Bursitis Inflammation of the bursa sac.
Diathermy Applying heat to deep tissues.
Dupuytren’s contracture Disease causing the ring finger and little finger to contract toward the palm.
Dyskinesia Difficult body movement.
Dystrophy Abnormal development.
Eversion Turning outward.
Extension Movement in which a limb is placed in a straight position.
Fascia Band of tissue surrounding muscle.
Fasciectomy Excision of fascia.
Fascitis Inflammation of fascia.
Flexion Movement in which a limb is bent.
Fibromyalgia Pain in  tissues of muscles, tendons, or ligaments.
Hyperkinesia Excessive body movement.
Inversion Turning inward.
Kinesiology Study of movement.
Leiomyoma Benign tumor of smooth muscle.
Leiomyosarcoma Malignant tumor of smooth muscle.
Ligament Material that binds one bone to another.
Muosarcoma Malignant tumor of muscle tissue.
Muscular Dystrophy Disease characterized by progressive weakness and degeneration of muscle fibers.
Myalgia Muscle pain.
Myasthenia Muscle weakness.
Myoclonus Relaxing and contracting a muscle in rapid succession.
Myology Study of muscles.
Myopathy The name for any type of muscular disease.
Myoplasty Surgical repair of a muscle.
Myorrhapy Suturing of a muscle.
Polymyalgia rheumatica Muscle pain without arthritis or signs of muscle weakness.
Pronation Movement that turns the palm of the hand downward.
Rotation Turning on its own axis.
Supination Movement that turns the palm of the hand downward.
Tendon The connective tissue that binds muscles to bones.
Tennis elbow Inflammation of the tendon that connects the arm muscle to the elbow.
Tenodesis Surgical fixation of a tendon.
Tenodynia Pain in a tendon.
Tenomyoplasty Surgical repair of a muscle and tendon.
Tenorrhapy Suturing of a tendon.
Tenosynovitis Inflammation of the tendon and the sheath around it
Tenotomy Incision of a tendon.
Torticollis Acute myositis of the cervical muscles.