MusculoSkeletal System


The human musculoskeletal system consists of the human skeleton, made by bones attached to other bones with joints, and skeletal muscle attached to the skeleton by tendons.

The human musculoskeletal system is an organ system that gives humans the ability to move using their muscular and skeletal systems. The musculoskeletal system provides form, support, stability, and movement to the body.


An adult human has approximately 206 distinct bones:

Spine and vertebral column (26)

Cranium (8)

Face (14)

Hyoid bone, sternum and ribs (26)

Upper extremities (70)

Lower extremities (62)

Skeletal System Overview

The Skeleton is a rigid framework that provides protection and structure in many types of animals.

The average adult human skeleton has around 206 bones. These bones meet at joints, the majority of which are freely movable. The skeleton also contains cartilage for elasticity. Ligaments are strong strips of fibrous connective tissue that hold bones together at joints, thereby stabilizing the skeleton during movement.

The Skeletal System serves many important functions; it provides the shape and form for our bodies in addition to supporting, protecting, allowing bodily movement, producing blood for the body, and storing minerals.

Its 206 bones form a rigid framework to which the softer tissues and organs of the body are attached.

Vital organs are protected by the skeletal system. The brain is protected by the surrounding skull as the heart and lungs are encased by the sternum and rib cage.

Bodily movement is carried out by the interaction of the muscular and skeletal systems. For this reason, they are often grouped together as the musculoskeletal system. Muscles are connected to bones by tendons. Bones are connected to each other by ligaments. Where bones meet one another is typically called a joint. Muscles that cause movement of a joint are connected to two different bones and contract to pull them together. An example would be the contraction of the biceps and the relaxation of the triceps. This produces a bend at the elbow. The contraction of the triceps and relaxation of the biceps produces the effect of straightening the arm.

Blood cells are produced by the marrow located in some bones. An average of 2.6 million red blood cells is produced each second by the bone marrow to replace those worn out and destroyed by the liver.

Bones serve as a storage area for minerals such as calcium and phosphorus. When an excess is present in the blood, buildup will occur within the bones. When the supply of these minerals within the blood is low, it will be withdrawn from the bones to replenish the supply.
The human skeleton is divided into two distinct parts:
The axial skeleton consists of bones that form the axis of the body and support and protect the organs of the head, neck, and trunk.

The Skull

The Sternum

The Ribs

The Vertebral Column

The appendicular skeleton is composed of bones that anchor the appendages to the axial skeleton.

The Upper Extremities

The Lower Extremities

The Shoulder Girdle

The Pelvic Girdle–(the sacrum and coccyx are considered part of the vertebral column)

MusculoSkeletal System Physiology

The musculoskeletal system consists of bones, joints, ligaments, muscles, and tendons. The skeleton gives shape to the body, provides physical support and protection for the organs, stores minerals, is responsible for blood cell formation, and provides sites for muscle attachment. The action of muscles holds the skeleton upright and creates physical movement of the body. The first figure depicts the bones of the skeleton. The next figures illustrate the major muscles of the body. Any disease or disorder of this system greatly affects activities of daily living.

The skeletal system consists of bones formed from osseous tissue that provide structure and function to the overall body. Also included in the skeletal system is the cartilage that forms the joints between bones and the ligaments that hold bones together at the joints. Bones can be subdivided into long bones (arms, legs, hands, and feet), short bones (wrist, ankles, and knee caps), flat bones (ribs, sternum, shoulder blades, hip bones, and cranial bones), and irregular bones (vertebrae and facial bones).

The adult skeletal system has two divisions: the axial skeletal system and the appendicular skeletal system. The axial skeleton is the center portion of the body and includes the bones of the skull, hyoid bone, bones of the middle ear, vertebral column, and rib cage. The appendicular skeleton is composed of the bones of the appendages or limbs and includes the bones of the arms and legs, the shoulders, and the pelvic girdle.

There are two types of bone: compact and spongy. Compact bone is the dense, hard tissue found in the shafts of long bones. Yellow marrow, which is composed of fat, is stored in these bones. Spongy bone, or cancellous bone, is less dense and is found at the ends of long bones and in the other bones of the body.

The muscular system holds the body upright and moves the skeletal system. Muscles have specialized cells for contraction wherein they shorten and pull a bone to produce movement. Muscle movement creates heat that helps to regulate body temperature.

There are three types of muscles:

  1. Skeletal muscle is also called voluntary muscle because it is attached to the skeleton and its movement is consciously controlled. The cells of this type of muscle are elongated and have the ability to stretch and return to their previous shape.
  2. Smooth muscle is also called involuntary or visceral muscle because it is found in the walls of organs and its function is not consciously controlled. This type of muscle has shorter cells with tapered ends and cannot stretch as much as skeletal muscle.
  3. Cardiac muscle is found only in the heart. This muscle is a combination of skeletal and smooth muscle. It is involuntarily controlled but has the ability to contract.

Types of Bones

The bones of the body fall into four general categories: long bones, short bones, flat bones, and irregular bones. Long bones are longer than they are wide and work like levers. The bones of the upper and lower extremities (ex. humerus, tibia, femur, ulna, metacarpals, etc.) are of this type. Short bones are short, cube-shaped, and found in the wrists and ankles. Flat bones have broad surfaces for the protection of organs and attachment of muscles (ex. ribs, cranial bones, bones of shoulder girdle). Irregular bones are all others that do not fall into the previous categories. They have varied shapes, sizes, and surface features and include the bones of the vertebrae and a few in the skull.

Bone Composition

Bones are composed of tissue that may take one of two forms. Compact, or dense bone, and spongy, or cancellous, bone. Most bones contain both types. Compact bone is dense, hard, and forms the protective exterior portion of all bones. Spongy bone is inside the compact bone and is very porous (full of tiny holes). Spongy bone occurs in most bones. The bone tissue is composed of several types of bone cells embedded in a web of inorganic salts (mostly calcium and phosphorus) to give the bone strength, and collagenous fibers, and ground substance to give the bone flexibility.

A living bone consists of three layers: the periosteum, or outside skin of the bone; the hard compact bone; and the bone marrow.


A ligament is a tough band of white, fibrous, slightly elastic tissue.
This is an essential part of the skeletal joints; binding the bone ends together to prevent dislocation and excessive movement that might cause breakage. Ligaments also support many internal organs; including the uterus, the bladder, the liver, and the diaphragm, and helps in shaping and supporting the breasts. Ligaments, especially those in the ankle joint and knee, are sometimes damaged by injury. A “torn” ligament usually results from twisting stress when the knee is turned while weight is on that particular leg. Minor sprains are treated with ice, bandages, and sometimes physical therapy, but if the ligament is torn, the joint may be placed in a plaster cast to allow time to heal or it may require surgical repairs.
If a ligament is made up of several thick bands of fibrous branches, it is called a “collateral ligament.”
The word “ligament” comes from the Latin word, “ligamentum,” meaning a band or tie.

Muscle Pain

Myofascial pain syndrome (MPS) is a fancy way to describe muscle pain. It refers to pain and inflammation in the body’s soft tissues.

Myofascial pain is a chronic condition that affects the fascia (the connective tissue that covers the muscles). Myofascial pain syndrome may involve either a single muscle or a muscle group. In some cases, the area where a person experiences the pain may not be where the myofascial pain generator is located. Experts believe that the actual site of the injury or the strain prompts the development of a trigger point that, in turn, causes pain in other areas. This situation is known as referred pain.

What Causes Myofascial Pain?

Injury to muscle fibers

Repetitive motions

Lack of activity (such as having a broken arm in a sling)

What Are the Symptoms of Myofascial Pain?

Myofascial pain symptoms usually involve muscle pain with specific “trigger” or “tender” points. The pain can be made worse with activity or stress. In addition to the local or regional pain associated with myofascial pain syndrome, people with the disorder also can suffer from depression, fatigue, and behavioral disturbances.

How Is Myofascial Pain Diagnosed?

Trigger points can be identified by pain that results when pressure is applied to an area of a person’s body. In the diagnosis of myofascial pain syndrome, two types of trigger points can be distinguished:

An active trigger point is an area of extreme tenderness that usually lies within the skeletal muscle and which is associated with local or regional pain.

A latent trigger point is a dormant (inactive) area that has the potential to act as a trigger point. It may cause muscle weakness or restriction of movement.

How Is Myofascial Pain Treated?

Medications such as non-steroidal anti-inflammatories, acetaminophen, or opioids may be used to treat myofascial pain. Medications for sleep, depression, or muscle spasm are sometimes used, as well. Non-drug treatments may include:

Physical therapy

“Stretch and spray” technique: This treatment involves spraying the muscle and trigger point with a coolant and then slowly stretching the muscle.

Massage therapy

Trigger point injection

In some chronic cases of myofascial pain, combinations of physical therapy, trigger point injections, and massage are needed.

Muscular Dystrophy

Dystrophy is any condition in which a part of the body weakens or wastes away. In muscular dystrophy, the weakness is in the muscles. An inherited genetic mistake prevents the body from making a protein that helps build muscles and keep them strong.
Children who are born with muscular dystrophy usually develop normally for the first few years of life. They may suddenly show signs of clumsiness. These signs include:

Trouble walking

Difficulty raising the front of their foot (called foot drop)


Over time, children with muscular dystrophy can become weaker and weaker, losing the ability to sit, walk, and lift objects. Because the disease can also affect muscles in the heart and lungs, serious heart and breathing problems can occur.
There are several different types of muscular dystrophy. Muscle weakness is a hallmark of each type. But the symptoms can vary and start at different ages.
Some muscular dystrophies are mild. Others are severe and cause greater muscle loss.

Duchenne Muscular Dystrophy

Duchenne muscular dystrophy is the most common and severe form of the disease. It usually starts when a child is between ages 2 and 5.

Symptoms of Duchenne muscular dystrophy include:

Muscle weakness that begins in the hips, pelvis, and legs

Difficulty standing

Trouble learning to sit independently and walk

Unsteady, waddling gait

Walking on the toes or balls of the feet

Clumsiness, falling often

Trouble climbing stairs

Difficulty rising from a lying or sitting position

Larger-than-normal calves that are sometimes painful

Trouble breathing

Learning disabilities or behavioral problems

The curvature of the spine (scoliosis). This can cause one hip to rise higher than the other.

Breathing problems that may eventually require the use of a ventilator

By age 12, most children with Duchenne muscular dystrophy must use a wheelchair to get around. The disease also damages the heart and the muscles needed to breathe, which can be life-threatening.

Becker Muscular Dystrophy

The symptoms of Becker muscular dystrophy are similar to those of Duchenne muscular dystrophy. But Becker muscular dystrophy starts later — around the teen years. It also develops much more slowly.
The first signs of Becker’s muscular dystrophy may be trouble walking fast, running, and climbing stairs. Other symptoms may include:

Muscle weakness that starts in the pelvis, shoulders, hips, and thighs

Difficulty learning how to walk

Waddling gait

Walking on the toes

Larger-than-normal calves

Muscle cramps when exercising

Trouble lifting objects above waist height because of shoulder and arm weakness

Heart and breathing problems (later in life)

Often children with Becker muscular dystrophy can walk. As they get older they may need to use a cane or wheelchair to get around.

Myotonic Dystrophy

The symptoms of myotonic dystrophy may be obvious from birth or they can develop later — during the teenage or adult years.
Like other forms of muscular dystrophy, myotonic dystrophy leads to muscle weakness that gets worse over time. But it usually affects small muscles, like those in the:




Symptoms of myotonic dystrophy can start at any time in a person’s life. The symptoms include:

Weakness in the muscles of the face, arms, hands, and neck

Muscle stiffness (myotonia) — difficulty relaxing the muscles after they are tightened

Shrinking of the muscles over time (muscle wasting)

Cataracts — clouding of the eye’s lens

Daytime sleepiness

Learning and behavioral problems

Heart problems, including irregular heartbeat (arrhythmia)

The type of myotonic dystrophy that begins at birth is more severe. Other forms get worse very slowly and can take 50 or 60 years to progress.

Limb-Girdle Muscular Dystrophy

This form of muscular dystrophy is actually a group of related conditions. It usually starts in childhood or during the teenage years.
Often the muscles that become weak first are the big muscles of the:




The muscle weakness gets worse very slowly over time.

Other symptoms include:

Loss of muscle in affected areas

Back pain

Trouble lifting objects

Difficulty running

Fast heartbeat (palpitations) or irregular heartbeat

How serious the effects depend on the child. Some children have only mild muscle weakness. Others are so weak they need to use a wheelchair.

In its later stages, limb-girdle muscular dystrophy can cause serious heart problems.

Facioscapulohumeral Muscular Dystrophy

Usually, this type of muscular dystrophy doesn’t appear until the teenage years or later in life. It also gets worse very slowly. Some people may not realize they have it until they are already old.

Symptoms include:

Muscle weakness in the face. This affects the child’s ability to close the eyes and purse the lips (whistle).

Muscle weakness in the shoulders, upper arms, upper back, and lower legs

Difficulty raising the arms or lifting objects because of muscle weakness in the shoulders and back

One side of the body may be more severely affected than the other.


Arthritis is a general term that means inflammation of the joints.

What Are the Common Types of Arthritis?

There are two major types of arthritis — osteoarthritis, which is the “wear and tear” arthritis, and rheumatoid arthritis, an inflammatory type of arthritis that happens when the body’s immune system does not work properly.

Gout, which is caused by crystals that collect in the joints, is another common type of arthritis. Psoriatic arthritis, lupus, and septic arthritis are other types of the condition.

Joint pain and progressive stiffness without noticeable swelling, chills, or fever during normal activities probably indicate the gradual onset of osteoarthritis.

Painful swelling, inflammation, and stiffness in the fingers, arms, legs, and wrists occurring in the same joints on both sides of the body, especially upon awakening, may be signs of rheumatoid arthritis.

Fever, joint inflammation, tenderness, and sharp pain, sometimes accompanied by chills and associated with an injury or another illness, may indicate infectious arthritis.

In children, intermittent fever, loss of appetite, weight loss, and anemia, or blotchy rash on the arms and legs, may signal the onset of some types of juvenile rheumatoid arthritis. Other forms of juvenile rheumatoid arthritis are associated with joint stiffness, a limp, or joint swelling.


Osteoarthritis, commonly known as wear and tear arthritis, is the most common type of arthritis. It is associated with a breakdown of cartilage in joints and can occur in almost any joint in the body. It commonly occurs in the weight-bearing joints of the hips, knees, and spine. It also affects the fingers, thumb, neck, and large toe. Osteoarthritis — also called OA — usually does not affect other joints unless previous injury or excessive stress is involved.
Cartilage is a firm, rubbery material that covers the ends of bones in normal joints. Its main function is to reduce friction in the joints and serve as a “shock absorber.” The shock-absorbing quality of normal cartilage comes from its ability to change shape when compressed (flattened or pressed together).

Osteoarthritis causes the cartilage in a joint to become stiff and lose its elasticity, making it more susceptible to damage. Over time, the cartilage may wear away in some areas, greatly decreasing its ability to act as a shock absorber. As the cartilage deteriorates, tendons and ligaments stretch, causing pain. If the condition worsens, the bones could rub against each other.

The chance of developing the disease increases with age. Most people over age 60 have osteoarthritis to some degree, but its severity varies. Even people in their 20s and 30s can get osteoarthritis. In people over 50, more women than men have osteoarthritis.

Hip problems

Hip problems may develop from overuse, bone changes with age, tumors, infection, changes in the blood supply, or a problem that was present from birth (congenital).

Pain when resting

Pain with movement

Pain with weight-bearing

Knee Osteoarthritis

Osteoarthritis in the knee begins with the gradual deterioration of cartilage. Without the protective cartilage, the bones begin to rub together, causing pain, loss of mobility, and deformity

Hand Osteoarthritis

In the joint located at the base of the thumb, where the thumb meets the wrist. You may have bumps or bony knobs located near the site of arthritis.

In the joint at the end of the finger closest to the nail

In the joint in the middle of the finger

How Is Osteoarthritis Treated?

Osteoarthritis usually is treated by a combination of treatments, including exercise, weight loss if needed, medications, physical therapy with muscle strengthening exercises, hot and cold compresses to the painful joint, removal of joint fluid, injection of medications into the joint, and use of supportive devices such as crutches or canes. Surgery may be helpful to relieve pain when other treatment options have not been effective.

The type of treatment will depend on several factors including your age, activities and occupation, overall health, medical history, location of your osteoarthritis, and severity of the condition.

How Does Weight and Exercise Impact Osteoarthritis?

Staying at your recommended weight helps prevent osteoarthritis of the knees, hips, and spine reduces the stress on these weight-bearing joints, and reduces pain in joints already affected. Once you have osteoarthritis, losing weight also can relieve the stress and pain in your knees.

Exercise is important to improve joint movement and to strengthen the muscles that surround the joints. Gentle exercises, such as swimming or walking on flat surfaces, are recommended because they are less stressful on your joints. Avoid activities that increase joint pain, such as jogging or high-impact aerobics. Exercises that strengthen the muscles reduce pain in patients with osteoarthritis, particularly with osteoarthritis of the knee.

What Medications Are Used to Treat Osteoarthritis?

The first step with medication is often over-the-counter pain relievers as needed. These include acetaminophen (Tylenol), ibuprofen (Advil, Motrin), and naproxen (Aleve). Don’t take over-the-counter medications for more than 10 days without checking with your doctor. Taking them longer than that increases the chance of side effects

Some medications in the form of creams, rubs, or sprays may be applied over the skin of affected areas to relieve pain. For some people with persistent pain despite these pills or creams, steroids can be injected directly into the joint. These injections can be given several times a year, though some experts believe this may ultimately accelerate joint damage.

Some medications in the form of creams, rubs, or sprays may be applied over the skin of affected areas to relieve pain. For some people with persistent pain despite these pills or creams, steroids can be injected directly into the joint. These injections can be given several times a year, though some experts believe this may ultimately accelerate joint damage.

When osteoarthritis pain is severe and other treatments are not working, some doctors will give stronger pain pills, such as narcotics.

Unfortunately, none of these will reverse or slow the progression of joint damage caused by osteoarthritis.

Acupuncture has also been shown to provide significant and immediate pain relief in some people with osteoarthritis.

There are several types of surgery for osteoarthritis

Arthroscopy to clean out the damaged cartilage or repair tissues

Joint replacement surgery to replace the damaged joint with an artificial one.

Joint fusion to remove the damaged joint and fuse the two bones on each side of the joint.

Rheumatoid Arthritis


The most serious side effect that can occur after influenza vaccination is an allergic reaction in people who have a severe allergy to eggs. For this reason, people who have an allergy to eggs should not receive the influenza vaccine.

Rheumatoid arthritis is a type of chronic arthritis that typically occurs in joints on both sides of the body (such as hands, wrists, or knees). This symmetry helps distinguish rheumatoid arthritis from other types of arthritis.

In addition to affecting the joints, rheumatoid arthritis may occasionally affect the skin, eyes, lungs, heart, blood, or nerves.

What Are the Symptoms of Rheumatoid Arthritis?

Symptoms of rheumatoid arthritis include:

Joint pain and swelling

Stiffness, especially in the morning or after sitting for long periods


Rheumatoid arthritis affects everyone differently. For some, joint symptoms develop gradually over several years. In others, rheumatoid arthritis may progress rapidly, while other people may have rheumatoid arthritis for a limited period of time and then enter a period of remission

What Causes Rheumatoid Arthritis?

The exact cause of rheumatoid arthritis is unknown, but it is thought to be due to a combination of genetic, environmental, and hormonal factors. With rheumatoid arthritis, something seems to trigger the immune system to attack the joints and sometimes other organs

How Is Rheumatoid Arthritis Treated?

There are many different ways to treat rheumatoid arthritis. Treatments include medications, rest and exercise, and surgery to correct damage to the joint.

The type of treatment will depend on several factors, including the person’s age, overall health, medical history, and severity of the arthritis

Drugs that offer relief of arthritis symptoms (joint pain, stiffness, and swelling) include:

Anti-inflammatory painkiller drugs, such as aspirin, ibuprofen, or naproxen

Topical (applied directly to the skin) pain relievers

Corticosteroids, such as prednisone

Narcotic pain relievers

A balance of rest and exercise is important in treating rheumatoid arthritis

When joint damage from rheumatoid arthritis has become severe or pain is not controlled with drugs, surgery may be an option to help restore function to a damaged joint

Degenerative Disc Disease

Degenerative disc disease is not really a disease but a term used to describe the normal changes in your spinal discs as you age. Spinal discs are soft, compressible discs that separate the interlocking bones (vertebrae) that make up the spine. The discs act as shock absorbers for the spine, allowing it to flex, bend, and twist. Degenerative disc disease can take place throughout the spine, but it most often occurs in the discs in the lower back (lumbar region) and the neck (cervical region).

How is it treated?

To relieve pain, put ice or heat (whichever feels better) on the affected area and use acetaminophen (such as Tylenol) or nonsteroidal anti-inflammatory drugs, including aspirin (such as Bayer), ibuprofen (such as Advil), or naproxen (such as Aleve). Do not give aspirin to anyone younger than 20 because of the risk of Reye syndrome. Acetaminophen (such as Tylenol) also can help relieve pain. Your doctor can prescribe stronger medicines if needed.

Further treatment depends on whether the damaged disc has resulted in other conditions, such as osteoarthritis, a herniated disc, or spinal stenosis. Physical therapy and exercises for strengthening and stretching the back are often recommended, and in some cases, surgery may be recommended.


Gout is a kind of arthritis. It can cause an attack of sudden burning pain, stiffness, and swelling in a joint, usually a big toe. These attacks can happen over and over unless gout is treated. Over time, they can harm your joints, tendons, and other tissues. Gout is most common in men.
Gout is caused by too much uric acid in the blood.

How is it treated?

To ease the pain during a gout attack, rest the joint that hurts. Taking ibuprofen or another anti-inflammatory medicine can also help you feel better. But don’t take aspirin. It can make gout worse by raising the uric acid level in the blood.

Paying attention to what you eat may help you manage your gout. Eat moderate amounts of a healthy mix of foods to control your weight and get the nutrients you need. Avoid regular daily intake of meat, seafood, and alcohol (especially beer). Drink plenty of water and other fluids.

Psoriatic Arthritis

Psoriatic arthritis is a form of inflammatory arthritis. Psoriasis is a skin disease that causes a red, scaly rash most commonly over the elbows, knees, ankles, feet, hands, and other areas.
How is psoriatic arthritis treated?
Treatment for psoriatic arthritis consists of twice-daily moist heat applications, exercises, and nonsteroidal anti-inflammatory drugs (NSAIDs).
Is there a cure for psoriatic arthritis?
There is no cure for psoriatic arthritis. But the use of biological agents has made remission a real possibility and goal of treatment.


Psoriatic arthritis is a form of inflammatory arthritis. Psoriasis is a skin disease that causes a red, scaly rash most commonly over the elbows, knees, ankles, feet, hands, and other areas.
How is psoriatic arthritis treated?
Treatment for psoriatic arthritis consists of twice-daily moist heat applications, exercises, and nonsteroidal anti-inflammatory drugs (NSAIDs).
Is there a cure for psoriatic arthritis?
There is no cure for psoriatic arthritis. But the use of biological agents has made remission a real possibility and goal of treatment.