This is also sometimes called an ellipsoidal joint. This type of joint allows angular movement along two axes, as seen in the joints of the wrist and fingers, which can move both side to side and up and down.
Condyloid : The metacarpophalangeal joints in the finger are examples of condyloid joints. Each bone in a saddle joint resembles a saddle, with concave and convex portions that fit together.
Saddle joints allow angular movements similar to condyloid joints, but with a greater range of motion. An example of a saddle joint is the thumb joint, which can move back and forth and up and down; it can move more freely than the wrist or fingers. Ball-and-socket joints possess a rounded, ball-like end of one bone fitting into a cup-like socket of another bone. This organization allows the greatest range of motion, as all movement types are possible in all directions.
Examples of ball-and-socket joints are the shoulder and hip joints. Rheumatologists are medical doctors who specialize in the diagnosis and treatment of disorders of the joints, muscles, and bones.
They diagnose and treat diseases such as arthritis, musculoskeletal disorders, osteoporosis, and autoimmune diseases such as ankylosing spondylitis and rheumatoid arthritis. Rheumatoid arthritis RA is an inflammatory disorder that primarily affects the synovial joints of the hands, feet, and cervical spine.
Affected joints become swollen, stiff, and painful. Immune cells from the blood enter joints and the synovium, causing cartilage breakdown, swelling, and inflammation of the joint lining. Breakdown of cartilage results in bones rubbing against each other, causing pain. RA is more common in women than men; the age of onset is usually 40—50 years of age.
Ball-and-socket : The shoulder joint is an example of a ball-and-socket joint. Rheumatologists diagnose RA on the basis of symptoms joint inflammation and pain , X-ray and MRI imaging, and blood tests. Arthrography, a type of medical imaging of joints, uses a contrast agent, such as a dye, that is opaque to X-rays. This allows the soft tissue structures of joints, such as cartilage, tendons, and ligaments, to be visualized. An arthrogram differs from a regular X-ray by showing the surface of soft tissues lining the joint in addition to joint bones.
An arthrogram allows early degenerative changes in joint cartilage to be detected before bones become affected. There is currently no cure for RA; however, rheumatologists have a number of treatment options available.
Early stages can be treated by resting the affected joints, using a cane or joint splints, to minimize inflammation. When inflammation has decreased, exercise can be used to strengthen the muscles that surround the joint in order to maintain joint flexibility.
If joint damage is more extensive, medications can be used to relieve pain and decrease inflammation. Anti-inflammatory drugs such as aspirin, topical pain relievers, and corticosteroid injections may be used. Surgery may be required in cases in which joint damage is severe.
Synovial joints are the most common type of joint in the body. A key structural characteristic for a synovial joint that is not seen at fibrous or cartilaginous joints is the presence of a joint cavity.
Arthritis is a common disorder of synovial joints that involves inflammation of the joint. This often results in significant joint pain, along with swelling, stiffness, and reduced joint mobility.
There are more than different forms of arthritis. Arthritis may arise from aging, damage to the articular cartilage, autoimmune diseases, bacterial or viral infections, or unknown probably genetic causes. Arthritis is the most common cause of disability in the USA. More than 20 million individuals with arthritis have severe limitations in function on a daily basis. Risk factors that may lead to osteoarthritis later in life include injury to a joint; jobs that involve physical labor; sports with running, twisting, or throwing actions; and being overweight.
Osteoarthritis begins in the cartilage and eventually causes the two opposing bones to erode into each other. Osteoarthritis typically affects the weight-bearing joints, such as the back, knee and hip. There is no cure for osteoarthritis, but several treatments surgery, lifestyle changes, medications can help alleviate the pain.
Gout is a form of arthritis that results from the deposit of uric acid crystals within a body joint. Usually only one or a few joints are affected, such as the big toe, knee, or ankle. The attack may only last a few days, but could return to the same or another joint. Gout occurs when the body makes too much uric acid or the kidneys do not properly excrete it. A diet with excessive fructose has been implicated in raising the chances of a susceptible individual developing gout.
Gout : Gout presenting in the metatarsal-phalangeal joint of the big toe: Note the slight redness of the skin overlying the joint. Amphiarthroses allow only slight movement; therefore, either type of cartilaginous joint is an amphiarthrosis.
Synovial joints are the only joints that have a space between the adjoining bones. This space, referred to as the synovial or joint cavity, is filled with synovial fluid. Synovial fluid lubricates the joint, reducing friction between the bones and allowing for greater movement. The ends of the bones are covered with articular cartilage, a hyaline cartilage. The entire joint is surrounded by an articular capsule composed of connective tissue. This allows movement of the joint as well as resistance to dislocation.
Articular capsules may also possess ligaments that hold the bones together. Synovial joints are capable of the greatest movement of the three structural joint types; however, the more mobile a joint, the weaker the joint. Knees, elbows, and shoulders are examples of synovial joints. Since they allow for free movement, synovial joints are classified as diarthroses. Depending on the type of cartilage involved, the joints are further classified as primary and secondary cartilaginous joints.
Primary cartilaginous joints, also known as synchondroses, only involve hyaline cartilage. These joints may be slightly mobile amphiarthroses or immobile synarthroses. The joint between the epiphysis and diaphysis of growing long bones is an example. The secondary cartilaginous joint, also known as symphysis, may involve either hyaline or fibrocartilage. These joints are slightly mobile amphiarthroses. A classic example is a pubic symphysis. Synovial joints are freely mobile diarthroses and are considered the main functional joints of the body.
Its joint cavity characterizes the synovial joint. An example of this type of joint is the cartilaginous joint that unites the bodies of adjacent vertebrae. Filling the gap between the vertebrae is a thick pad of fibrocartilage called an intervertebral disc Figure 9.
Each intervertebral disc strongly unites the vertebrae but still allows for a limited amount of movement between them. However, the small movements available between adjacent vertebrae can sum together along the length of the vertebral column to provide for large ranges of body movements. Another example of an amphiarthrosis is the pubic symphysis of the pelvis. This is a cartilaginous joint in which the pubic regions of the right and left hip bones are strongly anchored to each other by fibrocartilage.
This joint normally has very little mobility. The strength of the pubic symphysis is important in conferring weight-bearing stability to the pelvis. During pregnancy, increased levels of the hormone relaxin lead to increased mobility at the pubic symphysis which allows for expansion of the pelvic cavity during childbirth. This functional classification of joints describes all synovial joints of the body, which provide the majority of body movements.
Most diarthrotic joints are found in the appendicular skeleton and give the limbs a wide range of motion. These joints are divided into three categories, based on the number of axes of motion provided by each. An axis in anatomy is described as the movements in reference to the three anatomical planes: transverse, frontal, and sagittal.
Thus, diarthroses are classified as uniaxial, biaxial, or multiaxial joints. A uniaxial joint only allows for a motion in a single plane around a single axis. The elbow joint, which only allows for bending or straightening, is an example of a uniaxial joint. A biaxial joint allows for motions within two planes. An example of a biaxial joint is a metacarpophalangeal joint knuckle joint of the hand.
The joint allows for movement along one axis to produce bending or straightening of the finger, and movement along a second axis, which allows for spreading of the fingers away from each other and bringing them together. A joint that allows for the several directions of movement is called a multiaxial joint sometimes called polyaxial or triaxial joint. This type of diarthrotic joint allows for movement along three axes Figure 9. The shoulder and hip joints are multiaxial joints.
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