What type of cartilage is found in synovial joints

During a human stride, the Achilles calcaneal tendon stretches as the ankle joint undergoes dorsiflexion. During the last portion of the stride, as the foot undergoes plantar flexion pointing the toes downward , the stored elastic energy is released. Because the tendon stretches, the muscle is able to function with less or even no change in length, allowing it to generate greater force. Certain joints exhibit special movements including elevation, depression, protraction, retraction, inversion, eversion, dorsiflexion, plantar flexion, supination, pronation, and opposition.

A number of factors influence joint stability. These include:. Typically, the more stable the joint is, the less is its range of motion and vice versa. Aging is another factor that influences motion due to decreased fluid, thinning of cartilage, shortening of ligaments, and loss of flexibility. A synovial joint, also known as a diarthrosis, is the most common and most movable type of joint in the body of a mammal.

Synovial joints achieve movement at the point of contact of the articulating bones. Structural and functional differences distinguish synovial joints from cartilaginous joints synchondroses and symphyses and fibrous joints sutures, gomphoses, and syndesmoses. Several movements may be performed by synovial joints.

Abduction is the movement away from the midline of the body. Adduction is the movement toward the middle line of the body. Extension is the straightening of limbs increase in angle at a joint. Flexion is bending the limbs reduction of angle at a joint.

Rotation is a circular movement around a fixed point. Body Movements I : Image demonstrating the various joint movements. There are six types of synovial joints. Some are relatively immobile but more stable than mobile joints. Others have multiple degrees of freedom, but at the expense of greater risk of injury. The six types of joints include:. Six Types of Synovial Joints : Image demonstrating the six different types of synovial joints. There are six different types of synovial joint based on their shapes, each allowing a different kind of movement.

There are six basic types of synovial joints. Anatomical joints may consist of a combination of two or more joint types. Some synovial joints are relatively immobile but stable. The types of the synovial joints are based on their shapes and can be classified as plane, hinge, pivot, condyloid, saddle, and ball-and-socket. The following descriptions are in ascending order of mobility:.

In this example, the condyles of the femur join with condyles of tibia and the saddle joint, where the lower end of the femur joins with the patella. Plane Joint : The left shoulder and acromioclavicular joints, and the proper ligaments of the scapula.

Ball and Socket Joint : Hip joint: the ball of the femur head fits in the socket of the acetabulum of the pelvis. Saddle Joint : Sternoclavicular articulation. Anterior view.

Privacy Policy. Skip to main content. Search for:. Synovial Joints. Structure of Synovial Joints A synovial joint or diarthrosis occurs at articulating bones to allow movement. Learning Objectives Identify the structures of the synovial joint that allow it to move freely. Key Takeaways Key Points The bones of a synovial joint are surrounded by a synovial capsule, which secretes synovial fluid to lubricate and nourish the joint while acting as a shock absorber. The ends of the joint bones are covered with smooth, glass-like hyaline cartilage which reduces friction during movement.

A synovial joint contains a synovial cavity and dense, irregular connective tissue that forms the articular capsule normally associated with accessory ligaments.

Key Terms articulation : A joint or the collection of joints at which something is articulated, or hinged, for bending. With its yolk-like consistency, its principal role is to reduce friction between the articular cartilage of synovial joints during movement. A major constituent of the embryonic and young vertebrate skeleton, converted largely to bone with maturation. Synoviocytes The intimal cells are termed synoviocytes and can be either fibroblastic type B synoviocytes and macrophagic type A synoviocytes.

Structure of Synovium The surface of a synovium may be flat or covered with finger-like projections villi to allow the soft tissue to change shape as the joint surfaces move on one another. Synovial Bursa The synovial bursa is a small, fluid-filled sac lined by synovial membrane containing synovial fluid.

Nerve and Blood Supply Synovial joints are highly innervated but vascularized indirectly by nearby tissues. In a hinge joint , the convex end of one bone articulates with the concave end of the adjoining bone see Figure 9. This type of joint allows only for bending and straightening motions along a single axis, and thus hinge joints are functionally classified as uniaxial joints. A good example is the elbow joint, with the articulation between the trochlea of the humerus and the trochlear notch of the ulna.

Other hinge joints of the body include the knee, ankle, and interphalangeal joints between the phalanges of the fingers and toes.

At a condyloid joint ellipsoid joint , the shallow depression at the end of one bone articulates with a rounded structure from an adjacent bone or bones see Figure 9. The knuckle metacarpophalangeal joints of the hand between the distal end of a metacarpal bone and the proximal phalanx are condyloid joints. Another example is the radiocarpal joint of the wrist, between the shallow depression at the distal end of the radius bone and the rounded scaphoid, lunate, and triquetrum carpal bones.

In this case, the articulation area has a more oval elliptical shape. Functionally, condyloid joints are biaxial joints that allow for two planes of movement. One movement involves the bending and straightening of the fingers or the anterior-posterior movements of the hand. The second movement is a side-to-side movement, which allows you to spread your fingers apart and bring them together, or to move your hand in a medial or lateral direction.

At a saddle joint , both of the articulating surfaces for the bones have a saddle shape, which is concave in one direction and convex in the other see Figure 9. This allows the two bones to fit together like a rider sitting on a saddle.

Saddle joints are functionally classified as biaxial joints. The primary example is the first carpometacarpal joint, between the trapezium a carpal bone and the first metacarpal bone at the base of the thumb. This joint provides the thumb the ability to move away from the palm of the hand along two planes. Thus, the thumb can move within the same plane as the palm of the hand, or it can jut out anteriorly, perpendicular to the palm. The sternoclavicular joint is also classified as a saddle joint.

At a plane joint gliding joint , the articulating surfaces of the bones are flat or slightly curved and of approximately the same size, which allows the bones to slide against each other see Figure 9. The motion at this type of joint is usually small and tightly constrained by surrounding ligaments.

Based only on their shape, plane joints can allow multiple movements, including rotation and can be functionally classified as a multiaxial joint. However, not all of these movements are available to every plane joint due to limitations placed on it by ligaments or neighboring bones. Depending upon the specific joint of the body, a plane joint may exhibit movement in a single plane or in multiple planes. Plane joints are found between the carpal bones intercarpal joints of the wrist or tarsal bones intertarsal joints of the foot, between the clavicle and acromion of the scapula acromioclavicular joint , and between the superior and inferior articular processes of adjacent vertebrae zygapophysial joints.

The joint with the greatest range of motion is the ball-and-socket joint. At these joints, the rounded head of one bone the ball fits into the concave articulation the socket of the adjacent bone see Figure 9. The hip joint and the glenohumeral shoulder joint are the only ball-and-socket joints of the body. At the hip joint, the head of the femur articulates with the acetabulum of the hip bone, and at the shoulder joint, the head of the humerus articulates with the glenoid cavity of the scapula.

Ball-and-socket joints are classified functionally as multiaxial joints. The femur and the humerus are able to move in both anterior-posterior and medial-lateral directions and they can also rotate around their long axis.

The shallow socket formed by the glenoid cavity allows the shoulder joint an extensive range of motion. In contrast, the deep socket of the acetabulum and the strong supporting ligaments of the hip joint serve to constrain movements of the femur, reflecting the need for stability and weight-bearing ability at the hip.

Watch this video to see an animation of synovial joints in action. Synovial joints are places where bones articulate with each other inside of a joint cavity. The different types of synovial joints are the ball-and-socket joint shoulder joint , hinge joint knee , pivot joint atlantoaxial joint, between C1 and C2 vertebrae of the neck , condyloid joint radiocarpal joint of the wrist , saddle joint first carpometacarpal joint, between the trapezium carpal bone and the first metacarpal bone, at the base of the thumb , and plane joint facet joints of vertebral column, between superior and inferior articular processes.

Which type of synovial joint allows for the widest range of motion? 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. These factors put stress on the articular cartilage that covers the surfaces of bones at synovial joints, causing the cartilage to gradually become thinner.

As the articular cartilage layer wears down, more pressure is placed on the bones. The joint responds by increasing production of the lubricating synovial fluid, but this can lead to swelling of the joint cavity, causing pain and joint stiffness as the articular capsule is stretched.

The bone tissue underlying the damaged articular cartilage also responds by thickening, producing irregularities and causing the articulating surface of the bone to become rough or bumpy. Joint movement then results in pain and inflammation. In individuals with more advanced osteoarthritis, the affected joints can become more painful and therefore are difficult to use effectively, resulting in increased immobility.

There is no cure for osteoarthritis, but several treatments can help alleviate the pain. Treatments may include lifestyle changes, such as weight loss and low-impact exercise, and over-the-counter or prescription medications that help to alleviate the pain and inflammation.

For severe cases, joint replacement surgery arthroplasty may be required. Joint replacement is a very invasive procedure, so other treatments are always tried before surgery. However arthroplasty can provide relief from chronic pain and can enhance mobility within a few months following the surgery. This type of surgery involves replacing the articular surfaces of the bones with prosthesis artificial components. For example, in hip arthroplasty, the worn or damaged parts of the hip joint, including the head and neck of the femur and the acetabulum of the pelvis, are removed and replaced with artificial joint components.

The replacement head for the femur consists of a rounded ball attached to the end of a shaft that is inserted inside the diaphysis of the femur.

The acetabulum of the pelvis is reshaped and a replacement socket is fitted into its place. The parts, which are always built in advance of the surgery, are sometimes custom made to produce the best possible fit for a patient. Gout is a form of arthritis that results from the deposition 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 may 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. Other forms of arthritis are associated with various autoimmune diseases, bacterial infections of the joint, or unknown genetic causes.

Autoimmune diseases, including rheumatoid arthritis, scleroderma, or systemic lupus erythematosus, produce arthritis because the immune system of the body attacks the body joints. In rheumatoid arthritis, the joint capsule and synovial membrane become inflamed. As the disease progresses, the articular cartilage is severely damaged or destroyed, resulting in joint deformation, loss of movement, and severe disability.

The most commonly involved joints are the hands, feet, and cervical spine, with corresponding joints on both sides of the body usually affected, though not always to the same extent. Rheumatoid arthritis is also associated with lung fibrosis, vasculitis inflammation of blood vessels , coronary heart disease, and premature mortality.

With no known cure, treatments are aimed at alleviating symptoms. Exercise, anti-inflammatory and pain medications, various specific disease-modifying anti-rheumatic drugs, or surgery are used to treat rheumatoid arthritis. Visit this website to learn about a patient who arrives at the hospital with joint pain and weakness in his legs.

Watch this animation to observe hip replacement surgery total hip arthroplasty , which can be used to alleviate the pain and loss of joint mobility associated with osteoarthritis of the hip joint. The water component of synovial fluid is effectively trapped in the joint space by the hyaluronan due to its large, highly negatively charged moieties.

The macrophages are responsible for the removal of undesirable substances from the synovial fluid. The surface of a synovium may be flat or covered with finger-like projections villi to allow the soft tissue to change shape as the joint surfaces move on one another. Just beneath the intima, most synovia have a dense net of small blood vessels that provide nutrients for the synovia and the avascular cartilage.

In any one position, much of the cartilage is close enough to get nutrition directly from the synovium. Some areas of cartilage have to obtain nutrients indirectly and may do so either from diffusion through cartilage or by the stirring of synovial fluid. The synovial bursa is a small, fluid-filled sac lined by synovial membrane containing synovial fluid. Learning Objectives Identify the structures of the synovial joint that allow it to move freely.

Key Points The bones of a synovial joint are surrounded by a synovial capsule, which secretes synovial fluid to lubricate and nourish the joint while acting as a shock absorber.

The ends of the joint bones are covered with smooth, glass-like hyaline cartilage which reduces friction during movement. A synovial joint contains a synovial cavity and dense, irregular connective tissue that forms the articular capsule normally associated with accessory ligaments. Key Terms articulation : A joint or the collection of joints at which something is articulated, or hinged, for bending. With its yolk-like consistency, its principal role is to reduce friction between the articular cartilage of synovial joints during movement.