A&P Chapter 8: Joints

Cartilaginous joint: symphyses

(growing together), articular cartilage fused to an intervening pad or plate of fibrocartilage, fibrocartilage is compressible + resilient & acts as a shock absorber + permits a limited amount of movement at the joint, are amphiarthrotic joints designed for strength & flexibility. Example: 1. Intervertebral joints of the spinal column 2. Pubic symphysis of the pelvis.

Cartilaginous joint: synchondroses

(junction of cartilage), bar or plate of hyaline cartilage unites the bones, are synarthrotic (immovable joints) Example: 1. The epiphyseal plate connecting the diaphysis &epiphysis regions in long bones of children. 2. The costal cartilage of the first rib & the manubrium of the sternum.

Fibrous joint: gomphoses

(peg-in-socket joint), the fibrous tissue is the periodontal ligament. Example: Joint of a tooth with its bony alveolar socket.

Arthritis

- describes more than 100 different inflammatory or degenerative diseases that damage the joints, resulting in pain, stiffness, & swelling of the joint. - acute forms of arthritis usually result from bacterial invasion & are treated with antibiotics. - the synovial membrane thickens & fluid production decreases, causing increased friction & pain. - chronic forms of arthritis include osteoarthritis, rheumatoid arthritis, & gouty arthritis.

Movement of synovial joints: angular movements

angular movements increase or decrease the angle between two bones. They include: a.Flexion b.Extension c.Dorsiflexion d.Plantar flexion e.Abduction f.Adduction g.Circumduction

Synovial joints: plane joints

are the only examples of nonaxial(limited movement) joints. They have flat articular surfaces & allow gliding movements.

Functional classification of joints

based on the amount of movement allowed at the joint.

Structural classification of joints

based on the material binding the bones together & whether or not a joint cavity is present.

Cartilage injuries

description + injury sites: Although most cartilage injuries involve tearing of the knee menisci, overuse damage to the articular cartilages of other joints is becoming increasingly common in competitive athletes. healing: Cartilage is avascular and it cannot obtain sufficient nourishment to repair itself; thus, it usually stays torn. Cartilage fragments (called loose bodies) can interfere with joint function by causing the joint to lock or bind

Sprains

description: In a sprain, the ligaments or tendons reinforcing a joint are damaged by excessive stretching, or they are torn away from the bone. healing: Since both tendons & ligaments are cords of dense fibrous connective tissue with a poor blood supply, sprains heal slowly & are extremely painful. common sprain sites: The lumbar region of the spine, the ankle, & the knee

Diarthroses

freely movable joints

Synovial joints

freely movable, bones separated by fluid-containing joint cavity

Fibrous joint: sutures

made of short connective tissue fibers, immovable joints (seam-like) Example: Between bones of the skull

Fibrous joint: syndesmoses

made up of ligaments (cords/bands of fibrous tissue), fibers vary in length (are longer than those of sutures), slightly moveable (The amount of movement allowed depends on the length of the connecting fibers.) Example: Joint connecting the distal ends of the tibia & fibula

Knee joint: ligaments

many different types of ligaments stabilize and strengthen the capsule of the knee joint.

Cartilaginous joints

may be immovable or slightly movable, bones joined by cartilage, lack a joint cavity

Meniscus of the knee joint

medial meniscus lateral meniscus

Joints/articulations definition

sites where two or more bones meet. Joints give our skeleton mobility & hold it together

Amphiarthroses

slightly movable joints

Shoulder joints: movement

stability has been sacrificed to provide the most freely moving joint in the body.

Supination and pronation

supination: rotating the forearm laterally so that the palm faces anteriorly or superiorly. pronation: rotating the arm medially so that the palm faces posteriorly or inferiorly. In the anatomical position, the hand is supinated and the radius and ulna are parallel.

Bursae of the knee joint

suprapatellar bursae subcutaneous prepatellar bursae deep infrapatellar bursae

Osteoarthritis: systems, regions affected, prognosis

symptoms: The affected joints may make a crunching noise, called crepitus, as they move & the roughened articular surfaces rub together. regions frequently affected: The joints most often affected are those of the cervical & lumbar spine & the fingers, knuckles, knees, & hips. prognosis: Slow and irreversible progression, can be controlled with pain relievers & moderate activity to keep the joints mobile.

Synovial joints description

synovial joints (synovi-joint egg) are those in which the articulating bones are separated by a fluid-containing joint cavity, this arrangement permits substantial freedom of movement, & all synovial joints are freely movable diarthroses. Example: All joints of the limbs.

Elbow joints: tendons

tendons of several arm muscles, the biceps and the triceps, also provide additional stability by crossing the elbow joint.

Temporomandibular joint: characteristics

the joint contains an articular disc that divides the synovial cavity into compartments that support each type of movement.

Knee joint: tendons

the knee capsule is reinforced by muscle tendons such as the strong tendons of the quadriceps muscles & the tendon of the semimembranosus.

Temporomandibular joint: ligaments

the lateral aspect of the fibrous capsule contains a lateral ligament that reinforces the joint.

Elbow joint: ligaments

the ligaments involved in providing stability to the elbow joint are the annular ligament, the ulnar collateral ligament, and the radial collateral ligament.

Elbow joint: movement

provides a stable and smoothly operating hinge joint that allows flexion and extension only.

Tendons of the knee joint

quadriceps femoris tendon semimembranous muscle tendon

Hip joint: ligaments

several strong ligaments reinforce the capsule of the hip joint. 1. iliofemoral between the iliac and femur bones 2. Ischiofemoral between the ischium and femur bones 3. Pubofemoral between the pubis and femur bones

Rheumatoid arthritis: internal symptoms

- inflammatory cells (lymphocytes, & neutrophils) migrate into the joint cavity from the blood & release excessive amounts of inflammatory chemicals, destroying body tissues. - synovial fluid accumulates, causing joint swelling & gradually, the inflamed synovial membrane thickens into a pannus, an abnormal tissue that clings to the articular cartilages. - the pannus erodes the cartilage & the underlying bone & forms scar tissue & connects the bone ends. Later this scar tissue ossifies & the bone ends fuse together, immobilizing the joint. This end condition, called ankylosis ("stiff condition"), often produces bent, deformed fingers. - not all cases of RA progress to the severely crippling ankylosis stage, but all cases do involve restriction of joint movement and extreme pain.

Stability of Synovial joints

1. articular surfaces - The shapes of the articular surfaces of bones found at a synovial joint determine the movements that occur at the joint, but play a minimal role in stabilizing the joint. Many joints have shallow sockets or noncomplementary articulating surfaces ("misfits"), but when articular surfaces are large & fit snugly together, or when the socket is deep, stability is vastly improved. Example: Hip joint 2. ligaments - Ligaments at a synovial joint prevent excessive or unwanted movements & help to stabilize the joint; the greater the number of ligaments at the joint the greater the stability. 3. muscle tone - Muscle tone keeps tendons crossing joints taut, which is the most important factor stabilizing joints

Hip joints: tendons

The muscle tendons that cross the joint contribute to the stability and strength of the joint, but the majority of the stability of the hip joint is due to the deep socket of the acetabulum and the ligaments.

Joint(synovial) cavity of synovial joint

a space that is filled with synovial fluid.

Abduction, adduction, circumduction

abduction: movement of a limb (or fingers) away from the midline body (or of the hand). adduction: movement of a limb (or fingers) toward the midline of the body (or the hand). circumduction: moving a limb so that it describes a cone in the air

Gouty arthritis: age/gender affected, prognosis/treatment

age/gender affected: Gout is far more common in males than in females because males naturally have higher blood levels of uric acid (estrogens increase the rate of its excretion). Because gout seems to run in families, genetic factors are definitely implicated. prognosis/treatment: Untreated gout can be very destructive; the articulating bone ends fuse & immobilize the joint. Several drugs to prevent or terminate gout attacks are available. Patients should drink plenty of water, avoid alcohol consumption, & foods with high purine content such as liver, kidneys, & sardines.

Rheumatoid arthritis: age/gender affected, regions affected, prognosis

age/gender affected: Usually arises between the ages of 30 & 50, but may occur at any age. It affects 3 times as many women as men. regions frequently affected: Many joints, particularly the small joints of the fingers, wrists, ankles, & feet, are afflicted at the same time & bilaterally. For example, if the right elbow is affected, most likely the left elbow is also affected. prognosis/treatment: A wonder drug for RA sufferers is still undiscovered. Current RA therapy includes pain killers like aspirin, anti-inflammatory drugs, long-term antibiotic therapy, physical therapy & progressive treatment course using immunosuppressants. Joint prostheses, if available, are the last resort for severely crippled RA patients.

Gouty arthritis: cause, symptoms, internal symptoms

cause: Results when uric acid is deposited in the soft tissues of the joints. symptoms: An inflammatory response follows, leading into an agonizingly painful attack of gouty arthritis, or gout. The initial attack typically affects one joint, often at the base of the great toe. internal symptoms: Uric acid, a normal waste product of nucleic acid metabolism, is ordinarily excreted in urine without any problems. However, when blood levels of uric acid rise excessively (due to its excessive production or slow excretion), it may be deposited as needle-shaped urate crystals in the soft tissues of joints.

Synovial joints: hinge joints

consist of a cylindrical projection that nests in a trough-shaped structure, & allow movement along a single plane. These uniaxial(permit movement along one axis) joints permit flexion & extension only.

Synovial joints: pivot joints

consist of a rounded structure that protrudes into a sleeve or ring, & allow uniaxial rotation of a bone around its own long axis. Example is the joint between the atlas & dens of the axis, which allows you to move your head from side to side to indicate "no."

Synovial joints: ball-and-socket joints

consist of a spherical or hemispherical structure that articulates with a cuplike structure. They are the most freely moving joints & allow multiaxial movements (that is, in all axes and planes, including rotation). Examples: Shoulder & hip joints.

Synovial joints: condyloid/ellipsoid joints

consist of an oval articular surface that nests in a complementary depression, & permit all angular movements. These biaxial joints permit all angular motions - flexion & extension, abduction & adduction, & circumduction. Examples: Radiocarpal (wrist) joints & the metacarpophalangeal (knuckle) joints.

Synovial joints: saddle joints

consist of each articular surface bearing complementary concave & convex areas. These biaxial joints allow more freedom of movement than condyloid joints. Examples: Carpometacarpal joints of the thumbs, & the movements allowed by these joints are clearly demonstrated by twiddling your thumbs.

Reinforcing ligaments of synovial joint

cross synovial joints to strengthen the joint.

Bursitis

description: Inflammation of the bursa, may be caused by a blow or friction common injury locations: For example, falling on one's knee can cause a painful bursitis, called "water on the knee," due to inflammation of bursae or synovial membrane. Prolonged leaning on one's elbows may damage the bursa close to the olecranon process, producing student's elbow, or olecranon bursitis. healing: Severe cases are treated by injecting anti-inflammatory drugs into the bursa. If excessive fluid accumulates, removing some fluid by needle aspiration may relieve the pressure.

Rheumatoid arthritis: description, symptoms

description: It is an autoimmune disease in which the body's immune system attacks its own tissues. symptoms: In the early stages of RA, joint tenderness & stiffness are common. RA begins with inflammation of the synovial membrane of the affected joints. RA may include anemia, osteoporosis, muscle atrophy, & cardiovascular problems.

Osteoarthritis: description, cause, age/gender

description: It is the most common slow & irreversible form of chronic arthritis. It is rarely crippling. cause: It is the result of breakdown of articular cartilage & subsequent thickening of bone tissue forming bone spurs, which may restrict joint movement. age/gender affected: OA is most prevalent in the aged (more in women) and is probably related to the normal aging process (sometimes seen in younger people & may be genetic)

Dislocations

description: Occurs when bones are forced out of alignment. It is usually accompanied by sprains, inflammation, & joint immobilization. common injury locations: Dislocations may result from serious falls & are common contact sports injuries. Commonly dislocated regions - Joints of the jaw, shoulders, fingers, & thumbs. healing/repeat occurrences: Repeat dislocations of the same joint are common because the initial dislocation stretches the joint capsule & ligaments. The resulting loose capsule provides poor reinforcement for the joint.

Dorsiflexion and Plantar Flexion

dorsiflexion: decreases the angle between the top of the foot(dorsal surface) & the anterior surface of the tibia. plantar flexion: decreases the angle between the sole of the foot (plantar surface) & the posterior side of the tibia.

Elevation and depression

elevation: lifting a body part superiorly. depression: to move an elevated body part inferiorly.

Knee joint: characteristics

enclosed in one joint cavity, the knee joint is actually three joints in one: 1. femoropatellar joint (an intermediate one between the patella and the lower end of the femur) 2. lateral tibiofemoral joint between the femoral condyles and the menisci of the tibia (located laterally) 3. medial tibiofemoral joint between the femoral condyles, and the menisci of the tibia (located medially).

Articular capsule of synovial joint

encloses the joint cavity. The external layer is composed of dense irregular fibrous connective tissue capsule, that is continuous with the periostea of the articulating bones. It strengthens the joint so that the bones are not pulled apart. The inner layer is a synovial membrane composed of loose connective tissue. It lines the fibrous capsule internally & covers all internal joint surfaces that are not hyaline cartilage.

Flexion and extension

flexion: decreases the angle of the joint & brings the articulating bones closer together. extension: increases the angle between the articulating bones.

Synarthroses

immovable joints

Fibrous joints

immovable joints, bones joined by fibrous tissue, lack a joint cavity

Movements of the synovial joints: special movements

include: a.Supination b.Pronation c.Inversion d.Eversion e.Protraction f. Retraction g.Elevation h.Depression i. Opposition

Tendonitis

inflammation of the tendon sheaths, & is usually caused by overuse.

Inversion and eversion

inversion: turns the sole of the foot so that it faces medially. eversion: turns the sole of the foot so that it faces laterally.

A common knee injury

involves separating the femur from the tibia medially, such blows to the lateral side tear both the tibial collateral ligament and the medial meniscus because the two are attached. The anterior cruciate ligament also tears.

Hip joint: movements

is a ball-and-socket joint that provides a good range of motion.

Synovial fluid of synovial joint

is a viscous, slippery fluid that fills all free space within the joint cavity. This fluid is derived largely by filtration from blood flowing through the capillaries in the synovial membrane. It has a viscous, egg-white consistency due to hyaluronic acid (proteoglycan) secreted by cells in the synovial membrane, but it thins, becoming less viscous, as it warms during joint activity.

Temporomandibular joint: movement

joint allows both hinge-like movement and side-to-side lateral excursion.

Knee joint: movement

largest and most complex joint in the body. It allows extension, flexion, and some rotation.

Bursae and tendon sheaths of synovial joints

not part of synovial joints, but they are often found closely associated with them. They are bags of lubricant that reduce friction at synovial joints.

Opposition

occurs when you touch your thumb to the fingers on the same hand.

Movement of synovial joints: gliding

one flat, or nearly flat, bone surface glides or slips over another.

Types of synovial joints

plane, hinge, pivot, condyloid, saddle, ball and socket

Protraction and retraction

protraction: moves the mandible anteriorly, juts the jaw forward. retraction: returns the mandible to its original position

Shoulder joints: ligaments

the ligaments that help to reinforce the shoulder joint are the coracohumeral ligament and the three glenohumeral ligaments.

Shoulder joints: tendons

the tendons that cross the shoulder joint and provide the most stabilizing effect on the joint are the tendon of the long head of the biceps brachii and the four tendons that make up the rotator cuff.

Articular cartilage of synovial joint

thin, glassy-smooth hyaline cartilage covers the ends of the articulating bones. Its spongy cushions absorb compression placed on the joint & prevent the bone ends from being crushed.

Ligaments of the knee joint

tibial collateral ligament fibular collateral ligament anterior cruciate ligament posterior cruciate ligament patellar ligament oblique popliteal ligament arcuate popliteal ligament

Movements of the synovial joints: rotation

turning of a bone along its own long axis