Joints (Chp 8)

Osteoarthritis

-chronic degenerative condition-more cartilage gets destroyed than replaced. -most common. -more prevalent in the aged -wear and tear -cumulative effects of years of compression and abrasion on acting joint surfaces -results in eroded articular cartilages -joins most often affected are cervical and lumbar spine, fingers, knuckles, knees hips. -slow course and irreversible -pain reliever and moderate activity -more common in women

Rheumatoid Arthritis

-chronic inflammatory disorder-autoimmune disease:the body's immune system attacks its own tissues. -joints in the fingers, wrists, ankles and feet effected at the same time and bilaterally. -flare ups and remissions -anemia, osteoporosis, muscle weakness, cardiovascular problems -inflammation of synovial membrane -synovial fluid accumulates which causes joint swelling -over time the inflamed synovial membrane thickens into a pannus which erodes the cartilage. eventually scar tissue forms and connects the bone ends which eventually immobilizes the joint: ankylosis -more common in women

Lyme disease

-inflammatory disease -caused by spirochete bacteria transmitted by the bite of ticks that live on mice and deer -results in joint pain and arthritis -seen most in knees -skin rash, flu-like symptoms, foggy thinking

Factors influencing the stability of synovial joints

Articular surfaces and their shape. The larger and deeper the socket, the more stability offered. Ex-hip joint Ligaments-prevent excessive motion. the more ligaments the stronger the joint. Muscle tone-muscle tendons are kept under tension by muscle tone.

Synovial Joints

Articulating bones are separated by a fluid-containing joint cavity. Permits substantial freedom of movement. All synovial joints are freely movable diarthroses with six distinguishing features: Articular cartilage: hyaline cartilage covering opposing bone surfaces. Thin and spongy cushions. Absorb compression placed on the joint keeping the bone ends from crushing. Joint cavity: space containing synovial fluid Articular capsule: Encloses the joint cavity. Two layers: external Fibrous Layer composed of dense irregular connective tissue continuous with the periosteum. Strengthens the joint. Inner layer is the Synovial Membrane- loose connective tissue that lines the fibrous layer internally and covers all internal joint surfaces that aren't hyaline cartilage. Makes synovial fluid. Synovial fluid: Occupies all free spaces within the joint capsule. Derived by filtration from blood flowing through the capillaries in the synovial membrane. Viscous due to hyaluronic acid secreted by cells. Reduces friction between cartilages. Fluid is forced from the cartilages when the joint is compressed, then as pressure is relieved it goes back to the cartilages like a sponge (weeping lubrication). Also nourishes cartilage cells since it is avascular. Also has phagocytic cells. Reinforcing Ligaments: reinforce and strengthen the joint. Capsular ligaments: thickened parts of the fibrous layer. Nerves and blood vessels: Sensory nerve fibers that detect pain or monitor joint position and stretch. Monitoring joint stretch is a way our nervous system senses our posture and body movements. Blood vessels supply the synovial membrane and produce blood filtrate of synovial fluid.

Bursae and tendon sheaths

Bags of lubricant that reduce friction between structures during joint activity. Bursae: Flattened fibrous sacs lined with synovial membrane and containing synovial fluid. Occur where ligaments, muscles, skin, tendons or bones rub together. Tendon sheath: an elongated bursa that wraps completely around a tendon subjected to friction. Common where several tendons are crowded together in narrow canals.

Shoulder (Glenohumeral) joint

Ball and socket. Free moving. Glenoid labrum-fibrocartilage that deepens the rim of the glenoid cavity Articular capsule is thin and loose-provides freedom of movement. Ligaments: Coracohumeral ligament: provides the only strong thickening of the capsule. Helps support the weight of the upper limb. Between the coracoid process and the humerus. Glenohumeral ligaments (3): strengthen the front of the articular capsule. Muscle tendons contribute most to the joint's stability. Rotator cuff: made of four tendons and associated muscles. Encircles the joint and blends with the articular capsule.

Hip joint

Ball and socket. Movements in all planes. Head of femur in acetabulum of hip. Acetabular labrum-circular rim of fibrocartilage-enhances the depth of the acetabulum Articular capsule completely encloses the joint. Ligaments reinforce the capsule of the hip joint and screw the femur head into the acetabulum: Iliofemoral ligament-V shaped-between head of femur and ilium. Pubofemoral ligament-triangular Ischiofemoral ligament-spiraling Ligament of the head of the femur:flat intracapsular band that runs from the femur head to the acetabulum. Contains an artery that helps supply the head of the femur.

Cartilaginous joints

Bones are united by cartilage. No joint cavity. Not highly movable (amphiarthroses). Two types: Synchondroses and Symphyses. Synchondroses: Junction of cartilage. Bar or plate of hyaline cartilage uniting bones. All are synarthrotic (immovable). Ex-epiphyseal plates in long bones of children. Symphyses: Joint where fibrocartilage unites the bones. Compressible and resilient and acts as a shock absorber and permits a limited amount of movement in the joint. Hyaline cartilage is also present in the form of articular cartilage. Ex-intervertebral joints and the pubic symphysis of the pelvis.

Three general types of movements

Gliding: occurs when one flat or nearly flat bone surface glides or slips over another without appreciable angulation or rotation. Occurs at the intercarpal and intertarsal joints and between the flat articular processes of the vertebrae Angular: Increase or decrease the angle between two bones. Flexion, extension, hyperextension, abduction, adduction and circumduction. Rotation: Turning of a bone around its own long axis. Only movement allowed between the first two cervical vertebrae. Common at the hip and shoulder joints.

Fibrous joints

Joined by collagen fibers of connective tissue. No joint cavity is present. Most are immovable (synarthroses).Three types: Sutures, Syndesmoses, Gomphoses. Sutures: Seams. Occur only between bones of the skull. Short connective tissue fibers continuous with the periosteum. At middle age the fibrous tissue ossifies and the bones fuse into a single unit. The sutures are then called synostoses (bone junctions). Immovable to protect the brain. Syndesmoses: Ligaments. Bones connected by ligaments, cords or bands of fibrous tissue. Amount of movement allowed depends on the length of the connecting fibers. Ex-ligament connecting fibula and tibia allows no movement. Gomphoses: Peg-in-socket fibrous joint. Ex-tooth in a bony alveolar socket, fibrous connection is short periodontal ligament.

Knee joints

Largest and most complex joint Three joints: Femoropatellar-between the patella and lower end of the femur. Plane joint. Patella glides across the femur during flexion. Tibiofemoral-between the femoral condyles. acts as a hinge. flexion and extension. bicondylar joint structurally. Menisci-on the superior top of tibia. Shallow tibial articular surfaces. help prevent side to side rocking of the femur on the tibia and absorb shock.

Origin and insertion

Origin-attached to the immoveable bone Insertion-Attached to the moveable bone Muscles contract and their insertion moves toward their origin.

Types of synovial joints

Plane: flat articulated surfaces that allow gliding movements. Ex-metacarpals glide against carpals. Nonaxial movement Hinge: only allow flexion/extension. ex-knee, elbow. Uniaxial-permits movement of one axis and one plane. cylinder and trough Pivot:only allows rotation. Ex-head of radius pivots around radial notch of ulna-axle in sleeve. Uniaxial. Condylar:allows flexion/extension and abduction/adduction. Ex-knuckles and wrists. Biaxial-permit movement around 2 perpendicular axes in 2 perpendicular planes. oval and articular surfaces. Saddle: allows flexion/extension and abduction/adduction.biaxial. articular surfaces are both concave and convex. Ball-and-socket: flexion/extension, abduction/adduction, rotation, circumduction. multiaxial-most movable joints, permits movement around 3 or more axes and in 3 or more planes, but less stable. Ex-shoulder. spherical head in cup

Elbow joint

Provides a stable and smoothly operating hinge that allows flexion and extension. Hinge-close gripping of the trochlea by the ulna's trochlear notch Anular ligament-surrounds the head of the radius articular capsule is thin and allows freedom. Side to side movements are restricted by two strong capsular ligaments:Ulnar Collateral Ligament (medial) and Radial collateral ligament (lateral)

Joints/articulations

The sites where two bones meet. Give our skeleton mobility and hold it together. Weakest part of the skeleton but resist forces. Classified by structure and function. Structural classification: material binding the bones together and whether or not a joint cavity is present: Fibrous, cartilaginous, synovial. Functional classification: Amount of movement allowed at the joint: synarthroses, amphiarthroses, diarthroses.

bursitis

inflammation of the bursa. usually caused by a blow or friction.

tendonitis

inflammation of the tendon sheaths. caused by overuse.

Temporomandibular joint

modified hinge. condylar process of mandible meets with mandibular fossa posteriorly and articular tubercle anteriorly. lateral ligament-thickens loose articular capsule articular disc-divides the synovial cavity into superior and inferior compartments. depression and elevation during chewing

Knee ligaments

the knee joint is only covered by a capsule on the sides and posteriorly. Anteriorly three ligaments run from the patella to the tibia below: the Patellar ligament and the Medial and lateral patellar retinacula which flank the patellar ligament. three types of joint ligaments: extracapsular, capsular, intracapsular: stabilize and strengthen the capsule of the knee joint. Act to prevent hyperextension of the knee and are stretched tight when the knee is extended. Extracapsular: Fibular and Tibial Collateral ligaments:prevent lateral and medial rotation when the knee is extended. Oblique Popliteal Ligament: helps stabilize the posterior aspect of the knee joint Arcuate Popliteal Ligament: reinforces the joint capsule posteriorly Intracapsular: Anterior cruciate ligament: prevents forward sliding of the tibia on the femur and checks hyperextension. Posterior cruciate ligament:prevents backward displacement of the tibia or forward sliding of the femur.

sprains

the ligaments reinforcing a joint get stressed or torn.

Gouty arthritis

-blood levels of uric acid rise excessively and gets deposited as needle shaped urate crystals in the soft tissues of joints. -causes inflammatory response -painful -often occurs at the base of the big toe -more common in men -articulating bone ends could fuse and immobilize the joint

dislocation

aka luxation. bones get forced out of alignment. joints of the jaw, shoulders, fingers and thumbs are most commonly dislocated.

arthritis

describes over 100 types of inflammatory or degenerative diseases that damage the joints. Symptoms: pain, stiffness and swelling of the joint.

Functional classification

Synarthroses: immovable joints Amphiarthroses: slightly moveable joints Diarthroses: Freely movable joints-predonimate in the limbs

cartilage tears

overstressed cartilage. ex-tearing of the menisci- happens when it is subjected to compression and shear stress at the same time. cartilage is avascular and cannot obtain nourishment for repair so it usually stays torn.

Range of movement allowed by synovial joints

Nonaxial movement: slipping movements only Uniaxial movment: Movement in one plane Multiaxial movement: Movement in or around all three planes of space and axes.

Which joint types are nonaxial, uniaxial, biaxial, multiaxial?

Nonaxial: plane joint Uniaxial: Hinge and Pivot joints Biaxial: Condylar and Saddle joints Multiaxial: Ball-and-socket joints

Special movements

Supination and pronation: movements of the radius around the ulna. Pronation-two bones form an X. Dorsiflexion and plantar flexion of the foot: up and down movements. lifting=dorsiflexion. Inversion and eversion: movements of the foot from side to side. Inversion-sole of foot turns medially. Protraction and retraction: Nonangular anterior and posterior movements in a transverse plane (chin tuck) Elevation and Depression: lifting a body part superiorly and moving the elevated part inferiorly. Opposition: touching the thumb to the tips of the other fingers