Chapter 8 study guides

What factors influence the stability of synovial joints?

• *Three factors determine stability of joints to prevent dislocations*: 1. Shape of articular surface (minor role) Shallow surfaces less stable than ball-and-socket 2. Ligament number and location (limited role) The more ligaments, the stronger the joint 3. Muscle tone keeps tendons taut as they cross joints (most important) Extremely important in reinforcing shoulder and knee joints and arches of the foot

Depression

lowering body part - Example: opening jaw

Retraction

mandible is pulled toward neck

Protraction

mandible juts out

Abduction

movement along frontal plane, away from the midline

Adduction

movement along frontal plane, toward the midline

Hyperextension

movement beyond the anatomical position

Opposition

movement of thumb - Example: touching thumb to tips of other fingers on same hand or any grasping movement

plane joint

non-axial the flat surface if one bones slides in many directions along the flat surface of another bone.

Supination

o : palms face anteriorly • Radius and ulna are parallel

Synchondroses

o Bar or plate of hyaline cartilage unites bones o Almost all are synarthrotic (immovable) o Examples o Temporary epiphyseal plate joints Become synostoses after plate closure o Cartilage of 1st rib with manubrium of sternum

Describe the general structure of cartilaginous joints.

o Bones united by cartilage o Like fibrous joints, have no joint cavity o Not highly movable Two types: o Synchondroses o Symphyses

Lyme disease

o Caused by bacteria transmitted by tick bites o Symptoms: skin rash, flu-like symptoms, and foggy thinking o May lead to joint pain and arthritis o Treatment Long course of antibiotics

Plantarflextion

pointing toes

Sutures

• Rigid, interlocking joints of skull • Allow for growth during youth o Contain short connective tissue fibers that allow for expansion • In middle age, sutures ossify and fuse o Immovable joints join skull into one unit that protects brain o Closed, immovable sutures referred to as synostoses

What are the 3 structural classifications of joints?

Fibrous Cartilaginous Synovial

Dislocations

(luxations) o Bones forced out of alignment o Accompanied by sprains, inflammation, and difficulty moving joint o Caused by serious falls or contact sports o Must be reduced to treat Subluxation: partial dislocation of a joint

Circumduction

- Involves flexion, abduction, extension, and adduction of limb - Limb describes cone in space

Rotation

- turning of bone around its own long axis, toward midline or away from it o Medial: rotation toward midline o Lateral: rotation away from midline o Examples Rotation between C1 and C2 vertebrae Rotation of humerus and femur

What are the functional classifications of joints?

1. Functional classifications: three types based on movement joint allows Synarthroses: immovable joints Amphiarthroses: slightly movable joints Diarthroses: freely movable joints

Describe the general structure of synovial joints.

Are united by the dense irregular connective tissue of an articular capsule, and often by accessory ligaments. Has the presence of a space called synovial cavity between the articulating bones which allows a joint to be freely movable. Classified as the diarthroses. .

Flexion

Decreases the angle of a joint

Dorsiflexion

bending foot toward shin

Extension

increases the angle of the joint

Elevation

lifting a body part superiorly - Example: shrugging shoulders

Rheumatoid arthritis

o Chronic, inflammatory, autoimmune disease of unknown cause Immune system attacks own cells o Usually arises between ages 40 and 50, but may occur at any age; affects three times as many women as men o Signs and symptoms include joint pain and swelling (usually bilateral), anemia, osteoporosis, muscle weakness, and cardiovascular problems o RA begins with inflammation of synovial membrane (synovitis) of affected joint o Inflammatory blood cells migrate to joint, release inflammatory chemicals that destroy tissues o Synovial fluid accumulates, causing joint swelling o Inflamed synovial membrane thickens into abnormal pannus tissue that clings to articular cartilage o Pannus erodes cartilage, scar tissue forms and connects articulating bone ends (ankylosis) o Treatment includes steroidal and nonsteroidal anti-inflammatory drugs to decrease pain and inflammation o Disruption of destruction of joints by immune system o Immune suppressants slow autoimmune reaction o Some agents target tumor necrosis factor to block action of inflammatory chemicals o Can replace joint with prosthesis

Gout

o Deposition of uric acid crystals in joints and soft tissues, followed by inflammation o More common in men o Typically affects joint at base of great toe o In untreated gouty arthritis, bone ends fuse and immobilize joint o Treatment: drugs, plenty of water, avoidance of alcohol and foods high in purines, such as liver, kidneys, and sardines

Cartilage tears:

o Due to compression and shear stress o Fragments may cause joint to lock or bind o Cartilage rarely repairs itself o Repaired with arthroscopic surgery o Partial menisci removal renders joint less stable but mobile; complete removal leads to osteoarthritis o Meniscal transplant possible in younger patients o Perhaps meniscus grown from own stem cells in future

Symphyses

o Fibrocartilage unites bone in symphysis joint o Hyaline cartilage also present as articular cartilage on bony surfaces o Symphyses are strong, amphiarthrotic (slightly movable) joints o Examples o Intervertebral joints o Pubic symphysis

Bursitis

o Inflammation of bursa, usually caused by blow or friction o Treated with rest and ice and, if severe, anti-inflammatory drugs

Osteoarthritis

o Most common type of arthritis o Irreversible, degenerative ("wear-and-tear") arthritis o May reflect excessive release of enzymes that break down articular cartilage Cartilage is broken down faster than it is replaced Bone spurs (osteophytes) may form from thickened ends of bones o By age 85, half of Americans develop OA, more women than men o OA is usually part of normal aging process o Joints may be stiff and make crunching noise referred to as crepitus, especially upon rising o Treatment: moderate activity, mild pain relievers, capsaicin creams o Glucosamine, chondroitin sulfate, and nutritional supplements not effective

Gomphoses

o Peg-in-socket joints o Only examples are the teeth in alveolar sockets o Fibrous connection is the periodontal ligament o Holds tooth in socket

Sprains

o Reinforcing ligaments are stretched or torn o Common sites are ankle, knee, and lumbar region of back o Partial tears repair very slowly because of poor vascularization o Three options if torn completely Ends of ligaments can be sewn together Replaced with grafts Just allow time and immobilization for healing

Pronation

o palms face posteriorly • Radius rotates over ulna

Eversion

sole of foot faces laterally

Inversion

sole of foot faces medially

Describe the general structure of fibrous joints.

• Bones joined by dense fibrous connective tissue • No joint cavity • Most are immovable - Depends on length of connective tissue fibers • Three types of fibrous joints: - Sutures - Syndesmoses - Gomphoses