A&P Chapter 8: Articulations (Joints)

Exam 3 material [lab 7]

joints (articulations)

synarthroses

immovable joints

amphiarthroses

slightly movable joints

diarthroses

freely movable joints [synovial]

fibrous joints

Bones joined by dense fibrous connective tissue; movement depends on length of fibers

• no joint cavity present

cartilaginous joints

Bones joined by cartilage

• name depends on type of cartilage present

synovial joints

[most common] has space between bones filled with synovial fluid

• enclosed within articular capsule

• covered by articular cartilage

• ex: menisci, fat pads, accessory ligaments, bursae

suture

joint held together with very short, interconnecting fibers, and bone edges interlock

• found only in skull

• type of fibrous joint

• immovable

syndesmosis

joint held together by a ligament

• fibrous tissue varies in length [no longer than in sutures]

• found in areas where a slight amount of give is necessary [ulna and radius]

gomphosis

“peg in socket” fibrous joint

• periodontal ligament holds tooth in socket

• immovable

synchondroses

bones united by hyaline cartilage

• type of cartilaginous joint

• ex: epiphyseal plate, sternum, first rib and sternum

• most are immovable

symphyses

fibrocartilage is the intervening tissue

• amount of movement varies

• great for shock absorption

• ex: intervertebral discs, pubic symphysis

articular cartilage

hyaline cartilage that covers the end of articulating bones

• absorbs compression

• feature of synovial joints

joint cavity

space between the bones usually filled with synovial fluid

articular capsule

two layered

• outer layer holds bones together

• inner layer produces synovial fluid

synovial fluid

viscous fluid found in the joint cavity; lubricates joint and nourishes cartilage

fibrous capsule

outer articular capsule layer

• made of dense irregular CT

• holds bones together

synovial membrane

inner articular capsule layer

• secretes synovial fluid

• made of areolar CT

weeping lubrication

blood capillaries in synovial membrane is sucked up by cartilage and squeezed out when joint moves

• how cartilage gets its nutrients

synovial (fluid)

what fluid helps to:

1) lubricate the joint to reduce friction

2) nourish articular cartilage

3) shock absorption

reinforcing ligaments

made of dense regular CT; two types

• capsular ligaments

• extrinsic ligaments

capsular ligament

type of reinforcing ligament thickened by areas of joint capsule

extrinsic ligaments

type of reinforcing ligament

extracapsular = outside capsule

intracapsular = inside capsule

menisci

fibrocartilaginous pads that are found within the joint cavity of some joints

functions include:

• protect articular surfaces

• improve the fit of articular surfaces that aren’t congruent

• spread stress evenly over bone

bursae

flattened fibrous sac lined with synovial fluid membrane

• inserted at strategic points to protect soft tissues

• works like ball bearings

• occurs where ligaments, muscles, skin, tendons, or bones rub together

bursitis

inflammation of bursae due to repeated use, irritation, infection, or trauma

• pain in affected area where tendon or ligament moves

• musicians, golfers, baseball players have this in their shoulders

tendon sheaths

functions like bursae, but are elongated and wrapped around tendons

• common where several tendons are crowded together (i.e: wrists)

sprains

overuse or stress of a ligament, resulting in tearing or scratching

• common in wrists and ankles

arthritis

general term for all inflammatory and degenerative diseases affecting synovial joints

• damage to articular cartilage

osteoarthritis

degenerative condition (wear & tear) progressive deterioration of articular cartilage in weight bearing bones

• exacerbated by obesity and hard physical labor

• breakdown of cartilage outweighs building

bone spurs can grow and inflame surrounding tissues

rheumatoid arthritis

chronic inflammatory disorder {autoimmune disorder}

• involves flare ups and remissions

• synovial fluid accumulates in joints causing inflammation and swelling

Gout

sodium ureate crystals build up in joints and irritate articular cartilage causing inflammation, swelling, and pain

• most likely to occur in joint at base of big toe