Musculoskeletal System Joints

articular capsule

outside dense irregular connective tissue; synovial membrane is inside lining of capsule that makes synovial fluid to lubricate and nourish joint, does not cover cartilage

synovial joint condyloid movement

oval articular surfaces permit both flexion/extension, abduction/adduction, and rotation

arthritis

over 100 kinds

muscles

when contracted they hold the bone tight within a socket; helps stabilize joints by keeping tension on tendons

sprain

a stretching or tearing of a ligament; joint becomes less stable

strain

a stretching or tearing of a tendon or muscle

talocalcaneal joint

ankle and foot joint; joint between talus and calcaneus allows inversion/eversion

tibiotalus joint

ankle and foot joint; joint between tibia and talus only allows plantar and dorsiflexion

tarsometatarsal joints

ankle and foot joint; joints between tarsals/metatarsals allow gliding and help maintain arch

rheumatoid arthritis

autoimmune disease causing chronic inflammation of synovial membranes leading to swelling of joints and joint damage

glenohumeral (shoulder) joint

ball and socket type; most freely movable joint in body but least stable; synovial joint; glenoid labrum deepens glenoid cavity; articular capsule thin and loose; bursa and tendon sheaths of arm and shoulder muscles reduce friction; bicipital groove with long head biceps; rotator cuff muscle tendons contribute to joint stability

acetabulofemoral (hip) joint

ball-and-socket joint; head of femur articulates with acetabulum; movement occur in all axes, limited by ligaments, depth of acetabulum, and acetabular labrum; stability chiefly from acetabulum and capsular ligaments; muscle tendons contribute to stability; hip joint more stable than shoulder joint but less mobile

functional classification

based on amount of movement permitted; immovable joints, slightly moveable joints, freely movable joints

structural classification

based on type of material between two bones; solid: fibrous, cartilaginous; synovial

humeroulnar (elbow) joint

bone structure only allows flexion and extension; humerus' articulation with trochlear notch of ulna forms hinge; tendon of biceps and triceps brachii provide stability

syndesmosis

bones are connected by ligaments (bands of connective tissue); the longer the band the more movement

synovial joint saddle movement

both surfaces are concave and convexed allowing flexion/extension and abduction/adduction

bursae and tendon sheaths

closed sacks of synovial fluid protecting bone from rubbing tendons, ligaments, and muscles; reduce friction between body elements

knee injuries

common in sports activities; often due to excessive lateral force when foot is planted and knee is twisted

medial (deltoid) ligament

comprised of three small lateral ligaments between medial malleous of tibia and bones of foot; easily torn with over eversion

extrinsic ligaments

connect bone to bone outside the fibrous capsule

intrinsic ligaments

connect bone to bone, thickening of fibrous capsule

tendons

connect muscle to bone; dense regular connective tissue reinforce the joint capsule

unhappy triad

damage to tibial collateral ligament, medial meniscus (connected to tibial collateral ligament), anterior cruciate ligament

function of menisci of knee

deepen articular surface; act as shock absorbers

cartilaginous joints

different depending on type of cartilage between the two bones; synchondrosis, symphysis

gouty arthritis

elevated uric acid blood levels leads to crystals forming in synovial membranes causing joint inflammation and severe pain

tendon sheath

elongated bursa that wraps around a tendon

characteristics of synovial joints

ends of bones covered by hyaline cartilage; space (synovial cavity) between two bones; space surrounded by a capsule; may or may not have intervening fibrocartilagenous disc; support may come from shape of bones creating articular surface/amount of movement between bones, extrinsic and intrinsic ligaments, surrounding muscles

fibrous joints

no joint cavity, very stable with little or no movement; sutures, syndesmosis, gomphosis

fibrocartilagenous discs and labrums

occur where two bones, with different surface shapes, articulate; helps deepen the socket

strength and mobility

opposing characteristics; increase strength decrease mobility and vice versa

synovial joint ball and socket movement

multiaxial (e.g. shoulder and hip joints)

bursa

flattened fibrous sac lined by synovial membrane

synovial joint hinge movement

flex and extend (e.g. elbow, knee, and ankle)

rotator cuff

four muscles and their associated tendons: subscapularis, supraspinatus, infraspinatus, teres minor; injuries are common shoulder injuries; shoulder dislocation pops out into axilla, inferiorly

patella

glides across distal femur; increases leverage quadriceps tendon exerts on tibia; V-shaped posterior surface of patella faces knee joint cavity; stabilizes flexed knee joint by fitting in groove of femoral condyles

synovial joint plane movement

gliding type (e.g. carpal bones)

synchondrosis

immovable, stable joints between bone and hyaline cartilage (epiphyseal plate); epiphyseal plates, joint between first rib and manubrium

bursitis

inflammation of bursa due to injury or friction

factors influencing synovial joint stability

inverse relationship between amount of motion at joint and stability of joint; articular surfaces - shapes of articulating surfaces determine movements possible; ligaments - joint capsules and ligaments prevent excessive motions, in general the more ligaments the stronger the joint; muscle tone of skeletal muscles whose tendons cross the joint

symphysis

joint where fibrocartilage unites bones (pubic symphysis, intervertebral disc); resists tension and compression

articulation (joint)

junction between two or more bones, or parts of bones, of the skeleton

tibiofemoral (knee) joint

largest and most complex joint; hinge joint; flexion and extension with limited capacity for rotation; two fibrocartilage menisci within joint cavity

ligaments surrounding hip joint capsule

ligament arrangement makes extended thigh most stable joint position, lateral rotation and flexion of hip least stable joint position; hip dislocation easier when hip is flexed

ligament to femoral head

ligament within joint connects acetabulum to head of femur; helps hold femur in socket; provides route for major nutrient artery to supply femoral head

knee joint stability

ligaments: tibial and fibular collateral ligaments; medial and lateral menisci; muscles, tendons, and capsule; patella

fibular and tibial collateral ligaments

located external the fibrous joint capsule

anterior and posterior cruciate ligaments

located within fibrous capsule; named for position on tibia; each extends between proximal tibia to distal femur and cross each other like "X"

temporomandibular joint (TMJ)

modified hinge joint where head of mandible articulates with temporal bone; movements: hinge-like movement, gliding of superior surface anteriorly, lateral excursion is side-to-side

osteoarthritis (degenerative arthritis)

most common type; "wear and tear" arthritis; characterized by pitting and erosion of cartilage

synovial joints

most movable type of joint; hyaline cartilage covers the ends of the articulating bones; gliding surface, absorbs compression, protects bone

gomphosis

peg-in-socket joint (between the teeth and bone)

anterior cruciate ligament

prevents anterior sliding of tibia

posterior cruciate ligament

prevents posterior sliding of tibia

nerves and blood supply to joints

rich supply of sensory nerves: detect pain, most monitor stretching of capsule; rich blood supply: supply synovial membrane, extensive capillary beds produce synovial fluid

synovial joint pivot movement

rotate (e.g. radius/ulnar joint)

sutures

seams where bones are interconnected and tightly bound to one another by fibrous tissue

menisci of knee

semilunar wedge-shaped fibrocartilages within knee joint; medial and lateral bathed in synovial fluid and connected to joint capsule; most likely to be torn with rotation of femur

anular ligament

surrounds head of radius permitting rotational movement

ankle ligaments

thin capsule but supported by thickened ligaments

lateral ligaments

three bands connecting lateral malleous of fibula to bones of foot; easily sprained or torn when ankle is over inverted

elbow ligaments

ulnar and radial collateral ligaments; anular ligament