articulations and joints

BIOL 243

synarthroses joints

joints that are immovable

amphiarthroses

joints that are slightly movable

diarthroses

joints that are freely movable

fibrous joints

• bones joined by dense fibrous connective tissue

• no joint cavity

  • no space at all

• most are immovable (synarthrotic)

• 3 types

  • sutures

  • syndesmoses

  • gomphoses

sutures

• one of the types of fibrous joints

• ties in all skull bones

• lines in skull

• infant skull; allow for brain growth

  • skull isn’t fully developed

  • soft spots

syndesmoses

• one of the types of fibrous joint

• connected by ligaments and fibrous tissue

  • webbing

  • holds bones in their position

  • tibia/fibula (feet) and radius (thumb side)/ulna (pinky side) (amphiarthrotic)

    • allows for a little movement

gomphoses

• one of the types of fibrous joints

• teeth and periodontal ligament

  • teeth sewn into tissue by periodontal ligament

  • do not move (in adulthood)

cartilaginous joints

• bones united by cartilage

• no joint cavity

  • similar to fibrous

• not highly movable

• 2 types

  • synchondroses

  • symphyses

synchondroses

• one of the types of cartilaginous joints

• plate of hyaline cartilage connect bones

  • epiphyseal growth plates (synarthrotic)

symphyses

• one of the types of cartilaginous joints

• fibrocartilage in joint; strong but slightly movable (amphiarthrotic)

  • bones connected by tab of cartilage

  • intervertebral joints

    • cartilage cushions connection of bones

  • pubic symphysis

    • slightly movable during childbirth

synovial joints

• bones separated by fluid-filled joint cavity

• knees, hips, etc.

• all are diarthrotic (freely movable)

  • more movement = more likely to dilocate

• include almost all limb joints

• characteristics of synovial joints

  • have bursae (pack around joint for protection) and tendon sheaths (wrap tendons and connect joints to bones) associated with them

  • allow several types of movements

  • classified into 6 different types

general structure of synovial joints

1. articular cartilage

   1. hyaline cartilage coverings ends of bones

2. articular (joint) capsule: 2 layers thick

   1. connective tissue sac around ends of bones (filled with liquid)

3. joint (synovial) cavity:

   1. fluid filled space unique to synovial joints

4. synovial fluid:

   1. viscous, filtrate of plasma and hyaluronic acid

   2. lubricates and nourishes articular cartilage

5. reinforcing ligaments

6. nerves and blood vessels

   1. nerves detect pain; monitor joint position and stretch

   2. capillary beds supply filtrate for synovial fluid

articular discs

• similar to fibrocartilage discs but more squishy

• fibrocartilage separates articular surfaces to allow a better fit of bone ends, stabilize joint, and reduce wear and tear

  • in knee, referred to as meniscus

  • in shoulder/hips, referred to as labrum

bursae

• bags of synovial fluid

• not strictly a part of synovial joints, but closely associated

• reduce friction where ligaments, muscles, skin, tendons, or bones rub together

  • spaces things out, can push things out of place if too many or if they’re swollen

stability of synovial joints

• 3 factors determine joint stability

  • shape of articular surface (minor role)

    • shallow surfaces are less stable than ball-and-socket

    • glenoid fossa (shoulder) not as deep as the acetabulum (hip)

      • shoulder more likely to dislocate than hip

  • ligament number and location (medium role)

    • the more ligaments, the stronger the joint (hips)

  • muscle tone (most important role)

    • above and below a joint

    • extremely important in reinforcing shoulder and knee joints and arches of the foot

      • ex: rotator cuff of shoulder, quadriceps of thigh

flexion

• one of the synovial joint movements

• decreases the angle of the joint

  • close

• applies to spine, shoulder, elbow, wrist, hip, knee, and ankle

extension

• one of the synovial joint movements

• increases the angle of the joint

  • open

• applies to spine, shoulder, elbow, wrist, hip, knee, and ankle

hyperextension

• one of the synovial joint movements

• movement beyond the anatomical position

  • ex: elbow can only go 180º, if farther, injuries will occur

• applies to spine, shoulder, elbow, wrist, hip, knee, and ankle

abduction

• one of the synovial joint movements

• away from the midline

  • ex: top of a jumping jack

• applies to shoulder and hips (ball and socket joints)

adduction

• one of the synovial joint movements

• toward the midline

  • ex: bottom of a jumping jack

• applies to shoulder and hips (ball and socket joints)

circumduction

• one of the synovial joint movements

• involves flexion, abduction, extension, and adduction of limb

  • moving in all directions (circles) around joint

  • not the same as rotation

• applies to shoulder and hips (ball and socket joints)

rotation

• one of the synovial joint movements

• applies to shoulder and hips (ball and socket joints)

• turning of bone around its own long axis, toward midline or away from it

  • 2 types:

    • internal rotation

    • external rotation

internal rotation

• a type of synovial joint rotation

• rotation toward midline

  • sometimes called medial

external rotation

• a type of synovial joint rotation

• rotation away from midline

  • ex: moving arm bone outwards

    • sometimes called lateral

    • main way shoulder is dislocated

supination

• a type of synovial joint movement

• only happen in wrist or ankles

• palms face superior (up)

  • occurs in radioulnar joint of elbow

pronation

• a type of synovial joint movement

• only happens in wrist or ankles

• palms face inferior (down)

  • occurs in radioulnar joint of elbow

dorisflexion

• one of the special movements of the foot

• bending foot toward shin

  • putting toes up

  • ex: taking foot off the gas

plantar flexion

• one of the special movements of the foot

• pointing toes

  • ex: putting foot on gas

inversion

• one of the special movements of the foot

• sole of foot faces medially

  • sole faces in towards body 

  • ex: tripping on curb

eversion

• one of the special movements of the foot

• sole of foot faces laterally

  • ex: passing out

  • foot sole faces outward

plane

• one of the types of synovial joints

• carpals/tarsals, spine

  • moves foward, back, right, and left

saddle

• one of the types of synovial joints

• thumb

pivot

• one of the types of synovial joints

• atlantoaxial joint, radioulnar

  • found in vertebrae

  • allows rotation back and forth

condylar

• one of the types of synovial joints

• metacarpophalangeal

  • kind of like ball on bottom of mouse

  • found in fingers

hinge

• one of the types of synovial joints

• humeroulnar (elbow), tibiofemoral (knee)

  • jaw, moves forward and back like a door

ball-and-socket

• glenohumeral (shoulder)

• acetabulofemoral joint (hip)

  • highest degree of movement=most vulnerable

glenohumeral joint

• shoulder joint

• most freely moving joint in body

  • can do 360º

• stability is sacrificed for freedom of movement

• ball-and-socket joint

  • large head of humerus fits in shallow glenoid cavity of scapula

    • like a golf ball on a tee

  • contains glenoid labrum (fibrocartilage)

    • suction cup that holds head in socket

    • adds depth to socket

  • many reinforcing ligaments

    • mostly on anterior aspect

rotator cuff muscles

• reinforcing muscle tendons that contribute greatly to joint stability of the back of the shoulder

  • tendon of long head of biceps brachii muscle and deltoid muscle help stabilize shoulder anteriorly (in front)

    • secures humerus to glenoid cavity

  • four rotator cuff tendons encircle the shoulder joint

    • subscapularis (least injured)

    • supraspinatus (most commonly injured)

      • above scapula

      • performs most exterior rotation

    • infraspinatus

    • teres minor

shoulder dislocations

• a type of shoulder injury

• head of humerus forced from glenoid fossa

  • common injuries due to mobility in the shoulder

  • structures reinforcing shoulder are weakest anteriorly and inferiorly, so head of humerus can easily dislocate forward and downward

  • common with injuries involving excessive external rotation

labral tears

• a type of shoulder injury

• tears in the glenoid labrum

  • occur often in sports requiring use of shoulder (vollyball/baseball)

    • high force at high velocities - tear inferiorly

shoulder injuries

• shoulder dislocations

• labral tears

• rotator cuff tears

• biceps tendonitis

biceps tendonitis

• a type of shoulder injury

• common cause of anterior shoulder pain

humeroulnar joint (elbow)

• humerus articulates distally with radius and ulna

• hinge joint formed primarily from trochlear notch of ulna articulating with trochlea of humerus

  • allows for flexion and extension only

• 2 ligaments restrict side-to-side movement

  • ulnar collateral ligament

  • radial collateral ligament

• radius articulating proximally with ulna provides supination and pronation of elbow/wrist

  • commonly dislocated in children (nurse maid/pulled elbow)

    • ulna separates from humerus

ulnar collateral ligament

• one of the ligaments that restricts side-to-side movement

• on pinky side (inside)

• repaired in tommy john surgery

  • high velocity arm throwing

radial collateral ligament

• one of the ligaments that restricts side-to-side movement

• thumb side (outside)

hip joint

• ball-and-socket joint

• large head of the femur articulates with deep cup-shaped acetabulum

• great stability, good range of motion, but limited by the deep socket

  • acetabular labrum

  • many reinforcing ligaments

    • 6 or 7

acetabular labrum

• rim of the fibrocartilage that enhances (deepens) depth of socket in the hip joint

  • hip dislocations are rare

    • except in toddlers

  • tearing of this type of cartilage common in dancers, gymnastics

knee joint

• largest, most complex joint of the body

  • biggest degree of angles, not stable due to complexity

  • made up of 2 joints:

    • tibiofemoral joint

    • patellofemoral joint

  • quadriceps tendon on anterior surface

  • medial/lateral collateral ligaments

  • anterior/posterior cruciate ligaments

tibiofemoral joint

• one of the joints in the knee

• primary joint

• tibia and fibia

• joint between femoral condyles and lateral/medial menisci of tibia

• hinge joint that allows flexion, extension, and some rotation when knee partly flexed

patellofemoral joint

• one of the joints in the knee

• this is the articulation between the femur (thigh bone) and the patella (kneecap)

quadriceps tendon

• a part of the knee joint

• attaches quadriceps to patella

  • patella is attached to tibia via patellar ligament

medial/lateral collateral ligaments

• a part of the knee joint

• inside and outside of knee

  • prevent medial/lateral collapse of knee

anterior/posterior cruciate ligaments

• a part of the knee joint

• front and back

  • prevent hyperextension/hyperflexion injuries to knee

    • ligaments = bone to bone

    • tendons = muscle to bone

cartilage tears

• a joint disorder

• pieces of cartilage cause joint to lock - needs to be cleaned out

• due to compression and shear stress (rotation)

• cartilage rarely repairs itself (avascular)

• repaired with arthroscopic surgery

• partial menisci removal renders joint less stable but mobile; complete removal leads to osteoarthritis and often leads to knee replacements

• meniscus of knee, labrum of hip/shoulder, intervertebral discs of spine

arthroscopic surgery

• repairs cartilage tears

• cuts slits and puts small arms inside the knee to remove pieces of cartilage

sprains

• a type of joint injury

• occurs in tendons or muscles

• reinforcing ligaments are stretched or torn

• common sites are ankle, knee, and lumbar region of back

• partial tears repair very slowly because of poor vascularization (often require 8-12 weeks)

• 3 options if torn completely:

  • ends of ligaments can be sewn together

  • replaced with grafts

  • just allow time and immobilization for healing

    • for older pateints this is the worst option, joint will never be the same

dislocations (luxations)

• a type of joint injury

• bones forced out of alignment

• accompanied by sprains, tears, inflammation, and difficulty moving joint

• caused by serious falls or contact sports

• must be reduced (set back into place) to treat

bursitis

• a type of inflammatory condition

• inflammation begins here

• inflammation of bursa (packs joints), usually caused by blow or friction (of tendon)

• treated with rest and ice and, if severe, anti-inflammatory drugs

tendonitis

• a type of inflammatory condition

• inflammation moves to this stage after bursitis

• inflammation of tendon sheaths, typically caused by overuse

• symptoms and treatment similar to those of bursitis

arthritis

• a type of degenerative condition

• over 100 different types of inflammatory or degenerative diseases that damage joints

  • any form of breaking down

  • most widespread crippling disease in the US

  • symptoms: pain, stiffness, and swelling of joint

  • acute forms (short term - happens fast): caused by bacteria, treated with antibiotics (gonorrhea - blood moves it from the reproductive system)

  • chronic forms (long term - happens over time):

    • osteoarthritis

    • rheumatoid/psoriatic arthritis

    • gouty arthritis

osteoarthritis

• a chronic form of arthritis

• degenerative; wear/tear

rheumatoid/psoriatic arthritis

• a chronic form of arthritis

• auto-immune (self attacking)

gouty arthritis

• a chronic form of arthritis

• diet rich in purines

  • a type of amino acid

  • alcohol (esp. beer), red meat, sugary drinks, shellfish

    • create nitrogen in joint that causes arthritis

    • only affects feet and ankles