anatomy unit 3

joint

site where two or more bones meet

function of joints

give skeleton mobility and hold skeleton together

structural joint classification

three types based on what material binds the joints and whether a cavity is present

-fibrous

-cartilaginous

-synovial

functional classification of joints

three types based on movement joint allows

-synarthroses

-amphiarthroses

-diarthroses

fibrous joints

bones joined by dense fibrous connective tissue

no joint cavity

most are immovable

lock the ends of the bones together

sutures, gomphoses, syndesmoses

sutures

fibrous joints

rigid interlocking

skull 

allow for growth during youth, contain short connective tissue fibers that allow for expansion

middle age- sutures ossify and fuse to protect the brain

closed immovable sutures- synostoses

gomphoses

fibrous joint

peg in socket

teeth in alveolar sockets

fibrous connection is the periodontal ligament

syndesmoses

fibrous joint

bones are connected by ligaments

fiber length varies, movement varies

short fibers- little to no movement

longer fibers- large amount of movement

ligaments

bands of fibrous tissue, connect bones together

cartilaginous joints

bones united by cartilage

no joint cavity

not highly moveable

synchondroses and symphyses

synchondroses

a bar/ plate of hyaline cartilage unites bones

almost all are synarthrotic

temporal epiphyseal plate joints, cartilage of 1st rib with manubrium of sternum

symphyses

fibrocartilage unites bone

hyaline cartilage also present as articular cartilage on bony surfaces

strong, amphiarthrotic

intervertebral joints, pubic symphysis

synovial joints

bones separated by fluid filled joint cavity

all are diarthrotic

include almost all limb joints

have bursae and tendon sheaths

6 different types

plane joint

synovial joint

nonaxial movement

flat articular surfaces glide

wrist bones

hinge joint

synovial joint

uniaxial movement

cylinder and trough allow flexion and extension

elbow joints- humerus and ulna

pivot joint

synovial joint

uniaxial movement

rotation 

sleeve and axle

proximal radioulnar joint

condylar joint

synovial joint

biaxial movement

oval articular surfaces allow flexion and extension and adduction and abduction

knuckle joints

saddle joint

synovial joint

biaxial movement

articular surfaces are concave and convex to allow adduction and abduction and flexion and extension

thumbs

ball and socket joint

synovial joint

multiaxial movement

spherical head and cup allow flexion and extension, adduction and abduction, and rotation

shoulder and hip joints

articular cartilage

consists of hyaline cartilage covering ends of bones

prevents crushing of bone ends

characteristic of synovial joint

joint (synovial) cavity

small fluid filled space

characteristic of synovial joint

articular capsule

characteristic of synovial joint

two layers thick

-external fibrous layer- dense irregular CT

-inner synovial membrane- loose CT that makes synovial fluid

synovial fluid

characteristic of synovial joints

viscous slippery filtrate of plasma and hyaluronic acid

lubricates and nourishes articular cartilage

contains phagocytic cells to remove microbes and debris

different types of reinforcing ligaments

characteristic of synovial joints

capsular- thickened part of fibrous layer

extracapsular- outside the capsule

intracapsular- deep to capsule, covered by synovial membrane

nerves and blood vessels

characteristic of synovial joints

nerves detect pain, monitor joint position and stretch

capillary beds supply filtrate for synovial fluid

fatty pads

feature of some synovial joints

for cushioning between fibrous layer of capsule and synovial membrane or bone

articular disc

feature of some synovial joints

menisci

fibrocartilage separates articular surfaces to improve fit of bone ends, stabilize joint, reduces wear and tear

bursae

feature of synovial joints

reduce friction where ligaments muscles skin tendons or bones rub together

bags of synovial fluid act as lubricating ball bearing

tendon sheaths

feature of some synovial joints

elongated bursae wrapped around tendons subjected to friction

three factors determining synovial joint stability

shape of articular surface

ligament number and location

muscle tone

shape of articular surface

shallow surfaces are less stable than ball and socket

minor role in synovial joint stability

ligament number and location

the more ligaments the stronger the joint

limited role in synovial joint stability

muscle tone

keeps tendons taut as the cross joints

extremely important in reinforcing synovial joints

gliding movements

one flat bone surface glides or slips over another similar surface

intercarpal and intertarsal joints

between articular processes of vertebrae

angular movements

increase or decrease angle between two bones

flexion and extension

abduction and adduction

flexion

decreases the angle of the joint

extension

increases the angle of the joint

hyperextension

movement beyond the anatomical position

abduction

movement along frontal plane, away from the midline

adduction

movement along frontal plane, toward the midline

circumduction

involves flexion, abduction, extension, and adduction of limb

limb describes cone in space

ball and socket joints do this best

rotation

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

between C1 and C2 vertebrae

humerus and femus

medial rotation

toward midline

lateral rotation

away from midline

supination

palms face anteriorly

radius and ulna are parallel

pronation

palms face posteriorly

radius rotates over ulna

dorsiflexion

bending foot toward shin

plantar flexion

pointing toes

inversion

sole of foot faces medially

eversion

sole of foot faces laterally

protraction 

movement in lateral plane

mandible juts out

retraction

movement in lateral plane

mandible is pulled toward neck

elevation

lifting body part superiorly

depression

lowering body part

opposition

movement of thumb

grasping movement

5 synovial joints

jaw, shoulder, elbow, hip, knee

jaw

temporomandibular

shoulder

glenohumeral

elbow

humeroulnar

hip

acetabulofemoral

knee

tibiofemoral

temporomandibular joint

modified hinge

mandibular condyle articulates with temporal bone

articular capsule thickens into strong lateral ligament

hinge or gliding movement

most easily dislocated

dislocation of tempomandibular joint

anteriorly, causes mouth to remain open

ear and face pain, tender muscles, popping sounds when opening mouth, joint stiffness

caused by grinding teeth or jaw trauma

glenohumeral joint

most freely moving joint in the body

less stable

ball and socket- hemispherical head of humerus fits in small shallow glenoid cavity of scapula

articular capsule enclosing cavity is thin and loose- freedom of movement

reinforcing glenohumeral ligaments

coracohumeral ligament- helps support weight of upper limb

three glenohumeral ligaments- strengthen anterior capsule but are weak support

reinforcing glenohumeral muscle tendons

contribute to joint stability

tendon of long head of biceps brachii

four rotator cuff tendons

tendon of long head of biceps brachii muscle

superstabilizer of glenohumeral joint

travels through intertubercular sulcus

secures humerus to glenoid cavity

four rotator cuff tendons of glenohumeral joint

subscapularis, supraspinatus, infraspinatus, teres minor

shoulder dislocations

common due to mobility in the shoulder

head of humerus can easily dislocate forward and down due to weak anterior and superior structures

glenoid cavity provides poor support

humeroulnar joint

hinge joint formed from trochlear notch of ulna and trochlea of humerus

allows only flexion and extension

anular ligament and two capsular ligaments

anular ligament

surrounds head of radius

two capsular ligaments of humeroulnar joint

ulnar collateral and radial collateral ligament

restrict side to side movement

acetabulofemoral joint

ball and socket where the large spherical head of the femur articulates with deep cup shaped acetabulum

good range of motion but limited by deep socket

acetabular labrum

in acetabulofemoral joint

rim of cartilage that enhances depth of the socket

acetabulofemoral reinforcing ligaments

iliofemoral, pubofemoral, ischiofemoral, ligament of head of femur

ligament of head of femur

ligamentum teres

slack during most hip movements , not important in stabilizing 

contains an artery that supplies the head of femur

knee joint

consists of femoropatellar, lateral, and medial joints

joint capsule is thin and absent anteriorly

12 bursae associated with knee joint

femoropatellar joint

in the knee

plane joint

allows gliding motion during knee flexion

tibiofemoral joint

consists of lateral and medial knee joint

joint between femoral condyles and lateral and medial menisci of tibia

hinge joint that allows flexion extension and some rotation

quadriceps tendon

anterior of knee

gives rise to three broad ligaments that run from patella to tibia

medial and lateral patellar retinacula that plank the patellar ligament

stabilizers of the knee joint

capsular, extracapsular, intracapsular ligaments

capsular and extracapsular prevent hyperextension of knee

fibular and tibial collateral, oblique popliteal and arcuate popliteal ligaments 

fibular and tibial collateral ligaments

prevent rotation when knee is extended

oblique popliteal ligament

stabilizes posterior knee joint

arcuate popliteal ligament

reinforces joint capsule posteriorly

intracapsular ligaments

stabilize the knee

reside withing the capsule but outside the synovial cavity

help prevent anterior-posterior displacement

anterior cruciate ligament, posterior cruciate ligament, articular discs

anterior cruciate ligament

attaches to anterior tibia

prevents forward sliding of tibia and stops hyperextension of knee

posterior cruciate ligament

attaches to posterior ligament

prevents backwards sliding of tibia and forward sliding of femur

articular discs

fibrocartilage separates articular surfaces

improves fit of bone ends

stabilizes joint and reduces wear and tear

knee joint injuries

involve collateral ligaments, cruciate ligaments, and cartilages (menisci)

lateral blows to extended knee results in tears in tibial collateral ligament, medial meniscus, and anterior cruciate ligament

surgery need for repairs

cartilage tears

due to compression and shear stress

fragments may cause joint to lock or bind

cartilage rarely repairs itself

repaired with arthroscopic surgery

partial menisci removal renders joint less stable but mobile

complete removal- osteoarthritis

meniscal transplant is possible

sprains

reinforcing ligaments are stretched and torn

ankle, knee, lumbar region of back

partial tears repair slowly because of poor vascularization

sprain repair

ends of ligaments can be sewn together

replaced with grafts

allow time and immobilization for healing

dislocations

bones forced out of alignment

accompanied by sprains inflammation and difficulty moving joint

must be reduced (put back) to treat

subluxation

partial dislocation of a joint

bursitis

inflammation of bursa caused by blow or friction

treated with rest and ice, sometimes anti-inflammatories

tendonitis

inflammation of tendon sheaths caused by overuse

arthritis

most widespread crippling disease in US

pain stiffness and swelling of joint

acute forms caused by bacteria, treated with antibiotics

chronic forms osteoarthritis, rheumatoid arthritis, gouty arthritis

osteoarthritis

most common type

irreversible, degenerative

excess release of enzymes break down articular cartilage

bone spurs form from thickened ends of bones

more women than men

part of normal aging process

joints are stiff and make crunching noise

osteoarthritis treatment

moderate activity, mild pain reliever, capsaicin cream

rheumatoid arthritis

chronic inflammatory autoimmune disease

joint pain and swelling, anemia, osteoporosis, muscle weakness, cardiovascular problems

begins with inflammation of synovial membrane of affected joint

synovial fluid accumulates causing swelling

synovial membrane thickens into abnormal pannus tissue that clings to articular cartilage

pannus erode cartilage, scar tissue forms, connects articulating bone ends