Ch.9

joint

any point where tow bones meet whether or not bone are moveable at that interface

“arthro”

root word for joint

arthritis

inflammation of the joint

what are the 4 major joint cavities?

bony, fibrous, cartilaginous, synovial

Bong joints (synostosis)

immobile joint formed when the gap between two bones completely ossifies. and the bones become a single bone

what are examples of bony joints?

• left and right mandibles bones become one in infants

• two frontal bones in infants become one

• cranial sutures in elder often ossify

• attachment with first rib and sternum in elder

fibrous joints (synarthrosis)

adjacent bones are bound by collagen fibers that emerge from one bones and penetrate into the other

what are three kinds of fibrous joints?

sutures, gomphoses, syndesmoses

how are the three kinds of fibrous joints held together to some degree?

with collagen

sutures

immobile or slightly mobile fibrous joints in which short collagen fibers bind the bones of the skull to eachother

classifications of sutures

serrate, lap (squamous), plane (butt)

serrate

interlocking wavy libes

what are the serrate sutures?

coronal, sagital, and lambdoid sutures

lab (squamous) sutures

overlapping beveled edges

what are the lab sutures?

temporal and parietal bones

plane (butt) sutures

straight, non overlapping edges w

what is the plane suture?

palatine processes of the maxillae

gomphosis

• fibrous joint

• attachment of a tooth to its socket

• held in place by periodontal ligaments

what happens when a dentist pulls a tooth?

the ligaments that are holding the tooth in the socket are broken

syndesmosis

• fibrous joint

• two bones are bound together by collagen fibers called interosseus

example of very mobile syndesmosis

radius to ulna

example of less mobile syndesmosis

tibia to fibula

cartilaginous joint (amphiarthrosis)

two bones are linked by cartilage

what are the two types of cartilaginous joints

synchondroses and symphyses

whats synchondroses made of?

hyaline cartilage

what is symphyses made of?

fibrocartillage

Synovial Joints (diarthrosis)

joints in which two bones are separated by a joint cavity

what are synovial joints referred to as

freely moveable

articular cartilage (synovial joint)

layer of hyaline cartilage that covers the facing surfaces of two bones

how thick is articular cartilage?

2 or 3 mm

joint cavity

separates articular surfaces

synovial fluid

slippery lubricant in joint cavity

characteristics of synovial fluid

• rich in albumin and hyaluronic acid

• gives its viscous, slippery texture like raw egg whites

• nourishes articular cartilage and remove waste

• makes movement of synovial joints almost friction free

joint capsule

connective tissue that encloses that cavity and retains the fluid

two components of joint capsule

outer fibrous capsule and synovial membrane

outer fibrous capsule

continuous with periosteum of adjoining bones

synovial membrane

composed mainly of fibroblast-like cells that secrete synovial fluid and macrophages that remove debris from the joint cavity

articular disc

when fibrocartilage grows inward a pad forms between articulating bones that crosses the entire joint capsule (ex:TMJ)

meniscus

moon-shaped cartilage in the knee, in each knee, mneisci extend inward from the left and the right

what does the meniscus do?

• the cartilages absorb shock and pressure

• guide bones across each other and improve their fit together

• stabilizes the joints, reducing the chance of dislocation

tendon

strips of collagenous tissues attaching MUSCLE to BONE

Ligament

strip of collagenous tissue attaching one BONE to another

Bursa

Fibrous sac filled with synovial fluid, located between muscles, where tendons pass over bone, or between bone and skin

What does bursa do?

cushions muscles, help tendons slide more easily over joints, modifies direction of tendon pull

tendon sheath

elongated cylindrical bursa wrapped around a tendon

where is tendon sheath found?

hand and foot

what does exercise do to synovial fluid?

warms the synovial fluid, becomes less viscous, more easily absorbed cartilage allowing cartilage to swell?

what happens when the cartilage swells in exercise?

it provides a more effective cushion, warm-up period before vigorous exercises helps protect cartilage from undue tear and wear

what happens without cartilage?

cartilage deteriorates more rapidly from inadequate nutrition and waste removal and provides much less padding between the bones leading arthritis and osteoarthritis

Range of motion (ROM)

the degrees a joint can move

100% ROM

joint that is moving nomrally

what happens if someone has less ROM?

effects quality of life

What is ROM determined by?

structure of the articular surfaces, strength and tautness of ligaments and joint capsules, and action of the muscles and tendons

stretching of the ligaments

increases ROM

double jointed

people have long or slack ligaments

multiaxial

movement along many planes ( hip and shoulder)

monoaxial

one plane

biaxial

2 planes

multiaxial joints

ball and socket

Monoaxial joints

pivot, hinge,

biaxial joints

saddle joint, condylar joint, plane joint

what are the six classes of synovial joints?

ball and socket, condylar, saddle, plane, hinge, pivot

ball and socket joint

• smooth, hemispherical head fits with cup-like socket

• only in multiaxial

• hip and shoulder

condylar joints

• oval convex surface of one bone fits into a complementary- shaped depression on other

• biaxial joints- movement in two planes

• ex: radiocarpal joint, metacarpophalangel joints

saddle joints

• both joints have an articular surface that is shaped like a saddles, one concave, the other convex

• biaxial joints

• ex: trapeziometalcarpal (opposable thumb) and sternoclavicular joint

plane joints

• flat articular surfaces, bones slide over each other

• usually biaxial joints

• examples: between carpal bones of wrist, between tarsal bones of ankle, also between articular processes of vertebrae

hinge joints

• one bone with convex surface fits into a concave depression of another joint

• monoaxial joints

• ex: elbow, knee, joints in fingers, toes

pivot joint

• a bone spins on its longitudinal axis

• monaxial joints

• ex: atlantoaxial joint (c1 and c2). radioulnar joint at the elbow

Zero position

the position of a joint when a person is in the standard anatomical position

flexion

movement that decreases joint angle

extension

movement that straightens a joint and returns a body part to zero position

hyperextension

extension of a joint beyond the zero point

abduction

movement of a body part in the frontal plane away from the midline of the body

adduction

movement on frontal plane back toward the midline

circumduction

one end of an appendage remains stationary while other makes circular motion only hip and shoulder

rotation

movement in which a bones spin on its longitudal axis

medial (internal) rotation

turns the bone inward

lateral (external) rotation

turns the bones outward

supination

forearm movement that turns palm to face anteriorly upward

laying supine

means lying face up

pronation

forearm movement that turns palm to face either posterior or downward

laying prone

mean laying face down

what happens to ulna and radius in pronation?

they cross

flexion of head and trunk

forward bending movements at the waist or neck

extension of head or trunk

straightens trunk or neck

hyperextension of neck or trunk

bending over backward

lateral flexion of head or trunk

tilting the head or trunk to the right or left at the midline

radial flexion

tilting hand toward thumb

ulnar flexion

tilting hand toward little finger

abduction of fingers

spreading `

adduction of fingers

bringing them together

flexion of fingers

curling ex

extension of fingers

straightening of fingers

palmar abduction

thumb away from hand

radial abduction

moving thumb away from index finger

flexion of thumb

tip of thumb directed toward palm

extension of thumb

straighten

opposition

moving thumb to touch tip of a finger

reposition

returning the thumb zero position

dorsiflexion

elevating toes as you do while swinging your foot when walking