chapter 8 - articulations

articulations

joints

hold bones together and may permit movement, but don’t have to

-between bones, cartilage and bone, teeth and bones

arthrology

study of joints

kinesiology

study of motion

synarthrosis

immovable, allow no movement

amphiarthrosis

allow some movement

diarthrosis

allow for free movement with no restrictions

classification based on anatomy

fibrous, cartilaginous, synovial

fibrous joints

bones held together by fibrous connective tissues, allow for little to no movement, 4 structural types

-sutures

-syndesmoses

-synotosis

-gomphoses

sutures

thin layer of dense fibrous tissue that connects the bones of the skull, immoveable

syndesmosis

fibrous joint, bones united by a ligament, slightly moveable

-anterior tibiofibular joint and interosseous membrane

synostosis

two bones that completely fuse with eachother, allows no movement

-epiphyseal plate to epiphyseal line

gomphosis

ligament holds tooth in bony socket, immovable

-teeth in alveolar process

cartilage joints

allows little to no movement, bones tightly connected by fiborcartilage or hyaline cartilage

-2 types: synchondroses, symphyses

synchondrosis

connecting material is hyaline cartilage, immovable

-epiphyseal plate or joints between the ribs and sternum

(epiphyseal plate to line is NOT, it is synostosis)

symphysis

fibrocartilage is connective material, slightly moveable

-intervertebral discs or pubic symphysis

synovial joint

1)two bones seperated by a fluid filled cavity

2) 2 layers: synovial membrane, articular cartilage

3) synovial fluid (synovial membrane makes)

4) functions:

• lubricate joint

• nourish condrocytes

• shock absorber

ligaments

reinforce and strengthen joint capsule and connect bone to bone

extracapsular ligaments

outside the joint capsule

intracapsular ligaments

inside joint capsule, found between the bones

articular discs

pads of fibrous cartilage (meniscus)

-channel flow of synovial fluid

-modify articular surfaces

-restrict movements

-cushion articulating surfaces

-help distribute body weight by evening surfaces and allows weight to flow through the center of each bone

fat pads

adipose tissue surrounding the synovial capsule

-protects articular cartilage

-packing material

-fills spaces when the joint changes shape

bursae

small fluid filled pockets of connective tissue (almost pillows for the joint)

-provides cushion and support

-aids movement of tendons te

tendon sheath

covers tendon itself and helps reduce friction

(tendonitis is inflammation of tendon sheath itself)

labrum

extends the rim of the shoulder cavity and hip joint

synovial movement

diarthrosis- lots of movement

gliding

two opposing surfaces slide past each other in forward or backward movements

-sternum/clavical or carpals and tarsals

angular movement

a change in angle between the shaft and the articular surface

-abduction : moving away from midline

-adduction : moving to midline

-flexion : decreasing angle

-extension : bringing back to anatomical position

-hyperextension : moving past anatomical position

circumduction

a type of angular motion that rotates the shaft without changing the angle

-drawing a circle with full arm

rotation

spinning the shaft without changing the angle

-pronation : palms down

-supination : palms up

occurs at the proximal connection between the ulna and radius

used when turning a doorknob or screwing in a lightbuld

special movements

-eversion: sole outwards

-inversion: sole inwards

-dorsiflexion: toes up

-plantarflexion : toes down

-protraction: pushing forward

-retraction: bringing backward

-opposition: bringing thumb pad to pads of other fingers

-elevation: bring upwards

-depression: bring downwards

synovial joint trade off

more flexibility means less stability, or more stability means less flexibility

-shape of articulating surfaces

-tightness of ligaments (genetics)

-presence of accessory ligaments (more mean more stability)

-other bones, muscles or fat pads present in area

types of synovial joints

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

plane joint

bone surfaces are flat or slightly curves, side to side movement, no rotation

-intercarpal or tarsal, sernoclavicular, vertebrocostal

hinge joint

convex surface of one bone fit into concave surface of 2nd bone, uniaxial (door hinge)

-elbow, ankle, interphalangeal

can flex, extend, or hyperextend

knees are special- can circumduct as well when flexed

pivot joint

rounded surface of bone articulates with ring formed by second bone and a ligament

it is monoaxial - only allows rotation

-proximal radioulnar joint (supination and pronation)

-altanto-axial joint (saying no)

condylar (elipsoid) joint

oval shaped projection fits into oval shaped depression - biaxial

flex/extend, abduct/aduct

wrist and metacarpophalangeal for digits 2-5 (not including thumb)

saddle joint

thumb (person sitting on a saddle)

biaxial - cicumduction and opposition

ball-and-socket joint

multiaxial

flexion, extension, abduction, adduction, rotation

temporomandibular joint (TMJ)

hinge joint

between condylar process of mandible and mandibular fossa

-condyles slide back and forth along the joint socket

*2 synovial joints

intervertebral articulation

articulate at superior and inferior processes (plane joint)

-discs allow movement (flexion, extension, lateral flexion, rotation) 

• anulus fibrosus & nucleus pulposus (as we age loose water &discs compress)

  • herniated disc - nucleus pulposus breaks through the anulus fibrosus and compress nerve in vertebral column 

shoulder joint 

glenohumeral joint - head of humerous meets glenoid cavity which is covered by the glenoid labrum 

-is a joint capsule supported with ligaments and muscles

-ball-and-socket-joint that allows full range of motion in all directions

labrum

a ring of dense irregular connective tissue that is attached to the glenoid cavity and extends the cavity

elbow joint 

humerus and ulna - most stable hinge joint of the elbow that allows for flexion and extension 

radiocarpal joint

scaphoid, lunate, triquatium & radius

most movement of the wrist comes from this joint (flexion, extension, adduction, abduction, circumduction

hip joint

where the femoral head meets the acetabulum

ball and socket joint that allows free range of motion

also has labrum that extends the socket and allows for a more stable fit (but less than shoulder bc of the increase in muscle mass and stronger ligaments needed to support body weight)

abduction, adduction, lexion, extension, circumduction, rotation

knee joint 

must support body mass, have 160 deg. of motion, be unobstructed, strong ligaments but that allow for movement and flexability

rheumatism

pain or stiffness of the skeletal system, muscular system, or both

arthritis

a type of rheumatism that affects the synovial joint and damages the articular cartilage

osteoarthritis 

most common due to age and the wear away of the articular cartilage and bone on bone wear or genetic cause 

rheumatoid arthritis

autoimmune disease where antibodies attach the joints and cause inflamation or deformity

gouty arthritis

inflammation in joint due to a build up of uric acid (most commonly affects the big toe)