Joints

joint

where adjacent bones or adjacent bone and cartilage form a connection, categorized by funciton and structure

synarthrosis joints

immobile, provide protection; can be several kinds of strong connective tissue

ex: sutures in skull, fused parts of sternum

amphiarthrosis joints

limited mobility, stability- strong but also flexible

ex: fibrocartilage in intervertebral disc, pubic symphysis

diarthrosis joints

free mobility, body movement, 3 categories based on axis of motion (unilateral, bilateral, multiaxial)

uniaxial

moves along single axis (humerus/ulna, tibia/femur)

biaxial

can move in two directions/axis of motion (radiocarpal joint)

multiaxial

atleast 3 different types of axis of motion (humerus, femur)

fibrous joint

bones connected by fibrous connective tissue

cartilaginous

bones connected by hyaline cartilage or fibrocartilage

synovial joints

bones are indirectly connected by lubricated joint cavity; often allows for free and controllable movement

functional classifications of joints

synarthrosis, amphiarthrosis, diarthrosis

structural classification of joints

fibrous, cartilaginous, synovial

fibrous joints- suture

strong, rigid, narrow, often convoluted joint; bones connected by fibrous connective tissue

synostosis

connective tissue at a suture ossifies

fibrous joints- syndesmosis

parallel bones held together by fibrous connective tissue (interosseous membrane)

fibrous joints- gomphosis

anchoring teeth into bony sockets, ‘peg and socket joints’, only found in teeth, bones connected by fibrous connective tissue (peridontal ligament)

cartilaginous

synchondrosis, symphysis

cartilaginous joints- synchondrosis

hyaline; temporary (replaced by bone with age, ex: epithelial growth plate, joints between hip bones) or permanent (costal cartilage)

cartilaginous joints- symphysis

fibrocartilage, allows limited movement, provides stability and cushion (interverterbal disc, pubic symphysis)

synovial

bones are indirectly connected by lubricated joint cavity

synovial articular cartilage

hyaline cartilage that lines ends of bones if they articulate to prevent friction.

synovial joint cavity

filled with synovial fluid to push back against compression and maintain structural integrity of the joint

synovial articular capsule

fibrous membrane (superficial, made of dense connective tissue that maintains shape when body moves) and synovial membrane (deep, secretes and maintains synovial fluid)

articular disc and meniscus

cartilaginous discs between synovial joints (lubricated joint cavity); functions-strongly unite bones, extra cushion, shock absorption

bursae

fluid filled connective tissue sacs between moving soft tissue

submuscular bursae

between muscle and bone (suprapatellar bursae)

subcutaneous bursae

between skin and bone (prepatellar bursae)

subtendinous bursae

between a tendon and bone (infrapatellar bursae)

pivot

rounded part of one bone articulates in part of second bone+ligament, uniaxial

hinge

convex part of one bone articulates with concave part of other bone. uniaxial

condyloid

shallow depressions in one bone articulates with rounded part of other bone, biaxial

saddle

both sides are saddle shaped, concave and convex sides in one bone articulate with concave and convex of other bone, biaxial

plane

flatish surface slides against each other, no change in angles of bones

ball and socket

multiaxial, femur and acetabulum

flexion in trunk and girdles

anterior motion

extension in trunk and girdles

moves body backwards

flexion in lower limbs

brings bones together

extension in lower limbs

bones come apart

flexion and extension are in the ___ plane

sagittal

abduction and adduction are in the ___ plane

coronal/frontal

abduction

movement away from midline

adduction

movement towards midline

circumduction

circular movement of a body part around a fixed point, complicated movement

rotation

twisting movement of a body part along its axis, simple movement

lateral rotation

anterior surface turns outwards away from midline

medial rotation

anterior surface turns towards midline

pronation and supination are unique to ____

the forearm

pronated position

palm facing posterior (radius is crossed over ulna)

supinated position

palm facing anteriorly (radius and ulan are parallel

gliding

surfaces slide without changing angle between bones, occurs at plane synovial joints (ex: tarsals, superior articular facets

dorsiflexion (ankle)

turning plantar surface to face inferiorly

plantar felxion (ankle)

turning plantar surface to face posteriorly

inversion (ankle)

tipping plantar surface towards midline

eversion (ankle)

turning plantar surface away from midline

retraction (mandible)

inward motion

protraction (mandible)

outward motion

elevation (mandible)

upward motion (close mouth)

depression (mandible)

downward motion (open mouth)

lateral excursion (mandible)

movement of mandible away from midline

medial excursion (mandible)

movement of mandible toward midline