articulations a&p

main function of joints

joints connect two bones

how do joints help with movement

surrounding muscles and tendons exert the necessary amount of force across the joint allowing movement.

how do joints help with stability

joints that allow limited to no movement are very stable. critical for joints that protect underlying structures. 

how do joints help bones lenghten

the epiphyseal plate is the location in long bones that grow during skeletal development 

synarthrosis

no movement between two bones; provides most stability

ampiarthrosis

small amount of movement; provides significant amount of stability

diarthrosis

freely moveable joint with a wide variety of movements. least amount of stability.

fibrous joints

united by dense regular collagenous connective tissue, no joint space. synarthroses or ampiarthroses. 

cartilagenous joints

cartilage between articulating bone, no joint space. synarthroses or ampiarthroses.

synovial joint

joint cavity, filled with fluid between articulating bone. diarthroses.

sutures

joint between bones of the skull. held together by short collagen fibers. stable synarthroses.

gomphoses

joint between a tooth and corresponding alveolus in the mandible or maxilla. attached to bone fibers called peridontal ligament.

syndesmosomes

articulating bones are joined by an interosseous membrane or ligament. composed of dense regular collagenous connective tissue.

synchondroses 

bones united by hyaline cartilage 

symphyses

bones united by a fibrocartilage pad

articular capsule

double layered structure. outer fibrous layer made of dense irregular ct. inner synovial membrane is made of loose ct. 

lubrication

reduces friction

metabolic function

supplies nutrients like glucose. removes metabolic waste

shock absorption

evenly distributes force and stress on articular surfaces of bones during movement 

ligament

made of dense regular collagenous ct that connects one bone to another bone 

intrinsic ligament

thickened region of the articular capsule

extrinsic ligament

not part of articular capsule that may be inside or outside of the joint cavity

tendons

made of dense regular collagenous ct that connects a muscle to a bone or another structure

bursae

synovial fluid-filled structure with a synovial membrane. found in regions of high stress where bones, tendons, and muscles interact in a small space to minimize friction 

tendon sheaths

long bursae that surround some tendons in high stress regions of the body. protects long tendons as they course over and around synovial joints 

bursaitis

inflammation of a bursa, most commonly in the shoulder, elbow, hip, and knee 

arthritis

inflammation of one or more joints, resulting in pain, joint stiffness, and decreased range of motion

osteoarthritis

most common form of arthritis, occurs from wear and tear

rheumatoid arthritis

autoimmune disease that results in joint destruction mediated by individuals own immune system 

gouty arthritis 

joint damage due to inflammatory reaction to excess uric acid crystal deposits 

nonaxial joints

motion occurs in one or more planes, but don’t move around an axis.

uniaxial joints

motion around one axis

biaxial joints

motion around two axes

multiaxial joints

motion around three axes.

gliding movements 

sliding motion between the articulating surfaces of bones in a joint 

angular movements

increase or decrease the angle between articulating bone

flexion

decreases angle between articulating bones by bringing them together.

extension

increases angle between articulating bones 

hyperextension

extension beyond the anatomical position of a joint

abduction

motion of body away from midline or another reference point 

adduction

towards the midline of the body or another reference point

circumduction 

a freely moveable distal bone moves around a stationary proximal bone in a cone-shaped motion

rotation

nonangular pivoting movement one bone twists or rotates on a longitudinal axis (internal is rotation towards midline while external is rotation away from midline)

opposition 

occurs with thumb. movement of thumb across palmar surface of hand 

reposition

return of thumb to anatomical position

depression

movement of body part in an inferior direction

elevation 

movement of body part in a superior direction 

protraction

moves body part in an anterior direction

retraction 

moves a body part posteriorly 

inversion

rotational movement of foot, plantar surface rotates medially towards midline 

eversion

movement of plantar surface of foot laterally away from the midline

dorsiflexion

angle between foot and tibia decreases. toes are pulled towards head 

plantarflexion

angle between foot and tibia increases toes point towards ground 

supination 

forearm is supinated when palm faces anteriorly with thumb pointing laterally

pronation 

palmar surface of hand faces medially until it faces posteriorly with thumb pointing medially 

range of motion

amount of movement a joint is capable of under normal circumstances

nonaxial joints

smallest range of motion. ex = intercarpal joints

multiaxial joints

greatest range of motion. ex = shoulder

plane joint

nonaxial joint, two bones whose flat surfaces sit next to each other

hinge joint

uniaxial joint, convex surface of one bone fits into a concave depression of another bone 

pivot joint

uniaxial joint, rounded surface of one bone fits into a groove on the surface of another bone.

condylar joint

biaxial joint, oval, convex joint surface of one bone fits into a shallow concave surface of another bone 

saddle joint

biaxial joint, surface of each articulating bone has both convex and concave regions that complement each other. 

ball-and-socket joint

multiaxial joint. articulating surface of one bone is ball shaped and fits into a cup or socket formed by the articulating surface of the other bone 

elbow

hinge joint composed of two articulations

humeroulnar joint

between trochlea of humerus and trochlear notch of the ulna

humeroradial joint

between capitulum of humerus and the head of the radius

radial collateral ligament

supports lateral side of joint

ulnar collateral ligament

supports medial side of joint

anular ligament

stabilizes the radial head

knee

largest diarthrosis of the body. hinge joint that allows for some degree of rotation and lateral gliding

tibiofemoral joint

between femoral and tibial condyles.

patellofemoral joint

between patella and patellar surface of the femur.

medial and lateral menisci

pair of c-shaped fibrocartilage pads on the tibial condyles

tibial collateral ligament

links femur with the tibia and attaches to medial meniscus

fibular collateral ligament

links femur with fibula but does not attach to the lateral meniscus

anterior cruciate ligament

runs from anterior insertion site on tibia to the posterior aspect of the femur

posterior cruciate ligament

runs from posterior side of tibia to anterior femur

shoulder (glenohumeral joint)

made up of ball-shaped humeral head and the glenoid cavity on the lateral scapula 

glenoid labrum

fiqrocartilogenous ring that sits on the rim of the glenoid cavity

dislocated shoulder

glenohumeral joint with traumatic displacement of the head of the humerus from the glenoid cavity

separated shoulder 

acromioclavicular joint (not a component of the shoulder)

hip (coxal joint)

Articulation between the acetabulum and the ball-shaped head of the femur; Multiaxial ball-and-socket joint; More stable than the shoulder joint

Acetabular Labrum

Fibrocartilage ring strengthens the fit between the bones

Iliofemoral Ligament

Reinforces anterior side of the hip joint

Ischiofemoral Ligament

Supports posterior side of the hip joint

Pubofemoral Ligament

Triangular thickening of the inferior portion of the articular capsule

Ligament of the Head of the Femur

Links the center of the head of the femur with the acetabulum