UNIT 13 - THE JOINTS

What is the Functional Classification of Joints?

based on amount and range of motion a joint is capable of

• synarthrotic (not moveable)

• amphiarthrotic (slightly moveable)

• diarthrotic (freely moveable)

What is the Structural Classification of Joints?

relies on:

• the anatomical organization of the particular joint

• particular material that binds joint

What are the different Structural Joint Classifications?

fibrous; dense fibrous connective tissue btwn bones

cartilaginous; cartilage between bones

synovial; cavity between articulating bones, ligaments hold bones tgt

What are the different Fibrous joints?

• suture

• syndesmosis

• gomphosis

What are the different Cartilaginous joints?

• synchondrosis

• symphasis

What are the different Synovial joints?

• gliding

• hinge

• pivot

• ellipsoidal

• saddle

• ball and socket

How can we classify Fibrous Joints?

• articulating bones held very closely together by dense irregular connective tissue

• little or no movement

What is the Suture Fibrous Joint?

interlocking edges of skull plates (coronol suture)

• held by thin layer of dense fibrous connective tissue

• synarthrotic in adults, amphiarthrotic adolescence 

What is the Syndesmoses Fibrous Joint?

an interosseous membrane

• connection between tibia and fibula (synarthrotic)

• connection between radius and ulna (amphiarthrotic)

What is the Gomphosis Fibrous Joint?

thin fibrous tissue connecting socket bone to root of tooth (periodontal ligament)

• allows no movement in healthy people (synarthrotic)

How can we classify Cartilaginous Joints?

• joint is tightly connected by cartilage

• allows little or no movement

What is the Synchondrosis Cartilaginous Joint?

a bar or plate of hyaline cartilage

• unites bones together

• all are synarthrotic

example: present between rib and sternum

What is the Symphysis Cartilaginous Joint?

hyaline cartilage covering articulating surface

• fused to an intervening pad of fibrocartilage

• amphiarthrotic; designed for strength and flexibility

examples: pubic symphysis, symphyses btwn vertebrates

How can we classify Synovial Joints?

• diarthrotic joints

• ligaments holds bones tgt

• synovial cavity w/ fluid btwn bones

  • lubricates joint

  • acts as shock absorber

  • supplies O2 and nutrients to cartilage

What is the Joint Capsule / Articular Capsule?

sleeve-like layer of fibrous connective tissue that surrounds joints

• holds synovial fluid in place

• attaches to periosteum of articulating bones to help hold bones tgt

What is the Synovial Membrane?

lines inner surface of joint EXCEPT over articular cartilage

• secretes synovial fluid into synovial cavity

What is the Synovial Cavity?

space between two articulating bones

• contains synovial fluid

What is Synovial Fluid?

lubricates joints + serves as shock absorber

• helps to supply nutrients

• removes metabolic wastes from the articular cartilage

What is the Articular Cartilage?

covers ends of articulating bones in synovial joints

• reduces friction

• serves as shock absorber to prevent damage to ends of bones

What are Ligaments?

bands of fibres that provide added strength + holds bones together

• usually external to joint

What are the Menisci?

pads of cartilage which lie between articular surfaces of bones

• allows bones of diff shapes to fit tgt more tightly

• acts as spacer in joint to prevent bones from smashing tgt

What is the Bursae?

pockets of synovial fluid that cushion areas were tendons or ligaments rub tgt

• reduces friction at joints

• can be found inside or outside joint

What are all the factors that stabilize Synovial Joints?

• collagen fibres (joint capsule, ligaments)

• articulating surfaces and menisci

• other bones, muscles, or fat pads

• tendons of articulating bones

all prevent injury by reducing ROM

How can we describe the different types of Synovial Joints?

based on shapes of articulating bone surfaces

• not all synovial joints have all (or any) accessory structures

What types of movements do Synovial Joints allow?

• gliding

• angular

• rotation

• circumduction

all can be single or in combination with each other to describe all movements body is capable of

How does the Gliding Movement work?

movement of 1 bone over another

• side to side

• back and forth

How does the Angular Movement work?

angle between articulating bones increases or decreases

• abduction (away from midline)

• adduction (toward midline)

• flexion (decrease in angle)

• extension (increase in angle)

• circumduction (movement in circle)

How does Rotation Movement work?

rotation around long axis

• results in side to side turning action

What is the Gliding Joint?

1 bone glides over the other

• both surfaces are usually flat

• allows for sliding motion in various directions including circular

examples: carpals of wrist, tarsals of ankle, sternum and clavicle, scapula and clavicle

What is the Hinge Joint?

concave + convex articulating surfaces

• 1 bone remains stationary and the other moves around it in a door hinge action

• movement is angular in one plane only

examples: elbow, knee, bones of phalanges

What is the Pivot Joint?

rounded and ring shaped articulating surfaces

• allows for rotational movement only

example: atlas pivots around dens of axis, proximal joint between radius and ulna

What is the Ellipsoidal Joint?

concave and convex articulating surfaces

• capable of angular and circumduction movements

examples: radius and carpals, metacarpals and phalanges (except thumb)

What is the Saddle Joint?

articulating surfaces are “saddle” shaped

• allows for angular and circumduction movements

examples: metacarpal of the thumb

What is the Ball and Socket Joint?

rounded head of 1 bone in a depression of another

• allows for angular, rotational, and circumduction movements

example: shoulder and hip