Joint

Question 1

What are the function of joints

Answer 1

Allow movement in 3-dimensions

Bear weight

Transfer the load evenly to the musculoskeletal system

Question 2

What are the structural classifications of joints

Answer 2

Fibrous
Cartilaginous
Synovial

Question 3

What is an example of a fibrous joint

Answer 3

Teeth sockets

Question 4

What is an example of cartilaginous joints

Answer 4

Intervertebral discs

Question 5

What is an example of synovial joints

Answer 5

Metacarpophalangeal

Question 6

What are the functional classifications of joints

Answer 6

Synarthroses
Amphiarthroses
Diarthroses

Question 7

Define synarthroses with example

Answer 7

Immovable joints, mostly fibrous

e.g. skull sutures

Question 8

Define amphiarthroses with example

Answer 8

Slight moveable joints, mostly cartilaginous

E.g. intervertebral discs

Question 9

Define diarthroses with examples

Answer 9

Freely moveable joints, mostly synovial

E.g. hip

Question 10

What are the three examples of fibrous joints

Answer 10

Sutures
Syndesmoses
Gomphoses

Question 11

Explain sutures

Answer 11

Occur only between bones of the skull - allow skull growth in development

Adjacent bones interdigitate

Junction filled with very short tissue fibres

Question 12

Describe syndesmoses

Answer 12

Bones are connected by a cord (ligament) or sheet (interosseous membrane) of fibrous tissue

Amount of movement permitted is proportional to length of fibre

Question 13

Describe gomphoses

Answer 13

A peg-in-socket fibrous joint found only in tooth articulation

Question 14

Examples of cartilaginous joints

Answer 14

Synchondroses
Symphyses

Question 15

Describe synchondroses

Answer 15

Bones are directly connected by hyaline cartilage

Usually amphiarthroses e.g. slightly moveable e.g. costal cartilage of the rib

Question 16

Describe symphyses

Answer 16

Connecting cartilage is a pad or a plate of fibrocartilage e.g. intervertebral discs

Question 17

Joint classification summary

Answer 17

Fibrous - synarthrosis - suture, syndesmosis, gomphosis

Cartilaginous - amphiarthrosis - synchondrosis, symphysis

Synovial - diarthrosis

Question 18

Describe synovial joints

Answer 18

Articulating bones are separated by fluid-filled cavity

Most joints in the body fit into this category

Question 19

What are the 5 characteristic features of synovial joints

Answer 19

Articular cartilage

Joint capsule - the inner layer is the synovial membrane

Joint (synovial) cavity - a space filled with synovial fluid

Synovial fluid

Reinforcing ligaments

Question 20

What are the types of cartilage

Answer 20

Elastic cartilage

Fibrocartilage

Hyaline cartilage

• all contain chondrocytes - synthesise extracellular matrix

Question 21

Define bursae

Answer 21

Fluid filled sacs lined by synovial membrane

Question 22

Define menisci

Answer 22

Disc of fibrocartilage

2 cover surface of tibia and femur

Question 23

Describe articular (hyaline) cartilage

Answer 23

Almost frictionless surface

Resists compressive loads

High water content

Low cell content

No blood supply

Question 24

What are the articular cartilage zones

Answer 24

Superficial zone (10-20%)
Middle/intermediate zone (40-60%
Deep zone (30%)
Calcified zone
Subchondral zone

Question 25

Describe synovial fluid

Answer 25

Joint lubricant Covers articulating surfaces with thin film (0.5ml) Modified from plasma by synovial membrane (synoviocytes) Result = slimy fluid - like egg white Reduce friction during articulation

Question 26

Describe synovial membrane

Answer 26

Sits on the joint capsule and encloses synovial cavity Only a few cells thick Can have villi and projections to increase surface area Secretes synovial fluid components - hyaluronate and a source of inflammatory cells in rheumatoid arthritis

Question 27

What do ligaments connect

Answer 27

Bone to Bone

Question 28

What is the role of ligaments

Answer 28

Stabilise joints Less regularly arranged fibre than tendons Can stretch up to 6% before breaking May contain more elastic fibres than tendons (generalisation)

Question 29

What do tendons connect

Answer 29

Bone to muscle

Question 30

What is the role of tendons

Answer 30

Stabilise joints Made of dense regular connective tissue - rich in type 1 collagen Allow muscles to be accommodated at a distance from their insertion Provides a solid base (insertion to bone) on which muscles can pull

Question 31

What stabilises joints

Answer 31

Ligaments Tendons Muscles

Question 32

How do joint mechanics work

Answer 32

A synovial joint is the fulcrum of a level system A lever can apply a torque (twist) about a fulcrum, proportional to force x distance

Question 33

Describe a first class lever

Answer 33

Fulcrum is in the middle (elbow joint) The force is at one end (the triceps muscle) Resistance is at the other end (the weight being pulled) e.g. pulling weight downwards

Question 34

Describe a second class level

Answer 34

The fulcrum is at one end (e.g. temporomandibular joint) The force is at the other end (the muscles of the chin) Resistance is at the centre (the muscles attached to the coronoid process)

Question 35

Describe third class lever

Answer 35

Fulcrum is at one end (e.g. elbow joint) The force is in the middle (biceps muscle) Resistance is at the other end (the weight being pulled) e.g. pulling the weight upwards

Question 36

What type of joint is the hip joint

Answer 36

Synovial joint - ball and socket Held in securely in place by strong ligaments and heavy cylindrical joint capsule

Question 37

What are the main stabilising ligaments in the hip joint

Answer 37

Iliofemoral Pubofemoral Ischiofemoral

Question 38

Describe the shoulder joint

Answer 38

Ball and socket Stability sacrificed for rang of movement Joint capsule is loose Dislocation of the shoulder quite common Rotator cuff muscles help in stabilisation but are prone to injury - especially at tendon insertion sites

Question 39

What are the stabilising ligaments of the shoulder

Answer 39

Glenoidal labrum - fibrocartilage Coracohumeral ligament Three glenohumeral ligaments Transverse humeral ligament

Question 40

What are the tendons and muscles which stabilise the shoulder

Answer 40

Long head of biceps branchii Tendons of the rotator cuff - subscapularis - suprascapularis - infraspinatus - teres minor

Question 41

What is the knee joint

Answer 41

Not a hinge joint Femur and tibia = condyloid - ovoid head of one bone moves in an elliptical cavity of another Femur and patella = gliding Joint capsule thin but strengthened by many tendons and ligaments