Joints

Question 1

What is an articulation (joint)?

Answer 1

Where two or more bones connect to either allow movement or enable stability. These can be functional or structural

Question 2

How are functional joints classified?

Answer 2

Synarthrosis - immovable - interlocked surfaces joined by fibres, cartilage or bone
Amphiarthrosis - Slightly moveable joint - surfaces connected by collagen or cartilage
Diarthrosis - Freely moveable - synovial

Question 3

What movements occur in the sagittal plane?

Answer 3

Flexion- reducing the angle at a joint
Extension - Increasing the angle to 180 degrees
Hyperextension - extension past anatomical position

Question 4

What movements occur in the frontal plane?

Answer 4

Abduction- away from the longitudinal axis
Adduction - towards longitudinal axis
Circumduction - circular motion without rotation

Question 5

What movements occur on the longitudinal axis?

Answer 5

Rotation - motion around the longitudinal axis
Head and spine - left or right rotation
Limbs- lateral or medial

Question 6

What is the rotation of the forearm?

Answer 6

Pronation - radius crosses over the ulna - palm faces posteriorly
Supination - to the anatomical position

Question 7

What are the movements that occur at the foot?

Answer 7

Inversion - twist sole medially
Eversion - twist sole laterally
Dorsiflexion - flexion at the ankle
Plantarflexion - extension at the ankle

Question 8

How do we describe movement?

Answer 8

Type of movement and then the location

Question 9

How are structural joints classified?

Answer 9

Bony fusion, fibrous, cartilaginous, synovial

Question 10

What are bony joints classified?

Answer 10

Synostosis - synarthrosis - bones fused- joint between left and right frontal bone

Question 11

How are fibrous joints classified?

Answer 11

Suture - synarthrosis - articulating bones interlock and attached by collagen e.g. sutures in cranium
Gomphosis - Synarthrosis - tooth fits in socket attached by ligament e.g. joints between teeth and jaws
Syndesmosis - Amphiarthrosis - bones connected by ligaments e.g. joint between tibia and fibula

Question 12

How are cartilaginous joints classified?

Answer 12

Synchondrosis - synarthrosis - bones attached by cartilage e.g. costal cartilage (ribs)
Symphysis - Amphiarthrosis - bones separated by fibrocartilage disk e.g. pubic symphysis

Question 13

How are synovial joints classified?

Answer 13

Synovial - diarthrosis - cartilage, synovial fluid and joint capsule e.g. ends of long bones

Question 14

What are the features of a typical synovial joint?

Answer 14

Articular cartilage- smooth covering of bone, prevents bone touching, reduces friction
Synovial fluid- High protein contents (proteoglycans) secreted by fibroblasts - lube, nutrient distribution, shock absorption
Joint capsule - Fibrous connective tissue - protects and stabilises, synovial membrane (layer of cells)

Question 15

What are the joint accessory structures?

Answer 15

Cartilages - cushion the joint e.g. meniscus fibrocartilage pad in knee
Fat pads - Superficial, provide protection
Ligaments - Support, strengthen joint
Tendons - attach to muscles help support joint
Bursae- Pockets of synovial fluid - cushion where tendons or ligaments rub

Question 16

What are the types of synovial joint?

Answer 16

Gliding - slight movement - e.g. claviculo- sternal
Hinge - monoaxial e.g. elbow
Pivot - Monoaxial (rotation) e.g. atlanto- axial
Condylar - Biaxial - (convex/concave) - radiocarpal
Saddle - biaxial - base of the thumb - first carpometacarpal
Ball and socket - Triaxial - Shoulder and hip

Question 17

What factors affect function of joints?

Answer 17

Joint accessory structures - shapes of bones, joint capsule, ligaments, menisci
Tendons and muscles crossing the joint
Other structures e.g. bones muscles fat pads
Limiting movement increases stability

Question 18

What is the structure of the C2 to L5 intervertebral articulations

Answer 18

Intervertebral discs- fibrocartilage pads (symphyses) - shock absorption, limited movement
Vertebral end plate, anulus fibrosus, nucleus pulposus - elastic
Articular facets - Gliding joints
Intervertebral ligaments

Question 19

Outline the structure of a damaged intervertebral disc

Answer 19

slipped disc- pinched area of the anulus fibrous causing bulge of the nucleus pulposus into intervertebral foramen which compresses the spinal nerve

Question 20

Outline the structure of the shoulder joint

Answer 20

Ball and socket
Glenoid labrum - fibrocartilage ring deepens the cavity
Ligaments
Rotator cuff muscles - tendons reinforce joint capsule
Bursae - reduce friction between head of humerus and acromion process
Optimised for movement with a loose cavity

Question 21

Outline the structure of the hip

Answer 21

Head of femur articulates with the deep acetabulum
Acetabular labrum deepens the cavity
Fat pad
Strong more stable joint- limited movement
Strong joint capsule reinforced by ligaments

Question 22

Outline the structure of the elbow

Answer 22

Hinge joint
Articulation - humeroulnar - Trochlea (humerus) with trochlea notch - flexion and extension
Humeroradial - Capitulum (humerus) with head of radius - pronation and supination
Ligaments

Question 23

Outline the structure of the knee joint

Answer 23

Complex hinge
Two femur tibia joints - medial and lateral condyles and menisci
Patella patellar surface of femur
Ligaments- patellar, anterior and posterior cruciate - stability stops femur sliding, tibial and fibular collateral ligaments
Bursae
Fat pads

Question 24

What is the function of the tibial and fibular collateral ligaments?

Answer 24

Stability of the joint from the sides
They are loose when the knee flexes allowing some rotation they then tighten when the knee is extended these are tightened which locks the knee

Question 25

What are the joint injuries?

Answer 25

Sprain - tearing of ligament fibres
Dislocation (luxation)- Articulating surfaces displaced, damage articular cartilage, ligaments, joint capsule
Subluxation - partial dislocation

Question 26

What are the joint diseases?

Answer 26

Osteoarthritis - damage to articular cartilage and underlying bone, common with age, inflammation
Rheumatoid arthritis - Autoimmune - inflammation of articular cartilage
Gouty arthritis - deposition of crystal of uric acid in joint as a result of metabolic disorder