Bones And Joints Flashcards
What are the 6 main shapes of bones? Give an example of each
- FLAT (frontal)
- SUTRAL (cranial suture)
- SHORT (carpal)
- LONG (femur)
- IRREGULAR (vertebrae)
- SESAMOID (patella)
Put these in order of proximal to distal for a long bone: diaphysis, metaphysis, epiphysis
- Proximal epiphysis
- Metaphysis
- Diaphysis (shaft)
- Metaphysis
- Distal epiphysis
Describe the composition of a short, flat or sesamoid bone
- Consist mainly of SPONGY bone
- Thin layer of periosteum-covered compact bone on outside
- NO EPIPHYSIS OR DIAPHYSIS
- Contain marrow within the trabeculae
Describe the composition of a long bone
- Primarily compact bone but spongy bone at extremities
- Articular cartilage at epiphysis
- Red marrow within spongy trabeculae at metaphysis and diaphysis
- Yellow marrow within the diaphysis
Which region of a long bone contains the nutrient artery?
DIAPHYSIS (enters via nutrient foramen)
What is avascular necrosis?
Death of bone due to interrupted blood supply
List 5 causes of avascular necrosis of bone
- Fracture
- Dislocation
- Steroids
- Radiation
- Decompression
How can avascular necrosis lead to secondary osteoarthritis?
Collapse of the necrotic segment in a joint due to weight bearing/wear and tear
Define ‘joint’
Articulation between two or more bones
Name 2 ways in which joints can be classified
- STRUCTURAL (fibrous, cartilaginous, synovial)
- FUNCTIONAL (synarthosis, amphiarthrosis, diarthrosis)
Give 3 examples of a fibrous joint and where they may be found)
- SUTURE (synostosis of skull bones e.g. cranium)
- SYNDESMOSIS (two bones joined by connective tissue e.g. radio ulnar interosseous membrane
- GOMPHOSIS (between teeth and maxilla/mandible e.g. periodontal ligament)
What is the functional classification of a fibrous joint?
Amphiarthrosis (slightly moveable)
Give 2 examples of cartilaginous joints and state their functional classifications
- Primary SYNCHONDROSIS (synarthrosis)
- Secondary SYMPHYSIS (amphiarthrosis)
What is a ‘synchondrosis’? Give 2 examples
- Primary cartilaginous joint linked by hyaline cartilage
- SYNARTHROSIS (immovable)
- e.g. 1st sternocostal joint, epiphyseal growth plates
What is a ‘symphysis’? Give 2 examples
- Secondary cartilaginous joint where 2 articulating bones covered in hyaline cartilage are connected by fibrocartilage
- AMPHIARTHROSIS
- e.g. symphysis pubis, intervertebral disc
Define ‘synovial joint’ and state the functional classification
- Joint cavity containing synovial fluid
- DIARTHROSIS (freely moveable)
Name 5 structural and/or functional roles of the skeleton
- Support/posture
- Protection of organs (thorax)
- Movement
- Mineral and growth factor storage
- Haematopoiesis
What is the role of articular cartilage at synovial joints?
Layer of hyaline cartilage provides SMOOTH, LOW FRICTION MOVEMENT and RESISTS COMPRESSION
Name 3 synovial joints which do not contain hyaline articular cartilage. What cartilage do they contain?
- Contain FIBROCARTILAGE
- Acromioclavicular, sternoclavicular and temporomandibular joints
What is the role of the fibrous capsule around a synovial joint?
- Encloses the joint (except when interrupted by synovial protrusions e.g. bursa
- Stabilises the joint (permits movement but resists dislocation)
Which part of the synovial joint produces synovial fluid?
Synovial membrane
What is the role of the synovial membrane?
- Lines capsule, exposed bony surfaces, tendon sheaths and bursa (NOT ARTICULAR CARTILAGE)
- Produces synovial fluid
What is a ‘bursa’?
- Sac lined with synovial membrane and filled with synovial fluid
- Can be communicating or non-communicating with the joint cavity
- Involved in SHOCK ABSORPTION
What is meant by a ‘tendon sheath’?
Elongated bursa wrapped around a tendon
- e.g. Common flexor tendon sheath in the wrist which contains the tendons of FDS and FDP
Describe the composition of synovial fluid (4)
- Hyaluronic acid
- Lubricin
- Proteinase
- Collagenase
What is the role of synovial fluid in a joint?
- Reduces friction
- Shock absorption
- Transport of nutrients and waste products
Where is synovial fluid located?
Within the joint cavity of a joint
Describe the blood supply at a synovial joint
- Periarticular arterial plexus
- Articular cartilage is AVASCULAR, fibrous capsule and ligaments have a poor blood supply
- Synovial membrane is highly vascularised with a RICH BLOOD SUPPLY
What is Hilton’s Law?
The nerves supplying the joint capsule also supply the muscles moving the joint and the skin overlying the insertions of these muscles
What are the 6 types of synovial joint? Give an example of each
- Pivot (between C1 — C2 vertebrae)
- Ball and socket (hip)
- Hinge (elbow)
- Saddle (trapezium — 1st metacarpal)
- Condyloid (radius — carpals)
- Planar (between tarsals)
Describe the properties of a planar joint
- Flat/slightly curved articulating surface
- Gliding or sliding movements
- NON-AXIAL
Give 3 examples of a planar joint
- Sternoclavicular and acromioclavicular joints
- Intercarpal joints
- Vertebral facet joints
Describe the properties of a hinge joint
- UNIAXIAL (e.g. like a door hinge)
- Convex surface of one bone fits into the concave surface of another
Give 3 examples of a hinge joint
- Humeroulnar joint of elbow
- Knee
- Ankle
Describe the properties of a pivot joint
- UNIAXIAL
- Rounded surface of one bone articulates within a ring formed by the concavity of another bone and a fibrous ligament
Give 2 examples of a pivot joint
- Atlantoaxial joint (pivot in the neck)
- Proximal radioulnar joint
Explain why the proximal radioulnar joint is classed as a pivot joint
- Radial head articulates with the concave radial fossa of the ulna
- Surrounded by annular ligament (forming a ring) and permits UNIAXIAL movement
What is a ‘condyloid/ellipsoidal joint’?
- BIAXIAL joint where the oval shaped condyle of one bone rests on the elliptical cavity of another
- Permits flexion/extension, ab/adduction and circumduction
Give 3 examples of a condyloid joint
- MCP joints
- Radiocarpal joints
- Atlanto-occipital joint
Describe the properties of a saddle joint and give an example
- BIAXIAL joint where one bone is saddle shaped (concavoconvex) and the other bone resembles the legs of the rider
- E.g. between trapezium carpal bone and 1st metacarpal
What movements does a saddle joint permit?
- Flexion/extension
- Abduction/adduction
- Circumduction
How do the movements of a multiaxial joint (e.g. Hip) differ from that of a biaxial joint (e.g. MCP)?
- Both allow flexion/extension, abduction/adduction and circumduction
- Multiaxial joints allow ROTATION
Name 3 effects of ageing on joints
- Decreased production of synovial fluid
- Thinning of articular cartilage
- Shortening of ligaments and decreased flexibility
What is osteoarthritis?
Inflammation and stiffness of joints due to wear and tear (erosion) of articular cartilage
What are osteophytes?
- Bony projections that form along the margin of a joint, due to bone remodelling
- Commonly seen in osteoarthritis
What is the difference between osteophytes and enthesophytes?
- Osteophytes are bony spurs that form along the margin of a joint
- Enthesophytes are bony spurs that form at the attachment of a tendon or ligament
Describe the pathophysiology of rheumatoid arthritis
- Autoimmune disorder where autoantibodies attack the synovium
- Leads to inflammation of synovium, pannus formation, joint erosion and deformity
- Women more affected than men (3:1)
Which joints are at most risk of erosion in rheumatoid arthritis?
- MCP and interphalangeal joints of hand
- Cervical spine
- Feet
- Can involve large joints
What factors can affect the stability of a joint?
- Structure/shape of articulating bones
- Strength/tension of ligaments
- Arrangement and tone of muscles
- Use/disuse and hormones
- Apposition of neighbouring soft tissue
How does ‘cracking’ of joints occur?
- Bones pulled away from eachother, expanding the synovial cavity
- Volume of fluid is constant and a partial vacuum is formed
- Gases dissolved in fluid are pulled out, making a POP sound
