Rheumatoid arthritis Flashcards
What are the aspects of the brachial plexus?
Roots
Trunks
Divisions
Cords
Branches
What are the roots of the brachial plexus?
C5, C6, C7, C8 and T1
What are the trunks of the brachial plexus?
Superior
Middle
Inferior
What are the divisions of the brachial plexus?
Anterior of the superior trunk
Posterior of the superior trunk
Anterior of the middle trunk
Posterior of the middle trunk
Anterior of the inferior trunk
Posterior of the inferior trunk
What are the cords of the brachial plexus?
Lateral
Posterior
Medial
What are the branches of the brachial plexus?
Musculocutaneous
Median
Ulnal
Axillary
Radial
What nerves branch of the roots in the brachial plexus?
C5 > Dorsal scapular N.
C5,6,7 >Long thoracic N.
What nerves branch off the trunks of the brachial plexus?
Superior > Suprascapular N.
Superior > Subclavius N
What nerves branch off the cords of the brachial plexus?
Lateral > Lateral pectoral
Posterior > Superior subscapular
Posterior > Thoracodorsal
Posterior > Inferior subscapular
Medial > Medial brachial cutaneous
Medial > Medial antebrachial cutaneous
Where are the pulse points in the arm?
What muscles are in the superficial anterior distal arm? what do they do?
Pronator teres - pronation and flexion of the forearm
Flexor carpi radialis - flexes hand at wrist joint, abducts the hand
Palmaris longus - flexion at wrist, stabilisation of palmar aponeurosis
Flexor carpi ulnaris - flexion at wrist, adducts hand at radiocarpal joint
What muscles are in the intermediate anterior distal arm? what are their roles?
Flexor digitorum superficialis - flexes hand at wrist, index, middle, ring and little fingers
What muscles are in the deep anterior distal arm? what are their roles?
Flexor digitorum profundus - flexes hand at wrist, index, middle, ring and little fingers
Flexor pollicis longus - flexes hand at wrist and flexes thumb
Pronator quadratus - pronates forearm at radioulnar joints
What are the muscles of the superficial posterior forearm? what are their roles?
Brachioradialis - flexes forearm at elbow joint
Extensor carpi radialis longus - extends hand at radiocarpal joint, abducts hand at radiocarpal and midcarpal joints
Extensor carpi radialis brevis - extends hand at radiocarpal joint, abducts hand at radiocarpal and midcarpal joint
Extensor digitorum - extends fingers apart form thumb
Extensor digiti minimi - extends little finger
Extensor carpi ulnaris - extends and adducts hand at radiocarpal jont
What are the muscles in the deep posterior forearm? what are their roles
Aconeus - elbow extension
Supinator - supinates forearm at wrist
Adductor pollicis longus - abducts and extends thumb at first CMJ
Extensor pollicis brevis - extends thumb
Extensor pollicis longus - extends thumb
Extensor indicis - extends index finger
What does RA lead to overall?
Synovial hyperplasia and hypertrophy
Leads to pannus formation (area of proliferating synovium that leads to erosion of bone and cartilage)
What is the initial pathogenesis of RA? Macrophages and FLS
Trigger unknown - RF?
Macrophages: secrete cytokines - TNF-a, IL-1B, IL-6
Fibroblast-like synoviocytes (FLS) cells:
Cytokines activate FLS > cells proliferate and osteoclasts activate > bone erosion
FLS stimulate RANKL expression (binds to RANK of mature osteoclasts and pre-osteoclasts and causes activation and differentiation > degrade bone)
FLS secrete proteases > degrade cartilage > cartilage release proteases (+ve feedback loop)
When FLS activated, migrate from joint-joint = symmetrical arthritis
What role do CD4+ cells and neutrophils in RA pathogenesis?
CD4+ cells:
react with arthrogenic agent > secrete cytokines IL-y > activate macrophage activity and stimulate FLS > synovial proliferation > pannus formation > IL-17 > neutrophils recruited > TNF-a, IL-1, Il-6 > proteases secreted > hyaline cartilage destruction > bone-bone articulation > increased bone destruction
Neutrophils :
In synovial fluid > secrete proteases and ROS > causes bone and cartilage erosion = inflammation
What roles do antibodies and angiogenesis have in RA pathogenesis?
Antibodies:
Germinal centres within the synovium include plasma cells > secrete antibodies against self-antigens - autoantibodies specific for CCPs/arginine residues that are converted to citrulline > drives production and maintenance of antibodies to citrullinated proteins
Antibodies to fibrinogen, type II collagen > forms antibody-antigen complexes > deposited into the joints
Antibodies (IgM, IgA) against Fc regions of IgG antibodies form the rheumatoid factor > deposited in the joints
Angiogenesis:
Synovial hypoxia drives angiogenesis via HIF
Cytokines - TNF-a - promotesvascular permeability and are angiogenic and adhesion molecules allowing for immune cells to migrate into joints and other joints
How do TNF-a blocker Adalimumab work?
High affinity, binds to TNF-a (pro-inflammatory cytokine) > neutralises biological function - interacting with p55 and p75 cell surface receptors = disrupts cytokine-driven inflammatory processes
Reduction in production of inflammatory proteins = reduced inflammation
TNF-a also leads to osteoclast maturation and and activation > reduced destruction of cartilage and bone
What is adalimumab used for and how is it administered?
Autoimmune conditions e.g RA, psoriatic arthritis
SQ injection into thigh and lower abdomen rotated every two weeks
What are the symptoms of RA? 12
Pain and stiffness in hands, wrists and feet
1 hour of morning stiffness
Soft tissue swelling of joints
Symmetrical joints
Rheumatoid nodules
Swan neck deformity
Ulnar deviation - fingers bend towards ulnar
Fatigue and sleep problems
Feeling of walking on marbles
Periarticular osteopenia
Synovitis
Tenosynovitis
What are rheumatoid nodules
Firm, non-tender lumps which appear under the skin
Not fully understood why
Linked to risk factors like smoking and presence of RF
What is swan neck deformity?
In advanced RA
Damage to ligaments and joints
DIP hyperflexion and PIP hyperextension
Boutonniere’s deformity is the opposite PIP hyperflexion and DIP hyperextension
No longer common, as patients treated early with DMARDs
What is ulnar deviation?
Due to inflamed MCP joints, causes fingers to be dislocated
As tendons pull on dislocated joints, fingers drift towards ulnal side