MSK Flashcards
Valgus/varus stress test
Valgus tests MCL (push laterally)
Varus tests LFL (push medially)
McMurray test
Popping on external rotation: medial meniscus tear
Popping on internal rotation: lateral meniscus tear
Unhappy triad
Occurs due to lateral force applied to planted leg. Classicaly damages ACL, MCL, and medial meniscus
Prepatellar bursitis
Repeted trauma or pressure from extensive kneeling
Baker cyst
Popliteal fluid related to chronic joint disease
Muscles of the rotator cuff
Supraspinatus: abducts arm initially, assessed by empty can test; suprascapular nerve
Infraspinatus: laterall forates the arm; suprascapular nerve
Teres minor: adducts and laterally rotates arm; axillary nerve
Subscapularis: medially roates and adducts; upper and low subscapular nerve
Golfer’s elbow
Medial epicondylitis. Repetitive flexion
Tennis elbo
Lateral epicondylitis. Repetic extension
Bones of wrist
Scared lovers try positions that they can’t handle
Scaphoid Lunate Triquetrum Pisiform Trapezium Trapezoid Capitate Hamate
Fractures of wrist
Scaphoid most commonly fractured. Palpated in anatomic snuff box. Prone to avascular necrosis.
Hook of hamate fractured on fall on an outstretched hand. Can cause ulnar nerve injury
Axillary nerve damage
Occurs due to fractured surgical neck of humerus. Presents with loss of arm abductaion and loss of sensation over deltoid and lateral arm
Musculocutaneous nerve damage
Occurs due to upper trunk compreesion. Presents with loss of forearm flexion and supination, loss of sensation over lateral forearm
Radial nerve damage
Occurs due to midshaft fracture of humerus or compression of axilla. Presents with wrist drop, decreased grip strength, loss of sensation over posterior arm/forearm and dorsal hand
Median nerve damage
Occurs due to supracondylar fracture of humerus, carpal tunnel syndrome, wrist laceration. Presents with loss of wrist and lateral finger flexion, loss of opposition of thumb, inability to pronate. Loss of sensation over thenar eminence, lateral 3.5 fingers
Ulnar nerve damage
Occurs due to fracture of the medial epicondyle, fractured hook of hamate. Presents with ulnar claw, radial deviation of wrist, loss of wrist flexion and flexion of medial fingers, loss of ab and adduction of fingers, loss of sensation over medial fingers and hypothenar eminence
Recurrent branch of median nerve damage
Occurs due to superficial laceration of palm. Loss of thenar muscles - opposition, abduction, flexion of thumb. No loss of sensation.
Upper trunk of brachial plexus
Derived from C5, C6. Damaged in Erb palsy (waiter’s tip). Seen in infants due to lateral traction on neck during delivery. Deficits in axillary nerve (deltoid), suprascapular nerve (supraspinatus and infraspinatus) and musculocutanous nerve (biceps)
Lower trunk of brachial plexus
Derived from C8, T1. Damaged in Klumpke palsy. Seen in infants due to upward force on arm during delivery. Deficits in median and ulnar nerves resulting in total claw hand
Long thoracic nerve
Derived from C5 through C7. Presents with winged scapula due to loss of function in serratus anterior. Damaged with axillary node dissection after mastectomy and stab wounds.
Thoracic outlet syndrome
Seen in pancoast tumor. Causes compression of lower trunk and subclavian vessels. Presents with atrophy of intrinsic hand muscles and total claw hand plus with ischemia, pain, edema
Presentation of proximal and distal medial and ulnar nerve damage
Distal ulnar: can’t extend third and fourth fingers; remain clawed at rest or when extending fingers
Proximal ulnar nerve: ok gesture when trying to make a fist - can’t flex fourth and fifith fingers
Distal median nerve: cant extend first and second fingers at rest
Proximal median nerve: can’t flex first and second fingers when making a fist
Functions of dorsal and palmar interossei
DAB and PAD: dorsals abduct, palmars adduct
Obturator nerve
L2-L4. Damaged in pelvic surgery. Presents with decreased medial thigh sensation and decreased adduction
Femoral nerve
L2-L4. Damaged in pelvic fracture. Presents with decreased thigh flexion and leg extension.
Common peroneal nerve
L4-S2. Damaged with trauma to lateral leg, fibular neck fracture. Presents with foot drop - inverted and plantarflexed foot at rest. Loss of sensation on dorsum of foot
Tibial nerve
L4-S3. Damaged in knee trauma, Baker cyst, tarsal tunnel syndrome. Presents with inability to curl toes, everted foot, loss of sensation on sole of foot
Superior gluteal nerve
L4-S1. Damaged during IM infection to upper medial gluteus. Innervates gluteus minimus and medius. Presents with trendelenburg sign 0 pelvis tilts to side contralaterla to lesion
Inferior gluteal nerve
L5-S2. Damaged due to posterior hip dislocation. Innervates gluteus maximus. Presents with trouble clmbing stairs and standing up. Loss of hip extension.
Peroneal vs tibial nverve
Peroneal everts and dorsiflex
Tibial inverts and plantarflexes
Sciatic nerve
L4-S3. Innervates posterior thigh
Pudendal nerve
S2-S4. Innervates perineum
Dihydropyridine receptor
VG Ca++ channel in muscle cells
Sarcomere bands
A band: length of myosin, never changes H band: overlap of two myosin strands M line: where myosins meet I band: actin segment Z line: where actins meet
Endochondral vs membranous ossification
Endochondral: axial and appendicular skeleton and base of skull. Cartilaginous model made first my chondrocytes; osteoclasts and ocsteoblasts replace with woven bone and then with lamellar bone
Membranous ossification: bonds of calvarium and facial bones. Woven bone formed directly without cartilage; later remodeled to lamellar bone
Osteoblasts vs osteoclasts
Osteoblasts: secrete collagen and catalyze bone mineralization; differentiate from mesenchymal cells in periostium
Osteoclasts: Dissolve bone by secreting acid and collagenases. Differentiate from monocytes/macrophages
Achondroplasia
AD fully penetrant activating mutation in FGFR3
over 85% of mutations sporadic
Failed endochondral ossification with unaffected membranous ossification results in large head relative to limbs
Osteoporosis
Loss of trabecular bone mass with normal bone mineralization and normal lab values. Can cause vertebral compression fractures
Osteopetrosis
Defective osteoclasts lead to failure of normal bone resorption. Thickened dense bone that are prone to fracture and bone filling marrow space resulting in pancytopenia and extramedullary hematopoiesis.
X-ray: bone in bone appearance
Presentation: can cause cranial nerve impingement and palsies
Treatment: Bone marrow transplant - osteoclasts derived from monocytes
Osteomalacia
Vitamin D deficiency. Defective mineralization.
Labs: low vit D, low serum Ca++, increased PTH, low serum phosphate
Hyperactive osteoblasts results in elevated alk phos
Paget disease of bone
Localized bone disorder. Both increased osteoblastic and clastic activity.
Labs: Normal Ca++, phos, PTH, elevated alk phos
Path: Moszic pattern of woven and lammelar bone
Giant cell tumor
Benign tumor of bone. Seen in 20-40 year olds at epiphyseal end of long bones. Often around the keee. Locally aggressive.
Osteocondroma
Most common benign bone tumor, Seen in young males less than 25. Mature bone with cartilaginous cap. Rarely transforms
Osteosarcoma
Distribution bimodal: primary occurs in 10-20 yo, secondary in those over 65
Predisposing factors: PAget disease of bone, bone infarcts, radiation, familial retinoblastoma, Li Fraumeni
Coldman triangle on xray
Aggressive
Ewing sarcoma
Seen in boys less than 15
Seen in diaphysis of long bones
Anaplastic small blue cell tumor. Extremely aggressive. Onionstkin reaction
Associated with t(11;22)
HLA type associated with RA
HLA-4
Drugs used to treat RA
Anti-inflammatory: NSAIDs, glucocorticoids
Disease-modifying agents: methotrexate, sulfasalazine
Biologics: TNF-alpha inhibitors
Clinical findings of Sjogrens syndrome
Inflammatory joint pain Xerophthamia Xerostomia Anti-SS-A (anti-Ro), Anti-SS-B (Ant-La) Bilateral parotid gland enlargement
MALT lymphoma is complication
Treatment of pseudogout
Acute attacks: NSAIDs
Prophylaxis: colchicine
Systemic juvenile idiopathic arthritis
-recurrent and relapsing spiking fevers
-polyarticular join pain
-salmon pink macular rash
rheumatoid factor negative
-chronic uveitis and decreased growth
Presentation of psoriatic arthritis
Seen in less than 1/3 of psoriasis patients
Asymmetric, patchy involvement
Dactylitis
Clinical features of ankylosing spondylitis
Ankylosis: stiffness due to joint fusion in spine
Uveitis
Aortic regurgitation
Reactive arthritis
Triad of conjunctivitis, urethritis, and arthritis post-GI infection or GU infection
Renal syndromes associated with lupus
Nephritic: diffuse proliferative GN
Nephrotic: membranous GN
Cuases of drug induced lupus
Hydralazine, procainamide
Polymyalgia rheumatica
Seen in women over 50, often associated with temporal arteritis
Pain and stiffness in shoulders and hips, fever, malaise, weight loss
Polymyositis vs dermatomyositis
Polymyositis: proximal muscle weakness, CD8+ inflammation, often involves shoulders
Dermatomyositis: Malar rash, Gottram papules, heliotrope rash, shawl and face rash, mechanics hands, CD4+ inflammation, risk of occult malignancy
Myositis ossificans
Metaplasia of skeletal muscle into bone due to muscle trauma
Embryologic origin of parathyroid glands
Inferior from third pharyngeal pouch (along with thymus); superior from fourth pharyngeal pouch (along with ultimobranchial body)
Colchicine
MOA: binds intracellular tubulin, inhibiting polymerization into microtubules, disrupting cytosekletal-dependent functions like chemotaxis and phagocytosis
Use: gout flares, prophylaxis while initating allopuirnol
Adverse effects: nausea, abdominal pain, diarrhea
Heteroplasmy
Having different organellar genomes within a single cell. Can be used to describe differences among patients with a mitochondrial gene mutation: more severe disease associatd with having higher proportion of defective mitochondrial genomes wtihin cells
Mitochondrial encephalomyopathy
Neuromuscular lesions, ragged red skeletal fibers, lactic acidosis.
snRNPs
Involved in RNA splicing
Sporotrichosis
Subcutaneous mycosis caused by Sporothrix schenckii. Dimorphic fungi found on plants. Enters through breaks in skin often thorn pricks) and spreads along lymphatics
Succinylcholine
MOA: depolarizing NMJ blocker that causes continuous stimulation to the ACh receptor, preventing ACh from binding; results in flaccid paralysis
Adverse effects: nicotinic ACh receptor is a nonselective cation channel so it allows for K+ release as well as Na+ influx and can lead to hyperkalemia and arrhythmia in patients with crush or burn injuries, denervating injuries, and myopathies
Atracurium
MOA: nondepolarizing NMJ blocker.
Adverse effects: Causes histamine release which can result in hypotension, flushing, bronchoconstriction. Metabolized to laudanosine which can cause seizures
Baclofen
MOA: muscle relaxant that affects GABAb receptors in spinal cord
Dantrolene
MOA: Prevents release of Ca++ into cytoplasm by blocking RyR receptors
Use: Malignant hyperthermia
anti-Jo-1
Antibody seen in polymyositis and dermatomyositis. Also called anti-histidyl-tRNA synthetase
Acetaminophen OD
Metabolite depletes glutathione and forms toxic tissue byproducts in liver leading to hepatic necrosis. N-acetylcysteine is antidote - acts by regenerating glutathione
Bisphosphonates
Name: Alendronate
MOA: inhibits osteoclast activity by binding hydroxyapatite in bone
Use: osteoporosis, hypercalcemia, Paget disease of bone, multiple myeloma to prevent new bone lesions
Toxicity: corrosive esophagitis, osteonecrosis of jaw
Teriparatide
MOA: recombinant PTH, increases osteoblast activity
Use: osteoporosis
Allopurinol
MOA: inhibits xanthine oxidase, decreasing uric acid production
Use: gout, lymphoma and leukemia to prevent urate nephropathy
Febuxostat
MOA: inhibits xanthine oxidase
Pegloticase
MOA: Recombinant uricase; catalyzes metabolism of uric acid
Probenecid
MOA: Inhibits reabsorption of uric acid in proximal convoluted tubule
ADR: can precipitate uric acid calculi
Colchicine
MOA: binds and stabilizes tubulin, preventing MT polymerization
Etanercept
MOA: TNF-alpha decoy receptor
Use: RA, psoriasis, ankylosing spondylitis
ADR: infection, reactivation of latent TV due to disruption of granuloma formation and stabilization
Infliximab and adalimumab
MOA: anti-TNF-alpha monoclonals
Use: IBD, RA, ankylosing spondylitis, psoriasis
CREST syndrome
More benign version of systemic sclerosis with only localized skin involvement
- calcinonsis
- raynaud’s
- esophageal dysmotility
- sclerodactyly
- telangiectasias
Anti-centromere antibodies highly specific.
