uworld rheumatology/orthopedics/MSK Flashcards

Question

what is achondroplasia etiology presentation

Answer 1

AD xFGFR3 (90% de novo, 10% inherited) * abn endochondral ossification of long bones and portions of skull/face * constitutive FGFR3 --\> exxagerated inhibition of chondrocyte proliferation --\> bone shortening and craniofacial abn clin: -short limbs w normal torso length, frontal facial bossing w madfast hypoplasia, macrocephaly, genu varum

Answer 2

* inc Vit D breakdown ∝ anticonvulsants that induce CYP450 = phenytoin, phenobarbital, carbamazepine * dec estrogen ∝ aromatase inhibitors and medoxyprogesterone * dec T and estrogen ∝ GnRH agonists * dec Ca absorption ∝ PPIs * dec bone formation ∝ glucocorticoids

Answer 3

**golgi tendon organs**: sensory receptors located @ junction of Ms+tendons that are innervated by **group Ib sensory axons**, and are conected w contracting extrafusal sk. M fibers * when a M actively contracts against resistance, the increase in tension activates the GTO --\> Ib sensory axons in the GTO contact *_inhibitory interneurons in the SC_* -\> synapse on the *_α-motor neurons_* that innervate the same M --\> if the M exerts too much force, the GTO will inhibit contraction and cause sudden M relaxation * GTO is NOT sensitive to change in length i.e. when you lift a heavy load and your arms involuntarily give way and drop the weights to the ground

Answer 4

**A-delta fibers** = thin, myelinated N fibers whose free N endings detect T and nociceptive stimuli ∝ w acute, sharp pain : = the afferent portion of the reflex arc that mediates withdrawal from a noxious stimuli

Answer 5

**M spindles** (intrafusal M fibers), innervated by group Ia and II seonsey axons * =sensitive to change in M length * mediate stretch reflex (myotatic reflex) : the one tested on DTRs in neuro exam * when a M is stretched, there is monosynaptic reflex activation of the α motor neuron of the same M --\> contraction that resists the stretch

Answer 6

pacinian corpuscles * *_rapidly_* adapting mechanoreceptors in the subQ tissue of skin + mesentery, peritoneum, and joint capsules ruffini's end organs * *_slowly_* adapting mechanoreceptors in the skin, subQ tissue, and joint capsule FUNCTION: both help mediate touch, proprioception, and vibratory sensation INNERVATION: both innervated by myelinated A-beta fibers

Answer 7

anti-smith = antisnRNP smith proteins are synthesized by RNA polymerase into snRNAs , which complex w proteins to become snRNPs, which are essential to RNA splicing (removing introns by spliceosomes)

Answer 8

=a vasculitis that only affects the skin, typically arises due to drug or pathogen exposure (HepB/HepC) * use of certain drugs can case ∝ penicillins, cephalosporins, sulfonamide, phenytoin, allopurinol clin * present w nonblanching, palpable purpura often w the LEs * biopsy of skin purpra = markedly inflammed small BVs w fibrinoid necrosis * primary consists of neutrophils and fragmented neutrophilic nuclei (leukocytoclastic vasculitis)

Answer 9

* =osteitis deformans = chronic ds from excessive and disordered bone formation * bone weaknes --\>bone pain--\> bowing, frx, or arthritis of adjacent joints * xOPG(osteoprotogen-physiologic regulator of osteoclasts)--\> juvenile pagets * sk pain and deformities, focal warmth or bruits at areas of pagetic bone lesions * can sometimes lead to high out heart failure * pain and new protuberances of the long bones * change in hearing due to abn skeletal bone changes * labs = elevated serum alk phos ∝ inc bone formation * BUT **_n_** Ca, Phosphate, and PTH as homeostasis stays intact * diagnostic findings * x-rays showing mixed lytic-sclerotic lesions, thickening of corticol and trabecular bone, bony deformities * biopsy of bone will show enlarged osteoclasts, w up to hundreds of nuclei

Answer 10

- anti-centromere (scleroderma, nondiffuse type) CREST * calcinosis * subQ Ca depo: asx or painful * raynauds * esohageal dysmomtlity * --\>heartburn and regurge, GERD like sx: i.e.retrosternal burning and regurge when lying supine * sclerodactyly * thickening of skin of hands and feet, presentation begins w non-pitting edema of hands and fingers * telangiectasia

Answer 11

thin myofilament = actin thick myofilament= myosin actin in I band are bound to Z-line structural proteins myosin filaments in A band are bound to structural proteins at M-line

Answer 12

brachial A, radial N

Answer 13

deep brachial A and radial N : run behind the midshaft of the humerus

Answer 14

- axillary N runs with the posterior circumflex A, and a frx to the surgical neck of the humerus may damage them

Answer 15

* Ca + Vit D * given as needed to ensure adequate intake * bisphosphonates * alendronate, risedronate * attach to hydroxyapatite bindings sites on bone surfaces * inhibit osteoclast mediated bone resorp = slow the rate of bone loss * denosumab * bind RANK-L and inhibits RANK * = less differentiation and survival of osteoclasts * recombinant PT analog * teriparatide * stimulates maturation of preosteoblasts into bone forming osteoblasts * increases GI Ca absorption and renal tubular Ca reabsorption

Answer 16

scaphoid frx from falling on an outstretched hand (FOOSH) x dorsal scaphoid **branch of radial A --\> avascular necrosis of the scaphoid bone** with , which presents as pain in the anatomic snuffbox (dorsal lateral wrist)

Answer 17

triangle @ dorsoradial wrist medial side= extensor pollicis longus tendon lateral side= ABductor pollicus longus and extensor pollicis brevis tendons proximal= styloid process of radius floor= scaphoid and trapezium bones contents * radial A * branch of radial N * cephalic V this is where most of the blunt force of a FOOSH goes, which is why the scaphoid is the most frx bone in the hand

Answer 18

Paget ds of the bone

Answer 19

dx: **Dermatomyositis** * anti-Mi2 Abs, anti-Jo1 Abs, anti-PI55/PI40 Abs * as a **paraneoplastic** syndome, most commonly to an **adenocarcinoma of the ovary, lung, or pancreas** **Gottron papules** = raised, erythematous plaques over the joints and bony prominences of the hand M biopsy= daignostic finding: perifascicular inflammation and atrophy of the M @ the periphery of the fascicle vs. polymyositis * also can be paraneoplastic to adenocarcinoma of the ovary, lung, or pancreas * biopsy= endomysial and perimysial inflammation and inc CT vs inclusion body myositis * no Abs, no respond to trx, is the most common form of inflammatory Abs in 65+, can be associated w IBD * endomysial inflammation, with "rimmed vacuoles", w tubulofilamentous inclusions in themyofibrils --\> chronic ds=fatty replacement of M

Answer 20

osteoclasts * from mononuclear phagocytic cells * mature cells are multinucleated * two most important factors for differentiation = **MCSF** (mø-colony stimulating factor) and **RANKL** = made by osteoblasts and BM stromal cells * **osteoprotegerin** (OPG) = decoy RANK-L receptor --\> dec bone resorption osteoblasts * from mesenchymal stem cells * single nucleus * **IGF-1 (**insulin like growth factor-made by liver and bone) : inc osteoblast replication and collagen synthesis + dec collagen breakdown * **TGF-beta** inc replication of osteoblast precursors

Answer 21

anti-CCP Ab (RF is not specific)

Answer 22

T tubules = 'transverse' tubules =invaginations in the sarcolemma that allow depolarization to rapidly propogate through the interior of the M --\> allows uniform Ca release from the sarcolemma --\> synchronized contraction of myofibrils in each M cell uncoordinated firing of M fibers presents as M weakness

Answer 23

cytoplasmic processes of osteocytes lie w/in cannaliculi that span throughout the bone matrix via **gap junctions** btwn these processes, osteocytes can.. * send signals * exchange nutrients and waste products * serve their function to **maintain the structure of the matrix and maintain Ca homeostasis** * plasma concentration of Ca will directly the metaboic activity of osteocytes * PTH and calcitonin indirectly signal to osteocytes * also regulate osteoblasts in response to changes in mechanical stress

Answer 24

the cubital fossa = proximal forearm, just lateral to the medial epicondyle (the inside of the elbow) * medial border= pronator teres M * lateral border =brachioradialis M * base= line between medial and lateral epicondyle running through are the median N and the brachial A (right before it splits into the ulnar and radial As) injury to median N = * sensory loss over median N pattern * loss of forearm pronation * loss of proximal IP joint flexion (x flexor digitorum superficialis innervation)

Answer 25

senile Oporosis= low turnover = dec osteoblast proliferation and bone synthesis postmenopausal Oporosis= high turnover = inc osteoclast activity that outpaces osteoblast ability

Answer 26

* primary osteoporosis * renal failure or vitamin deficiency * PTH-ind hyperCa = hyperCa of malignancy and Vit D toxicity

Answer 27

= an immunosuppressant used in transplant pts, RA, IBD, autoimmune hepatitis * inhibit PRPP amidotransferase --\> x purine synthesis * act as false nucleotides to interrupt DNA replication.. =can cause pancytopenia * require routine CBC monitoring

Answer 28

IL-6 : mediates the inflammatory infiltrate of the BV walls trx= anti-IL6 abs = tocilizumab

Answer 29

DMARDS= disease monitoring anti-rheumatic drugs = alleviate pain and inflammation, and reduce long term joint destruction and disability * = methotrexate (first line) , salfasalazine, hydroxychloroquine, minocycline, TNF-alpa inhibitors (etanercept) * DMARDs take up to 3 weeks to set in, so gap that with glucocorticoids or NSAIDs to relive sx in the mean time Methotrexate: competitive inhibitor of DHF reductase = x purine/pyrimidine synthesis AE= * oral ulcerations * GI mucosal ulcerations * alopecia * hepatotoxicity (cirrhosis, fibrosis, hepatitis) * pulmonary fibrosis

Answer 30

the latissimus dorsi humerus extension, ADduction, + IR =C on the picture

Answer 31

the ACL = prevent anterior movement of the tibia relative to the femur the PCL= prevent posterior movement of the tibia relative to the femur \*in injury of either, you'll see excessive movement that it was supposed to prevent (too much anterior tibia= x acl)

Answer 32

= eosinophilic granulomatosis w polyangitis * late onset asthma, rhinosinusitis, eosinophilia * mononeuropathy multiplex = assymetric, multifocal neuropathy * ∝ vasculitis of the epineural vessels = i.e. wrist drop * skin nodules * migratory/transient pulmonary infiltrate * peripheral eosinophilia w + anti-MPO Abs

Answer 33

proximal clavicle: pulled superior by SCM and trap distal clavicle: pulled inferolateral by deltoid

Answer 34

dorsiflexion= common fibular N * lesion= foot drop plantarflexion = tibial N * also does inversion, and toe flexion + sensation of plantar surface * lesion = stuck dorsiflexed and everted, dec sensation on plantar foot

Answer 35

thiazides - they inc Ca reabsorption in the DT \*\*NOT loop diuretics = lose Ca = inc risk of osteoporosis\*\*

Answer 36

acute rheumatic fever = migratory arthritis + (+)streptolysin O Ab + fever + new onset murmur (associated w mitral regurge= holosystolic) greatest risk of death is from pancarditis/myocarditis * severe mitral regurge --\> myocarditis --\> cardiact dilation --\> heart failure--\> death

Answer 37

=episodes of systemic, muscular, and GI sx biopsy= * _transmural inflammation_ of _segments_ of midsized arteries, w areas of amorphous eosinophilic necrosis of the arterial wall * internal elastic lamina disruption * if associated w HepB, can see ab-ag complexes in the affected tissue =usually idiopathic BUT 30% are secondary to HepB (i.e. hx of IV drug use..)

Answer 38

* retroperitoneal hematoma (associated w chronic warfarin use) * pts present w acute, severe groin, lower abd, or back pain * the femoral N can also be injured: femoral neuropathy = quadriceps wknss, dec patellar wknss, sensory loss over the anterior and medial thigh and leg

Answer 39

=systemic infectious ds that primarily presents as malabsorption * associated w weight loss, diarrhea, joint pain, and arthritis * may present as migratory, non-deforming arthritis mainly in the big joints, years before any other sx appear * advanced ds: malapsorption leads to wasting and enlarged lymph nodes * steathorrhea * loss of albumin --\> peripheral edema Non-GI sx include * hyperpigmentation, uveitis, * endocarditis (rare) * neuro (more associated w advanced ds) = * dementia, memory loss, confusion, dec level of consciousness * eye movement abn, random twitching of facial Ms * weakness, poor coordination, seizures

Answer 40

* femoral head * x knee flexion * fibular neck * x common fibular N * x dorsiflexion, eversion : x sensation to lateral leg and dorsal foot * anterior leg (shin) * x tibial N * xplantar flexion, inversion * x sensation to plantar surface of foot * x achilles reflex compartment syndrome: initially present w pain out of proportion to the degree of injury --\> wknss and sensory loss * anterior compartment syndrome (leg) * x deep branch of fibular N * x dorsiflexion, sensory loss btwn first and second toes, * lateral compartment syndrome (leg) * x superficial branch of fibular N * x eversion * x sensation of lateral shin and dorsum of foot

Answer 41

SA node = R atria, upper part of the crista terminalis near the SVC opening AV node= R atria side of interatrial septum near the opening of the coronary sinus (venous collection site for heart M)