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98 Cards in this Set
- Front
- Back
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How do long bones ossify vs. cranial bones?
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Long bones: enchondral (from cartilage)
Skull: intramembranous ossification (from mesenchyme) |
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What type of collagen is synthesized by osteoblasts?
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Type I collagen
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If you wanted to do a transplant in a bone disease involving genetically-malfunctioning osteoclasts what would you transplant?
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Monocytes
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If you were looking at a section of marrow-containing bone from what cell would you need to differentiate an osteoclast?
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Megakaryocyte
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Name that basic unit of bone: Central core (the Haversian Canal) contains blood vessels and nerves and is surrounded by concentric lamellae.
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Osteon
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What type of non-calcified bone do osteoblasts lay down?
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Osteoid
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Put the zones of ossification in order, from epiphysis to metaphysis:
Hypertrophy Ossification Resting cartilage Calcification Proliferation |
Resting cartilage
Proliferation Hypertrophy Calcification Ossification |
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Shortening of the proximal segment of the limbs is also known as
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Rhizomelia
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Shortness of one or more limbs is also known as
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Micromelia
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Shortening of the distal segment of the limbs is also known as
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Acromelia
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What disorder is caused by mutations causing defective alpha 1 and alpha 2 chains in type I collagen?
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Osteogenesis imperfecta
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Which (Type 1 or 2) osteogenesis imperfecta patients have a longer life span?
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Type I
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A mutation in a single copy of FGFR3, causing activation, typically presents with what phenotype?
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achondroplasia
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A mutation in FGFR3 that does not result in achondroplasia typically results in which phenotype?
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Thanatophoric dysplasia (death in utero)
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What cell type is aberrent in osteopetrosis?
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Osteoclasts. Number may be normal, but they do not resorb bone normally.
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What is the cell dysfxn that results in Paget's disease (osteosclerosis)?
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Osteoclast
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What type of bone is most affected in hyperparathyroidism?
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Cortical (compact) bone, via increased osteoclast action
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In osteomyelitis (bone infection), what is the most common pathogen?
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S aureus
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Contrast the usual site of bone infection (osteomyelitis) in children vs. adults.
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Kids: Metaphysis
Adults: epiphysis/subchondral |
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Where do most osteosarcomas arise?
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Knee
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People with mutations in p53(Li-Fraumeni) or RB genes are more susceptible to which bone cancer?
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Osteosarcoma
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If a osteosarcoma shows evidence of neoplastic change in cartilage, what is it called?
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Chondroblastic osteosarcoma
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Where do most osteosarcoma metastases occur?
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Lung or other bone
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What are mutations in GNAS gene and Mc-Cune Albright syndrome associated with in terms of bone formation?
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Fibrous dysplasia
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A child who presents with a multiloculated cystic tumor and has a t(17;p13) is consistent with what diagnosis?
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Aneurismal bone cyst
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A chondroma with sufficient atypia may raise suspicions for what?
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chondromsarcoma
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How does a conventional chondrosarcoma differ from a chondroblastic osteosarcoma?
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Conv chondrosarcoma arises from cartilage-forming cells.
Chondroblastic osteosarcoma arises from bone-forming cells that begin to produce cartilage, too. |
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Which type of muscle (I/II) is packed with oxidative enzymes, more fat and mitochondria?
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Type I - red meat for sustained action
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Which type of muscle (I/II) is packed with glycolytic enzymes, and is designed for rapid action?
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Type II - white meat for fast action (posture muscles)
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Do endurance athletes have more or less Type II muscle fibers than couch potatoes?
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Less Type II in endurance athletes vs. couch potatoes
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What type of muscle atrophies with corticosteroid use?
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Type II (fast twitch)
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What disorder of the dystrophin gene on the X-chromosome presents with proximal muscle weakness, calf pseudohypertrophy, lumbar lordisis and elevated CPK, mostly in boys?
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Duchenne MD
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What dystrophin gene mutation (x-linked) presents later in life?
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Becker MD
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What is the normal role of dystrophin, implicated in muscular dystrophies?
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Anchors actin filaments to sarcolemma (muscle cell membrane)
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What sarcolemma associated proteins are implicated in limb-girdle MD?
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sarcoglycans, caveolin
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How does myotonic dystrophy differ from other MDs?
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DISTAL weakness. Can't relax muscles, so they atrophy, particularly masseter. Frontal baldness
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How is myotonic dystrophy inherited?
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Maternal in congenital form. 19q mutation
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What type of muscle atrophies in Myotonic dystrophy?
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Type I (red, slow twitch)
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Which muscles are often involved in mitochondrial myopathy?
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Extraocular
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What is the likeliest cause of acquired myopathy?
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Statins
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Contrast the lymphoid infiltrate of polymyositis vs. dermatomyositis.
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Polymyositis - CD8+ T cells, Inflammation around muscle fibers. Direct cell damage
Dermatomyositis - B, CD4+ Th cells. Inflammation around vasculature. Ischemic fiber damage |
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What does distal upper extremity weakness and proximal lower extremity weakness indicate?
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Inclusion body myositis, arising from an inflammatory myopathy
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What is the target of antibodies in myasthenia gravis?
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ACh receptor at NMJ
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What is the target of antibodies in the often paraneoplastic Lambert-Eaton syndrome, which presents as increasing strength with repeated action
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Presynaptic Ca channels
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What is the amino acid repeated in every ligament's collagen Type I triplets?
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Glycine
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What amino acid is both responsible for the helical structure of collagen Type I alpha chains, and often implicated in ligament pathology?
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proline
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Name the ultrastructure of ligaments that has a crimp responsible for initial non-linear stiffness in response to stress (toe region of stress-strain curve)
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Fascicles
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What does viscoelastic creep refer to?
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Progressive deformation of an elastic structure with a constant load (think old hair tie).
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What does viscoelastic stress relaxation refer to?
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As a load remains constant, the stress on an elastic structure will decrease (think stress on a stretched out vs. new hair tie).
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What is the phenomenon of hysteresis?
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The energy stored in an elastic structure with deformation
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How does a mechanical load stimulate anabolism in ligaments?
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Cytoskeleton disruption of fibroblasts cause upregulation of anabolism.
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What is the name for an injury that moves a medial structure laterally?
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Valgus
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What is the name for an injury that moves a lateral structure medially?
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Varus
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What is the "unhappy triad"?
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A valgus knee strain: MCL/ACL and lateral meniscal tear.
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What feature of a torn ligament most affects the likelihood of healing?
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Where it lies in the joint determines blood supply. Extra-articular ligaments are likeliest to heal non-surgically.
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What is the predominant collagen in articular cartilage?
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Type II
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What componant of articular cartilage is responsible for its high water content?
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Hyaluronic acid (a proteoglycan)
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Where is a meniscal tear likeliest to heal without intervention?
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At it's attachment to the joint capsule. Just like ligaments, meniscal tears closest to the outside of the joint are likeliest to get blood supply.
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Which knee meniscus transmits most force?
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Lateral meniscus (the smaller, more mobile one)
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What changes to a menisectomy produce in knee joint contact pressure?
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Distribute the load over a smaller area, increasing risk for arthritis.
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Which meniscus is likelier to be injured with ACL injury?
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Medial meniscus
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Which is likelier to heal: a disruption of cartilage alone, or of cartilage and subchondral bone.
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A disruption of cartilage AND subchondral bone. Only bone has a blood supply.
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What is a drawback to microfracture arthroplasty for cartilage repair?
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Though microfracture recruits marrow cells, the newly formed cartilage is fibrocartilage / hyaline composite and is inferior to normal cartilage.
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What is the primary protector of articular cartilage?
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menisci
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What type of collagen predominates in bone?
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Type I
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How would a lack of functional osteoclasts present?
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Osteopetrosis - hyperlucent bones on XRay
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What are the usual tumors that metastasize to bone?
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Adenocarcinomas:
PT Barnum Loves Kids Prostate Thyroid Breast Lung Kidney |
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What drugs can be used to treat osteoclast disorder?
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Bisphosphonates
RANK-L antibodies Calcitonin |
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Is osteoporosis a disorder of osteoblasts or clasts?
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Osteoblasts
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What agents stimulate osteoblasts?
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FORTEO (recomb parathyroid hormone)
Estrogen / HRT Vit D, Calcium |
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By what process does avascularly necrotic bone heal?
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Creeping substitution (unless the bone forms fissures and collapses first)
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Which hip fracture is likelier to heal fastest ? intertrochanteric, subtrochanteric or femoral neck?
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intertrochanteric - require screw or rod
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What benign reactive bony lesion is on the differential for an osteosarcoma?
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myositis ossificans - bony metaplasia
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In what "benign" process are APC mutations and beta-catenin overexpression common?
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Fibromatosis
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What is another name for a benign fibrous histiocytoma?
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dermatofibroma - fibroblasts interlaced with histiocytes
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A pleomorphic fibrous tumor that does NOT stain for S-100, desmin, actin, myoD1 EMA or anything else you throw at it is likely a...
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Malignant fibrous histiocytoma
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What tumor always has t(12;16) fusion proteins?
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Myxoid liposarcoma
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What does increased transcription of MDM2 cause downstream?
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Product binds and inactivates p53
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A tumor staining positive for desmin, vimentin, myogenin or myoD1 likely arose from what type of tissue?
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Skeletal muscle
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What translocation do most rhabdomyosarcomas exhibit?
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t(2;13) PAX3 + FKHR fusion likely dysregulates muscle differentiation
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Which translocation carries the worst prognosis for synovial sarcoma?
SSX1/SYT SSX2/SYT |
SSX1
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Which two LE compartments will result in top of foot numbness in compartment syndrome?
Anterior Deep posterior Lateral Superficial posterior |
anterior
lateral |
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In a normotensive patient, a muscle pressure greater than 40mmHg would indicate...
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compartment syndrome
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For each wound type, match the correct usual bacteria associated:
Cat Human All bites Staph Strep Pasturella Eikenella |
Staph/Strep: all bites
Pasturella: cats Eikenella: humans |
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What level of nerve anatomy is responsible for the blood/brain barrier in the periphery?
epineurium perineurium endoneurium |
perineurium
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What nerve innervates:
back of hand pinky and part of ring finger middle 3 digits |
back of hand: radial
pinky: ulnar middle digits: median |
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What is the usual reason for a complaint of thumb pain in women over 40?
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Carpometacarpal arthritis at 1st metacarpal / trapezial joint
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Why shouldn't you aspirate a ganglion cyst on the volar aspect of someone's wrist?
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It is very close to the radial artery
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Which patients are likeliest to develop DeQuervains tenosynovitis in the first dorsal compartment of the wrist?
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Mothers of infants
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What is the usual presenting symptom for tennis elbow?
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Pain about 4cm from the elbow on dorsolateral forearm in the radial tunnel
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Fracturing the humerus can lead to damage in what nerve (and how does it present)
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Radial - can't extend fingers
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What hormone is responsible for stimulating DNA synthesis in growth plate proliferation zones of bones?
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Thyroxine
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What goes wrong in ricketts?
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Growth plate cells are not mineralized properly
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What are children with renal tubular acidosis at risk for?
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Ricketts
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What does hypophosphatemia resemble clinically?
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Ricketts
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How does the MPS Morquio syndrome differ from achondroplasia?
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GAGs accumulate in eye - opacity. Pectis carinatum and organomegaly also present. Intelligence is normal.
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Apart from the bone abnormalities in OI, what is the characteristic physical finding?
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blue sclerae and teeth
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What gene in some staph strains make them so likely to infect bone?
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Collagen-binding adhesion genes
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