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USMLE Step 1 Systems > MSK, Skin, Connective > Flashcards

MSK, Skin, Connective Flashcards

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USMLE® Step 1 flashcards
1
Q

Flattening of deltoid muscle with axillary n. injury = what injury?

A

Anterior Shoulder Dislocation

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2
Q

What nerve injury results in weak forearm flexion and absent biceps reflex? Where is loss of sensation associated with it?

A

Musculocutaneous N - innervates flexors and LATERAL forearm

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3
Q

Xeroderma Pigmentosum

A

Pigmented Dry Skin: erythema, scaling, hyperpig in light exposed areas, telangectasias, hypo/hyperpig areas AR - due to defect in DNA excision repair

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4
Q

What does the psoas major and iliacus function to do?

A

Sit up from a chair. Q7621

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5
Q

What does the obturator n. innervate?

A

ADductors of the thigh

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6
Q

Anatomy of Striated Muscle Sarcomere

A

Test ID: 36624218 “An Interesting Zoo Must Have Mammals” Actin in the I band attaches at the Z line, Myosin in the H band attached at the M-line”

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7
Q

What cytokines induce isotype switching?

A

IL 4 (from TH2 cells)

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8
Q

Anthrax results in what clinical picture?

A

Necrotic center with erythematous/edematous border.

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9
Q

Classic picture of N. gonorrhea

A

Young male/female, sexually active asymmetric polyarthritis of large joints Aspiration: intracellular org + high neutrophil

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10
Q

What factors are impt for osteoclast differentiation?

A

M-CSF and RANKL (produced by osteoblast)

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11
Q

What is the presentation of Rubeola?

A

Cough Coryza Conjunctivitis Koplick Spots (white, blue gray specks on buccal mucosa) Maculopapular Rash

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12
Q

What arteries are associated with the radial nerve and median nerve?

A

Radial - Deep Brachial Median - Brachial.

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13
Q

What part of long bone is hematogenous osteomyelitis most likely to occur?

A

Metaphysis - slow flowing sinusoidal vasculature, conductive to microbial passage. Adults less likely to develop this bc of epiphyseal closure

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14
Q

Wrinkles are due a decrease in what?

A

Collagen fibril production.

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15
Q

Embryologic origin of melanoma?

A

Melanocytes - derived from neural crest cells.

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16
Q

What is the difference btwn excitation contraction coupling in skeletal vs. cardiac vs. smooth muscle?

A

Skeletal - does not depend on extracellular Ca - depolarize L-type Ca channel -> conformational change -> opening of RyR1 Ca channel on SR -> release of Ca Cardiac - Ca induced Ca release - depolarize L-type Ca channel -> influx of extracellular Ca -> Ca activates RyR2 channels -> release of Ca from SR Smooth - - depolarize L-type Ca channel -> influx of extracellular Ca -> Ca dependent RyR Ca channel -> release of Ca from SR -> Ca binds CALMODULIN (no troponin in smooth muscle) -> activates myosin light chain kinase -> phosphorylation of myosin -> bind acting and cause contraction

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17
Q

What are markers of osteoblast activity vs. osteoclast?

A

Osteoblast = bone specific alkaline phosphatase Osteoclast = tartrate resistant acid phosphatase, urinary hydroxyproline, urinary deoxypyridinoline

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18
Q

Actinic Keratosis - risk of what?

A

SCC!

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19
Q

How are osteocytes connected to each other?

A

Gap Junctions! Send signals, exchange nutrients and waste products, can sense stress and modulate osteoblast activity

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20
Q

What substances stimulate acne formation?

A

Androgens, ex: anabolic steroids (methyltestosterone). Increase steps 1 and 2 below. Pathophys of Acne 1. Follicular epidermal proliferation 2. excessive sebum production 3. inflammation 4. Propionibacterium Acnes

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21
Q

What anti-inflam agent does not impair platelet aggregation?

A

Celecoxib (selective COX2 inhibitor) plts predominantly use COX1.

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22
Q

Vitiligo occurs as a result of ?

A

Autoimmune destruction of melanocytes. Decreased number of melanocytes (vs. albinism - decreased melanin)

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23
Q

Empty can tests what muscle

A

Supraspinatus

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24
Q

Cleft lip vs. Cleft palate

A

Lip = maxillary prominence and medial nasal prominence Palate = maxillary prominence fusion or its fusion to primary palate

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25
Q

What is a Glomus Tumor?

A

Glomus Tumor: Sx: bluish neoplasm underneath the nail bed. Nl function: Thermoregulation. Glomus body is a neurovascular organ wrapped in smooth muscle -> shunts blood away from skin in cold temps; shunts blood toward skin to dissipate heat when hot temp.

26
Q

Attachments of ACL vs. PCL

A

Note: coronal MRI is always looking from the FRONT, idiot. ACL = lateral epicondyle -> ant. intercondylar area of tibia PCL = medial epicondyle -> post intercondylar area of tibia

27
Q

What condition associated with pathological fracture? What are the lab values PTH, Ca, PO4 associated with it?

A

Osteoporosis - Decrease in trabecular bone mass - NORMAL lab values.

28
Q

Bullous pemphigoid - antibodies against ?

A

Hemidesmosome “antibdodies are “bullow” the epidermis”

29
Q

What do integrins bind to?

A

Collagen, Laminin, Fibronectin.

30
Q

How is the pulmonary system involved in ankylosing spondylitis?

A

Costovertebral Enthesopathy -> Dec. Chest Expansion and Hypoventilation.

31
Q

Anterior and Posterior Dislocation of the Knee would injure what structure?

A

Popliteal Artery.

32
Q

What nerve and artery go with each of the following: Axilla/Lateral thorax Surgical neck of the humerus Midshaft of the humerus Distal humerus/Cubital Fossa Popliteal Fossa Posterior to the Medial Malleolus

A

Axilla/Lateral Thorax = Long thoracic n., Lateral thoracic a.

Surgical neck of the Humerus = Axillary, Posterior Circumflex

Midshaft of the Humerus = Radial, Deep Brachial

Distal Humerus/Cubital Fossa = Median, Brachial

Popliteal Fossa = Tibial n., Popliteal Artery

Posterior to the Medial Malleolus = Tibial n., Posterior Tibial

33
Q

Achondroplasia - gene and inheritance

A

FGF3 constitutive activation -> inhibits chondrocyte proliferation -> inhibits endochondral ossification -> failure of longitudinal growth -> short extremities, large head.

Inheritance: Sporadic -> AD

34
Q

What bone disease associated with eating mostly processed foods + little sun exposure?

A

Vit D deficiency = Rickets or Osteomalacia.

35
Q

What bone disease associated with each of the following:

  • osteoid matrix, unmineralized
  • pancytopenia, nerve impingement
  • mosiac of woven and lamellar bone
  • hearing loss
  • spongy bone loss
  • endochondral ossification failure
A
  • osteoid matrix, unmineralized = Osteomalacia, Rickets (Vit D deficiency)
  • pancytopenia, nerve impingement = Osteopetrosis - thickened bone from defective osteoclasts
  • mosiac of woven and lamellar bone = Paget’s
  • hearing loss = Paget’s
  • spongy bone loss = Osteoporosis
  • endochondral ossification failure = Achondroplasia
36
Q

Callus caused by thickening of which skin layer?

A

Most superficial - Stratum corneum.

37
Q

What injuries predispose to ulnar n. injury?

A
  1. Fracture of the Medial Epicondyle
  2. Fractured hook of hamate.
38
Q

How does Avascular Necrosis present? What are some conditions are predispose to it?

A

Pain upon weight-bearing, passive, active movement. No erythema, swelling, or temperature changes. MRI is diagnostic modality.

Predisposed:

  • Sickle Cell
  • SLE (vasculitis)
  • High dose corticosteroids
  • Alcoholism
39
Q

What type of muscle fiber has high myoglobin and mitochondrial content? And what muscles have these fibers?

A

Type I fibers = aerobic metabolism (have myoglobin for O2 and mitochondra for oxidative phos)

  • predominantly muscles that maintain posture, such as PARASPINAL and soleus.

(Type II fibers = anaerobic, rapid forceful pulses of movement)

40
Q
A
41
Q

What muscles does the median n. traverse?

A

Flexor digitorum profundus and Flexor digitorum superficialis before entering wrist and hand under flextor retinaculum.

42
Q

What are the following Buzzwords associated with?

  • osteoid matrix
  • trabecular thinning with fewer interconnection
  • subperiosteal bone resorption with cystic degeneration
  • lamellar bone resembling mosaic
  • spongiosa filling medullay canal with no mature trabeculae
A
  • osteoid matrix: unmineralized bone - Vit D Deficiency
  • trabecular thinning, few interconnection: Osteoporosis
  • subperiosteal bone resorption: HyperPTH
  • mosaic: Paget’s
  • spongiosa filling medullary canal: Osteopetrosis (normally BM replaces spongiosa, but here you have persistence of primary, unmineralized bone)
43
Q

Sweat glands - what type of gland?

A

APOCRINE. secrete into hair follicles rather than directly onto skin.

44
Q

Contact Derm Histology

A

Spongiosis = epidermal accumulation of edematous fluid in intracellular spaces

45
Q

Buzzwords:

  • Acanthosis
  • Dyskeratosis
  • Hyperparakeratosis
  • Spongiosis
  • Hypergranulosis
A
  • Acanthosis = Psoriasis (inc. in stratum spinosum)
  • Dyskeratosis = Squamous cell carcinoma (abnl keratinization of individual cells)
  • Hyperparakeratosis = Actinic Keratosis (retained nuclei in stratum corneum)
  • Spongiosis = Contact Derm
  • Hypergranulosis = Lichen Planus (excessive granulation of stratum granulosum)
46
Q

Fibromyalgia

A

Pt: Female, 20-50s

  • Diffuse MSK pain with stiffness, paresthesia, poor sleep, fatigue, emotional disturbance.
  • Gets worse with exercise.
  • Tenderness in specific points - “trigger points”

Tx: regular exercise, Pregabalin, SNRI

47
Q

Polymyalgia Rheumatic

A

Pt: Women > 50. Old!

  • proximal JOINT pain and stiffness - shoulder, hips, pelvic girdle.
  • NO muscle weakness
  • fever, malaise, weight loss.
  • Assoc. with temporal arteritis

Labs: Inc. ESR, CRP

Tx: low dose corticosteroids

48
Q

PABA in sunscreen blocks what type of UV rays?

A

UVB ONLY!

49
Q

Psoas Abscess - presentation? Where on CT?

A

Hematogenous, Lymphatic, or Local Spread of infection.

Fever, Back/Flank pain, Inguinal mass, Difficulty walking

PSOAS SIGN: pain when hip is extended OR pain upon hip flexion against resistance

CT: located immediately lateral to the vertebral bodies

50
Q

Muscle regulatory fibers

A
  1. Muscle spindle/Group 1a, II sensory axons = Intrafusal fibers (parallel to the extrafusal fibers).
    - sense changes in muscle length
    - stretch reflex: if muscle stretched, reflexive activation of alpha neuron - contraction to resist the stretch (DTR)
  2. Golgi Tendon Organ
    - sense changes in mucle tension/force
    - once it reaches a threshold, sends inhibitory signal to alpha neuron - sudden muscle relaxation - protects muscle.
51
Q

Differences in Bone density curves most due to what?

A

Genetic factors

Smaller role: Ca intake, physical activity.

52
Q

Hypercalcemia in Sarcoidosis?

A

Increased extrarenal formation of 1,25 dihydroxy vit D by activated macrophages (T cells release IFNg which increases activity of 1 alpha hydroxylase in macrophages).

53
Q

Epithelial Junctions

A

Tight = claudins

Adherens = actin + cadherins

Desmosome = keratin + desmoplakin

Gap = connexons

Hemidesmosome = keartin to basement membrane

Integrins = collagen, laminin, fibronectin.

54
Q

Neurovascular Pairings for the following locations:

Axillary/lateral thorax

cubital fossa/distal humerus

posterior to medial malleolus

A

axillary = long thoracic n., lateral thoracic a.

cubital fossa/distal hum = median n., brachial artery

post medial malleolus = tibial, posterior tibial

55
Q

Osteoporosis = tx, and what to avoid

A

Tx:

  • bisphosphonates - inhibit osteoclasts
  • denosumab - monoclonal Ab against RANKL
  • raloxifene - SERM bone agonist
  • PTH pulsatile - stimulates osteoblasts, no more than 2 yrs

Avoid

  • smoking, EtOH, chronic steroid use
  • PPI - inhibits absorption of Ca
56
Q

Dermatologic Lesions associated with:

Hyperkeratosis

Parakeratosis

Spongiosis

Acantholysis

Acanthosis

A

Hyperkeratosis - inc. s. corneum = psoriasis, calluses

Parakeratosis - retained nuclei in s. corneum = psoriasis

Spongiosis - edema in epidermis = eczema

Acantholysis = separation of cells = pemphigus vulgaris

Acanthosis = inc s. spinosum = acanthosis nigricans

57
Q

Lumbar Lordosis caused by excessive contraction of ______.

A

Hip flexors.

58
Q

What muscle pulls the clavicle inferolaterally?

A

Deltoid.

59
Q

What muscle pulls the clavicle superomedially?

A

Trapezius

60
Q

Reactive Arthritis Sx

A

Can’t pee, see, climb a tree

Urethritis
Conjunctivitis, Anterior Uveitis
Arthritis
+ Sacroillitis 20% cases

HLAB27 associated.
Post GI (shigella, salmonella, yersinia, campylobacter)
Post GU (urethritis)
Post Chlamydia

61
Q

Dysplastic Nevus

A

Numerous dysplastic nevi in young person with FHx of melanoma in more than 3 1st degree relatives.

Mutations in CDKN2a - 9p21.

62
Q

Knee arthritis, conjunctivitis, vesicular rash on palms.

Arthritis treated with ibuprofen.

Conjunctivitis treated with topical antibiotics.

What was initiating event?

A

Reiter’s Reactive Arthritis.

Commonly following GI or UTIs.

USMLE Step 1 Systems (11 decks)

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