MSK/Skin/Connective Tissue Flashcards
Cause of axillary nerve damage
C5-C6
Fractured surgical neck of humerus; anterior dislocation of humerus
Presentation of axillary nerve damage
C5-C6
Flattened deltoid
Loss of arm abduction at shoulder (> 15°)
Loss of sensation over deltoid muscle and lateral arm
Cause of musculocutaneous nerve damage
Upper trunk compression
Presentation of musculocutaneous nerve damage
C5-C7
Loss of forearm flexion, supination and lateral arm sensation
Cause of median nerve damage
C5-T1
Supracondylar fracture of humerus (proximal lesion); carpal tunnel syndrome and wrist laceration (distal lesion)
Presentation of median nerve damage
“Ape hand” and “Pope’s blessing”
Loss of wrist flexion, flexion of lateral fingers, thumb opposition, lumbricals of 2nd and 3rd digits
Loss of sensation over thenar eminence and
dorsal and palmar aspects of lateral 31⁄2 fingers with proximal lesion
Cause of ulnar nerve damage
C8-T1
Fracture of medial epicondyle of humerus “funny bone” (proximal lesion); fractured hook of hamate (distal lesion) from fall on outstretched hand
Presentation of Ulnar nerve damage
“Ulnar claw” on digit extension
Radial deviation of wrist upon flexion (proximal lesion)
Loss of wrist flexion, flexion of medial fingers, abduction and adduction of fingers (interossei),
actions of medial 2 lumbrical muscles Loss of sensation over medial 11/2 fingers including hypothenar eminence
Cause of recurrent branch of median nerve damage
Superficial laceration of palm
Erb palsy (“waiter’s tip”)
Traction or tear of upper trunk: C5-C6 roots
Deficit in deltoid, supraspinatus, infaspinatus and biceps brachii: adducted, medially rotated, extended and pronated
Klumpke palsy
Traction or tear of lower trunk: C8-T1 root
Deficit lumbricals, interossei, thenar, hypothenar
Total claw hand
Winged scapula
LTN; serrates anterior
Thenar eminence
Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis, superficial head (deep head by ulnar nerve)
Hypothenar eminence
Opponens digiti minimi, Abductor digiti minimi, Flexor digiti minimi brevis
Dorsal interossei
abduct the fingers
Palmar interossei
adduct the fingers
Iliohypogastric (T12-L1)
Damage occurs via?
Sensory—suprapubic region
Motor—transversus abdominis and internal oblique
Abdominal surgery
Genitofemoral nerve (L1-L2) Damage occurs via?
Sensory—scrotum/labia majora, medial thigh
Motor—cremaster
Laparoscopic surgery
Lateral femoral cutaneous (L2-L3)
Damage occurs via?
Sensory—anterior and lateral thigh
Tight clothing, obesity, pregnancy
Obturator (L2-L4)
Damage occurs via?
Sensory—medial thigh (L2-L4)
Motor—obturator externus, adductor longus, adductor brevis, gracilis, pectineus,
adductor magnus
Descends and exits through obturator canal
Pelvic surgery
Femoral (L2-L4)
Damage occurs via?
Sensory—anterior thigh, medial leg
Motor—quadriceps, iliopsoas, pectineus, sartorius
Pelvic fracture
Sciatic (L4-S3)
Damage occurs via?
Sensory—posterior thigh
Motor—semitendinosus, semimembranosus, biceps femoris, adductor magnus
Herniated disc
Common peroneal (L4-S2) Damage occurs via?
Sensory—dorsum of foot
Motor—biceps femoris, tibialis anterior, extensor muscles of foot
Trauma or compression of lateral aspect of leg, fibular neck fracture
Tibial (L4-S3)
Damage occurs via?
Sensory—sole of foot
Motor—triceps surae, plantaris, popliteus, flexor muscles of foot
Knee trauma, Baker cyst (proximal lesion); tarsal tunnel syndrome (distal lesion)
Superior gluteal (L4- S1) Damage occurs via?
Exits pelvis via greater sciatic foramen (above piriformis)
Motor—gluteus medius, gluteus minimus, tensor fascia latae (abduction)
Iatrogenic injury during intramuscular injection to upper medial gluteal region
Inferior gluteal (L5-S2) Damage occurs via?
Exits pelvis via greater sciatic foramen below piriformis
Motor—gluteus maximus (extension)
Posterior hip dislocation
Pudendal (S2-S4)
Damage occurs via?
Sensory—perineum
Motor—external urethral and anal sphincters
Stretch injury during childbirth
Abductors of the hip
Gluteus medius, gluteus minimus
Adductors of the hip
Adductor magnus, adductor longus, adductor brevis
Extensors of the hip
Gluteus maximus, semitendinosus, semimembranosus
Flexors of the hip
Iliopsoas, rectus femoris, tensor fascia lata, pectineus
Internal rotation of the hip
Gluteus medius, gluteus minimus, tensor fascia latae
External rotation of the hip
Iliopsoas, gluteus maximus, piriformis, obturator
Osteitis fibrosa cystica
Primary hyperparathyroidism
Incr: Ca, ALP, PTH
Decr: PO4
Brown tumors (fibrous bone replacement)
Osteochondroma
Most common benign bone tumor
Bony exostosis with cartilaginous (chondroid) cap
Giant cell tumor
Benign; 20–40 years old.
Epiphysis of long bones
Locally aggressive; “Soap bubble”
express RANKL
Osteosarcoma
Most common malignant bone tumors
Codman triangle
(Rb and Li Fraumeni)
Ewing sarcoma
Boys < 15 years old.
Commonly appears in diaphysis of long bones, pelvis, scapula, ribs.
“Onion skin” periosteal reaction
Presentation of osteoarthritis
Pain in weight-bearing joints after use
Joint finding in osteoarthritis
Osteophytes, joint space narrowing, subchondral sclerosis and cysts
Presentation of Rheumatoid arthritis
Pain, swelling, and morning stiffness lasting > 1 hour, improving with use
Joint finding in Rheumatoid arthritis
Erosions, juxta-articular osteopenia, soft tissue swelling, subchondral cysts, joint space narrowing.
Sjögren syndrome
Autoimmune destruction of exocrine glands
Antiphospholipid syndrome
1° or 2° autoimmune disorder
Dx clinically: hx of thrombosis or spontaneous abortion w/ lab findings of lupus anticoagulant, anticardiolipin, anti-β2 glycoprotein antibodies
Sarcoidosis
Characterized by immune-mediated, widespread noncaseating granulomas
↑: ACE, CD4 and 8
Polymyositis/dermatomyositis markers
↑ CK, ⊕ ANA, ⊕ anti-Jo-1, ⊕ anti-SRP, ⊕ anti-Mi-2 antibodies
Polymyositis presentation
Progressive symmetric proximal muscle weakness w/ endomysial inflammation and CD8
Dermatomyositis presentation
Like polymyositis but w/ mallar rash, Grotton papule, heliotrope rash, shawl and face rash, mechanics hands
Scleroderma
Triad of autoimmunity, noninflammatory vasculopathy, and collagen deposition with fibrosis
Appearance of scleroderma
Sclerosis of skin, manifesting as puffy, taut skin without wrinkles, fingertip pitting
Albinism
Decreased melanin d/t decreased tyrosinase activity
Glomus tumor
Benign, painful, red-blue tumor, commonly under fingernails
Derived from thermoregulatory cells
Pyogenic granuloma
Polypoid lobulated capillary hemangioma that can ulcerate and bleed.
Associated with trauma and pregnancy.
Pemphigus vulgaris
IgG antibody against desmoglein
Flaccid intraepidermal bullae caused by acantholysis
Type II hypersensitivity reaction
Nikolsky sign ⊕
Bullous pemphigoid
IgG antibody against hemidesmosomes
IF: linear pattern at epidermal-dermal junction
Dermatitis herpetiformis
Deposits of IgA at tips of dermal papillae.
Associated with celiac disease
Lichen Planus
Pruritic, Purple, Polygonal Planar Papules and Plaques
Sawtooth infiltrate of lymphocytes at dermal-epidermal junction
Associated with hepatitis C
Basal cell carcinoma
Most common skin cancer
Waxy, pink, pearly nodules, commonly with telangiectasias, rolled borders, central crusting or ulceration
“Palisading” nuclei
Squamous cell carcinoma
Ulcerative red lesions with frequent scale
keratin “pearls”
Leflunomide
Reversibly inhibits dihydroorotate dehydrogenase, preventing pyrimidine synthesis; suppresses T-cell proliferation
Use: RA and psoriatic arthritis
SE: Diarrhea, hypertension, hepatotoxicity, teratogenicity
Bisphosphonates
Pyrophosphate analogs; bind hydroxyapatite in bone, inhibiting osteoclast activity
SE: Esophagitis, osteonecrosis of jaw, atypical stress fractures
Teriparatide
Recombinant PTH analog given subq; increases osteoblast activity
Use: osteoporosis
SE: increased risk of osteosarcoma
Etanercept
TNF-α inhibitor: Fusion protein (receptor for TNF-α + IgG1 Fc), produced by recombinant DNA
Use: RA, psoriasis, ankylosing spondylitis
Anti-TNF-α monoclonal antibody
Infliximab, adalimumab, certolizumab, golimumab
Mixed connective tissue disease
Features of SLE, systemic sclerosis, and/or polymyositis
Associated with anti-U1 RNP antibodies (speckled ANA)
Polymyalgia rheumatica Sx and treatment
Pain and stiffness in shoulders and hips, often with fever, malaise, weight loss; NO weakness
Low-dose corticosteroids
Polymyalgia rheumatica labs
Incr ESR, Incr CRP, normal CK
McMurray test
Pain w/ external rotation of knee: medial meniscus tear
Internal: lateral
Prepatellar bursitis
Repeated trauma or pressure from excessive kneeling (also called “housemaid’s knee”)
Baker cyst
Popliteal fluid collection in gastrocnemius-semimembranosus bursa
Arm abduction
Supraspinatus, deltoid, serrates anterior
Measurements of osteoblast activity
ALP, osteocalcin, propeptides of type I procollagen
Lab changes in osteoporosis
None (dx via DEXA)
Stages of pagets dx of bone
Lytic (clasts)
Mixed
Sclerotic (blasts; clasts have burnt out)
anti-Scl-70 antibody
aka anti-DNA topoisomerase I antibody
Diffuse scleroderma
Vitiligo
autoimmune destruction of melanocytes
Cherry hemangioma
Benign capillary hemangioma of the elderly
Cystic hygroma
Cavernous lymphangioma of the neck (Turner)
Strawberry hemangioma
Benign capillary hemangioma of infancy; grows then spontaneously regresses
Pityriasis rosea
“Herald patch” followed by scaly erythematous plaques, often in a “Christmas tree”distribution on trunk
Self-resolving
Radial nerve damage presentation
Wrist drop: loss of elbow, wrist, and finger extension
↓ grip strength
Loss of sensation over posterior arm/forearm and dorsal hand
Cause of radial nerve damage
C5-C7
Midshaft fracture of humerus; compression of axilla (crutches or arm over chair)
