Musculoskeletal, Skin and CT for COMLEX 1

Anterior Talofibular ligament

"ATF = Always Tears First"

Anterior Talofibular Ligament (ATF)

"Always Tears First" Origin: *lateral malleolus* Insertion: *NECK of the talus*

Layers of the *epidermis*

"Californians Like Girls in String Bikinis" -Superficial to deep 1) Stratum corneum (anucleate cells) 2) Stratum lucidum 3) Stratum graunlosum 4) Stratum spinous (contain desmosomes) 5) Stratum basalis (regenerative/stem cell layer)

Layers of the Epidermis (superficial to deep)

"Californians Like Girls in String Bikinis" 1) stratum Corneum 2) stratum Lucidum 3) stratum Granulosum 4) stratum Spinosum 5) stratum Basalis

Medial epicondylitis

"Golfer's elbow" -Repetitive *flexion* of forearm -Pain near *medial epicondyle*

3 drugs known to cause *drug-induced lupus*

"HIP" 1) Hydralazine 2) Isoniazid 3) Procainamide

Elbow ossification sequence

"S-CRITOL" 1) Shaft 2) Capitellum 3) Radial head 4) Internal epicondyle 5) Trochlea 6) Olecranon 7) Lateral epicondyle

Rotator Cuff muscles and functions

"SITS" 1) Supraspinatus: shoulder *ABduction* 2) Infraspinatus: shoulder *external rotation* 3) Teres minor: shoulder *ADduction*, external rotation 4) Subscapularis: shoulder *ADduction*, internal rotation

Rotator Cuff muscles

"SItS" 1) Supraspinatus 2) Infraspinatus 3) teres minor 4) Subscapularis -Innervated by *C5-C6*

Psoriatic arthritis (dactylitis)

"Sausage fingers

Carpal bones

"Some Lovers Try Positions That They Cannot Handle" -Start at *thumb* -8 bones -Scaphoid = anatomical "snuff box"

Lateral epicondylitis

"Tennis elbow" -Repetitive *extension* of forearm (i.e. backhand) -Pain near *lateral epicondyle*

Type 1 muscle fibers

*1 slow red ox* -*Slow* twitch -*Red fibers* (due to increased mitochondria and myoglobin conc.) -Increased *ox*idative phosphorylation --> sustained contraction

SJS-TEN

*10-30%* of total body surface area involved

Labs for osteoporosis

*ALL NORMAL* -Very high yield

Women of which ethnicity have a much *lower* risk of developing osteoporosis?

*African American* women -The risk of them developing osteoporosis is much *lower* than women of other ethnicities

Bisphosphonates

*Alendronate, other "-dronates"* -*Pyrophosphate* analogs -Bind *hydroxyapatite* in bone --> inhibits *osteoclast* activity Use: -*Osteoporosis (PMP), hypercalcemia, Paget disease of bone*

Spondylolisthesis

*Anterior displacement* of one vertebral segment in relationship to the one below it -P.E. will show a *step-off* at affected levels -Usually due to defects in the *pars interarticularis*

Rheumatoid arthritis

*Autoimmune* condition -Seen in *middle-aged women* -Caused by *inflammatory destruction of synovial joints* -*Pannus, subcutaneous rheumatoid nodules, ULNAR deviation of fingers*, *RADIAL deviation of wrist* -Involves *MCP and PIP* with NO DIP involvement -Strong assoc. w/ *HLA-DR4* (rheum has 4 walls) -*Morning stiffness lasting > 30 mins that IMPROVES with use* -*Symmetric* joint involvement, *systemic symptoms* (fever, fatigue, weight loss, pleuritis) -*(+) Rheumatoid factor* (see next slide) -Synovial will show *neutrophils and high protein* -Tx: *NSAIDs, glucocorticoids, disease-modifying agents* -Pannus: inflammatory granulation tissue

Bechet's syndrome

*Autoimmune* disease Characteristic findings: (recurrent) 1) *Oral ulcers* 2) *Genital ulcers* 3) *Arthralgia* of *ankles,knees* Characteristic "waxing and waning" of symptoms

Myotonic dystrophy

*Autosomal dominant* -*CTG repeat* expansion in the *DMPK gene* C.P.: -*Myotonia, muscle rigidity, cataracts, frontal balding* -Occurs in adults *20-40 years old*

Osteogenesis imperfecta

*Autosomal dominant* -Decreased production of *type 1* collagen -Deficient in *glycine* C.P. -*Blue sclera* -*Multiple fractures* -*Hearing loss* (due to fractures ossicles) -*Dental imperfections* (due to lack of dentin)

Osteogenesis Imperfecta (OI)

*Autosomal dominant* defect in *type 1 collagen* synthesis -Congenital defect in bone formation --> structurally *weak bones* C.P.: 1) *Multiple fractures* 2) *Blue sclera* 3) *Hearing loss* -Bones of the *middle ear* easily fracture

Nevus (mole)

*Benign* neoplasm of melanocytes -*Congenital* nevus: present at birth, assoc. w/ *hair* -*Acquired nevus* 1) Begins as *junctional nevus* (most common mole in *children*) 2) Ends in *intradermal nevus* (most common mole in *adults*)

Giant cell tumor

*Benign* tumor -Occurs in ages *20-40 years old* -*Soap bubble* appearance on x-ray -Occurs at *epiphyseal* end of long bones The *ONLY* bone tumor that arises from the *epiphyseal* end of long bones

Lipoma

*Benign* tumor of *adipose tissue* -*Most common* benign soft tissue tumor in *adults*

Osteoid osteoma

*Benign* tumor of *osteoblasts* -Surrounded by a rim of *reactive bone* -Occurs in young adults *<25 years old* -Presents as *bone pain that resolves w/ aspirin* (high yield)

Osteoma

*Benign* tumor of bone -Most commonly arises on the surface of *facial bones* -Assoc. w/ *Gardner syndrome* (GI adenocarcinoma)

Chondroma

*Benign* tumor of cartilage -Arises from the *medulla* of small bones in the *hands and feet*

Rhabdomyoma

*Benign* tumor of skeletal muscle -*Cardiac rhabdomyoma* is assoc. w/ *tuberosus sclerosis* (high yield)

Best test for a *tibial stress fracture*

*Bone scan* w/in 72 hours

Osteopetrosis x-ray

*Bone-in-bone* appearance

Most important *prognostic* factor in predicting metastasis of melanoma

*Breslow thickness* -Determines the *DEPTH* of extension

Osteoblasts

*Build bone* by secreting *collagen and catalyzing mineralization* -Differentiate from *mesenchymal stem cells in periosteum*

Melanocytic nevus

*Common mole*

Hemidesmosome

*Connects keratin* in basal cells to basement membrane -Autoantibodies = *bullous pemphigoid*

C.P. of a patient with *osteopetrosis*

*Cranial nerve impingement and palsies* as a result of narrowed foramina (vision and/or hearing loss) -Pt may also have hx of *multiple fractures* caused by minimal trauma

Necrotizing fasciitis

*Deeper* tissue injury -Usually from *Strep pyogenes* or *anaerobic bacteria spp.* -Results in *crepitus* from *methane and CO2 production* -*Flesh-eating bacteria* -*Pain out of proportion to PE* -Often seen in *post-surgical pts*

Staphlococcal SSS

*Exotoxins A and B* destroy keratinocyte attachments in stratum *granulosum* only -*Sloughing off* of the upper layers of the epidermis

What nerve is at the highest risk for damage in a patient undergoing a total thyroidectomy? What muscle does it innervate?

*External branch* of *superior laryngeal nerve* -Muscle: *cricothyroid*

Type 2 muscle fibers

*Fast* twitch -*White* fibers (due to *decreased* mitochondria and myoglobin -Uses *anaerobic glycolysis* -Ex: weight training results in hypertrophy of fast-twitch muscle fibers

Lumbricals (hand)

*Flexion* at the *MCP joint* *Extension* at the *PIP and DIP joints*

Urticaria

*Hives* -Pruritic *wheals* that form after *mast cell degranulation*

Impetigo

*Honey-crusted lesions* -Usually caused by *Strep pyogenes* or *Staph aureus* -*Highly contagious*

Aspirin

*IRREVERSIBLY* inhibits both *COX-1 and COX-2* via *acetylation* -Results in *decreased* synthesis of both *TXA2 and prostaglandins* -Low dose (<300 mg/day) to decrease platelet aggregation

NSAIDs

*Ibuprofen, Naproxen, Indomethacin, Ketorolac, Diclofenac* -*REVERSIBLY* inhibit both *COX-1 and COX-2* -*Blocks prostaglandin synthesis* -Use: *antipyretic, anti-inflammatory* -Toxicity: *interstitial nephritis, gastric ulcer, renal ischemia*

Rheumatoid factor

*IgM autoantibody* against the *Fc portion of IgG* -Marker for tissue damage and disease activity

Sarcoidosis

*Immune-mediated*, widespread *NON-caseating granulomas* 1) Elevated serum *ACE levels* 2) Elevated *CD4+/CD8+ ratio* 3) *Hypercalcemia* (due to Vit. D activation in macrophages) -Most common in *black females w/ enlarged lymph nodes* -CXR/CT scan shows extensive *bilateral adenopathy* -Assoc. w/ *restrictive lung disease (interstitial fibrosis), Bell palsy* -Epitheloid granulomas containing microscopic *Schaumann and asteroid bodies* -Tx: *steroids*

Polymyositis/Dermatomyositis

*Increased CK* -(+) antibodies 1) *ANA* 2) *anti-Jo-1* 3) *anti-SRP* 4) *anti-Mi-2* Tx: *steroids* followed by *long-term immunosuppressive therapy* (i.e. Methotrexate)

Dermatomyositis

*Inflammation* of both the *skin and skeletal muscle* -*Proximal muscle weakness* -Assoc. w/ *carcinoma* (i.e. *gastric carcinoma) (high yield) Similar to polymyositis +: -*Malar rash (similar to SLE) -*Gottren papules* (on fingers) -*Helitrope rash* (rash on upper eyelids) -*Shawl and face rash* -*Perimysial* inflammation --Think about "skin being outer layer" = "perimysial" inflammation -*C4+ T-cells* (D = higher in alphabet = 4) -*(+) ANA and (+) anti-Jo-1 antibody* -*Increase CK*

Probenecid

*Inhibits "reabsorption"* or uric acid in the *PCT* -Also *inhibits "secretion" of Penicillin* -*P*robenecid = works in the *P*CT by making you *P*ee out uric acid (inhibits reabsorption) -*P*robenecid also INHIBITS secretion of *P*enicillin

Febuxostat

*Inhibits xanthins oxidase* -Same MoA as allopurinol

Oral retinoids for acne vulgaris

*Isotretnoin* (Acutane) is an oral retinoid that is very effective for severe acne -Side effects are often *reversible with d/c* -Side effects similar to those of *Vit. A toxicity* ADR's: 1) *Dry skin* 2) *Nosebleed* 3) *Muscle pains* 4) *Increased liver enzymes* 5) *Increased blood lipid levels* Don't forget, *INCREASED* risk for fetal abnormalities

Squamous cell carcinoma (histology)

*Keratin pearls* q

Obturator nerve (trauma)

*L2-L4* -Causes decreased sensation in the *medial thigh* as well as decreased *adduction*

Femoral nerve (trauma)

*L2-L4* -Decreased *thigh flexion* and *leg extension*

Lumbar puncture site

*L4-L5 joint space* -Landmark: iliac crests

Superior gluteal nerve (trauma)

*L4-S1* Cause: -Iatrogenic injury during *IM injection to upper medial gluteal region* Presentation: -*Trendelenburg gait* (pelvis tilts) -Lesion is *contralateral* to the side of the hip that drops Innervation: -The *superior* gluteal nerve innervates the gluteus *medius and minimus*

Common peroneal (trauma)

*L4-S2* -Often cause by trauma or compression to the *lateral aspect of the knee* or a *fibular neck fracture* Presentation: -*Foot drop* -*Steppage gait* -LOSS of eversion and dorsiflexion

Tibial nerve (trauma)

*L4-S3* Causes: -Knee trauma -Baker cyst -Tarsal tunnel syndrome Presentation: -*Inability to curl toes* and *loss of sensation on sole of foot*

Inferior gluteal nerve (trauma)

*L5-S2* Cause: -*Posterior* hip dislocation Presentation: -Difficulty *climbing stairs, rising from seated position* Innervation: -The *inferior* gluteal nerve innervates the gluteus *maximus*

Bullous pemphiGoid (IgG)

*Less severe* than pemphigus vulgaris -*IgG* antibody against *HEMIdesmosomes* --Epidermal *basement membrane* -Tense blisters that contain *eosinophils* -Does *NOT* involve oral mucosa -Immunofluorescence reveals a *linear pattern* at the epidermal-dermal junction -*(-) Nikolsky sign*

Paget disease of bone (osteitis deformans)

*Localized disorder* (one or more bones) of bone remodeling caused by *increase in BOTH osteoblastic and osteoclastic activity* -*Mosiac pattern of bone* or *long bone chalk-stick fractures* -Increased blood flow from *increased arteriovenous shunts* may lead to *high-output heart failure* -Increased risk of *osteogenic sarcoma* -Labs: the *only lab* that will be abnormal is *elevated ALP* (serum Ca2+. phosphorus and PTH will be NORMAL)

Vitiligo

*Localized* areas of complete depigmentation -Caused by *autoimmune DESTRUCTION of melanocytes* by *lymphocytes* -Decreased *number* of melanocytes -Associated w/ *other autoimmune diseases* --Ex: *thyroid disease, diabetes, Addison's disease, etc.* -Lesions are *Wood lamp (+)* --Means they *fluoresce* in a dark room under Wood's lamp

Paget disease of the bone (osteitis deformans)

*Localized* disorder of bone remodeling -Due to increase in BOTH *osteoblastic and osteoclastic* activity (increased bone turnover) --> -*Mosiac pattern* of woven and lamellar bone -C.P.: *hearing loss* (due to skull deformation), *pain, deformity of long bones*, *thickening of bones or skull* -Increased *ALP* -Abnormal *osteoclasts* can show up as *very large with up to 100 nuclei*

Best test for a potential *scaphoid fracture*

*MRI* -Much more sensitive than plain film -Must do this because of the risk of *avascular necrosis* due to the scaphoid fracture

Osteosarcoma

*Malignant* bone tumor -Predisposing factors: 1) *Paget disease of bone* 2) *Radiation* 3) *Familial retinoblastoma* Characteristics: a) *Codman triangle* --Elevation of periosteum b) *Sunburst appearance* on X-ray -Spiculated periosteal formation circumscribing the tumor C.P.: -Pathologic fracture or *bone pain w/ swelling* -Usually seen in the *METAPHYSIS* of long bones 1) *Distal femur* 2) *Proximal tibia* 3) *Proximal humerus* Biopsy: -*Pleomorphic cells* that *produce osteoid*

Melanoma

*Malignant* neoplasm of melanocytes -*Most common cause of death* from skin cancer -*Significant risk* of *metastasis* -*S-100* tumor marker (think "S" for "s"kin) -The *DEPTH* (*Breslow thickness*) of the tumor correlates w/ the *risk of metastasis* -Use *ABCDE* method --Asymmetry, Borders (irregular), Color (not uniform), Diameter (>6mm) -Often driven my mutation in the *BRAF kinase* -Tx: *excision w/ WIDE margins*

Liposarcoma

*Malignant* tumor of *adipose tissue* -*Most common* malignant soft tissue tumor in *adults* -*Lipoblast* is the characteristic cell

Chondrosarcoma

*Malignant* tumor of cartilage -Arises from the *medulla* of the *pelvis or skeleton* -Most commonly seen in *adults* between the *4th and 6th decades* of life -Has a predilection for *flat bones* of the *shoulder and pelvis*

Rhabdomyosarcoma

*Malignant* tumor of skeletal muscle -*Most common* malignant soft tissue tumor in *children* -*Rhabdomyoblast* is the characteristic cell -*Desmin (+)* -Most common site is *head and neck* -*Vagina* is the classic site in *young girls*

Ewing sarcoma

*Metastatic* bone tumor -Common in * young boys < 15 years old* -Occurs in the *diaphysis* (middle) of long bones -*Anaplastic small BLUE cell* malignant tumor -*Extremely aggressive*, but *responds well* to *chemotherapy* -*"Onion skin"* periosteal reaction in bone -Assoc. w/ *t(11;22)* translocation --"11+22 = 33" = Patrick *Ewing's* basketball number

Paget disease of bone (biopsy)

*Mosiac pattern* -Looks like puzzle pieces stuck together

Myasthenia gravis

*Most common* NMJ disorder -Autoantibodies (compete with ACh) against the *POST*synaptic *ACh receptor* -C.P.: *ptosis, diplopia, muscle weakness* (*ascending paralysis*) (eyes most commonly affected) --Symptoms *worsen* with use -Assoc. w/ *thymoma, thymic hyperplasia* --*Thymectomy* improves symptoms -An AChE inhibitor (Edrophonium) will *reverse symptoms* (allows more ACh to compete with the autoantibodies)

Basal cell carcinoma

*Most common* skin cancer -Found in *sun-exposed areas* of the body -Risk factors: 1) Prolonged sun exposure (UVB) 2) Albinism 3) Xeroderma pigmentosum -*Locally invasive*, but *rarely* metastasizes -*Pink, pearly nodule* --Elevated nodule w/ *central ulceration* surrounded by *dilated (telangiectatic) vessels* -Most commonly seen on *upper lip* -May appear as *nonhealing ulcer* or as a *scaling plaque* -Tx: surgical excision -"Pink, pearly nodule"

Superficial spreading melanoma

*Most common* subtype -Dominant early *radial growth* -Prognosis: *good*

Baby born to a mom with gestational diabetes. Difficult delivery. Presents w/ arm *by her side*, *medially* rotated, forearm fully *extended*, *pronated*. What nerve is damaged?

*Musculocutaneous nerve* -"Erb Duchenne's palsy" -"Shoulder dystocia"

Albinism

*Normal* melanocyte number -*Decreased melanin production* --Due to *decreased tyrosinase activity* or *defective tyrosine transport* ---Remember, *tyrosine* is the precursor for melanin production --May also be caused by *failure of neural crest cell migration* -Increased risk for *skin cancer*

Ewing sarcoma (onion skin 2)

*Onion-skin thickening* of the *diaphysis* (middle) of a long bone

Cholinergic crisis

*Organophosphate poisoning* leads to *complete AChE inhibition* --> *excess ACh* at the NMJ "DUMBBELSS" -Diarrhea, Urination, Miosis, Bradycardia, Bronchospasm, Excitation (CNS), Lacrimation, Salivation, Sweating When a pt is given *Edrophonium* (AChE inhibitor) symptoms *worsen*

Osteoblasts secrete:

*Osteoid* -Which turns into *bone* in the present of *calcium and phosphate*

Erythema nodosum

*Painful* lesions on the *anterior shins*

Basal cell carcinoma (histology)

*Peripheral palisading* nuclei (high yield) *BP* = "Basal=Palisading"

*Type 1* osteoporosis*

*Postmenopausal* -*Increased bone resorption* due to decreased estrogen levels

Actinic keratosis

*Premalignant lesions* -Caused by *sun exposure* -Small, rough, erythematous or brownish papule -Risk of *SQUAMOUS cell carcinoma*

Tight junction (zone occludens)

*Prevent paracellular movement* of solutes -Composed of *claudins and occludins*

Polymyositis

*Progressive symmetric "proximal" muscle weakness* -Most often affects *shoulders* (i.e. pt has *trouble combing hair*) -Characterized by *endomysial* inflammation -*CD8+ T-cells* (P = lower in alphabet = 8) -(+) ANA* and *anti-Jo-1 antibodies (most specific)* -*Increased CK* EMG shows *fibrillations* and *high frequency actions potentials* (HY) Definitive dx: *muscle biopsy*

Teriparatide

*Recombinant PTH* -teri*para*tide = *para*thyroid hormone -Given *SQ daily* -*Increases osteoblastic* activity --> *builds bone* Use: -*Osteoporosis* --Increases bone growth vs antiresorptive therapies (i.e. bisphosphonates) Toxicity: -Transient *hypercalcemia* -May *increase risk for osteosarcoma*

Pegloticase

*Recombinant uricase* that *catalyzes the metabolism* of *uric acid --> allantoin*

Osteoclasts

*Resorb bone* by *secreting acids and collagenases* -Differentiate from *monocytes, macrophages*

Celecoxib

*Reversibly* inhibits *COX-2* (specific) -No effet on COX-1 --COX-1 helps maintain the GI tract, so a COX-2 specific agent (Celecoxib) has *NO corrosive GI effects* -However, it *spares platelet function of TXA2* --> *platelet aggregation* -Toxicity: 1) *Increased risk for thrombosis* 2) *Sulfa allergy*

Acetaminophen

*Reversibly* inhibits *cyclooxygenase* -Mostly in the *CNS* (inactivated peripherally) -Used as *antipyretic, analgesic* --*NO* anti-inflammatory properties (NOT an NSAID) -Used instead of aspirin to avoid Reye syndrome in children -Metabolized in the *liver*

Pseudogout (crystals)

*Rhomboid-shaped* -*Blue* under parallel light

Psoriasis

*Salmon-colored plaques* w/ *silvery scaling* -Common on *elbows and knees* (EXTENSOR surfaces) -*Nail pitting* may also be present -Due to *excessive keratinocyte proliferation* --Increase in the stratum *spinosum* -*Auspitz sign* = pinpoint bleeding spots from exposure of dermal papillae where scales are scraped off -Assoc. w/ *HLA-C* ("c for coriasis) -Lesions often arise in *areas of trauma* Tx: -Corticosteroids, UV light w/ psoralen, immune-modulating therapies

Lichen planus (histology)

*Saw-tooth appearance* -Dermal-epidermal junction

*Type 2* osteoporosis

*Senile* osteoporosis -Occurs in men and women *>70 years old* -Best to use *prophylactic treatment* including *weight-bearing exercise, adequate Ca2+ and Vit. D intake*

Nursemaid's elbow

*Slight flexion, ADduction, pronation*

In patients who suffer from chronic "itching disorders", breaks/tears in the skin may result. What pathogen is most likely to infect this pt via the breaks in the skin?

*Staph aureus*

Leser-Trelat sign

*Sudden* onset of *multiple seborrheic keratoses* in the eldery -Suggests underlying *GI malignancy* (high yield)

Osteosarcoma (image)

*Sunburst* appearance *Codman triangle* -Outline of bone is raised (arrows) Locations = *metaphysis* of long bones 1) *Distal femur* 2)* Proximal tibia* 3) *Proximal humerus*

Hallmark of Rheumatoid Arthritis

*Synovitis* that leads to *formation of a pannus* -Pannus: *inflammed granulation tissue* -Synovitis: inflammation of the synovium (lines the joint capsule, secretes synovial fluid)

Etanercept

*TNF-alpha inhibitor* -Etaner*cept* is a TNF decoy re*cept*or Use: -Rheumatoid arthritis, psoriasis, ankylosing spondylitis

Infliximab, adalimumab

*TNF-alpha inhibitors* -*Anti-TNF-alpha monoclonal antibody* Use: -Rheumatoid arthritis, psoriasis, ankylosing spondylitis

Paget disease of bone (calvarium)

*Thickened calvarium* -Hat doesn't fit anymore, hearing impairment

Osteopetrosis

*Thickened, dense* bones that are *prone to fracture* -Due to *failure* of normal bone *resorption* due to *defective osteoclasts* -Bone fills the medullary space --> *pancytopenia, extramedullary hematopoiesis* -Caused by *mutations* in *carbonic anhydrase II* which impairs the ability of the osteoclasts to generate an *acidic environment* --Carbonic anhydrase II deficiency can also lead to *renal tubular acidosis* -X-rays show *bone-in-bone* appearance -May result in *cranial nerve impingement and palsies* as a result of narrowed foramina (vision and hearing loss) -Labs will be *normal* -Tx: *bone marrow transplant* --Osteoclasts are derived from *monocyte,macrophage*

*Poison ivy* is a:

*Type IV* hypersensitivity reaction

Molluscum contagiosum

*Umbilicated papules* -Caused by a *poxvirus*

What structure is most commonly injured in a pt undergoing a *hysterectomy*?

*Ureter* -Close to the uterine artery -The ureter passes *inferior and lateral* to the *uterine artery* at the level of the *internal cervical os* ("water under the bridge")

Verrucae

*Warts* -Caused by *HPV 6,11* -Soft, tan, *cauliflower-like papules* -*Condyloma acuminatum* on genitals

Both Duchenne and Becker Muscular Dystrophies are:

*X-linked recessive*

Allopurinol

*Xanthine oxidase inhibitor* -*Decreases* conversion of *xanthine to uric acid* (decreases uric acid levels) -*Increases* concentrations of *azathioprine and 6-Mercaptopurine*

Gout (crystals)

-*Needle-shaped* -*Negative birefringent* -ye*LL*ow under para*LL*el light -Blue under perpendicular light

Latissimus dorsi muscle

-*Origin*: iliac crest and lumbar fascia to spinous process of T7-T12 -*Insertion*: bicipital groove of humerus -*Innervation*: thoracodorsal nerve -*Action*: extension, adduction, internal/medial rotation of humerus

teres minor

-Action: *ADducts and laterally rotates arm* -Innervation: *axillary nerve*

Infraspinatus

-Action: *laterally* rotates arm -Innervation: *suprascapular nerve* -Common *pitching injury*

Subscapularis

-Action: *medially rotates and ADducts arm* -Innervation: *upper and lower sub-scapular nerves*

Supraspinatus

-Actions: *"initial" shoulder ABduction* -Innervation: *suprascapular nerve* -Test: "full can/empty can"

Rheumatoid Arthritis

-Age: 40-60 -Joints: *MCP, PIP, wrists* -Morning stiffness: *prolonged* -Systemic symptoms present -Exam: soft, spongy, warm joints

Osteoarthritis

-Age: >40 -Joints: Hips, knees, *DIP* joint -Morning stiffness: *none/brief* (<30 mins) -Exam: hard, bony enlargement of joints

Rickets (C.P.)

-Pigeon-breast deformity -Frontal bossing -Rachitic rosary -Genu varum

Q angle (knee)

1) *ASIS to patella* 2) *Patella to tibial tubercle* Men = 14 degrees Women = 17 degrees Factors that *increase* Q angle: 1) *Genu valgum* 2) *Femoral anteversion* 3) *External tibial torsion* 4) *Laterally positioned tibial tuberosity* 5) *Tight lateral retinaculum*

Psoriasis (histology)

1) *Acanthosis* (epidermal hyperplasia) 2) *Parakaratosis* (hyperkeratosis w/ retention of keratinocyte nuclei) 3) *Munro micro abscesses* (collection of *neutrophils* in the stratum *corneum*) 4) *Auspitz sign* (thinning of epidermis w/ elongated dermal papillae; results in bleeding when scale is picked off)

Skin Disease-Specific Lab Tests

1) *Anti-centromere antibody* = CREST syndrome 2) *Anti-DNA topoisomerase I antibody* = diffuse systemic sclerosis (scleroderma) 3) *Anti-histone antibody* = drug-induced lupus 4) *Anti-Ro antibody* = Sjogren syndrome 5) *Anti-U1 RNP antibody* = Mixed CT disease

Endochondral ossification

1) *Axial skeleton* 2) *Appendicular skeleton* 3) *BASE of skull* a) *Cartilagenous model* of bone first made by *chondrocytes* b) Osteoclasts and osteoblasts later replace w/ *woven bone* c) Then remodeled to *lamellar bone*

Paget disease of bone (C.P.)

1) *Bone pain* 2) *Increasing hat size* -Skull is commonly affected 3) *Hearing loss* -Impingement of cranial nerve 4) Isolated *elevated ALP*

Bisphosphonates (toxicity)

1) *Corrosive esophagitis* -Advise its to *take w/ water* and *remain upright for 30 mins* -Due to changes in *acid production and reflux* 2) *Osteonecrosis of the jaw*

What is the (normal) action of the lumbricals?

1) *Flex* MCP joints 2) *Extend* DIP and PIP joints -"Claw hand" is due to *loss of lumbricals* --Results in remaining flexors of the digits exaggerate the loss of the lumbricals --> fingers extend at MCP, flex at DIP and PIP

Where does the *dura attach to the spine*? (4 places)

1) *Foramen magnum* 2) *C2* 3) *C3* 4) *S2* (craniosacral motion)

Paget disease of bone (complications)

1) *High-output cardiac failure* -Due to increased # of AV shunts 2) *Osteosarcoma*

Estrogen

1) *Inhibits apoptosis* in *osteoblasts* 2) *Induces apoptosis* in *osteoclasts*

Damage to the *Common peroneal nerve*

1) *Lateral hit* to the knee 2) *Posterior fibular head* dysfunction (i.e. ankle *inversion* sprain) Usually presents w/ *drop foot* -However, *ANY weakness* in ankle *dorsiflexion* (i.e. muscle strength 4/5) can represent damage to the common peroneal nerve

Treatment for *Acute* gout

1) *NSAIDs* (1st line) -Inhibit cyclooxygenase -NOT salicylates -Much better side effect profile 2) Glucocorticoids 3) Colchicine

Vertebral Ostomyelitis

1) *New onset/worsening back pain* 2) *Fever* 3) *Recent endocarditis or bacteremia* -Esp. *Staph aureus* Diagnose w/ *MRI of the spine*

Rickets

1) *Pigeon-breast deformity* -Inward bending of ribs w/ anterior protrusion of sternum 2) *Frontal bossing* -Enlarged forehead 3) *Rachitic rosary* -Due to osteoid deposition at the costochondral junction 4) *Bowing of legs* -Genu varum -All of the above signs are due to abnormal *osteoid deposition*

Growth phases of melanoma (2)

1) *Radial growth* -Horizontal growth -Low risk of metastasis 2) *Vertical growth* -Increased risk for metastasis

Two signs for a *PCL tear*

1) *Sag sign* -Pt is supine, knees flexed to 90 degrees -If (+), the *tibial tubercles lie POSTERIOR* 2) *Quadriceps Activation Test* -Pt is supine and *activated quadriceps against resistance* -*(+) test* when the *tibia translates anteriorly* into its normal position

Types of UV radiation

1) *UVA* -Dominant in *tAnning beds* and causes *photoAging* (premature aging) 2) *UVB* -Mainly causes *sunburn* -Linked *strongly* to *skin cancer*

O'Donahue's triad (Unhappy triad)

1) ACL 2) MCL 3) Medial meniscus -Often occurs due to *lateral force* to a planted leg

Muscle contraction

1) Action potential depolarization opens presynaptic Ca2+ channels, results in NT release 2) Depolarization travels down T-tubule 3) Depolarization of the dihydropyridine receptor (T-tubule) and the ryanodine receptor (S.R.) causes release of Ca2+ from the S.R. 4) Ca2+ binds to *troponin C*, which moves *tropomyosin* out of the way of the binding sites 5) Myosin *releases ADP + Pi* --> displacement of myosin (power stroke) --Contraction results in *shortening of H band, I band and Z line* --*A band remAins the same length (*A*lways the same length) 6) Binding of *new ATP* causes *detachment of the myosin head from the actin filament* 7) Hydrolysis of bound ATP --> ADP, myosin head adopts *high-energy position (cocked position)* "Youtube: Muscle contraction Process 3D Animation"

Complications of Rheumatoid Arthritis

1) Anemia of chronic disease 2) Secondary amyloidosis

Reactive arthritis (Reiters syndrome) (triad)

1) Arthritis 2) Conjunctivitis 3) Nongonococcal urethritis -"Can't see, can't pee, can't bend my knee" -Assoc. with *HLA-B27*

What *nerve and artery* pass around the surgical neck of the humerus?

1) Axillary nerve 2) Posterior humeral circumflex artery -In a pt with a fx to the surgical neck of the humerus, these two structures are most likely to be damaged

Membranous ossification

1) Bones of the *calvarium* (skull) 2) *Facial* bones a) *Woven bone* formed directly *WITHOUT* cartilage b) Later remodeled to *lamellar bone*

C.P. of a child with DMD

1) Calf pseudohypertrophy 2) Gower's sign 3) Waddling gait 4) Toe walking gait 5) Difficulty climbing stairs 6) Hyporeflexia

TNF-alpha inhibitors

1) Etanercept 2) Infliximab, adalimumab -All TNF-alpha inhibitors *predispose to infection* --Most commonly, *reactivation of latent TB*

What structures are *shortened* during muscle contraction?

1) H band 2) I band 3) Z line "HIZ shrinkage"

Risk factors that *increase* risk for Osteoporosis

1) Increased age 2) Female 3) Family history 4) Smoking (duhhh) 5) Low BMI (low weight = increased risk)

Supination of the foot involves:

1) Inversion 2) Plantar flexion 3) ADduction

3 major branches of the celiac trunk

1) Left gastric artery 2) Common hepatic artery 3) Splenic artery

Labs for osteomalacia/rickets

1) Low Vit. D 2) Low serum Ca2+ (leads to..) 3) Elevated PTH secretion (leads to..) 4) Decreased PO4 3- 5) Increased ALP (due to hyperactivity of osteoblasts)

*Osteoclastic* differentiation factors:

1) M-CSF 2) RANK-L (receptor for activated nuclear factor kappa-B ligand)

Dermatlogic morphology

1) Macule: flat lesion, < 1cm 2) Patch: macula > 1cm 3) Papule: elevated lesion < 1cm 4) Plaque: papule > 1cm 5) Vesicle: fluid-containing blister < 1cm 6) Bulla: fluid-containing blister > 1cm

McCune-Albright Syndrome (image)

1) Multiple unilateral bone lesions 2) Precocious puberty 3) Cafe-au-lait spots

What 3 muscles comprise the *hamstrings*?

1) Semitendinosis 2) Semimembranosis 3) Biceps femoris

Subtypes of melanoma

1) Superficial spreading 2) Lentigo maligna melanoma 3) Nodular melanoma 4) Acral lentiginous

Triangular space of shoulder

1) Teres major 2) Teres minor 3) Long head of triceps Contains the *circumflex scapular artery*

Compression of the *lateral femoral cutaneous nerve*

1) Truck driver 2) Pt who wears pants too tight -Pain and paresthesia in the *anterolateral thigh*

Thyroglossal duct cyst

A *congenital cyst* that is often first recognized as a *TENDER neck mass* that occurs *after a URTI* in *early childhood*

Fibrosarcoma

A *very rare* type of bone tumor -*DO NOT* pick this one one the test!!

Anterior interosseous nerve

A branch of the *median nerve* -Provides *isolated motor* innervation to the deep muscles of the hand -Damage to this nerve, the pt can NOT make the *A-OK sign* -There will be NO sensory loss if damaged, only motor loss

McCune-Albright Syndrome

A form of *polyostotic fibrous dysplasia* -Characterized by: 1) *Multiple, unilateral bone lesions* --Assoc. w/ *precocious puberty* (child's body begins changing into adult body too soon) 2) *Cafe-au-lait* spots

Dysplastic nevus

A nevus (mole) is a *benign neoplasm* of melanocytes -Dysplasia may arise (*dysplastic nevus*), which is a *precursor for melanoma*

Atopic Dermatitis vs. Seborrheic Dermatitis

A) *Atopic Dermatitis* -AKA *Eczema* -Produces *intensely pruritic* dry papule and plaques -Often seen in neonates -Has a *predilection* for *flexor surfaces* -*Weekping* can also be seen B) *Seborrheic Dermatitis* -AKA *cradle cap* -Presents as *greasy scales* over and erythematous base -Often seen in neonates "Be able to differentiate b/t the two!!"

Key diff. b/t Avascular Necrosis of the femoral head (Legg-Calve-Perthes) and Slipped Capital Femoral Epiphysis

A) *Avascular Necrosis of the Femoral Head* --Affects boys aged *4-10* --Plain film shows *flattened and widened femoral head* B) *Slipped Capital Femoral Epiphysis* --Affects *overweight, African American* boys aged *10-16* --Plain film shows *posterior and inferior* displacement of the femoral head on the femoral neck

CREST Syndrome vs. Diffuse Systemic Sclerosis

A) *CREST syndrome* -Calcinosis, Raynaud phenomenon, Esophageal dysmotility, Sclerodactyly, Telangiectasis on skin -ONLY involves the *skin* B) *Diffuse Systemic Sclerosis* -Involves BOTH the *skin and visceral organs* --Lungs, kidneys, etc.

Ankle sprain (grades)

A) *Grade 1* -Stretching of ligament w/ *microscopic tears* -Little/no loss of function, minimal/no joint instability, able to partially/fully bear weight -Torn lig. = *Anterior talofibular ligament* (ATF) --"ATF = Always Tears First" B) *Grade II* -Stretching of ligament w/ *partial tearing* -Mod/severe swelling, ecchymosis, mod-severe joint instability, difficulty bearing weight -Torn ligs. --1) *Anterior Talofibular ligament* --2) *Calcaneofibular ligament* C) *Grade III* -*Complete tear/rupture* of ligaments -Immediate and severe swelling, ecchymoses, inability to bear weight, mod-severe joint instability -Torn ligs. --1) *Anterior Talofibular ligament* --2) *Calcaneofibular ligament* --3) *Posterior talofibular ligament* -The *anterior drawer test* and *talar tilt test* will show *instability* in *grades 2 and 3*

Parathyroid hormone (PTH)

A) *Low, intermittent* levels -Exerts *anabolic effects* (building bone) on osteoblasts and osteoclasts B) *Chronic, high* levels -Primary hyperparathyroidism -Exerts *catabolic effects* (osteitis fibrous cystica)

Difference in Pemphigus Vularis vs. Bullous Pemphigoid

A) *Pemphigus vulgaris* -Superficial, painful blisters that *rupture very easily* -Autoantibodies against *desmosomes* B) *Bullous pemphigoid* -Bullae at the *dermal-epidermal junction* that do *NOT rupture* easily -Autoantibodies against *basement membrane/hemidesmosomes*

Urethral injury

A) *Posterior* urethral injury -Most commonly due to *pelvic fracture* -Presents w/ inability to void/full bladder sensation B) *Anterior* urethral injury -Most commonly due to *saddle injury* -Presents w/ inability to void/full bladder sensation If urethral injury is suspected, placement of a Foley catheter is *contraindicated*

Primary vs Secondary Gout

A) *Primary gout* -*Most common* form -Etiology of hyperuricemia is *unknown* B) *Secondary gout* (seen with:) 1) *Leukemia and myeloproliferative disorders* -Increased cell turnover leads to *hyperuricemia* 2)*Lesch-Nyhan syndrome* -X-linked deficiency of *hypoxanthine-guaning phosphoribosylatransferase (HGPRT)* -Mental retardation and self mutilation 3) *Renal insufficiency* -Decreased renal excretion of uric acid

Causes of Osteoporosis

A) *Younger pts* w/ Osteoporosis -Due to *decreased osteoblastic activity* B) *Elderly* w/ osteoporosis -Due to *increased bone resorption* (increased osteoclastic activity)

Gout (treatment)

A) Acute attack -*NSAIDs* (inhibit cyclooxygenase) B) Chronic (preventative) -*Xanthine oxidase inhibitors* (Allopurinol, Febuxostat) -(+) NSAID, colchicine or corticosteroid

Dorsal vs Palmar interossi

A) Dorsal interossi (*DAB*) -Dorsal = ABduction B) Palmar interossi (*PAD*) -Palmar = ADduction

Forward vs Backward FOOSH

A) Forward FOOSH --Radial head will be *posterior* --Forearm will be *held* in *pronation* --*Restriction* in *supination* B) Backward FOOSH --Radial head will be *anterior* --Forearm will be *held* in *supination* --*Restriction* in *pronation*

Gout vs Pseudogout

A) Gout -*YeLLow under paraLLel light* -Crystals are *needle-shaped* -*Monosodium-urate crystals* B) Pseudogout -*Blue* under parallel light -Crystals are *basophilic, rhomboid-shaped* -*Calcium pyrophosphate* crystals

Hairy leukoplakia vs. oral thrush

A) Hairy leukoplakia -*CANNOT* be scraped off -Associated with *EBV* -*PREcancerous* B) Oral thrush -*CAN* be scraped off -Benign

Myasthenia gravis vs. Lambert Eaton

A) Myasthenia gravis -Autoantibodies to *POST*synaptic ACh receptor -Muscle weakness *worsens* w/ use B) Labert Eaton -Autoantibodies to *PRE*synaptic *Ca2+* channel --Leads to *decreased ACh release* -Muscle weakness *improves w/ muscle use*

Cremasteric reflex

A) Normal response -Immediate contraction of the *cremasteric muscle* that pulls the *ipsilateral* testis up -Sensory: *ilioinguinal nerve* -Motor: *genital branch* of *genitofemoral nerve* B) Abnormal response -Pts with a *testicular torsion* -Spine injury to *L1-L2* -Damage to the *ilioinguinal nerve* (sensory) during a hernia repair

Types of Collagen (Defects)

A) Type 1 -*Osteogenesis imperfecta* -Found in bone, tendons, skin, dentin B) Type II -Found in *cartilage* C) Type III -Seen in *VASCULAR Ehler-Danlos* syndrome D) Type IV 1) *Goodpasture's syndrome* 2) *Alport syndrome* -Found in *basement membrane* E) Type V 1) *CLASSIC Ehler-Danlos* syndrome

Klumpke palsy

AKA *Claw hand* -Caused by trauma/traction to the *lower* trunk *C8-T1* Causes: 1) Infants: upward force on arm during delivery 2) Adults: grabbing a tree branch to break a fall Functional *deficits*: -Intrinsic hand muscles --Lumbricals, interossei, thenar, hypothenar Appearance: -*Claw hand* --Clawing due to *loss of lumbricals*

Atopic Dermatitis

AKA *Eczema* -Produces *intensely pruritic* papules and plaques -Most commonly occurs on the *flexor surfaces* -*Weeping* can also be seen

Adhesive capsulitis

AKA *Frozen shoulder* Pts who are at an *increased risk*: 1) *Diabetics* 2) *Females* 3) *Hypothyroidism* 4) * Joint immobilization* C.P.: *decreased ROM* OMM tx: *Spencer technique*

Avascular Necrosis of the Femoral Head

AKA *Legg-Calve-Perthes* disease -Due to an *interruption of adequate blood flow* to the femoral head -Most commonly affects *boys aged 4-10 yo* -Presents with insidious onset *limp and pain in the anterior hip or knee* -Pt will have *decreased ROM of hip* -Pain becomes progressively worse w/ exertion -Plain film will show *collapse of the femoral head*, which causes the femoral head to appear *flattened and widened*

Radial head subluxation

AKA *Nursemaid's elbow* -The *radial head* in children is prone to subluxation due to the *Annular ligament* not being fully formed -Seen when child's arm is quickly jerked while in excessive pronation -The child's elbow will be held in *slight flexion, ADduction, pronation* -To reduce, *flex* the elbow to *160 degrees* while *supinating* the forearm

Erb's Palsy

AKA *Waiter's Tip* -"Erb = Erber = Upper trunk" Causes: 1) Traction of *upper trunk (C5-C6)* -Seen in *birth trauma* in babies with DM Functional *deficit*: -Abduction, Lateral rotation, Flexion, Supination Appearance: -Arm is *ADducted, Medially rotated, Supinated*

Amyloidosis

Abnormal *aggregation of proteins* into *beta-pleated sheets* -Causes *enlargement of kidneys and liver* --Become palpable

Scleroderma (systemic sclerosis)

Abnormal *collagen deposition w/ fibrosis* -Presents as *puffy, taut skin w/out wrinkles* -75% female

Scoliosis

Abnormal curvature of the spine -*Respiratory compromise* generally occurs *before* cardiovascular compromise -Severity of scoliosis measured radiographically by *Cobb angle*

Gout

Acute inflammatory *monoarthritis* caused by precipitation of *monosodium urate crystals* in joints -Assoc. w/ *hyperuricemia*, mainly caused by: --*Underexcretion of uric acid* (90%) -Crystals are *needle shaped* and *negative birefringent* under polarized light (*ye"LL"ow under para"LL"el light*) (*blue under perpendicular light)*

Testicular torsion

Acute twisting of the *spermatic cord* that impedes blood flow to the testicle -Can lead to *infarction* of the testis -C.P.: *acute onset* scrotal pain, testis in a *horizontal* lie -P.E. may show *absence* of *cremasteric reflex*

Cellulitis

Acute, painful, spreading infection of deeper *dermis* -Usually caused by *Strep pygenes* or *Staph aureus* Risk factors: 1) Recent surgery 2) Trauma 3) Insect bite Can *progress to necrotizing fasciitis* -Necrosis of SQ tissues due to infxn w/ *flesh-eating bacteria* -Production of *CO2* causes *crepitus* -Surgical emergency

A pt breaks out on wrist from wearing a metal watch and also breaks out around waist line. What do you suspect?

Allergic contact dermatitis -*Type IV* hypersensitivity reaction

Indomethacin

An *NSAID* that is used to *close a PDA*

Infectious arthritis (gonococcal arthritis)

An *STD* that presents as *migratory arthritis* w/ an *asymmetric pattern* in a *sexually active* young adult -Joint will be *swollen, red, painful, limited ROM* -There will also be *fever, increased WBC count, elevated ESR* Most common agents: 1) *S. aureus* 2) *Streptococcus* 3) *N. gonorrhoeae*

Most *specific* lab test for polymyositis

Anti-Jo antibody

Melanoma (appearance)

Any skin lesion that is *DARK*

Acral lentiginous

Arises on the *palms or soles* -Often seen in *dark-skinned* persons -*NOT* related to UV light exposure

Seronegative spondyloarthropathies

Arthritis *withOUT* rheumatoid factor -Strong assoc. w/ *HLA-B27* (gene that encodes for *MHC class I*) -"PAIR" 1) Psoriatic arthritis 2) Ankylosing spondylitis 3) Inflammatory bowel disease 4) Reactive arthritis (Reiter syndrome)

Lambert Eaton Syndrome

Associated w/ *small cell lung carcinoma* (high yield) -*central nodule* seen on CXR Autoantibodies against *PREsynaptic CALCIUM channels*

Anterior and Middle scalene muscles

Attach to *rib 1* -Assist in the *elevation* of rib 1 during *forced inhalation*

Posterior scalene muscle

Attaches to *rib 2* -Assists in the *elevation* of rib 2 during *forced inhalation*

Pectoralis minor muscle (respiration)

Attaches to *ribs 3-5* and assists in *inhalation*

Pinpoint bleeding spots where exposure of dermal papillae when psoriatic scales are scraped off

Auspitz sign

Myasthenia Gravis

Autoantibodies to *post*synaptic ACh receptor -C.P.: ptosis, diplopia, weakness that *worsens* with use -Assoc.: (thymoma, thymic hyperplasia* -AChE admin causes *reversal* of symptoms

Lambert-Eaton

Autoantibodies to *pre*synaptic Ca2+ channel -Results in *decreased ACh release* -C.P.: proximal muscle weakness that *improves* w/ use -Assoc.: *small cell lung cancer* -AChE admin = *no effect*

Lambert-Eaton syndrome

Autoantibodies to the *PRE*synaptic *Ca2+ channel* -Results in *decreased ACh release* -C.P.: proximal muscle weakness that *improves* w/ muscle use --Eyes are usually *spared* -Assoc. w/ *small cell lung cancer* -Resection of the tumor improves symptoms -AChE inhibitors have *minimal effect*

Basal cell vs. Squamous cell carcinomas (location)

Basal cell: *Upper* lip Squamous cell: *Lower* lip -Think of them in alphabetical order, top to bottom

What causes the *detachment* of the myosin head from the actin filament?

Binding of a *new ATP molecule*

Colchicine

Binds and stabilizes *tubulin* to *inhibit microtubule polymerization* -*Impairs neutrophil chemotaxis* ADR -VERY bad *GI side effects*

Seborrheic keratosis (biopsy/histology)

Biopsy will show *horn cysts* filled w/ *cornified cells containing melanin* Seborrheic keratosis = *horn cysts*

Polyostotic fibrous dysplasia

Bone is replaced by *fibroblasts, collagen, and irregular bony trabeculae*

Celiac trunk

Branches off the abdominal aorta Supplies oxygenated blood to: -Liver -Stomach -Abdominal espohagus -Spleen -Superior 1/2 of duodenum and pancreas

Subconjunctival hemorrhage

C.P.: *painless redness* of the *subconjunctival hemorrhage* Caused by *rupturing of blood vessels*

What structures are contained in the *DERMIS*? -NOT the epidermis

CT, nerve endings, blood and lymphatic vessels, hair shafts, sweat glands, sebaceous glands

What causes the movement of tropomyosin out of the myosin-binding groove on actin filaments?

Ca2+ binding to troponin C

Deficiency in *carnitine palmitoyltransferase*

Can be a cause of *rhabdoyolysis* -These pts often have recurrent episodes of rhabdomyolysis and myoglobinuria dating back to childhood

Musculocutaneous nerve injury (C5-7)

Cause: -*Upper trunk compression* Presentation: -Loss of *forearm flexion and supination* -Loss of sensation over *lateral forearm* The musculocutaneous nerve innervates the *biceps, brachialis, and coracobrachialis* -Musculocutaneous, think "muscle", then think "biceps"

Radial nerve injury (C5-T1)

Cause: 1) *Midshaft fracture* of humerus 2) *Compression of axilla* ("Saturday night palsy") --*Crutches, sleeping with arm over chair* Presentation: 1) *Wrist drop* 2) *Decreased grip strength* 3) Loss of sensation over *posterior arm, forearm and dorsal hand* -The radial nerve runs *DIRECTLY underneath the axilla* and then *posterior* to the *midshaft of the humerus* in the *spiral groove* and then runs down to the thumb

Recurrent branch of the median nerve injury (C5-T1)

Cause: 1) *Superficial laceration of palm* Presentation: 1) "Ape hand" 2) Loss of *thenar muscle group: opposition, abduction, flexion of thumb* 3) *NO* loss of sensation

Median nerve injury (C5-T1)

Cause: 1) *Supracondylar fracture* of humerus 2) *Carpal tunnel syndrome* 3) *Wrist laceration* Presentation: 1) Loss of *wrist flexion, finger flexion, thumb opposition, lumbricals of 2nd and 3rd fingers* 2) Loss of sensation over *thenar eminence, and lateral 3 1/2 fingers* The median nerve runs along the *medial aspect of the biceps* and then continues down the *middle of the forearm* and through the *flexor retinaculum*

Pott Disease

Caused by *Mycobacterium tuberculosis* -Form of *vertebral osteomyelitis* -C.P.: night sweats, fatigue, weight loss, back pain -Hx of *recent travel* or *immigrant* -Histology: *caseating granuloma* (remember, its caused by M. tuberculosis)

Scabies

Caused by the *mite*, *Sarcoptes scabiei( -Tx'd by *DIRECT CONTACT* from another person who is infected -Commonly affects the *webs of the fingers* -*Linear burrows* may be seen on the hands

Obstructed right brachiocephalic vein

Causes congestion of UNILATERAL veins, resulting in engorgement of superficial veins on skin -App. similar to SVC, but unilateral

Piriformis syndrome

Causes irritation to the *sciatic nerve* C.P.: -Pain/soreness in the buttock -"Shooting pain" down the back of the leg

Ulnar nerve injury (C8-T1)

Causes: 1) Fracture of *medial epicondyle* of the humerus 2) "Funny bone" 3) Fractured *hook of hamate* Presentation: 1) "Ulnar claw" 2) *Radial deviation of wrist* upon flexion 3) Loss of *wrist flexion, flexion of medial fingers, abduction and adduction of fingers (interossei)* 4) Loss of sensation over *medial 1 1/2 fingers + hypothenar eminence* The ulnar nerve runs along the *most medial* portion of the arm and forearm and runs directly *behind the medial epicondyle* of the elbow and then through *Guyon's canal*

Axillary nerve injury (C5-C6)

Causes: 1) Fractured *surgical neck of humerus* 2) *Anterior* humerus dislocation Presentation: -*Flattened deltoid* -*Loss of ABduction > 15 degrees* -Loss of sensation over *deltoid muscle* -The axillary nerve runs *posterior* to the surgical neck of the humerus -Axillary nerve innervates: 1) *Deltoid* 2) *Teres minor*

Gap junction

Channel proteins that permit *electrical and chemical communication between cells* -Ex: *cardiac pacemaker cells*

Steven-Johnson syndrome

Characterized by *fever, bullae formation and necrosis, sloughing of skin* -HIGH mortality rate -Usually assoc. w/ *adverse drug reaction* -*<10%* of total body surface involved

Sydenham's chorea

Child with *rapid, involuntary, purposeless jerking movements* -Seen in kids w/ Acute Rheumatic Fever (JONES criteria)

Ankylosing spondylitis

Chronic inflammatory disease of the *spine and sacroiliac joints* -*Ankylosis* = stiff spine due to *fusion of joints* -*Bamboo spine* -Also see * uveitis, aortic regurgitation*

Ankylosing spondylitis

Chronic inflammatory disorder of the *SI joint* and *axial skeleton* -A *seronegative spondyloarthropathy* --Associated w/ *HLA-B27* -Most common in *young and middle-aged men* -C.P.: *morning stiffness, LBP, decreased spinal ROM* -Characterized by *destruction of articular cartilage* and *fusion of joints* -Xray may show *vertebral fusion* (bamboo spine)

Abscess

Collection of *pus* -Almost always cause by *Staph aureus*

Sarcoidosis (erythema nodosum)

Commonly on shins (painful bumps on shins)

Seborrheic keratosis (image)

Commonly seen in *elderly*

Polymyalgia rheumatica (association)

Commonly seen in *females > 50 yo* -Presents w/ *myalgia* of *shoulder and hip muscles* -Assoc. w/ *Giant cell/Temporal arteritis* (high yield)

Small nuclear RNA (snRNA)

Complex w/ proteins to form *snRNPs* -snRNPs are components of the *splicesome*, which *remove introns* to form mature RNA -Pts with *SLE* can have autoantibodies against snRNPs (i.e. *anti-Smith anitbodies*)

Guyon canal syndrome

Compression of the *ulnar nerve* at wrist or hand -Commonly seen in *cyclists*, due to pressure from handlebars -C.P.: pain, paresthesia, numbness in *lateral 1/2 of ring finger + pinky*

Adherens junction (zonula adherens)

Connects actin cytoskeletons of adjacent cells with *CADherins* (*Ca2+*-dependent *ad*hesion proteins)

Deep brachial artery

Courses *posterior* to the *midshaft of the humerus* -Runs *right along the radial nerve -May be damaged in a patient with a *midshaft fracture of the humerus*

Inflammatory bowel disease

Crohn disease or Ulcerative colitis accompanied by ankylosing spondylitis or peripheral arthritis

Molluscum contagiosum (histology)

Cytoplasmic inclusions -*Molluscum bodies*

X-linked Muscular Dystrophy

Degenerative disorder characterized by *muscle wasting* and *replacement of skeletal muscle by adipose tissue* -Due to *mutation* in the *dystrophin gene* -Mutations are often *spontaneous*

Damage to the ulnar nerve most commonly occurs at the elbow. What will the these deficits present as?

Diminished: -Wrist flexion/adduction -Flexion of 4th and 5th digits -Sensory loss over 5th digit and 1/2 of 4th digit

What nerve innervates BOTH the rhomboid major and minor?

Dorsal scapular nere

What nerve innervates the levator scapula?

Dorsal scapular nerve

Osteomalacia/rickets

Due to *Vit. D deficiency* -Results in *defective mineralization/calcification of osteoid* --> *soft bones* that *bow out* -Osteomalacia = adults -Rickets = children "Osteomalacia" means *soft bones*

Ape hand

Due to *atrophy of the thenar eminence* -Loss of *opponens pollicus* muscle -Result: *unopposable thumb*

Acne vulgaris

Due to *chronic inflammation* of hair follicles and sebaceous glands -*Hormone-related increase* in *sebum production* and *excess keratin production* -*Propionibacterium acnes* (infection) produces *lipases* that *break down sebum* --This results in a release of *proinflammatory fatty acids* --> pustule or nodule formation -Tx: *benzoyl peroxide* (antimicrobial) or *vitamin A derivatives* (reduce keratin production)

Thoracic outlet syndrome

Due to *compression of the LOWER trunk* and *subclavian vessels* Causes: 1) *Pancoast tumor* 2) Cervical rib Appearance: -*Claw hand* + *atrophy of the intrinsic hand muscles* + *ischemia, pain, edema*

Avascular (aseptic) necrosis

Due to *ischemia* of bone or bone marrow -NOT related to infection -Causes include *trauma or fracture, steroids, sickle cell anemia* -Complications: *osteoarthritis, fracture*

Becker muscular dystrophy

Due to *mutated* dystrophin gene -Due to a *Non-frameshift* insertion into dystrophin gene -*X-linked recessive* -Clinically *milder* -Usually presents *>10 years old*

Duchenne muscular dystrophy

Due to a *deletion* of dystrophin (Duchenne = deletion) -C.P.: proximal muscle weakness at *1-4 years of age* -*Calf pseudohypertrophy* (fat deposition) is a characteristic finding -Serum *creatine kinase* is *elevated* -Death is usually due to *cardiac or respiratory failure* --Most commonly involves the *myocardium*

Chronic Granulomatous Disease (CGD)

Due to a defect/deficiency in *NADPH oxidase* -Poor O2-dependent killing of bacteria C.P.: 1) *Recurrent infections* 2) Granuloma formation Tests: 1) *Nitroblue tetrazolin* -Blue color: NADPH oxidase *present* -Colorless: NADH oxidase *absent* 2) *Dihydrorhodamine flow cytometry* -Absence of fluorescence = *absence* of NADPH oxidase

Spondylolisthesis (image)

Due to defect in the *pars interarticularis*

Ankle dorsiflexion -What is the motion of the tibia, fibula and talus?

During ankle *dorsiflexion*, -The tibia and fibula *externally rotate* -The talus *glides posteriorly*

Anabolic steroids

E.g. *Methyltestosterone* -*Androgens* stimulate follicular epidermal hyper proliferation and excessive sebum production -Often cause development of *acne* -Esp. in *competitive athletes*

Junctional nevus

Early *acquired* nevus -Most common nevus in *children*

Nodular melanoma

Early *vertical growth* -Prognosis: *poor* (very bad!!)

Carpal tunnel syndrome

Entrapment of the *median* nerve -C.P.: pain, paresthesia, numbness in *thumb to middle of ring finger* -Assoc. with: *pregnancy, RA, hypothyroidism, repetitive use* -Median nerve runs through the *flexor retinaculum*

Acanthosis nigricans

Epidermal hyperplasia (stratum *spinosum*) -Symmetric, *hyperpigmented thickening* of the skin -Most common in *neck*, groin, axilla* -Associated w/: 1) *Hyperinsulinemia* 2) *Visceral malignancy* (e.g. *gastric adenocarcinoma*)

snRNPs

Essential component of *splicesome* -Function to *remove introns* to form mature RNA

Sunburn

Excessive UV radiation causes *DNA mutations*, inducing *apoptosis of keratinocytes*

Rosacea

Facial skin disorder characterized by *erythematous papule and pustules* -NO comedones -May be assoc. w/ *facial flushing* in response to external stimuli (*alcohol, heat*)

Achondroplasia

Failure of *longitudinal bone growth* (*endochondrial ossification*) -However, membranous ossification (flat bones) is *not affected* -So, pt will have *large head and short limbs* -Caused by *ACTIVATING mutation of FGFR3* which actually *inhibits* chondrocyte proliferation -Assoc. with *increased paternal age* -*85%* of cases occur *sporadically* -Others = *autosomal dominant* -*Most common cause* of *dwarfism* -Mental function, life span, and fertility are *NOT* affected

Seborrheic keratosis

Flat, pigmented squamous proliferation that looks *stuck-on* -"Seborrheic looks *stuck on*" -Common *benign* neoplasm in *elderly* *Leser-Trelat sign*: sudden appearance of *multiple seborrheic keratoses*, indicating an *underlying GI malignancy*

Brown fat/adipose tissue

Found in *newborns* Brown fat cells contain several intracytoplasmic fat droplets and *many more mitochondria* than adipose cells Function to provide *thermoregulation* by *uncoupling oxidative phosphorylation* -Loss of brown fat = *hypothermia*

The only bone tumor that arises from the *epiphyseal* end of a long bone

Giant cell tumor -"Soap-bubble" appearance

Which medication class is *contraindicated* in pts with osteoporosis?

Glucocorticoids -Worsen osteoporosis

Degenerative spondylolisthesis

Grade *III* -Most commonly occurs at the *L4-L5* level

Spondylolisthesis Grades

Grade I: *0-25%* displacement Grade II: *25-50%* displacement Grade III: *50-75%* displacement Grade IV: *>75%* displacement -Displacement = *anterior*

*Synovial* joints

Have a *joint space* that allow for motion (i.e. knee) -The *articular surface* of adjoining bones is made of *hyaline* cartilage (*Type II collagen*)

Huntington Disease and histones

Huntington Disease is in part due to *deacetylation of histones* -This results in the prevention of gene transcription --> neuronal cell death

What causes the myosin head to adopt the *high-energy/cocked* position?

Hydrolysis of ATP --> ADP

Melasma

Hyperpigmentation assoc. w/ *pregnancy* or *OCP use* -*Mask of pregnancy*

Acanthosis

Hyperplasia of the stratum *spinosum* -Ex: acanthosis nigricans

Both pemphigus vulgaris and bullous pemphigoind are associated w/ what *immunoglobulin*?

IgG -Notice each one has a *g* in the name

Paget disease of bone (Pathophysiology)

Imbalance between *both* osteoblasts and osteoclasts -3 stages 1) Osteoclastic overactivity 2) Mixed osteoblastic-osteoclastic activity 3) Osteoblastic overactivity Result: *thick, sclerotic bone* that *fractures easily* Biopsy: *Mosiac pattern* of lamellar bone

Hyperkeratosis

Increased thickness of the *stratum corneum* (most superficial layer)

Osteomyelitis

Infection of *bone and marrow* -Most common in *children* -#1 cause = *S. aureus* -Most commonly *bacterial* via *hematogenous spread* Adults: bacteria seeds the *epiphysis* (end) Children: bacteria seeds the *metaphysis* C.P.: -*Bone pain* with signs of infection (*fever, leukocytosis* Diagnosis: *blood culture*

Parotitis

Infection of the *parotid gland* -R.F.'s: dehydration, *intubation* (esp. in elderly), anticholinerics -C.P.: *acute onset, firm preauricular swelling* -Parotid gland secretes *amylase* --In parotitis, *amylase* levels will be *elevated* -Most common causative agent: *S. aureus*

Erysipelas

Infection of the *upper dermis and superficial lymphatics* (puffiness) -Usually caused by *Strep pyogenes*

Rhabdomyolysis

Injury to skeletal muscle leads to release of intracellular contents into the bloodstream -Elevated *myoglobin, creatine kinase* -Pt may also have *hyperkalemia* -Severe elevation of these contents could lead to *renal failure*

Winged scapula

Injury to the *long thoracic nerve (C5-C7)* Causes: 1) *Axillary node direction after mastectomy* 2) *Stab wound* Deficit: 1) *Serratus anterior* Presentation: -Inability to *anchor scapula to thoracic cage*

Muscles of mastication

Innervated by *CN-V* 1) Masseter 2) Temporalis 3) Lateral pterygoid 4) Medial pterygoid The *Lateral pterygoid" is the ONLY muscle of mastication that *depresses the jaw* (i.e. opens the mouth)

Muscles of the *thenar eminence*

Innervated by the *median* nerve "OAF" 1) Opponens pollicis 2) ABductor pollicis brevis 3) Flexor pollicis brevis

Muscles of the *hypothenar eminence*

Innervated by the *ulnar* nerve "OAF" 1) Opponens digiti minimi 2) ABductor digiti minimi 3) Flexor digiti mini

Pt can only walk 1 block before getting muscle cramps, but are relieved by rest

Intermittent claudication -Due to *atherosclerosis of larger arteries*

Hairy leukoplakia

Irregular, *white, painless plaques on tongue* -*CANNOT* be scraped off -*EBV-mediated* -Occurs in immunocompromised pts (HIV, transplant pts) -*PRECANCEROUS*

Landmark for a pudendal nerve block (i.e. during delivery)

Ischial spine

Gout (symptoms)

Joint is *red, swollen and painful* -The *monosodium urate crystals* activate *neutrophils* (this is what causes the symptoms) -Most commonly affects *MTP joint of big toe* (podagra) (*acute* gout) -May cause *tophus formation* (external ear, olecranon bursa, Achilles tendon) (*chronic* gout) -*Acute attacks* occur after a *large meal of meat* or *alcohol consumption* --Alcohol metabolites compete for *same excretion site* in kidney --> *decreased uric acid excretion*

Psoriatic arthritis

Joint pain + stiffness w/ *psoriatic arthritis* -1) *Dactylitis* (sausage fingers) -2) *Pencil-in-cup* deformity on x-ray

Intradermal nevus

Late *acquired* nevus -Most common nevus in *adults*

Lentigo maligna melanoma

Lentiginous proliferation (*radial growth*) -Prognosis: *good*

Synovium

Lines a synovial *joint capsule* and secretes a fluid rich in *hyaluronic acid* -Lubricates the joint and facilitates motion

What nerve innervates the serratus anterior?

Long thoracic nerve

Primary osteoporosis

Loss of *trabecular (spongy) bone* and interconnections -However, there is *normal* lab values (Ca2+, PO4 3-, PTH) -Diagnosed with *DEXA* scan w/ a T-score *</= (-2.5)* -C.P.: *vertebral compression fracture, loss of height, kyphosis* -Can also present w/ fractures of the *femoral neck and distal radius (Colles fx)*

Complications of a Radical Prostatectomy

May cause injury to the *prostatic plexus*, which innervates the *corpus cavernosa* of the penis -May result in *erectile dysfunction*

*Most common cause* of death from *skin cancer*

Melanoma

S-100 tumor marker

Melanoma

Where is melanin *synthesized*?

Melanosomes -NOT melanocytes

Integrins

Membrane proteins that maintain the *integrity* of the basolateral membrane by binding to collagen and laminin

Acetaminophen (toxicity)

Metabolized in the *liver* -Overdose produces *hepatic necrosis* -Acetaminophen metabolite (*NAPQI*), *depletes glutathione* -Antidote: *N-acetylcysteine* --*Regenerates glutathione*

Myositis ossificans

Metaplasia of *skeletal muscle into bone* -Following muscular trauma

Most common tumor of bones *overall*

Metastatic tumors

Where are osteoclasts derived from?

Monocyte,macrophage lineage

Osteomalacia (C.P.)

More commonly seen in *darker-skinned* pts -Melanin absorbs UV radiation -C.P.: *chronic fatigue, muscle pain, abnormal gait*

Osteochondroma

Most common *benign* tumor of bone -Seen in *males < 25 years old* -Mature bone w/ *cartilaginous (choindroid) cap* -*lateral projection* of the growth plate (metaphysis) -Overlying cartilage can rarely *transform to chondrosarcoma*

Fibromyalgia

Most common in *females 20-50 years old* -*Chronic, widespread MSK pain* assoc. w/ *stiffness, paresthesia, poor sleep, fatigue*

Rib infarctions

Most common seen in patients with *Sickle Cell Disease* -Check a *peripheral blood smear*

Slipped Capital Femoral Epiphysis

Most commonly affects *overweight* *African American males* ages *10-16* -C.P.: insidious onset *limp and knee or hip pain, decreased hip ROM* -Plain film shows *posterior and inferior displacement* of the femoral head on the femoral neck

Polymyalgia rheumatica

Most commonly presents in *females > 50 yo* -Pain and stiffness in the *shoulder and hip muscles*, often assoc. w/ *fever, malaise, weight loss* -There is *NO* muscular weakness -Assoc. with *Temporal (giant cell) arteritis* (high yield) (know this!) -Labs: Elevated *ESR and CRP* -Tx: Low-dose *corticosteroids*

*Eversion* ankle sprain

Much *less common* than inversion sprains -Involves damage to the *deltoid ligament* (medial ankle) -Includes the *tibiocalcaneal ligament*

*Inversion* ankle sprain

Much more common Involves: 1) *Anterior Talofibular ligament* (ATF) -ATF = always tears first -Grade 1 sprain 2) *Calcaneofibular ligament* -Grade II sprain 3) *Posterior Talofibular ligament* -Grade III sprain

Sarcoidosis

Multisystem granulomatous disorder -Characterized by *NON-caseating granulomas* -C.P.: *A.A. female with dyspnea, erythema nodosum, uveitis, blurry vision* -CXR shows *bilateral hilar lymphadenopathy* -Labs: 1) Elevated *ACE* 2) *Hypercalciuria* 3) *Elevated* CD4+/CD8+ ratio -May cause *restrictive* lung disease

Mutation involved with *melanoma*

Mutation in *BRAF kinase*

What causes the *power stroke*?

Myosin *releases Pi* (+ ADP) -The release of these molecules *propels the myosin head forward*

Most common cause of infectious arthritis

N. gonorrhoeae

Esophageal squamous metaplasia

Normal esophageal cell type: *Columnar epithelium* *Squamous metaplasia* is a reversible, adaptive response due to *chronic irritation* -Ex: *smoking, Barrett's esophagus* -Squamous metaplasia is *more resistant to irritation*, but leads to *decreased mucociliary clearance*

Achondroplasia (image)

Normal sized head and chest with *short limbs* Due to ACTIVATION of *FGFR3* which *inhibits* endochondral ossification

Ewing sarcoma (onion skin)

Notice the *thickening layers* of the *diaphysis* (middle of a long bone)

Peak bone mass

Occurs around *age 30* -Decreases about *1%* each year Factors affecting peak bone mass: 1) *Genetics* (Vit. D receptors inherited 2) *Weight-bearing exercise* 3) *Diet*

A female in labor undergoes a vertical midline episiotomy. What is the most likely structure to be damaged?

Perineal body -A vertical midline episiotomy is cut from the *posterior vaginal opening* to the *perineal body*

PemphiGus vulGaris (IgG)

Potentially fatal *autoimmune* skin disorder -*IgG* antibody against *desmoglein 3* -Flaccid *intraepidermal bullae* -Oral mucosa *IS involved* -Immunofluorescence reveals antibodies in a *reticular, net-like pattern* -*Tombstone appearance* on histology -*(+) Nikolsky sign* (separation of epidermis on manual stroking)

Avascular Necrosis of the femoral head (plain film)

Presents are *insidious onset limp and pain* in *boys 4-10 yo*

Erythema multiforme

Presents w/ *"TARGETOID-shaped rashes"* of different sizes (i.e. multiforme) -*Macules, papules, vesicles, "target lesions"* Most commonly assoc. w/ *HSV* -Also caused by *drugs* -*Sulfa drug, B-lactams, phenytoin*

Pseudogout

Presents with *pain and effusion in a LARGE joint* -Deposition of *calcium pyrophosphate crystals* into joint -Crystals are *weakly birefringent* and are *basophilic, rhomboid shaped* -Usually affects *knee* -Affects pts > 50, *men = women* -Tx: --Acute: NSAIDs, glucocorticoids --Prophylaxis: Colchicine

Osteoarthritis (Degenerative Joint Disease)

Progressive degeneration of *articular cartilage* -*Most common type* of arthritis -Joint *wear & tear* destroys *articular* cartilage -Major risk factors: *Age>60* (#1), *obesity, trauma* -Findings: *osteophytes, eburnation, Heberden (DIP) and Bouchard (PIP) nodes* --NO MCP involvement -C.P.: *pain in weight-bearing joints after use, improves with rest*, Knee cartilage loss that begins *medially* -C.P.: joint stiffness in the morning that *worsens during the day* -NO systemic inflammatory symptoms -Tx: *Acetaminophen, NSAIDs* -Eburnation: polished, ivory-like app. of bone -Bouchard node: PIP -Heberden node: DIP

Unique fact about the *L5-S1* level

Protected by the strong *transverse alar ligaments* -Degenerative changes at this level are *uncommon*

Muscles of the hand (median nerve)

Provides *motor innervation* to: 1) Thenar eminence (OAF) 2) 1st and 2nd lumbricals (flexion at MCP joint)

Derm*A*titis herpetiformis

Pruritic *vesicles and bullae* grouped together --Looks similar to *herpes* -Often found on *elbows* -Lesions are *intensely pruritic* -Deposits of *IgA* at tips of dermal papillae -Assoc. w/ *Celi*A*c Disease* (high yield) -Resolves w/ a *gluten-free diet*

Atopic dermatitis (eczema)

Pruritic, erythematous, oozing rash commonly seen on *skin flexures* -Usually assoc. w/ other atopic diseases *(asthma, allergic rhinitis)* --*Type I* hypersensitivity -Usually starts on the *face during infancy* -Later appears in the *antecubital fossa*

(Allergic) Contact dermatitis

Pruritic, erythematous, oozing rash w/ vesicles *Type IV* hypersensitivity reaction -Lesions occur at site of contact --E.g. *nickel, poison ivy, irritant chemicals (detergents)* -Pt breaks out at belly button (belt buckle or button on pants) -Remember, *poison ivy* is a *type IV* reaction

McMurry test

Pt *supine* -*Hyperflex the knee* a) External rotation (tibia) + valgus stress --*Medial meniscus* b) Internal rotation (tibia) + varus stress --*Lateral meniscus*

FOOSH

Radial head goes *posterior* -*Decreased anterior glide* -*RESTRICTION in supination* --"Fall on pronated hand, hand is stuck in pronation"

McArdle disease

Relatively healthy pt w/ *severe muscle aches after exercise* -Caused by a *deficiency* in *glycogen breakdown enzymes*

Medial vs lateral fingers

Remember to place your hand in the *anatomical position* -After that, the *medial finger* is you *pinky* -The most *lateral* finger is your *index*

Hallmark of Muscular Dystrophy

Replacement of skeletal muscle by adipose tissue (high yield)

Melanocytes

Responsible for *skin pigmentation* -Present in the *basal layer* of the epidermis -Derived from the *neural crest* -Melanin is *synthesized* in *melanosomes* using *tyrosine* as a precursor molecule

Function of *carnitine palmitoyltransferase*

Responsible for the *transport of long-chain fatty acids* from the *cytosol to the mitochondria*

What two vessels combine to form the SVC?

Right and Left Brachiocephalic veins

Squamous cell carcinoma

Risk factors: 1) Excess sun exposure *UVB* 2) Albinism 3) Xeroderma pigmentosum Associated w/: 1) *Excessive exposure to sunlight* 2) *Immunosuppressive therapy* (high yield) 3) *Arsenic exposure* -Commonly appears on *face, lower lip, ears, hands* -*Locally invasive*, but *rarely* metastasizes -*Ulcerative red lesion w/ scaling* -Assoc. w/ *chronic draining sinuses* (Actinomyces) -Precursors: 1) *Acitinic keratosis* 2) *Keratoacanthoma* -"ulcerative, red lesion"

Most common cause of *osteomyelitis*

S. aureus

*Schaumann and asteroid bodies*

Sarcoidosis

Non-caseating granulomas (histology)

Sarcoidosis

Localized scleroderma

Scleroderma confined to *skin + face* -Assoc. w/ *CREST syndrome* --Calcinosis, Raynaud phenomenon, Esophageal dysmotility, Sclerodactyly, Telangiectasia of skin -Assoc. w/ *anti-centromere antibody*

Sebaceous glands

Secrete *sebum* -Assoc. with hair follicle

Apocrine gland

Secretes *milky, viscous fluid* -Found in *axillae and genital regions* -Do not become functional until *puberty* -Malodorous due to *bacterial action*

Eccrine gland

Secretes *sweat* -Found *e*verywhere (eccrine = everywhere)

Erythema migrans

Seen in *Lyme disease*

Ewing sarcoma

Seen in *boys* that are *<15 years old* -C.P.: pain + swelling w/ a distinct soft tissue mass -The malignant tumor is composed of *small blue cells* w/ *hyperchromatic nuclei and scant cytoplasm* that is *clear* due to the presence of *abundant glycogen* -Lesion looks like *onion-skinning* on radiograph -Appears at the *diaphysis* on radiograph -Stains (+) for *MIC2 and CD99* -Possess *11:22 translocation*

Thenar eminence (innervation)

Sensory: *palmar branch* of median nerve -Does NOT pass through flexor retinaculum Motor: *median nerve*

Thoracentesis

Should be performed at the *superior portion* of a rib -The NV bundle lies closer to the inferior border of the rib -Midclavicular line: superior portion of *8th rib* -Midaxillary line: superior portion of *10th rib* -Posterior scapular: superior portion of *12th rib*

Scoliosis (side-bending vs scoliosis)

Sidebent *left* *Dextroscoilosis* -Sidebending is named for the *concave* curve -Scoliosis is named for the *convex* curve

Toxic epidermal necrolysis (TEN)

Similar to SJS w/ *>30%* of body surface area involved

Granuloma annulare

Skin disease consisting of *smooth, shiny dermal papule* that are arranged in a *circle or ring* -Papules are usually *ASYMPTOMATIC* --Unlike dermatitis herpetaformis -Cause: *clustering of T-cells under the skin* which eventually arise to the skin's surface -Assoc. w/ autoimmune diseases

Ewing sarcoma (biopsy)

Small, *round BLUE cells* -Resemble lymphocytes

Freckle

Small, tan, brown macule -Darkens when exposed to sunlight -Due to *increased number* of *MELANOSOMES* (synthesize melanin) --NOT melanocytes

What nerve innervates the trapezius?

Spinal accessory nerve (CN XI)

Regenerative (stem cell) layer of the epidermis

Stratum *basalis*

In pts w/ SSSS, what layer of the epidermis is affected?

Stratum *granulosum*

In what layer of the epidermis are *desmosomes* found?

Stratum *spinosum* -Connect keratinocytes together

Tongue that is "red, with raised papilla"

Strep throat (Strep pyogenes)

Desmosome (macula adheres)

Structural support via *keratin* -Autoantibodies to desmosomes = *pemphigus vulgaris*

Vitamin D

Sun exposure (85%) Diet (15%)

Gout (fluid)

Synovial fluid reveals: -*Negatively birefringent crystals* -Cloudy *yellow* -*Elevated WBC's* -*Few RBC's* -*Normal glucose*

Sensation to the hand

Take a look at where each nerve runs

Lichen *p*lanus

The *6 P's* of lichen *p*lanus -*Pruritic, Purple, Polygonal, Planar, Papules and Plaques* -*Sawtooth infiltrate* of lymphocytes at the dermal-epidermal junction -Assoc. w/ *hePatitis C*

What structure stays the same length during muscle contraction?

The *A-band* *A*lways stays the same length

What structure *prevents hyperextension* of the knee?

The *ACL* -NOT the PCL

Mongolian spots

The *most common congenital skin lesion* in *newborns* -Appear as *blue-gray macules* on the *lumbosacral area, buttocks, flanks* *NO treatment* necessary

Cricothyrotomy (incision)

The incision passes through: 1) *Skin* 2) *Superficial cervical fascia* 3) *Platysma muscle* 4) *Pretracheal fascia* 5) *Cricothyroid membrane* It does NOT pass through the cricoid cartilage!

Arcuate line

The middle arrow on the right side Below the arcuate line, the rectus abdominis muscles are only covered by an *anterior sheath* During C-section with a *horizontal incision* the physician must be careful with the incision not to damage the *inferior epigastric arteries*

Pain after tearing ATF

The pt will have *pain and difficulty w/ supination* -When the ligaments are torn, the pt does NOT want to move it into supination

Falling on outstretched hand (FOOSH). What happens to the radial head?

The radial head will be *posterior* -Remember, the radial head is at the *elbow* -There will be *restricted ANTERIOR glide* of the radial head -The forearm will be held in *pronation*

The ACL, PCL, MCL, LCL. Their anatomic direction (i.e. anterior, posterior, medial, lateral) all refer to:

Their site of *tibial attachment* -NOT femoral attachment

What causes the blue sclera in OI?

Thinning of scleral collagen reveals *underlying choroidal veins*

What nerve innervates the latissimus dorsi?

Thoracodorsal nerve

*Solid* joints

Tightly connected to provide structural strength -Ex: *cranial sutures*

Lymph from the *testes* drains where?

To the *para-aortic* lymph nodes -If pt has testicular cancer that has metastasized, it will spread to the *para-aortic* lymph nodes

Lymph from the *scrotum* drains where?

To the *superficial inguinal* lymph nodes -If pt has scrotal cancer, metastases will be seen in the *superficial inguinal* region

Aspirin (toxicity)

Toxicity: -*Gastric ulceration* -*Tinnitus* (CN VIII) -*Reye's syndrome* in children -Chronic use may lead to *acute renal failure, interstitial nephritis, GI bleeding*

Reactive arthritis (Reiter syndrome)

Triad: 1) *Conjunctivitis* 2) *Urethritis* 3) *Arthritis* -"Can't see, Can't pee, Can't climb a tree"

T/F Paget disease of bone only affects *one or a few bones* (localized)

True

What is the most important feature of melanoma regarding the risk of metastasis?

Tumor *depth*

Precursor molecule for melanin?

Tyrosine

What nerve is responsible for finger ABduction and ADduction (interossi muscles)?

Ulnar nerve

Allopurinol (other uses)

Used in lymphoma and leukemia to *prevent tumor lysis syndrome*

Ottawa rules

Used to determine the need for a *radiograph* when an *ankle injury* is sustained Guidelines: 1) *Pain in the midfoot* 2) *Inability to bear weight right after the injury or at the E.R.* -*4 steps* 3) *Bone pain at the posterior edge or tip of the medial malleolus*

Tibial stress fracture

Usually due to *overuse* -Most commonly seen in: 1) *Female* runners 2) Pts with *bilateral pes planus* (flat footed) -A *bone scan* will pick up the fracture *96%* of the time if within a *72 hour* window A *bone scan w/in 72 hours* is the best diagnostic test for a *tibial stress fracture*

IT Band Syndrome

Very common injury in *athletes, long distance runners* -Arises from the *iliac crest, tensor fasciae late, gluteus medius and minimus* -Inserts on *Gerdy's tubercle* on the lateral aspect of the *TIBIA* (not the fibula)

Rhus dermatitis

When a pt comes into contact w/ *poison ivy/oak* -The sap (*oleoresin*) from the plants causes a *Type IV delayed* hypersensitivity rxn

ACL and PCL attachments

When going *away from the tibia*, the: -*ACL* goes *lateral* (attaches to the lateral femoral condyle) -*PCL* goes *medial* (attaches to the medial epicondyle)

Diffuse scleroderma

Widespread skin involvement + *visceral involvement* -*Rapidly progressive* -Assoc. w/ *anti-Scl-70 antibody* (anti-DNA topoisomerase I antibody)

Do dermatitis heretiformis lesions itch?

YES! They are intensely pruritic

Pityriasis rosea

a) *Primary lesion* -"Herald patch" -Single oval, raised 2-5 cm plaque w/ scaly appearance b) *Secondary lesion* -Scattered lesions in a *Christmas tree-like pattern* Most often seen in *fall or spring* Thought to be due to *reactivation of HHV-6 or HHV-7* -Self-resolves in 6-8 weeks

Innervation to the *biceps femoris*

a) Short head: *common peroneal branch* of sciatic nerve b) Long head: *tibial branch* of the sciatic nerve