NBCE Part I cheat sheet

Anatomical position: body erect, face forward, upper limbs at sides with palms facing anteriorly (supinated) and thumbs lateral.

Three cardinal planes: sagittal divides left and right, coronal (frontal) divides anterior and posterior, transverse divides superior and inferior.

Four basic tissue types: epithelium, connective tissue, muscle, and nervous tissue.

Bone shapes: long (femur), short (carpal), flat (sternum), irregular (vertebra), and sesamoid (patella).

Muscle naming roots: rectus = straight, oblique = slanted, maximus/medius/minimus = relative size, brevis/longus = length, and -ceps = heads.

Nerve plexuses and levels: cervical C1-C4, brachial C5-T1, lumbar L1-L4, sacral L4-S4.

Spinal nerve count: 31 pairs (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal); cranial nerves are 12 pairs.

Serous membranes: pleura surrounds lungs, pericardium surrounds heart, peritoneum lines the abdominopelvic cavity.

Ligament connects bone to bone; tendon connects muscle to bone; aponeurosis is a flattened tendon sheet.

Vertebral formula: 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, 3-4 fused coccygeal, giving 33 segments but 26 adult bones.

C1 (atlas) lacks a body and a true spinous process; C2 (axis) bears the dens (odontoid process) around which the head rotates.

Typical cervical vertebrae (C3-C7) have bifid spinous processes, transverse foramina transmitting the vertebral artery, and uncinate processes.

Thoracic vertebrae bear costal facets on the body and transverse process; their spinous processes are long and angled inferiorly.

Lumbar vertebrae have large kidney-shaped bodies, mammillary and accessory processes, and horizontal spinous processes.

Anterior longitudinal ligament limits extension; posterior longitudinal ligament limits flexion; ligamentum flavum is elastic and connects adjacent laminae.

Intervertebral disc: outer annulus fibrosus of fibrocartilage surrounds the inner nucleus pulposus; there are 23 discs in the adult spine.

In adults the conus medullaris ends near L1-L2, so lumbar puncture is performed below that level where only cauda equina roots lie.

Roughly half of all cervical rotation occurs at the atlantoaxial joint; the most mobile lumbar segment is usually L4-L5.

Resting membrane potential is about -70 mV, generated chiefly by the Na+/K+ ATPase moving 3 Na+ out for every 2 K+ in.

Threshold is about -55 mV; depolarization reflects Na+ influx, repolarization reflects K+ efflux, and hyperpolarization follows.

Cardiac output = heart rate x stroke volume, normally about 5 L/min; stroke volume = end-diastolic volume - end-systolic volume.

Blood pressure = cardiac output x total peripheral resistance; mean arterial pressure approximates diastolic pressure + 1/3 of the pulse pressure.

Frank-Starling relationship: rising preload increases contractile force and stroke volume until overstretch reduces output.

Henderson-Hasselbalch: pH = 6.1 + log([HCO3-] / (0.03 x PaCO2)); normal values are pH 7.35-7.45, PaCO2 35-45 mmHg, HCO3- 22-26 mEq/L.

Renal clearance: Cx = (Ux x V) / Px; inulin clearance equals glomerular filtration rate, about 125 mL/min.

Countercurrent multiplication in the loop of Henle plus ADH action in the collecting duct determines urine concentration.

pH = -log[H+]; a one-unit pH fall means a tenfold rise in hydrogen ion concentration, and buffers resist this change.

Gibbs free energy: ΔG = ΔH - TΔS; a negative ΔG indicates a spontaneous (exergonic) reaction, zero indicates equilibrium.

Enzyme kinetics: v = Vmax[S] / (Km + [S]); Km equals the substrate concentration at half-maximal velocity and is inversely related to affinity.

Le Chatelier's principle: a system at equilibrium shifts to oppose imposed changes in concentration, pressure, or temperature.

Henderson-Hasselbalch buffer equation: pH = pKa + log([A-]/[HA]); buffering capacity is best when pH is within one unit of pKa.

DNA base pairing: adenine with thymine by two hydrogen bonds, guanine with cytosine by three; A = T and G = C in content.

Glycolysis net yield per glucose is 2 pyruvate, 2 ATP, and 2 NADH, occurring in the cytoplasm; the TCA cycle yields 3 NADH, 1 FADH2, and 1 GTP per acetyl-CoA.

Osmolarity counts all dissolved particles per liter; 1 M NaCl is roughly 2 osmolar because it dissociates into two ions.

First law of thermodynamics: energy is conserved; enthalpy change equals heat absorbed at constant pressure.

Reversible cell injury shows swelling and fatty change; irreversible injury is marked by mitochondrial permeability transition, membrane rupture, and enzymatic digestion.

Necrosis patterns: coagulative from ischemia (except brain), liquefactive in brain and abscesses, caseous in tuberculosis, fibrinoid in vasculitis, fat necrosis in pancreatitis.

Apoptosis is caspase-dependent, energy-requiring, and non-inflammatory; Bcl-2 is anti-apoptotic and p53 promotes it after DNA damage.

Acute inflammation features neutrophils and edema; chronic inflammation features macrophages and lymphocytes; granulomas contain epithelioid cells and giant cells.

Healing: primary intention in clean apposed wounds, secondary intention in open wounds with granulation tissue; type III collagen is replaced by type I.

Neoplasia: benign tumors are encapsulated and non-metastatic; malignant tumors invade and metastasize; grading describes differentiation, TNM describes stage.

Tumor suppressors include p53, RB, APC, and BRCA1/2; oncogenes include RAS, MYC, and HER2.

Virchow triad for thrombosis: endothelial injury, abnormal flow (stasis or turbulence), and hypercoagulability.

Shock types: hypovolemic, cardiogenic, distributive (septic, anaphylactic, neurogenic), and obstructive; edema arises from hydrostatic, oncotic, lymphatic, or permeability causes.

Gram stain: gram-positive organisms retain crystal violet (purple) due to thick peptidoglycan; gram-negative organisms stain pink and possess an outer membrane.

Bacterial growth curve phases are lag, log (exponential), stationary, and death; obligate aerobes require oxygen, obligate anaerobes are killed by it, facultative organisms tolerate both.

Exotoxins are proteins, heat labile, converted to toxoids, and highly specific; endotoxin is lipopolysaccharide, heat stable, and causes fever and shock via TLR4.

Sterilization kills all organisms including spores; autoclave standard is 121°C (250°F) at 15 psi for 15 minutes with biological indicator monitoring.

Immunoglobulins: IgM is the first responder, IgG is most abundant and crosses the placenta, IgA guards mucosa, IgE mediates allergy, IgD is a B-cell receptor.

Incidence counts new cases over time; prevalence counts all existing cases and approximates incidence multiplied by disease duration.

Sensitivity = true positives / (true positives + false negatives); specificity = true negatives / (true negatives + false positives); PPV depends on prevalence.

Relative risk compares incidence between exposed and unexposed groups; odds ratio is used in case-control studies.

Herd immunity reduces transmission when a sufficient proportion of a population is immune; some diseases require notification to public health authorities.

Standard adult vital signs: heart rate 60-100/min, respiratory rate 12-20/min, blood pressure below 120/80 mmHg, oral temperature 36.5-37.5°C.

Examination sequence for most systems is inspection, palpation, percussion, then auscultation, except abdominal auscultation which precedes palpation.

S1 is closure of mitral and tricuspid valves at the onset of systole; S2 is closure of aortic and pulmonic valves at the end of systole.

S3 is an early diastolic filling sound suggesting volume overload; S4 is a late diastolic sound from a stiff ventricle, indicating reduced compliance.

Systolic murmurs occur between S1 and S2 (stenosis or regurgitation); diastolic murmurs between S2 and S1 are always pathologic.

Murmur grading I-VI: I barely audible, II soft, III moderately loud, IV loud with a thrill, V audible with stethoscope edge off chest, VI audible without the stethoscope.

Deep tendon reflexes graded 0 absent, 1+ diminished, 2+ normal, 3+ exaggerated, 4+ hyperactive with clonus.

Muscle strength graded 0-5: 0 no contraction, 3 antigravity movement, 4 movement against some resistance, 5 normal.

Special tests: straight leg raise for L4-S1 root irritation, Spurling for cervical radiculopathy, Phalen and Tinel for carpal tunnel, Lachman for the anterior cruciate ligament.

Upper motor neuron lesion signs: spasticity, hyperreflexia, Babinski sign, and clonus with little atrophy; lower motor neuron signs: flaccidity, hyporeflexia, atrophy, and fasciculations.

Dermatomes: C5 lateral arm, C6 thumb, C7 middle finger, C8 little finger, T4 nipple, T10 umbilicus, L1 groin, L4 medial leg, L5 dorsum of foot, S1 lateral foot.

Myotomes: C5 deltoid and biceps, C6 wrist extensors, C7 triceps, C8 finger flexors, L4 tibialis anterior, L5 extensor hallucis longus, S1 gastrocnemius.

Reflex roots: biceps and brachioradialis C5-C6, triceps C7, patellar L4, Achilles S1.

A posterolateral disc herniation typically compresses the nerve root one level below the disc; a C5-C6 herniation affects the C6 root.

Positive straight leg raise (Lasègue) between 30 and 70 degrees with pain below the knee suggests L4-S1 root irritation; crossed sign is more specific.

Red flags for serious spinal pathology: bowel or bladder dysfunction, saddle anesthesia, fever, night pain, unexplained weight loss, and cancer history.

Radicular pain follows a dermatomal pattern and is sharp and shooting; myelopathy produces gait disturbance, hyperreflexia, and clumsiness.

Adson and Roos tests assess thoracic outlet syndrome; FABER and Gaenslen tests assess sacroiliac joint dysfunction.