High-Yield Exam Mnemonics
- 5th left MCL – apex is felt well.
Recall: The apex beat is palpable at the 5th left intercostal space, just medial to the midclavicular line.
- RCA is Anterior – Right in front.
Recall: The right coronary artery arises from the anterior aortic sinus.
- Right is usually Right (dominant).
Recall: Right coronary dominance (RCA giving posterior descending artery) occurs in approximately 70% of people.
- Fibrous pericardium sits on the Central tendon.
Recall: The fibrous pericardium fuses inferiorly with the central tendon of the diaphragm.
- Cardiac T-tubules at Z – Zebra stripes.
Recall: In cardiac muscle, T-tubules are located at the Z lines (forming diads with sarcoplasmic reticulum).
- Right to Left via Oval hole.
Recall: The foramen ovale shunts oxygenated blood from the right atrium to the left atrium, bypassing the pulmonary circulation.
- No Spiral = Switched arteries.
Recall: In transposition, the aorticopulmonary septum fails to spiral, causing the aorta to arise from the right ventricle and pulmonary trunk from the left ventricle.
- Intima = Innermost with endothelium.
Recall: The tunica intima is the innermost layer containing endothelium (simple squamous epithelium) and subendothelial connective tissue.
- 4th = Subclavian and aortic arch.
Recall: The right subclavian artery develops from the right 4th aortic arch and the right 7th intersegmental artery.
- SA = Superior + Atrial junction.
Recall: The SA node (pacemaker) is located at the junction of the SVC and right atrium, near the crista terminalis.
- Purkinje = Under the endocardium, pushing impulses.
Recall: Purkinje fibers are large, specialized conducting cells in the subendocardial layer of the ventricles.
- VAN goes down the groove.
Recall: In the costal groove, structures are arranged VAN (Vein, Artery, Nerve) from superior to inferior.
- C7 = Cervical rib (extra rib above the first).
Recall: Cervical ribs arise from C7 vertebra and may compress the lower trunk of brachial plexus or subclavian artery, causing thoracic outlet syndrome.
- T12 = Aorta, Thoracic duct, aZygos (ATZ).
Recall: The aortic hiatus (T12) transmits the aorta, thoracic duct, and azygos vein.
- Right crus = 3 vertebrae (Larger and Right).
Recall: The right crus of the diaphragm arises from L1–L3 vertebral bodies, while the left crus arises from L1–L2 only.
- Sclerotome = Skeleton (ribs and vertebrae).
Recall: Ribs develop from the costal processes of the sclerotome portion of somites.
- Right = 3 lobes (3 letters in ‘tri’).
Recall: The right lung has three lobes (superior, middle, inferior) separated by oblique and horizontal fissures.
- Ventral = Voicebox and lungs.
Recall: The laryngotracheal (respiratory) diverticulum arises from the ventral wall of the foregut during week 4.
- Pseudo = Pretends to be stratified, with cilia and goblets.
Recall: Respiratory epithelium is pseudostratified ciliated columnar epithelium with goblet cells.
- Type I = Thin for gas exchange.
Recall: Type I pneumocytes are thin, squamous cells covering 95% of alveolar surface and forming the air-blood barrier.
- CK-MB – 4 letters, rises in 4–6 hours.
Recall: CK-MB starts rising 4–6 hours post-MI, peaks at 12–24 hours, and returns to normal within 48–72 hours.
- AST is Ancient Stuff for the hearT.
Recall: AST (aspartate aminotransferase/SGOT) was historically used but lacks cardiac specificity–it’s elevated in liver disease, skeletal muscle injury, and hemolysis.
- Reductase is Rate-limiting; Statins Reduce cholesterol by blocking it.
Recall: HMG-CoA reductase converts HMG-CoA to mevalonate, the committed step in cholesterol synthesis.
- Chylomicrons = Chyloterglycerides – Chyle is fatty lymph loaded with fat.
Recall: Chylomicrons are the largest lipoproteins and contain the highest percentage of triglycerides (55%) but less than chylomicrons.
- Linoleic is Linked to diet – you need to eat it.
Recall: Linoleic acid (omega-6) and alpha-linolenic acid (omega-3) are essential fatty acids because humans lack the desaturases to introduce double bonds beyond carbon 9.
- Glycolysis = 2 ATP net, 2 NADH, 2 pyruvate.
Recall: Glycolysis produces 4 ATP but consumes 2 ATP in the preparatory phase, yielding a net of 2 ATP.
- Lactate Dehydrogenase makes Lactate when oxygen is Down.
Recall: Lactate dehydrogenase (LDH) converts pyruvate to lactate, regenerating NAD⁺ for continued glycolysis under anaerobic conditions.
- Arsenate Arrests GAPDH.
Recall: Arsenate replaces inorganic phosphate in the GAPDH reaction, forming an unstable product that hydrolyzes spontaneously–bypassing ATP generation at this step (arsenolysis).
- Isocitrate DH is the Important controller.
Recall: Isocitrate dehydrogenase is the key regulatory enzyme, activated by ADP and inhibited by ATP and NADH.
- ATP = Abundant energy, so Avoid making more citrate.
Recall: ATP inhibits citrate synthase, signaling adequate energy and slowing the cycle.
- Complex I = I accept NADH.
Recall: Complex I (NADH dehydrogenase) accepts electrons from NADH.
- Uncoupling = Unusual warmth (heat, not ATP).
Recall: Uncoupling proteins allow protons to flow back into the matrix without passing through ATP synthase, releasing energy as heat instead of ATP.
- Oligomycin Obstructs the Opening (F₀ channel).
Recall: Oligomycin binds the F₀ channel of ATP synthase, preventing proton flow and halting ATP synthesis.
- Bohr effect = Better oxygen Bye-bye (release) in acidic tissues.
Recall: The Bohr effect states that increased CO₂, H⁺ (low pH), temperature, and 2,3-BPG decrease hemoglobin’s oxygen affinity, promoting O₂ release to metabolically active tissues.
- “ITAs are INside TT” – Internal Thoracic Artery is inside (deep to) Transversus Thoracis.
Recall: The internal thoracic artery descends behind the upper six costal cartilages, lying deep to the transversus thoracis muscle.
- “Left atrium Loves Left laryngeal” – left atrial enlargement affects left recurrent laryngeal nerve.
Recall: The left recurrent laryngeal nerve loops under the arch of aorta and ascends in the groove between trachea and esophagus.
- 8-10-12 rule: Vena cava at 8, Esophagus at 10, Aorta at 12.
Recall: The vena caval foramen is located at the T8 vertebral level in the central tendon of the diaphragm.
- “BOCHDALEK = BACK and LEFT” – posterolateral, predominantly left-sided.
Recall: Congenital diaphragmatic hernia (Bochdalek hernia) occurs due to failure of the pleuroperitoneal membrane to close, leaving a posterolateral defect.
- Transverse sinus = Finger can TRAVERSE behind great arteries.
Recall: The transverse pericardial sinus is located posterior to the ascending aorta and pulmonary trunk, and anterior to the superior vena cava and left atrium.
- Big Elastic arteries need Blood vessels (vasa vasorum) in their walls.
Recall: Elastic arteries (like the aorta) have thick walls requiring vasa vasorum to supply the outer media and adventitia.
- Carina at the angle of Louis = T4, bifurcation angle ~70°.
Recall: The carina (tracheal bifurcation) is located at the level of T4 vertebra (sternal angle level).
- EXTRA-lobar = EXTRA pleural covering, completely SEPARATE.
Recall: Extralobar sequestration is a mass of lung tissue that is completely separate from the normal lung, has its own visceral pleural covering, receives blood supply from the systemic circulation (usually aorta), and has no bronchial connection.
- LAD and Great cardiac vein are Groove partners in the anterior interventricular sulcus.
Recall: Anterior wall MI with V1-V4 changes indicates occlusion of the left anterior descending (LAD) artery, which runs in the anterior interventricular sulcus.
- Thorel’s takes the POSTERIOR-SEPTAL route.
Recall: Three internodal pathways conduct impulses from SA to AV node.
- Pulmonary Stenosis causes Pressure overload → RV Hypertrophy.
Recall: In Tetralogy of Fallot, right ventricular hypertrophy develops secondary to the outflow obstruction caused by pulmonary stenosis (infundibular narrowing).
- In the Carotid sheath: Vein lateral, Artery medial, Vagus in between posteriorly.
Recall: Within the carotid sheath, the internal jugular vein lies lateral, the common/internal carotid artery lies medial, and the vagus nerve lies posteriorly in the groove between these two vessels.
- Muscular arteries have distinct internal AND external ELASTIC laminae sandwiching MUSCLE.
Recall: Muscular (distributing) arteries have a well-defined internal elastic lamina that appears wavy in sections, a prominent muscular tunica media (up to 40 layers of smooth muscle), and an external elastic lamina.
- Left Bundle has THREE fascicles: APS (Anterior, Posterior, Septal).
Recall: The left bundle branch divides into three fascicles: anterior (anterosuperior), posterior (posteroinferior), and septal fascicles.
- 6th arch = Pulmonary arteries; LEFT 6th = ductus arteriosus.
Recall: The sixth aortic arch gives rise to the pulmonary arteries.
- Lower trunk = Lower in the neck, causes hand problems (T1 dermAtome, hand intrinsics).
Recall: The lower trunk of the brachial plexus (C8-T1) passes over the first rib and can be compressed in thoracic outlet syndrome.
- Membranous septum = Meeting point of THREE structures (cushion, conus, muscular).
Recall: The membranous interventricular septum develops from fusion of three components: the inferior endocardial cushion (AV cushion tissue), the right side of the conus (conal septum), and the muscular ventricular septum growing upward.
- Squamous Swallowing Surface – stratified squamous for the entire esophagus.
Recall: The esophagus is lined throughout by stratified squamous non-keratinized epithelium, which provides protection against abrasion from food passage.
- Phrenic goes in FRONT of the lung root.
Recall: The phrenic nerve passes anterior to the lung root on both sides.
- AV node–85% Right, 15% Left circumflex.
Recall: The AV node receives blood supply from the AV nodal artery, which arises from the right coronary artery in approximately 85% of individuals (right-dominant circulation).
- Hypertrophy = Huge cells, Half the blood supply.
Recall: Hypertensive heart disease causes concentric left ventricular hypertrophy, where cardiomyocytes increase in size (hypertrophy, not hyperplasia) by adding sarcomeres in parallel.
- Right Atrium = Right border; Receives Sinus venosus (Smooth posterior wall).
Recall: The right border of the cardiac silhouette on PA chest X-ray is formed primarily by the right atrium.
- Smooth muscle = Synthesizes Subendothelial matrix.
Recall: The subendothelial space (tunica intima) contains proteoglycans that bind LDL, contributing to atherosclerosis.
- L-type channels in T-tubules = Let calcium Trigger release.
Recall: L-type calcium channels (dihydropyridine receptors) are concentrated in T-tubule membranes, positioned opposite the terminal cisternae of SR.
- Oxygen = Open ductus closes; PDA = Prostaglandins keep it Patent.
Recall: The ductus arteriosus normally closes within 24-48 hours after birth through smooth muscle contraction triggered by increased arterial oxygen tension.
- TOF = Tilted Outflow Forwards (anterosuperior deviation).
Recall: Tetralogy of Fallot results from anterosuperior deviation of the infundibular (conal, outlet) septum.
- Membranous VSD = Meeting of Three structures failed (cushions, muscular, conotruncal).
Recall: The membranous interventricular septum forms from fusion of three structures: the inferior endocardial cushion tissue, the muscular interventricular septum growing superiorly, and the right and left conotruncal (bulbar) ridges.
- AV node = Above the septal Tricuspid leaflet; Deliberate Delay.
Recall: The AV node is located in the interatrial septum at the apex of the triangle of Koch, just above the septal leaflet of the tricuspid valve.
- His on the Left, then Left bundle branches Left again.
Recall: The bundle of His penetrates the central fibrous body and runs along the left ventricular side (leftward) of the interventricular septum’s membranous portion before bifurcating.
- Cupula rises above the Clavicle–Central line risk.
Recall: The cervical pleura (cupula) extends 2-3 cm above the medial third of the clavicle, covering the lung apex at the thoracic inlet.
- T5 = Thoracic duct crosses (5 = center, switches sides).
Recall: The thoracic duct ascends in the posterior mediastinum between the aorta and azygos vein.
- Bochdalek = Back and Left (posterolateral, pleuroperitoneal membrane).
Recall: Bochdalek hernia (posterolateral congenital diaphragmatic hernia) results from failure of the pleuroperitoneal membrane to close, most commonly on the left side (due to the liver protecting the right).
- Septum transversum = Central tendon (both are Central structures).
Recall: The central tendon of the diaphragm develops from the septum transversum, which originates at C3-C5 level and migrates caudally.
- SVC = Superior Mediastinum (Superior structures above the sternal angle).
Recall: The SVC is located in the superior mediastinum, which lies above the transverse thoracic plane (sternal angle to T4/5 disc).
- Azygos Arches at T4 over the right lung root (bronchus below the bow).
Recall: The azygos vein arches over the root of the right lung at approximately T4 level to drain into the posterior aspect of the SVC.
- C7 cervical rib = C7-T1 (lower trunk) compression.
Recall: Cervical ribs arise from the costal element of C7 vertebra (which normally regresses).
- Right = Route for aspiration (wider, straighter, shorter).
Recall: Aspirated foreign bodies preferentially enter the right main bronchus because it is wider, shorter, and more vertical (25° from midline) than the left (45°).
- Type II = Two functions (surfactant + stem cells); contain Lamellar bodies.
Recall: Type II pneumocytes (great alveolar cells) are cuboidal cells located at alveolar septal junctions.
- Saccular = Sacs present but Surfactant insufficient.
Recall: At 26 weeks, the lungs are in the saccular stage (24-36 weeks), characterized by terminal saccules (primitive alveoli) and proliferating capillaries.
- Pleuropericardial membrane = Pleura-Pericardium separation; defect = herniation between.
Recall: The pleuropericardial membranes separate the developing pleural cavities from the pericardial cavity during weeks 5-7.
- M3 = Muscarinic constriction; Beta-2 = Breathe easier (bronchodilation).
Recall: Bronchiolar smooth muscle is most prominent in terminal and respiratory bronchioles (relative to wall thickness), making these “small airways” the primary site of bronchoconstriction in asthma.
- “Rest = Compensated, Stress = Unmasked” – exercise unmasks fixed coronary stenosis.
Recall: Coronary blood flow at rest may be adequate despite significant stenosis due to autoregulatory vasodilation.
- Accessory pathway = Direct highway bypassing AV node traffic light.
Recall: This describes Wolff-Parkinson-White syndrome.
- Hypertensive brain adapts UP–now needs higher pressure to perfuse.
Recall: Chronic hypertension causes structural remodeling of cerebral arterioles, shifting the autoregulatory curve rightward.
- L-type calcium = Little trigger for Big SR release.
Recall: L-type calcium channels (dihydropyridine receptors) in the T-tubules allow extracellular calcium to enter during the plateau phase of the cardiac action potential.
- Emphysema = Elastic destruction = Early airway collapse = Air trapping.
Recall: Emphysema destroys alveolar walls and their elastic fibers.
- Bases get most Blood → Bases set Blood gases.
Recall: Due to gravity, pulmonary blood flow is much greater at the bases than apices (roughly 5-10 times more in upright position).
- Normal or high CO₂ in acute asthma = Tired muscles = Trouble ahead.
Recall: In acute asthma, patients typically hyperventilate initially (low PCO₂) due to anxiety and hypoxic drive.
- Breathe IN = Active muscle work; Weak muscles = Shallow breaths = Ventilatory failure.
Recall: Inspiration is an active process requiring diaphragm and intercostal muscle contraction to expand the thorax and generate negative intrapleural pressure, which creates the pressure gradient driving air into the lungs.
- No blood flow to ventilated alveoli = Wasted ventilation = Dead space.
Recall: Pulmonary embolism blocks blood flow to ventilated alveoli, creating high V/Q or “dead space” units–ventilated but not perfused (alveolar dead space).
- Reserve units activated = Recruitment = More surface area from remaining lung.
Recall: At rest, not all alveoli and pulmonary capillaries are fully perfused (especially in upper lung zones).
- Shunt = Skip lung = Supplemental O₂ can’t help blood that never sees alveoli.
Recall: True shunt occurs when blood passes through nonventilated alveoli (consolidation, atelectasis, ARDS) without gas exchange (V/Q = 0).
- CO₂ retainer breathes for hypoxia–kill hypoxia, kill drive.
Recall: In chronic CO₂ retainers (like severe COPD/emphysema patients), central chemoreceptors become desensitized to chronically elevated CO₂.
- PEEP = keeps them Popped open when they want to collapse.
Recall: In RDS, surfactant deficiency causes high alveolar surface tension and alveolar collapse at end-expiration.
- Alkalosis = Albumin grabs calcium = Low ionized Ca²⁺ = Twitchy.
Recall: Respiratory alkalosis increases pH, which increases the negative charge on plasma proteins (especially albumin).
- C3-4-5 keep the diaphragm alive–above C3 = ventilator dependent.
Recall: The phrenic nerve originates from C3-C5 (“C3, 4, 5 keeps the diaphragm alive”).
- pre-Bötzinger = primary pacemaker; destroy it = rhythm dies.
Recall: The pre-Bötzinger complex in the ventrolateral medulla is the primary respiratory rhythm generator–it contains pacemaker neurons that generate the basic respiratory rhythm.
- Type A = Aerobic failure (hypoxia → anaerobic → lactate); Type B = Bad drugs/liver.
Recall: This patient has metabolic acidosis (low pH, low HCO₃⁻) with respiratory compensation (low PCO₂) and elevated lactate.
- No Troponin, No True cardiac damage.
Recall: Electrical cardioversion delivers energy through chest wall skeletal muscles, which contain small amounts of CK-MB (up to 3% of total CK).
- Troponin is TIED to myofibrils = extended TIME.
Recall: Cardiac troponin exists in two pools: a small cytosolic free pool (6-8%) released early, and a larger structurally-bound myofibrillar pool (92-94%) released gradually as myofibrils degrade.
- HMG-CoA Reductase = Highway Master Gate–controls everything downstream.
Recall: HMG-CoA reductase catalyzes the rate-limiting conversion of HMG-CoA to mevalonate, the committed step of the entire mevalonate pathway.
- Small LDL = Same apoB, Smaller cholesterol cargo–more trucks carrying less freight.
Recall: Diabetic dyslipidemia features small, dense LDL particles that carry less cholesterol per particle but retain one apoB molecule each.
- Arsenate = ATP-sabotage–reaction runs but energy is lost.
Recall: Normally, GAPDH uses inorganic phosphate to form 1,3-bisphosphoglycerate, which then donates its high-energy phosphate to ADP via phosphoglycerate kinase (substrate-level phosphorylation).
- PK deficiency → 2,3-BPG ↑ → P50 ↑ → better O₂ delivery.
Recall: Pyruvate kinase deficiency causes accumulation of upstream glycolytic intermediates, including 1,3-BPG, which is converted to 2,3-bisphosphoglycerate (2,3-BPG) by bisphosphoglycerate mutase.
- Thiamine → TPP → PDC → Pyruvate entry–blockade here, pyruvate piles up.
Recall: Pyruvate dehydrogenase complex (PDC) requires thiamine pyrophosphate (TPP) as a cofactor.
- IDH = NAD+ sensor–high NADH = cycle stops here first.
Recall: Isocitrate dehydrogenase (IDH3, mitochondrial isoform) is highly sensitive to NADH/NAD+ ratio.