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// ══════════════════════════════════════════════════════════════
//  SLIDE 1 — TITLE
// ══════════════════════════════════════════════════════════════
mkTitle("ANATOMY EXAM NOTES",
  "Ch 01: Basic Anatomy 01 & 02  |  Ch 02: Embryology (Complete)  |  Ch 03: Back & Spine  |  Ch 04: Imaging");

// ══════════════════════════════════════════════════════════════
//  CHAPTER 01 — BASIC ANATOMY
// ══════════════════════════════════════════════════════════════
mkSection("CHAPTER 01", "Basic Anatomy — Parts 1 & 2");

mkContent("CH 01 | Anatomical Planes of the Body", [
  {t:"SAGITTAL PLANE — vertical, divides body into LEFT & RIGHT portions", b:true},
  {t:"Median (mid-sagittal) — passes through exact midline", i:true},
  {t:"Para-sagittal — parallel to midline, off-centre", i:true},
  {t:"CORONAL (FRONTAL) PLANE — vertical, divides body into ANTERIOR (front) & POSTERIOR (back)", b:true},
  {t:"TRANSVERSE (HORIZONTAL / AXIAL) PLANE — divides body into SUPERIOR (upper) & INFERIOR (lower)", b:true},
  {t:"OBLIQUE PLANE — any plane not parallel to standard planes", b:false},
  {t:"BODY AXES: Longitudinal (head-to-foot) | Transverse (side-to-side) | Anteroposterior (front-to-back)", b:false},
], "Sections through planes: sagittal section, coronal section, cross-section (transverse)");

mkContent("CH 01 | Directional Terms — Upper Body", [
  {t:"Anterior / Ventral — toward the FRONT", b:true},
  {t:"Posterior / Dorsal — toward the BACK", b:true},
  {t:"Superior / Cranial / Cephalad — toward the HEAD", b:true},
  {t:"Inferior / Caudal / Caudad — toward the FEET / tail", b:true},
  {t:"Medial — toward the midline (median plane)", b:false},
  {t:"Lateral — away from the midline, toward the side", b:false},
  {t:"Ipsilateral — same side of the body", b:false},
  {t:"Contralateral — opposite side of the body", b:false},
  {t:"Superficial — near the body surface", b:false},
  {t:"Deep — away from the body surface", b:false},
  {t:"Central — toward the centre/interior; Peripheral — away from the centre", b:false},
], "Rostral = toward the nose/brow (used in neuroanatomy); Caudal = toward the tail");

mkContent("CH 01 | Directional Terms — Limbs", [
  {t:"Proximal — closer to the point of attachment / trunk", b:true},
  {t:"Distal — farther from the point of attachment / trunk", b:true},
  {t:"Radial — pertaining to the radius / LATERAL side of forearm", b:false},
  {t:"Ulnar — pertaining to the ulna / MEDIAL side of forearm", b:false},
  {t:"Tibial — pertaining to the tibia / MEDIAL side of leg", b:false},
  {t:"Fibular (Peroneal) — pertaining to the fibula / LATERAL side of leg", b:false},
  {t:"Palmar (Volar) — pertaining to the PALM of the hand", b:false},
  {t:"Plantar — pertaining to the SOLE of the foot", b:false},
  {t:"Dorsal — back of the hand OR top of the foot", b:false},
  {t:"Apical — pertaining to the tip/apex; Basal — pertaining to the base", b:false},
], "Remember: Proximal-Distal axis only used for limbs, NOT for trunk");

mkContent("CH 01 | Body Cavities", [
  {t:"DORSAL CAVITY — posterior, protects CNS", b:true},
  {t:"Cranial cavity — contains the brain", i:true},
  {t:"Vertebral (spinal) canal — contains the spinal cord & meninges", i:true},
  {t:"VENTRAL CAVITY — anterior, larger; divided by the DIAPHRAGM", b:true},
  {t:"THORACIC CAVITY (superior to diaphragm):", b:false},
  {t:"Pleural cavities (right & left) — contain the lungs", i:true},
  {t:"Pericardial cavity — contains the heart", i:true},
  {t:"Mediastinum — central compartment between pleural sacs (heart, great vessels, trachea, oesophagus)", i:true},
  {t:"ABDOMINOPELVIC CAVITY (inferior to diaphragm):", b:false},
  {t:"Abdominal cavity — stomach, liver, spleen, pancreas, small intestine, kidneys, most of large intestine", i:true},
  {t:"Pelvic cavity — bladder, rectum, internal reproductive organs", i:true},
], "Serous membranes: pleura (lungs), pericardium (heart), peritoneum (abdominopelvic) — reduce friction");

mkContent("CH 01 | Abdominal Regions & Quadrants", [
  {t:"4 QUADRANTS (quick clinical use):", b:true},
  {t:"RUQ — liver, gallbladder, right kidney, hepatic flexure", i:true},
  {t:"LUQ — stomach, spleen, left kidney, splenic flexure, tail of pancreas", i:true},
  {t:"RLQ — appendix, cecum, right ureter, right ovary/testis", i:true},
  {t:"LLQ — sigmoid colon, left ureter, left ovary/testis", i:true},
  {t:"9 ABDOMINAL REGIONS (detailed anatomy):", b:true},
  {t:"Superior row: Right Hypochondriac | Epigastric | Left Hypochondriac", i:true},
  {t:"Middle row: Right Lumbar (lateral) | Umbilical | Left Lumbar (lateral)", i:true},
  {t:"Inferior row: Right Iliac/Inguinal | Hypogastric (Pubic) | Left Iliac/Inguinal", i:true},
], "McBurney's point (appendix) = junction of lateral 1/3 and medial 2/3 of line from ASIS to umbilicus — in RLQ");

mkContent("CH 01 | Structural Organisation of the Body", [
  {t:"LEVELS (smallest → largest):", b:true},
  {t:"Chemical → Cellular → Tissue → Organ → Organ System → Organism", i:true},
  {t:"4 PRIMARY TISSUE TYPES:", b:true},
  {t:"EPITHELIAL: covers/lines surfaces; protection, secretion, absorption, sensation", i:true},
  {t:"Simple (1 layer) vs Stratified (multiple layers); Squamous / Cuboidal / Columnar", i:true},
  {t:"CONNECTIVE: supports, binds & connects; most widely distributed tissue type", i:true},
  {t:"Includes: loose, dense, bone, cartilage, blood, adipose, fascia, tendons, ligaments", i:true},
  {t:"MUSCLE: contractile tissue — Skeletal (striated, voluntary) | Cardiac (striated, involuntary) | Smooth (involuntary)", i:true},
  {t:"NERVOUS: neurons + neuroglia; transmits electrical impulses; integration & communication", i:true},
], "Homeostasis = maintaining stable internal environment via negative & positive feedback loops");

mkContent("CH 01 | Organ Systems of the Body", [
  {t:"Integumentary — skin, hair, nails, glands: protection, temperature regulation", b:false},
  {t:"Skeletal — 206 bones (adult): support, protection, movement, hematopoiesis, mineral storage", b:false},
  {t:"Muscular — ~700 skeletal muscles: movement, posture, heat production", b:false},
  {t:"Nervous — brain, spinal cord, nerves, sense organs: control & communication", b:false},
  {t:"Endocrine — pituitary, thyroid, adrenals, pancreas, gonads: hormonal regulation", b:false},
  {t:"Cardiovascular — heart + blood vessels: transport O₂, nutrients, hormones, remove CO₂/waste", b:false},
  {t:"Lymphatic/Immune — lymph nodes, spleen, thymus, MALT: immunity, fluid balance", b:false},
  {t:"Respiratory — lungs, airways, diaphragm: gas exchange (O₂ in / CO₂ out)", b:false},
  {t:"Digestive — mouth to anus + liver/pancreas: digestion, absorption, elimination", b:false},
  {t:"Urinary — kidneys, ureters, bladder, urethra: filtration, fluid/electrolyte balance", b:false},
  {t:"Reproductive — gonads & ducts (male/female): reproduction", b:false},
]);

mkContent("CH 01 | Bones — Classification & Structure", [
  {t:"5 BONE TYPES BY SHAPE:", b:true},
  {t:"Long (femur, humerus) | Short (carpals, tarsals) | Flat (skull, sternum, scapula)", i:true},
  {t:"Irregular (vertebrae, pelvis) | Sesamoid (patella — embedded in tendon)", i:true},
  {t:"LONG BONE STRUCTURE:", b:true},
  {t:"Diaphysis (shaft) — compact bone shell; medullary (marrow) cavity inside", i:true},
  {t:"Epiphyses (ends) — spongy/cancellous bone; articular surface covered in hyaline cartilage", i:true},
  {t:"Epiphyseal plate (growth plate/physis) — cartilage; site of longitudinal growth", i:true},
  {t:"Periosteum — outer fibrous membrane on bone surface; nutrient foramina pierce it", i:true},
  {t:"Endosteum — thin membrane lining marrow cavity", i:true},
  {t:"OSTEOGENESIS: Intramembranous (direct, from mesenchyme) — flat skull bones, clavicle, mandible", b:false},
  {t:"Endochondral (indirect, via cartilage template) — most other bones (long bones, vertebrae)", b:false},
], "Primary ossification centre = fetal diaphysis; Secondary = postnatal epiphysis (visible on X-ray at known ages)");

mkContent("CH 01 | Joints (Arthrology)", [
  {t:"FIBROUS JOINTS — held by fibrous connective tissue; mostly immovable (synarthrosis):", b:true},
  {t:"Sutures (skull) | Gomphoses (teeth in socket) | Syndesmoses (interosseous membrane — tibiofibular)", i:true},
  {t:"CARTILAGINOUS JOINTS — united by cartilage; slightly movable (amphiarthrosis):", b:true},
  {t:"Synchondroses (hyaline cartilage — epiphyseal plate, 1st rib-sternum)", i:true},
  {t:"Symphyses (fibrocartilage — pubic symphysis, intervertebral discs)", i:true},
  {t:"SYNOVIAL JOINTS — freely movable (diarthrosis); most common type:", b:true},
  {t:"Articular cartilage + fibrous capsule + synovial membrane + synovial fluid", i:true},
  {t:"6 TYPES: Hinge (elbow, knee) | Pivot (atlanto-axial, radioulnar) | Ball-and-socket (hip, shoulder)", i:true},
  {t:"Condyloid (radiocarpal) | Saddle (1st carpometacarpal — thumb) | Plane/Gliding (intercarpal)", i:true},
], "Bursae = fluid-filled sacs near joints that reduce friction; Tendon sheaths wrap tendons near joints");

mkContent("CH 01 | Muscles — Structure & Actions", [
  {t:"STRUCTURE: Epimysium → Perimysium (surrounds fascicles) → Endomysium (surrounds individual fibres) → Sarcomere", b:false},
  {t:"ATTACHMENTS: Origin = proximal/fixed end; Insertion = distal/movable end", b:true},
  {t:"FUNCTIONAL ROLES: Prime mover/Agonist | Antagonist | Synergist | Fixator/Stabiliser", b:false},
  {t:"FASCICLE ARRANGEMENTS: Parallel | Pennate (uni/bi/multi) | Circular/Sphincter | Convergent", b:false},
  {t:"KEY MOVEMENTS:", b:true},
  {t:"Flexion / Extension | Abduction / Adduction | Medial & Lateral Rotation | Circumduction", i:true},
  {t:"Pronation / Supination (forearm) | Dorsiflexion / Plantarflexion (foot/ankle)", i:true},
  {t:"Inversion / Eversion (foot) | Protraction / Retraction | Elevation / Depression | Opposition", i:true},
], "Muscle names often indicate: shape (deltoid), size (maximus/minimus), location (brachii), action (flexor), attachment (coracobrachialis)");

mkContent("CH 01 | Nervous System — Overview & Spinal Nerves", [
  {t:"CNS: Brain + Spinal cord — protected by skull + vertebral column + meninges + CSF", b:true},
  {t:"PNS: All neural tissue outside CNS — 12 cranial nerve pairs + 31 spinal nerve pairs", b:true},
  {t:"SOMATIC NS: voluntary control of skeletal muscles & skin sensation", b:false},
  {t:"AUTONOMIC NS: involuntary; Sympathetic ('fight or flight') | Parasympathetic ('rest & digest')", b:false},
  {t:"SPINAL NERVES (31 pairs): 8 Cervical + 12 Thoracic + 5 Lumbar + 5 Sacral + 1 Coccygeal", b:true},
  {t:"Each nerve has DORSAL ROOT (sensory — afferent) + VENTRAL ROOT (motor — efferent)", i:true},
  {t:"Dorsal Root Ganglion (DRG) — contains cell bodies of sensory neurons, outside spinal cord", i:true},
  {t:"DERMATOME = skin area supplied by single spinal nerve (sensory map)", b:false},
  {t:"MYOTOME = muscles innervated by a single spinal nerve (motor map)", b:false},
  {t:"PLEXUSES: Cervical (C1–C4) | Brachial (C5–T1) | Lumbar (L1–L4) | Sacral (L4–S4)", b:false},
], "C3,4,5 keeps the diaphragm alive — phrenic nerve; loss = respiratory paralysis");

mkContent("CH 01 | Vascular System — Arteries, Veins & Lymphatics", [
  {t:"ARTERIES: carry blood AWAY from heart; high pressure; thick elastic/muscular walls; NO valves", b:true},
  {t:"Elastic arteries (aorta, pulmonary) → Muscular arteries → Arterioles → Capillaries (exchange vessels)", i:true},
  {t:"VEINS: carry blood TOWARD heart; low pressure; thinner walls; have VALVES (prevent backflow)", b:true},
  {t:"Capillaries → Venules → Veins → Vena cava (systemic) or pulmonary veins (pulmonary)", i:true},
  {t:"CAPILLARIES: 3 types — Continuous (muscle, CNS) | Fenestrated (kidney, intestine) | Sinusoidal (liver, spleen, bone marrow)", b:false},
  {t:"PORTAL CIRCULATION: blood passes through 2 capillary beds — e.g., hepatic portal system", b:false},
  {t:"LYMPHATIC SYSTEM: one-way drainage of interstitial fluid back to venous circulation", b:true},
  {t:"Lymph capillaries → lymph vessels → lymph nodes (filter) → lymph trunks → thoracic duct / right lymphatic duct", i:true},
  {t:"Thoracic duct drains EVERYTHING EXCEPT: right head, right neck, right arm, right thorax (→ right lymphatic duct)", b:false},
], "Anastomoses = connections between vessels; collateral circulation provides alternative blood supply routes");

// ══════════════════════════════════════════════════════════════
//  CHAPTER 02 — EMBRYOLOGY
// ══════════════════════════════════════════════════════════════
mkSection("CHAPTER 02", "Embryology — Complete Chapter");

mkContent("CH 02 | Molecular Regulation & Gene Expression", [
  {t:"~23,000 genes in human genome → code for ~100,000 proteins (disproves one gene–one protein)", b:true},
  {t:"CHROMATIN: DNA + histones; basic unit = NUCLEOSOME (octamer + ~140 bp DNA)", b:false},
  {t:"HETEROCHROMATIN: tightly coiled, inactive (not transcribed)", b:false},
  {t:"EUCHROMATIN: uncoiled, active — allows transcription by RNA polymerase", b:false},
  {t:"GENE REGIONS: Exons (translated → protein) + Introns (non-coding, removed by splicing)", b:false},
  {t:"PROMOTER region: contains TATA box → binds RNA polymerase (requires transcription factors)", b:false},
  {t:"Gene expression regulated at: Transcription | RNA processing | Translation | Post-translational modification", b:true},
  {t:"METHYLATION of cytosine in promoter → SILENCES gene (basis of X-inactivation & genomic imprinting)", b:false},
  {t:"ALTERNATIVE SPLICING: different introns removed → multiple proteins from one gene", b:false},
], "Chromatin = DNA + histones; nucleosome = core particle; H1 histones = linker proteins");

mkContent("CH 02 | Cell Signalling Pathways in Development", [
  {t:"PARACRINE SIGNALLING: diffusible factor acts on nearby cells via transmembrane receptor", b:true},
  {t:"Ligand → Receptor → Kinase cascade (phosphorylation) → Transcription factor → Gene expression", i:true},
  {t:"JUXTACRINE SIGNALLING: cell–cell contact OR ECM ligands (no diffusion needed)", b:true},
  {t:"NOTCH PATHWAY (juxtacrine): Notch receptor + DSL ligand (Jagged/Delta) → NICD released → gene activation", i:true},
  {t:"INTEGRINS: link extracellular matrix (fibronectin, laminin, collagen) to cytoskeleton; regulate migration & differentiation", b:false},
  {t:"GAP JUNCTIONS: connexin proteins form channels → direct intercellular communication of small molecules/ions", b:false},
  {t:"KEY DEVELOPMENTAL PATHWAYS: SHH (Sonic Hedgehog) | WNT | FGF | BMP | Notch | Retinoic acid", b:true},
  {t:"HOX GENES: transcription factors with homeobox domain; control body axis patterning craniocaudally", b:true},
  {t:"Extracellular matrix: collagen, proteoglycans (hyaluronic acid), fibronectin, laminin — scaffold for cell migration", b:false},
], "Epigenetics: heritable changes in gene expression WITHOUT DNA sequence change — methylation, histone modification");

mkContent("CH 02 | Gametogenesis — Oogenesis & Spermatogenesis", [
  {t:"PRIMORDIAL GERM CELLS (PGCs): arise in EPIBLAST (2nd week) → migrate via primitive streak → yolk sac wall → gonads (by 5th week)", b:true},
  {t:"OOGENESIS (female):", b:true},
  {t:"Oogonia (2n,44XX) → Primary oocytes (diploid) → arrested in PROPHASE I until puberty", i:true},
  {t:"LH surge at ovulation → completes Meiosis I → Secondary oocyte (haploid) + 1st polar body", i:true},
  {t:"Meiosis II completed only if FERTILISATION occurs → Mature ovum + 2nd polar body", i:true},
  {t:"Result: 1 mature ovum + 3 polar bodies (4 haploid cells; only 1 functional)", i:true},
  {t:"SPERMATOGENESIS (male):", b:true},
  {t:"Spermatogonia (2n) → Primary spermatocyte (44XY) → 2 Secondary spermatocytes → 4 Spermatids → 4 Spermatozoa", i:true},
  {t:"Regulated by LH (→ Leydig cells → testosterone) + FSH (→ Sertoli cells → fluid & androgen receptors)", i:true},
  {t:"SPERMIOGENESIS: spermatid → spermatozoon — acrosome formation, nucleus condensation, tail formation", b:false},
], "Acrosome contains hydrolytic enzymes (acrosin, hyaluronidase) — digest zona pellucida during fertilisation");

mkContent("CH 02 | Ovarian Cycle & Ovulation", [
  {t:"Hypothalamus releases GnRH → Anterior pituitary releases FSH + LH", b:true},
  {t:"FSH: 15–20 primary follicles recruited each cycle; only ONE reaches full maturity (rest become atretic)", b:false},
  {t:"FOLLICULAR PHASE: granulosa & theca cells produce OESTROGEN → endometrium proliferates; LH stimulated", b:false},
  {t:"LH SURGE at mid-cycle (day 14): triggers — completion of Meiosis I; follicular rupture; OVULATION", b:true},
  {t:"Mature vesicular (Graafian) follicle ruptures → secondary oocyte released into peritoneal cavity → captured by fimbriae", b:false},
  {t:"CORPUS LUTEUM: formed from ruptured follicle; produces PROGESTERONE (secretory phase of endometrium)", b:true},
  {t:"If no fertilisation: corpus luteum degenerates → corpus albicans; progesterone drops → menstruation", b:false},
  {t:"If fertilisation: hCG from trophoblast maintains corpus luteum → continues progesterone production", b:false},
  {t:"LUTEAL PHASE: progesterone prepares endometrium for implantation; lasts ~14 days", b:false},
], "Corpus luteum = 'yellow body'; corpus albicans = 'white body' (fibrosed regressed corpus luteum)");

mkContent("CH 02 | Fertilisation (Week 1)", [
  {t:"Site: usually AMPULLA of uterine (Fallopian) tube — widest, most lateral part", b:true},
  {t:"PHASE 1: Spermatozoon penetrates CORONA RADIATA (granulosa cells) — hyaluronidase helps", b:false},
  {t:"PHASE 2: ACROSOME REACTION — acrosome dissolves, enzymes digest ZONA PELLUCIDA", b:false},
  {t:"PHASE 3: Sperm & oocyte cell membranes fuse — spermatozoon enters oocyte", b:false},
  {t:"CORTICAL REACTION: cortical granules released → zona pellucida hardens → POLYSPERMY PREVENTED", b:true},
  {t:"Oocyte completes Meiosis II → mature ovum + 2nd polar body", b:false},
  {t:"Male and female pronuclei form → SYNGAMY (pronuclei fuse) → ZYGOTE (2n, 46 chromosomes)", b:true},
  {t:"Fertilisation RESTORES diploid chromosome number (23+23=46)", b:false},
  {t:"Sex determination: X-bearing sperm → XX (female); Y-bearing sperm → XY (male)", b:false},
], "Ectopic pregnancy (95% in uterine tube — ampulla most common): risk if tubal adhesions, PID, previous surgery");

mkContent("CH 02 | Cleavage, Morula & Blastocyst (Day 1–7)", [
  {t:"CLEAVAGE: rapid mitotic divisions; cells = BLASTOMERES; total cell mass unchanged", b:true},
  {t:"DAY 3–4: MORULA — solid ball of ~16 blastomeres; still surrounded by zona pellucida", b:true},
  {t:"DAY 4–5: BLASTOCYST — fluid accumulates (blastocoele); 2 distinct cell populations form:", b:true},
  {t:"Inner Cell Mass (ICM / Embryoblast) — gives rise to the EMBRYO PROPER (all 3 germ layers)", i:true},
  {t:"Outer Cell Mass (Trophoblast) — gives rise to PLACENTA & extraembryonic membranes", i:true},
  {t:"DAY 5–6: Zona pellucida dissolves (hatching) → enables implantation", b:false},
  {t:"DAY 6–7: IMPLANTATION begins — trophoblast adheres to posterior wall of uterine body", b:true},
  {t:"Trophoblast differentiates into:", b:false},
  {t:"Cytotrophoblast (inner, cellular — proliferative layer)", i:true},
  {t:"Syncytiotrophoblast (outer, multinucleated, invasive — erodes endometrial stroma)", i:true},
  {t:"hCG produced by SYNCYTIOTROPHOBLAST → maintains corpus luteum → basis of PREGNANCY TEST", b:true},
], "Twinning: Monozygotic (identical, 1 zygote splits) vs Dizygotic (fraternal, 2 separate fertilisations)");

mkContent("CH 02 | Week 2 — Bilaminar Disc ('Week of 2s')", [
  {t:"BILAMINAR EMBRYONIC DISC: formed from ICM — 2 layers:", b:true},
  {t:"EPIBLAST (dorsal): columnar cells — will form ALL 3 germ layers + amnion", i:true},
  {t:"HYPOBLAST (ventral): cuboidal cells — will line yolk sac (does NOT form embryo)", i:true},
  {t:"AMNIOTIC CAVITY: forms ABOVE (dorsal to) epiblast — lined by amnioblasts", b:false},
  {t:"PRIMARY YOLK SAC: forms BELOW (ventral to) hypoblast", b:false},
  {t:"EXTRAEMBRYONIC MESODERM: forms between cytotrophoblast and amnionic/yolk sac cavities", b:false},
  {t:"CHORIONIC CAVITY (extraembryonic coelom): large cavity within extraembryonic mesoderm", b:false},
  {t:"TROPHOBLAST: lacunae appear in syncytiotrophoblast → maternal sinusoids open → uteroplacental circulation begins", b:true},
  {t:"PRIMARY CHORIONIC VILLI: cytotrophoblast core grows into syncytiotrophoblast lacunae", b:false},
], "Week 2 = 'Week of 2s': 2 layers (bilaminar disc), 2 cavities (amniotic + yolk sac), 2 trophoblast layers");

mkContent("CH 02 | Week 3 — Gastrulation & Trilaminar Disc", [
  {t:"GASTRULATION: most critical developmental event — establishes 3 germ layers & body axes", b:true},
  {t:"PRIMITIVE STREAK: thickening at caudal midline of epiblast; defines cranial-caudal & left-right axes", b:true},
  {t:"Epiblast cells migrate through primitive streak:", b:false},
  {t:"Invaginate → displace hypoblast → form DEFINITIVE ENDODERM", i:true},
  {t:"Invaginate → spread laterally between ectoderm & endoderm → form MESODERM", i:true},
  {t:"Remaining epiblast cells → become ECTODERM", i:true},
  {t:"THREE GERM LAYERS: ECTODERM (dorsal) | MESODERM (middle) | ENDODERM (ventral)", b:true},
  {t:"PRIMITIVE NODE (Hensen's node): cranial end of streak; 'organiser' of development", b:false},
  {t:"NOTOCHORD: axial mesoderm structure from node; induces overlying ectoderm → neural plate (neurulation)", b:true},
  {t:"Fate of notochord: mostly degenerates; NUCLEUS PULPOSUS of intervertebral discs is its remnant", b:false},
], "INGRESSION: epiblast cells detach, migrate through streak, undergo epithelial-to-mesenchymal transition");

mkContent("CH 02 | Germ Layer Derivatives (HIGH YIELD)", [
  {t:"ECTODERM derivatives:", b:true},
  {t:"Neural tube → Brain (all parts) & Spinal cord; Retina; Posterior pituitary (neurohypophysis)", i:true},
  {t:"Neural crest (head) → Facial skeleton (bones + cartilage), corneal stroma, dental pulp, parafollicular cells", i:true},
  {t:"Neural crest (trunk) → DRG, autonomic ganglia, adrenal MEDULLA, Schwann cells, melanocytes", i:true},
  {t:"Surface ectoderm → Epidermis, hair, nails, cutaneous glands, mammary glands, lens, inner ear, anterior pituitary", i:true},
  {t:"MESODERM derivatives:", b:true},
  {t:"Paraxial (somites) → Vertebrae, ribs, skull base; Skeletal muscle of trunk/limbs; Dermis of trunk/back", i:true},
  {t:"Intermediate → Kidneys, ureters, gonads, reproductive ducts (Wolffian/Müllerian)", i:true},
  {t:"Lateral plate → Heart, all blood vessels; Limb skeleton (bones & ligaments); Parietal serosa; Adrenal cortex", i:true},
  {t:"ENDODERM derivatives:", b:true},
  {t:"Epithelium of GI tract, respiratory tract, bladder; Liver (hepatocytes); Pancreas; Thyroid; Parathyroid; Tonsils", i:true},
], "MNEMONIC: Neural crest = 'AMEN': Adrenal medulla, Melanocytes, Enteric NS, Nerve ganglia (DRG + autonomic)");

mkContent("CH 02 | Neurulation & Neural Tube Defects", [
  {t:"NEURULATION: notochord induces NEURAL PLATE in overlying ectoderm (day ~18)", b:true},
  {t:"Neural plate → neural folds elevate → converge at midline → fuse → NEURAL TUBE (day 22–28)", b:false},
  {t:"CRANIAL NEUROPORE closes: Day 25 (anterior; failure → ANENCEPHALY)", b:true},
  {t:"CAUDAL NEUROPORE closes: Day 27 (posterior; failure → SPINA BIFIDA)", b:true},
  {t:"NEURAL CREST CELLS: detach from lateral neural fold edges at fusion; undergo EMT; migrate extensively", b:false},
  {t:"SOMITES: paired blocks of paraxial mesoderm; first appears day 20; 42–44 total pairs formed craniocaudally", b:true},
  {t:"Somite → SCLEROTOME (ventral) → vertebrae & ribs | MYOTOME (lateral) → skeletal muscle | DERMATOME (dorsal) → dermis", b:false},
  {t:"SPINA BIFIDA types: Occulta (hidden, no protrusion) | Meningocele (meninges protrude) | Myelomeningocele (cord + meninges protrude, worst)", b:true},
  {t:"PREVENTION of NTDs: FOLIC ACID 400 mcg/day started BEFORE conception", b:true},
], "Holoprosencephaly: failure of prosencephalon to divide → cyclopia; associated with trisomy 13, SHH mutations");

mkContent("CH 02 | Extraembryonic Membranes & Amniotic Fluid", [
  {t:"AMNION: innermost membrane; surrounds embryo; forms amniotic cavity filled with amniotic fluid", b:true},
  {t:"Amniotic fluid functions: cushion, temperature, allow movement, lung maturation, swallowing", i:true},
  {t:"1st trimester = maternal filtrate; 2nd/3rd trimester = mainly FETAL URINE (+ lung fluid)", i:true},
  {t:"POLYHYDRAMNIOS (excess fluid >2000 mL): oesophageal/duodenal atresia, anencephaly, diabetes", b:false},
  {t:"OLIGOHYDRAMNIOS (<500 mL): renal agenesis (Potter sequence), urinary obstruction, postmaturity", b:false},
  {t:"CHORION: outermost membrane; trophoblast + extraembryonic mesoderm; chorionic villi → placenta", b:true},
  {t:"YOLK SAC: site of EARLY BLOOD CELL FORMATION (hematopoiesis, weeks 3–6); early nutrition", b:true},
  {t:"ALLANTOIS: evagination of hindgut; allantoic vessels → umbilical vessels; urachus remnant (median umbilical ligament)", b:false},
  {t:"UMBILICAL CORD: 2 umbilical ARTERIES (deoxygenated, TO placenta) + 1 umbilical VEIN (oxygenated, TO fetus)", b:true},
], "Single umbilical artery (SUA): associated with chromosomal abnormalities & fetal structural defects");

mkContent("CH 02 | Placenta — Structure & Function", [
  {t:"Formed from: fetal CHORION FRONDOSUM + maternal DECIDUA BASALIS", b:true},
  {t:"CHORIONIC VILLI: branching projections that exchange substances with maternal blood in intervillous space", b:false},
  {t:"PLACENTAL BARRIER: Syncytiotrophoblast + Cytotrophoblast + Fetal capillary endothelium", b:true},
  {t:"FUNCTIONS: Gas exchange (O₂/CO₂) | Nutrition (glucose, amino acids) | Waste removal | Hormone production", b:true},
  {t:"HORMONES: hCG (early) | Progesterone (after 8–10 wks, replaces corpus luteum) | Oestrogen | hPL (human Placental Lactogen)", i:true},
  {t:"hPL: promotes maternal lipolysis; diabetogenic; ensures glucose available for fetus", i:true},
  {t:"WHAT CROSSES PLACENTA: O₂, CO₂, glucose, amino acids, IgG (maternal antibodies), drugs, viruses (TORCH)", b:false},
  {t:"WHAT DOES NOT CROSS: heparin, large proteins, most bacteria, maternal cells", b:false},
  {t:"PLACENTA PREVIA: placenta covers internal os — painless antepartum haemorrhage, C-section needed", b:false},
  {t:"PLACENTA ACCRETA: abnormal adherence of placenta to myometrium — PPH risk", b:false},
], "TORCH infections cross placenta: Toxoplasma, Other (syphilis, VZV, parvovirus B19), Rubella, CMV, Herpes");

mkContent("CH 02 | Chromosomal Abnormalities", [
  {t:"NONDISJUNCTION: chromosomes fail to separate in meiosis → aneuploidy", b:true},
  {t:"TRISOMY 21 — DOWN SYNDROME: flat face, Brushfield spots, single palmar crease, hypotonia, +/- VSD/ASD; risk ↑ maternal age", b:false},
  {t:"TRISOMY 18 — EDWARDS: rocker-bottom feet, clenched fists, micrognathia, VSD; poor prognosis (50% die by 2 weeks)", b:false},
  {t:"TRISOMY 13 — PATAU: bilateral cleft lip/palate, holoprosencephaly, polydactyly, anophthalmia, small head", b:false},
  {t:"KLINEFELTER (47,XXY): MALE; small testes, gynaecomastia, infertility, tall, may have mild learning difficulties", b:true},
  {t:"1 Barr body present (1 inactivated X); incidence ~1/500 males; most common sex chromosome disorder in males", i:true},
  {t:"TURNER (45,X): FEMALE; only viable monosomy; gonadal dysgenesis, short stature, webbed neck, wide-spaced nipples, lymphoedema", b:true},
  {t:"98% spontaneously abort; streak ovaries; primary amenorrhoea; often normal intelligence", i:true},
  {t:"TRIPLE X (47,XXX): female; mild phenotype; speech/learning difficulties; 2 Barr bodies", b:false},
  {t:"CRI DU CHAT: deletion 5p; cat-like cry in infants, microcephaly, intellectual disability", b:false},
], "Barr body = condensed inactivated X chromosome; number of Barr bodies = (number of X chromosomes - 1)");

mkContent("CH 02 | Carnegie Stages & Fetal Growth", [
  {t:"EMBRYONIC PERIOD: Weeks 1–8 (organogenesis — MOST VULNERABLE to teratogens)", b:true},
  {t:"FETAL PERIOD: Week 9 to birth (growth & maturation)", b:false},
  {t:"CARNEGIE STAGES (23 stages; defined by Streeter 1942, O'Rahilly 1987):", b:true},
  {t:"Stage 1: Zygote | Stage 2: 2–16 cell (days 2–3) | Stage 3: Morula | Stage 4: Blastocyst", i:true},
  {t:"Stage 14 (5th wk, GL 5–7mm): future cerebral hemispheres identifiable", i:true},
  {t:"Stage 17 (6th wk, GL 11–14mm): digital rays visible (fingers forming)", i:true},
  {t:"Stage 20 (7th wk, CRL 18–22mm): elbows bent, hands pronated", i:true},
  {t:"Stage 23 (8th wk, GL 27–31mm): eyelids fuse; external genitalia start differentiation", i:true},
  {t:"FETAL GROWTH: 9–12 wk: CRL 5–8 cm, 10–45 g | 17–20 wk: 15–19 cm, 250–450 g | 25–28 wk: 24–27 cm, 900–1300 g", b:false},
  {t:"Viability: ~22–24 weeks (surfactant appears ~28 wks — type II pneumocytes)", b:false},
], "GL = greatest length (excludes lower limbs); CRL = crown-rump length; CR = crown-rump distance");

// ══════════════════════════════════════════════════════════════
//  CHAPTER 03 — BACK & SPINE  (Snell pg 44–85)
// ══════════════════════════════════════════════════════════════
mkSection("CHAPTER 03", "Back and Spine  (Snell's Anatomy pg 44–85)");

mkContent("CH 03 | Vertebral Column — Overview & Curves", [
  {t:"33 vertebrae total → 26 bones in ADULT (due to fusion of sacrum & coccyx)", b:true},
  {t:"7 Cervical + 12 Thoracic + 5 Lumbar + 5 Sacral (fused = sacrum) + 4 Coccygeal (fused = coccyx)", b:true},
  {t:"PRIMARY CURVES (concave anteriorly — present at birth): Thoracic kyphosis + Sacral kyphosis", b:true},
  {t:"SECONDARY CURVES (concave posteriorly — develop postnatally): Cervical lordosis + Lumbar lordosis", b:true},
  {t:"Cervical curve: develops when infant raises head (~3 months)", i:true},
  {t:"Lumbar curve: develops when child begins to walk (~12–18 months)", i:true},
  {t:"ABNORMAL CURVES:", b:false},
  {t:"Kyphosis — exaggerated thoracic curve (hunchback); causes: osteoporosis, Scheuermann's disease, TB (Pott's)", i:true},
  {t:"Lordosis — exaggerated lumbar curve; causes: pregnancy, obesity, muscular dystrophy", i:true},
  {t:"Scoliosis — abnormal lateral curvature (coronal plane); idiopathic (most common, adolescent females)", i:true},
], "Vertebral column functions: support weight | protect spinal cord | allow movement | attachment for muscles & ribs");

mkContent("CH 03 | Typical Vertebra — Anatomy", [
  {t:"BODY: cylindrical, anterior weight-bearing part; connected by intervertebral discs", b:true},
  {t:"VERTEBRAL ARCH: 2 pedicles + 2 laminae; forms posterior wall of vertebral foramen", b:true},
  {t:"VERTEBRAL FORAMEN: space enclosed by body + arch; stacked vertically = VERTEBRAL CANAL", b:false},
  {t:"PROCESSES (7 total):", b:true},
  {t:"1 Spinous process (posterior, palpable) | 2 Transverse processes (bilateral) | 4 Articular processes (2 superior + 2 inferior)", i:true},
  {t:"PEDICLES: notched (superior & inferior) → INTERVERTEBRAL FORAMINA (exit routes for spinal nerves)", b:false},
  {t:"FACET (ZYGAPOPHYSEAL) JOINTS: between articular processes; SYNOVIAL joints; guide spinal movement", b:false},
  {t:"INTERVERTEBRAL DISC (IVD):", b:true},
  {t:"Nucleus pulposus: gelatinous core — REMNANT OF NOTOCHORD; acts as shock absorber", i:true},
  {t:"Annulus fibrosus: concentric rings of fibrocartilage — outer containment ring", i:true},
  {t:"IVD HERNIATION: nucleus pulposus protrudes POSTEROLATERALLY (PLL is weak laterally) → nerve root compression → radiculopathy", i:true},
], "Spinal cord ends at L1–L2 (conus medullaris); below this = cauda equina (roots of L2–Co1)");

mkContent("CH 03 | Regional Vertebral Characteristics", [
  {t:"CERVICAL (C1–C7): SMALLEST bodies; bifid spinous processes (C2–C6); TRANSVERSE FORAMINA (vertebral artery)", b:true},
  {t:"ATLAS (C1): NO body, NO spinous process; anterior + posterior arches + lateral masses; superior articular facets for occiput", i:true},
  {t:"AXIS (C2): DENS (odontoid process) projects superiorly into C1 ring → pivot joint (rotation); strongest spine", i:true},
  {t:"C7 (VERTEBRA PROMINENS): longest spinous process (non-bifid) → easily palpable surface landmark", i:true},
  {t:"THORACIC (T1–T12): medium bodies; COSTAL FACETS / demifacets on body & transverse processes → rib articulation", b:true},
  {t:"Long spinous processes angled INFERIORLY; limited range of movement due to rib cage", i:true},
  {t:"LUMBAR (L1–L5): LARGEST bodies (weight bearing); short, thick, horizontal spinous processes; NO costal facets, NO transverse foramina", b:true},
  {t:"ILIAC CREST = L4 level → landmark for lumbar puncture", i:true},
  {t:"SACRUM: 5 fused vertebrae; sacral promontory (most prominent anterior edge); sacral foramina (S1–S4 nerve exits)", b:false},
  {t:"COCCYX: 3–5 fused segments; attachment for gluteus maximus, coccygeus, pelvic floor ligaments", b:false},
]);

mkContent("CH 03 | Ligaments of the Vertebral Column", [
  {t:"ANTERIOR LONGITUDINAL LIGAMENT (ALL): along ANTERIOR vertebral bodies & discs, from skull to sacrum", b:true},
  {t:"Prevents HYPEREXTENSION; strongest & widest spinal ligament", i:true},
  {t:"POSTERIOR LONGITUDINAL LIGAMENT (PLL): inside vertebral canal, along POSTERIOR bodies & discs", b:true},
  {t:"Prevents HYPERFLEXION; NARROWER (hourglass) — disc herniates POSTEROLATERALLY (not midline)", i:true},
  {t:"LIGAMENTA FLAVA: connect LAMINAE of adjacent vertebrae; YELLOW ELASTIC fibres", b:true},
  {t:"Prevent excessive flexion; under tension when erect → stabilises spine WITH back muscles", i:true},
  {t:"Thickening = spinal canal stenosis (narrows canal, compresses cord)", i:true},
  {t:"INTERSPINOUS LIGAMENTS: between adjacent spinous processes (C2 to sacrum)", b:false},
  {t:"SUPRASPINOUS LIGAMENT: over TIPS of spinous processes (T1 to sacrum); continuous with NUCHAL LIGAMENT in neck", b:false},
  {t:"NUCHAL LIGAMENT: from EOP (external occipital protuberance) to C7; strong posterior midline attachment in neck", b:false},
  {t:"INTERTRANSVERSE LIGAMENTS: between transverse processes", b:false},
], "Atlantoaxial ligaments (transverse ligament of atlas, alar ligaments, apical dental ligament) stabilise C1–C2 joint");

mkContent("CH 03 | Muscles of the Back — Layers", [
  {t:"SUPERFICIAL LAYER (appendicular — connect upper limb to trunk):", b:true},
  {t:"Trapezius (CN XI + C3,C4) | Latissimus dorsi (thoracodorsal n. C6,7,8) | Rhomboids (dorsal scapular n. C5) | Levator scapulae (dorsal scapular n.)", i:true},
  {t:"INTERMEDIATE LAYER (respiratory):", b:true},
  {t:"Serratus posterior superior (inspiration — elevates ribs) | Serratus posterior inferior (expiration — depresses ribs)", i:true},
  {t:"DEEP / INTRINSIC BACK MUSCLES — innervated by POSTERIOR (DORSAL) RAMI of spinal nerves:", b:true},
  {t:"SPLENIUS GROUP (superficial): Splenius capitis & cervicis — bilateral: extend head/neck; unilateral: lateral flex & rotate", i:true},
  {t:"ERECTOR SPINAE (intermediate) — 3 columns from medial to lateral: SPINALIS | LONGISSIMUS | ILIOCOSTALIS", i:true},
  {t:"Main extensor of vertebral column; maintains upright posture; bilateral = extension; unilateral = lateral flexion", i:true},
  {t:"TRANSVERSOSPINAL GROUP (deep): Semispinalis | Multifidus | Rotatores", i:true},
  {t:"Rotation & extension; span 2–5 segments; MULTIFIDUS is most important lumbar stabiliser", i:true},
  {t:"SUBOCCIPITAL MUSCLES: Rectus capitis posterior major/minor; Obliquus capitis superior/inferior — fine head movements", i:true},
], "Intrinsic muscles innervated by DORSAL RAMI; extrinsic muscles innervated by VENTRAL RAMI");

mkContent("CH 03 | Spinal Cord — Anatomy", [
  {t:"Length: ~45 cm; extends from medulla oblongata to CONUS MEDULLARIS at L1–L2 vertebral level", b:true},
  {t:"CERVICAL ENLARGEMENT (C4–T1): brachial plexus → upper limbs", b:false},
  {t:"LUMBOSACRAL ENLARGEMENT (L2–S3): lumbosacral plexus → lower limbs", b:false},
  {t:"CONUS MEDULLARIS: tapered lower end at L1–L2; FILUM TERMINALE (pia) continues to coccyx", b:true},
  {t:"CAUDA EQUINA ('horse's tail'): L2–Co1 nerve roots descend through subarachnoid space below conus", b:true},
  {t:"GREY MATTER: H-shaped; Dorsal horns (sensory) + Ventral horns (motor) + Lateral horns (T1–L2 = sympathetic; S2–S4 = parasympathetic)", b:true},
  {t:"WHITE MATTER: surrounds grey; dorsal, lateral & ventral funiculi (columns) containing ascending & descending tracts", b:false},
  {t:"BLOOD SUPPLY: 1 Anterior spinal artery (2/3 of cord via anterior 2/3) + 2 Posterior spinal arteries", b:true},
  {t:"Artery of Adamkiewicz: major segmental input to anterior spinal a. at T9–L2 level; risk in aortic surgery", b:false},
], "Lateral funiculus has: corticospinal tract (motor, descending), spinothalamic tract (pain/temp, ascending)");

mkContent("CH 03 | Meninges & Spinal Spaces", [
  {t:"3 MENINGES (outer to inner):", b:true},
  {t:"DURA MATER: tough outer fibrous sheath; forms dural sac from foramen magnum to S2 level", i:true},
  {t:"ARACHNOID MATER: middle layer; avascular; separated from dura by SUBDURAL SPACE (potential space — bleeds here)", i:true},
  {t:"PIA MATER: delicate inner; closely adherent to cord surface; has denticulate ligaments + filum terminale", i:true},
  {t:"EPIDURAL (EXTRADURAL) SPACE: between vertebral canal wall and dura; contains fat + internal vertebral venous plexus", b:true},
  {t:"Epidural anaesthesia & anaesthesia injected HERE (esp. L3–L4)", i:true},
  {t:"SUBDURAL SPACE: between dura and arachnoid; potential space; site of subdural haematoma", b:false},
  {t:"SUBARACHNOID SPACE: between arachnoid & pia; filled with CSF; site of LUMBAR PUNCTURE", b:true},
  {t:"LP performed at L3–L4 or L4–L5 interspace (below conus at L1–L2 — safe!)", i:true},
  {t:"DENTICULATE LIGAMENTS: 21 pairs of lateral pia extensions → dura; suspend cord laterally", b:false},
], "Lumbar cistern: enlarged subarachnoid space below conus (L2 to S2) — ideal site for LP & spinal anaesthesia");

mkContent("CH 03 | Spinal Nerves — Roots, Dermatomes & Myotomes", [
  {t:"31 PAIRS total: C1–C8, T1–T12, L1–L5, S1–S5, Co1", b:true},
  {t:"Each nerve: DORSAL ROOT (sensory) + VENTRAL ROOT (motor) → merge at/near intervertebral foramen", b:false},
  {t:"DORSAL ROOT GANGLION (DRG): cell bodies of first-order sensory neurons; outside spinal cord", b:false},
  {t:"KEY DERMATOMES (high-yield):", b:true},
  {t:"C6 = thumb | C7 = middle finger | C8 = little finger | T4 = nipple level | T10 = umbilicus | L1 = inguinal region", i:true},
  {t:"L3 = anterior knee | L4 = medial leg/foot | L5 = dorsum of foot/big toe | S1 = lateral foot | S3–S5 = perineum/saddle area", i:true},
  {t:"KEY MYOTOMES:", b:true},
  {t:"C5 = shoulder abduction (deltoid) | C6 = elbow flexion (biceps) | C7 = elbow extension (triceps)", i:true},
  {t:"L2–L3 = hip flexion | L3–L4 = knee extension (quadriceps) | L5 = big toe extension (EHL) | S1 = plantar flexion (gastrocnemius)", i:true},
  {t:"L4–L5 disc herniation → L5 root compression; L5–S1 → S1 root compression", b:false},
], "C8–T1 lesion → Horner syndrome (ptosis, miosis, anhidrosis); also seen with Pancoast tumour");

mkContent("CH 03 | Nerve Plexuses", [
  {t:"CERVICAL PLEXUS (C1–C4):", b:true},
  {t:"Phrenic nerve (C3,4,5 — 'keeps the diaphragm alive'); cutaneous branches (great auricular, transverse cervical, supraclavicular, lesser occipital)", i:true},
  {t:"BRACHIAL PLEXUS (C5–T1) — upper limb; Roots → Trunks → Divisions → Cords → Branches:", b:true},
  {t:"Upper trunk (C5,6); Middle trunk (C7); Lower trunk (C8,T1)", i:true},
  {t:"Lateral, Posterior, Medial cords → terminal branches: Musculocutaneous, Axillary, Radial, Median, Ulnar nerves", i:true},
  {t:"Erb's palsy (C5,C6): 'waiter's tip' — arm extended, adducted, internally rotated, pronated", i:true},
  {t:"Klumpke's palsy (C8,T1): claw hand, intrinsic hand muscle weakness; Horner's if T1 involved", i:true},
  {t:"LUMBAR PLEXUS (L1–L4): femoral n. (L2–L4), obturator n. (L2–L4), iliohypogastric, ilioinguinal, genitofemoral", b:true},
  {t:"SACRAL PLEXUS (L4–S4): sciatic nerve (L4–S3, largest nerve in body = tibial + common peroneal)", b:true},
  {t:"Common fibular (peroneal) n.: most commonly injured nerve in lower limb (foot drop); winds around fibular neck", b:false},
]);

// ══════════════════════════════════════════════════════════════
//  CHAPTER 04 — BASIC CONCEPTS OF IMAGING
// ══════════════════════════════════════════════════════════════
mkSection("CHAPTER 04", "Basic Concepts of Imaging");

mkContent("CH 04 | X-Ray (Plain Radiography) — Principles", [
  {t:"X-rays: high-energy ELECTROMAGNETIC RADIATION; shorter wavelength than UV/visible light", b:false},
  {t:"ATTENUATION: differential absorption of X-rays by different tissue densities → creates image", b:true},
  {t:"5 BASIC DENSITIES on X-ray (dark/black → bright/white):", b:true},
  {t:"1. AIR — BLACK (radiolucent, most transparent)", i:true},
  {t:"2. FAT — Dark grey", i:true},
  {t:"3. SOFT TISSUE / WATER — Grey (cannot distinguish between these two on X-ray)", i:true},
  {t:"4. BONE / CALCIFICATION — White (radiopaque; Ca²⁺ absorbs X-rays strongly)", i:true},
  {t:"5. METAL — BRIGHTEST WHITE (most opaque; surgical clips, pacemaker, bullets)", i:true},
  {t:"MNEMONIC: 'A Fat Student Will Meet success' — Air, Fat, Soft tissue, Water (same as soft), Metal", b:false},
  {t:"SILHOUETTE SIGN: when two structures of equal density touch → their interface disappears (e.g., cardiac border lost in lobar pneumonia)", b:false},
], "Radiation dose: CXR ≈ 0.02 mSv (≈ 3 days background); CT chest ≈ 7 mSv (≈ 3 years background)");

mkContent("CH 04 | X-Ray Views & Projections", [
  {t:"PA (Posterior-Anterior): beam enters posteriorly, exits anteriorly; STANDARD for chest X-ray", b:true},
  {t:"AP (Anterior-Posterior): beam enters anteriorly; used for portables, trauma, infants — MAGNIFIES anterior structures", b:false},
  {t:"LATERAL view: taken at 90° to PA; used to localise lesions, assess spine, sinuses", b:false},
  {t:"OBLIQUE: used for ribs, facet joints, oblique fractures", b:false},
  {t:"ERECT vs SUPINE: erect preferred (shows air–fluid levels, free gas under diaphragm)", b:false},
  {t:"Heart size measured on PA: cardiothoracic ratio (CTR) — normal < 0.5 (50%); > 0.5 = cardiomegaly on PA", b:true},
  {t:"LORDOTIC VIEW: for apices of lungs (detect TB)", b:false},
  {t:"DECUBITUS view: patient lying on side — detects free fluid or pneumothorax", b:false},
  {t:"STRESS VIEWS: joint ligament laxity assessment", b:false},
  {t:"FLUOROSCOPY: real-time continuous X-ray (moving images) — swallowing studies, cardiac catheterisation, orthopaedic procedures", b:false},
], "Always interpret CXR systematically: ABCDE — Airway, Breathing, Cardiac, Diaphragm, Everything else");

mkContent("CH 04 | CT Scan — Principles & Hounsfield Units", [
  {t:"CT: rotating X-ray tube + multiple detectors → CROSS-SECTIONAL axial images; rapid acquisition", b:true},
  {t:"HOUNSFIELD UNITS (HU): scale of tissue density (named after Sir Godfrey Hounsfield — Nobel Prize 1979)", b:true},
  {t:"Water = 0 HU | Air = -1000 HU | Fat = -100 to -50 HU", i:true},
  {t:"Soft tissue = +20 to +80 HU | Blood (acute) = +50–60 HU | Bone cortex = +400 to +1000 HU | Metal = +1000+", i:true},
  {t:"WINDOW SETTINGS: Window Width (WW) + Window Level/Centre (WL) control image contrast:", b:true},
  {t:"Lung window: WW=1500, WL=-600 | Bone window: WW=2000, WL=500 | Soft tissue: WW=400, WL=60 | Brain: WW=80, WL=40", i:true},
  {t:"IV CONTRAST: iodinated contrast agent → enhances blood vessels & vascular structures (appears hyperdense)", b:false},
  {t:"PHASES: Non-contrast → Arterial (25–35s) → Portal venous (60–70s) → Delayed (3–5 min)", b:false},
  {t:"SPIRAL/HELICAL CT: continuous rotation; multiplanar reconstruction (MPR) in axial, coronal, sagittal, 3D", b:false},
  {t:"ADVANTAGES: fast, bone detail, available 24/7, good for trauma, CTA/CTV", b:false},
], "Contrast contraindications: iodine allergy, renal impairment (AKI risk), metformin (hold before contrast), thyrotoxicosis");

mkContent("CH 04 | MRI — Principles & Sequences", [
  {t:"MRI: strong MAGNETIC FIELD + radiofrequency (RF) pulses → NO ionising radiation", b:true},
  {t:"Signal based on behaviour of HYDROGEN PROTONS (H₂O content of tissues)", b:false},
  {t:"T1 RELAXATION TIME: time for protons to realign with magnetic field after RF pulse (longitudinal)", b:false},
  {t:"T2 RELAXATION TIME: time for proton dephasing after RF pulse (transverse)", b:false},
  {t:"T1-WEIGHTED IMAGES:", b:true},
  {t:"FAT = BRIGHT (hyperintense) | Water/CSF = DARK | Gadolinium-enhanced areas = bright | Good for ANATOMY", i:true},
  {t:"T2-WEIGHTED IMAGES:", b:true},
  {t:"Water/CSF = BRIGHT (hyperintense) | Fat = intermediate | Ideal for PATHOLOGY (oedema, tumour, fluid, MS plaques)", i:true},
  {t:"FLAIR (Fluid Attenuated Inversion Recovery): T2 with CSF SUPPRESSED → best for periventricular lesions", b:false},
  {t:"DWI (Diffusion-weighted): detects restricted diffusion → acute STROKE, abscess, dense tumour", b:false},
  {t:"GADOLINIUM CONTRAST: paramagnetic; T1-bright; enhances areas of blood–brain barrier (BBB) breakdown", b:false},
], "MNEMONIC: T1 = 1 letter in 'fat' (fat is bright); T2 = 2 letters in 'water' (water is bright on T2)");

mkContent("CH 04 | MRI — Contraindications & Artefacts", [
  {t:"ABSOLUTE CONTRAINDICATIONS:", b:true},
  {t:"Pacemakers (most older models) | Cochlear implants | Certain aneurysm clips (ferromagnetic) | Metallic foreign bodies in eye", i:true},
  {t:"RELATIVE CONTRAINDICATIONS:", b:true},
  {t:"1st trimester pregnancy (avoid if possible) | Claustrophobia (sedation may be needed) | Some older metallic implants", i:true},
  {t:"MRI-SAFE vs MRI-CONDITIONAL vs MRI-UNSAFE: implants now classified by manufacturer", b:false},
  {t:"ADVANTAGES: Superior soft tissue contrast; multiplanar; no radiation; excellent for CNS, MSK, pelvis, heart", b:false},
  {t:"DISADVANTAGES: Long scan times; expensive; noisy (gradient coils); claustrophobia; contraindications", b:false},
  {t:"COMMON ARTEFACTS: Motion artefact | Susceptibility (metal) | Chemical shift | Aliasing (wrap-around) | Gibbs (truncation)", b:false},
  {t:"SPECIFIC SEQUENCES: MRA (magnetic resonance angiography) | MRCP (biliary/pancreatic) | fMRI (brain function)", b:false},
]);

mkContent("CH 04 | Ultrasound (USG) — Principles", [
  {t:"High-frequency sound waves (2–15 MHz); NO ionising radiation; REAL-TIME dynamic imaging", b:true},
  {t:"Transducer both emits and receives sound waves; tissue interfaces REFLECT waves (echoes) → image", b:false},
  {t:"Higher frequency = BETTER resolution but LESS penetration (and vice versa)", b:true},
  {t:"ECHOGENICITY TERMS:", b:true},
  {t:"Hyperechoic (echogenic/bright): solid/dense — bone cortex, gallstones, tendons, fat, calcifications", i:true},
  {t:"Hypoechoic (grey/darker): soft tissue — lymph nodes, muscle, some solid masses", i:true},
  {t:"Anechoic (black — NO echoes): fluid — simple cysts, urine in bladder, blood in vessels, bile", i:true},
  {t:"Isoechoic: same echogenicity as surrounding tissue (e.g., some thyroid nodules)", i:true},
  {t:"ACOUSTIC SHADOWING: dense structure (bone, calculus) blocks sound → dark shadow posterior to it", b:false},
  {t:"POSTERIOR ACOUSTIC ENHANCEMENT: fluid transmits sound well → bright area BEHIND cyst", b:false},
], "Doppler USG: detects blood flow — Colour Doppler (direction + speed); Spectral Doppler (velocity waveform)");

mkContent("CH 04 | Ultrasound — Transducers & Clinical Uses", [
  {t:"LINEAR TRANSDUCER (5–15 MHz): superficial structures — thyroid, breast, testes, MSK, vascular (veins/arteries)", b:true},
  {t:"CURVILINEAR/CONVEX TRANSDUCER (2–5 MHz): deep structures — abdomen, pelvis, obstetric scans", b:true},
  {t:"PHASED ARRAY (1–3 MHz): cardiac (echocardiography) — small footprint, deep penetration through intercostal space", b:true},
  {t:"ENDOVAGINAL / TRANSVAGINAL: pelvic organs close-up (uterus, ovaries, early pregnancy)", b:false},
  {t:"ENDORECTAL: prostate gland assessment", b:false},
  {t:"OBSTETRIC USG: fetal dating (CRL in 1st trimester), anomaly scan (~20 wks), growth monitoring", b:false},
  {t:"ADVANTAGES: Safe (no radiation), real-time, portable, cheap, guides procedures (biopsy, drain)", b:false},
  {t:"DISADVANTAGES: Poor through bone & gas; limited depth; highly operator-dependent; FOV limited", b:false},
  {t:"ELASTOGRAPHY: measures tissue stiffness — liver fibrosis staging; breast/thyroid lesion characterisation", b:false},
], "FAST exam (Focused Assessment with Sonography for Trauma): 4 windows — subxiphoid, RUQ, LUQ, pelvic");

mkContent("CH 04 | Nuclear Medicine — SPECT, PET/CT, Bone Scan", [
  {t:"Radiopharmaceutical (tracer) injected → emits gamma rays → detected externally → FUNCTIONAL images", b:true},
  {t:"Shows PHYSIOLOGICAL ACTIVITY (metabolism, perfusion, receptor binding) — not just anatomy", b:true},
  {t:"BONE SCAN (Tc-99m MDP): detects areas of ↑ bone turnover — fractures, metastases, osteomyelitis, Paget's", b:true},
  {t:"Half-life of Tc-99m = 6 hours; images taken 2–4 hours after injection", i:true},
  {t:"PET SCAN (Positron Emission Tomography): uses F-18 FDG (fluorodeoxyglucose)", b:true},
  {t:"FDG = glucose analogue; taken up by metabolically active cells (malignant tumours, brain, heart)", i:true},
  {t:"Half-life of F-18 = ~110 minutes; patient radioactive for several hours", i:true},
  {t:"PET/CT: combines PET (functional) with CT (anatomical) → gold standard for cancer STAGING & restaging", b:true},
  {t:"SPECT: Single Photon Emission CT — brain perfusion, myocardial perfusion (MIBI/Sestamibi), thyroid", b:false},
  {t:"RADIATION: patient emits radiation post-injection; staff precautions (distance, time, shielding) required", b:false},
], "Hot spot = area of ↑ uptake (e.g., metastasis on bone scan); Cold spot = ↓ uptake (e.g., infarct, cold thyroid nodule)");

mkTwoCol("CH 04 | Imaging Modality Comparison (Exam Summary)",
  "Modality",
  ["X-Ray: cheapest, fastest, best for bone/chest", "CT: cross-sectional, excellent for trauma/bone/chest", "MRI: best soft tissue contrast, no radiation", "Ultrasound: real-time, safe in pregnancy, no radiation", "PET/CT: functional + anatomical, cancer staging", "Fluoroscopy: real-time contrast studies"],
  "Key advantage vs Key limitation",
  ["X-Ray: LIMITATION: 2D, radiation, poor soft tissue", "CT: LIMITATION: highest radiation dose, contrast risk", "MRI: LIMITATION: slow, expensive, contraindications", "USG: LIMITATION: poor through bone/gas, operator-dependent", "PET/CT: LIMITATION: expensive, limited availability, radiation", "Fluoro: LIMITATION: high radiation dose, contrast risks"]
);

mkContent("CH 04 | Interventional Radiology & Special Techniques", [
  {t:"INTERVENTIONAL RADIOLOGY (IR): minimally invasive image-guided procedures", b:true},
  {t:"ANGIOGRAPHY: iodinated contrast injected into vessels under fluoroscopy — visualises arteries/veins", b:false},
  {t:"DSA (Digital Subtraction Angiography): mask image subtracted → clear vessel-only image", b:false},
  {t:"PROCEDURES: Angioplasty + stenting | Embolisation (haemostasis, fibroid, AVM) | Thrombolysis", i:true},
  {t:"TIPS (transjugular intrahepatic portosystemic shunt) | Biopsy | Drain insertion | IVC filter | PICC lines", i:true},
  {t:"BARIUM STUDIES: barium sulphate (inert, not absorbed) as contrast", b:false},
  {t:"Barium swallow (oesophagus) | Upper GI series (stomach + duodenum) | Barium enema (colon)", i:true},
  {t:"NEVER use barium if GI perforation suspected — use water-soluble contrast (Gastrografin/Omnipaque) instead", b:true},
  {t:"MRI-guided biopsy: no radiation; good for prostate, breast lesions only seen on MRI", b:false},
  {t:"CT-guided biopsy: most common — lung, liver, retroperitoneal masses", b:false},
], "Radiation protection: Time (reduce) | Distance (increase — inverse square law) | Shielding (lead apron, thyroid shield)");

// ── FINAL SUMMARY / EXAM TIP SLIDE ──────────────────────────────
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    {text:"Ch01: Know all planes, directional terms, cavity contents, tissue types, organ systems — pure MCQ gold", options:{breakLine:true, fontSize:13.5, color:WHITE, fontFace:"Calibri"}},
    {text:"Ch01: Bone types, synovial joint types, muscle roles (agonist/antagonist), nerve plexus overview", options:{breakLine:true, fontSize:13.5, color:WHITE, fontFace:"Calibri"}},
    {text:"Ch02: Germ layer derivatives = most tested embryo topic. LEARN the ECTODERM/MESODERM/ENDODERM table", options:{breakLine:true, fontSize:13.5, color:WHITE, fontFace:"Calibri"}},
    {text:"Ch02: Week-by-week: Week1=blastocyst, Week2=bilaminar, Week3=gastrulation, Weeks4-8=organogenesis", options:{breakLine:true, fontSize:13.5, color:WHITE, fontFace:"Calibri"}},
    {text:"Ch02: Chromosomal syndromes: Down(T21), Edwards(T18), Patau(T13), Klinefelter(47,XXY), Turner(45,X)", options:{breakLine:true, fontSize:13.5, color:WHITE, fontFace:"Calibri"}},
    {text:"Ch03: Vertebral column: 7C/12T/5L + sacrum/coccyx; Atlas=C1 (no body), Axis=C2 (dens); LP at L3-L4 or L4-L5", options:{breakLine:true, fontSize:13.5, color:WHITE, fontFace:"Calibri"}},
    {text:"Ch03: ALL prevents hyperextension; PLL prevents hyperflexion; Lig. flava=elastic; intrinsics=dorsal rami", options:{breakLine:true, fontSize:13.5, color:WHITE, fontFace:"Calibri"}},
    {text:"Ch04: HU scale (air=-1000, water=0, bone=+400 to +1000); T1=fat bright; T2=water bright; USG echogenicity terms", options:{fontSize:13.5, color:GOLD, bold:true, fontFace:"Calibri"}},
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