NEET-MDS cheat sheet

Axillary artery is divided into three parts by pectoralis minor; first part gives superior thoracic, second gives thoracoacromial and lateral thoracic, third gives subscapular and anterior and posterior circumflex humeral arteries.

Brachial plexus cords are named by relation to the second part of the axillary artery; lateral cord gives musculocutaneous and lateral root of median, medial cord gives ulnar and medial root of median, posterior cord gives radial and axillary.

Cranial nerve exits: I cribriform plate; II optic canal; III, IV, VI and V1 superior orbital fissure; V2 foramen rotundum; V3 foramen ovale; VII and VIII internal acoustic meatus; IX, X, XI jugular foramen; XII hypoglossal canal.

Parotid duct opens opposite the maxillary second molar; submandibular duct opens at the sublingual caruncle; sublingual gland drains through lesser sublingual ducts.

Inguinal canal: anterior wall external oblique aponeurosis; posterior wall transversalis fascia and conjoint tendon; floor inguinal ligament; roof internal oblique and transversus abdominis.

Femoral triangle boundaries are inguinal ligament, sartorius, and adductor longus; contents from lateral to medial are femoral nerve, artery, vein, empty space, and lymphatics.

Diaphragm openings: inferior vena cava at T8, esophagus at T10, aorta at T12; the right crus surrounds the esophageal hiatus.

Thyroid blood supply: superior thyroid artery from external carotid; inferior thyroid artery from thyrocervical trunk; thyroidea ima artery when present arises from brachiocephalic trunk or aortic arch.

Scalp layers are skin, dense connective tissue, aponeurosis, loose areolar tissue, and pericranium; the loose areolar layer is the danger space of the scalp.

Cardiac output equals heart rate multiplied by stroke volume; the Fick principle states oxygen consumption equals cardiac output times the arteriovenous oxygen difference.

Renal clearance Cx = Ux x V / Px; inulin clearance measures glomerular filtration rate; PAH clearance measures effective renal plasma flow.

Oxygen-hemoglobin curve shifts right with increased CO2, hydrogen ion, temperature, and 2,3-BPG; it shifts left with fetal hemoglobin, carbon monoxide, alkalosis, and hypothermia.

Cardiac action potential: phase 0 sodium influx; phase 1 transient potassium efflux; phase 2 calcium influx plateau; phase 3 potassium efflux; phase 4 pacemaker current in SA node.

Michaelis-Menten equation v = Vmax[S]/(Km + [S]); Km is substrate concentration at half Vmax; Lineweaver-Burk plot y-intercept equals 1/Vmax.

Rate-limiting enzymes: glycolysis phosphofructokinase-1; TCA cycle isocitrate dehydrogenase; gluconeogenesis fructose-1,6-bisphosphatase; HMP shunt glucose-6-phosphate dehydrogenase.

Insulin lowers blood glucose; glucagon raises it; ADH inserts aquaporin-2 in collecting duct; aldosterone increases ENaC and Na+/K+-ATPase activity.

Henderson-Hasselbalch equation: pH = 6.1 + log([HCO3-]/(0.03 x pCO2)); metabolic acidosis lowers bicarbonate; respiratory acidosis raises pCO2.

Deficiencies: thiamine B1 causes beriberi and Wernicke encephalopathy; niacin B3 causes pellagra; B12 causes megaloblastic anemia with neuropathy; vitamin C causes scurvy; vitamin D causes rickets or osteomalacia.

Reversible cell injury shows swelling and fatty change; irreversible injury shows mitochondrial permeability transition, membrane damage, and necrosis or apoptosis.

Acute inflammation shows vasodilation and increased vascular permeability; mediators include histamine, bradykinin, prostaglandins, and leukotrienes; neutrophils predominate early.

Granuloma contains epithelioid macrophages and Langhans giant cells; causes include tuberculosis, sarcoidosis, leprosy, and fungal infection.

Healing by primary intention has apposed clean edges and minimal granulation; secondary intention has tissue loss, more granulation tissue, wound contraction, and scarring.

Malignant tumors invade and metastasize; grading describes differentiation; staging describes extent and is the stronger prognostic factor.

Apoptosis intrinsic pathway releases cytochrome c and is regulated by Bcl-2; extrinsic pathway uses Fas/FasL and caspase-8.

Shock types are hypovolemic, cardiogenic, distributive, and obstructive; septic shock is distributive with vasodilation and endothelial injury.

Virchow triad is endothelial injury, stasis or turbulence, and hypercoagulability; these factors predispose to thrombosis.

Amyloid stains with Congo red and shows apple-green birefringence under polarized light; it is a beta-pleated sheet protein deposit.

Gram-positive cell wall has thick peptidoglycan and teichoic acid; Gram-negative wall has thin peptidoglycan plus an outer membrane containing lipopolysaccharide.

Autoclave uses 121 degrees C at 15 psi for 15 minutes; dry heat uses 160 degrees C for 2 hours; both kill bacterial spores.

Beta-lactams inhibit cell wall transpeptidase; aminoglycosides bind 30S; macrolides bind 50S; fluoroquinolones inhibit DNA gyrase; rifampicin inhibits RNA polymerase.

TB regimen RIPE uses rifampicin, isoniazid, pyrazinamide, and ethambutol; isoniazid inhibits mycolic acid synthesis; ethambutol causes optic neuritis.

Amphotericin B binds ergosterol; azoles inhibit 14-alpha demethylase; terbinafine inhibits squalene epoxidase.

Acyclovir is a guanosine analog activated by viral thymidine kinase; it inhibits viral DNA polymerase.

Local anesthetics block voltage-gated sodium channels; inflamed tissue has lower pH and less unionized drug, reducing anesthetic efficacy.

Infective endocarditis prophylaxis for high-risk dental procedures uses amoxicillin 2 g orally 30-60 minutes before the procedure; prophylaxis is not for routine mitral valve prolapse.

Rifampicin induces hepatic cytochrome P450 enzymes and can reduce levels of oral contraceptives and warfarin.

FDI permanent teeth are numbered 11-48; primary teeth are numbered 51-85; first digit indicates quadrant and second digit indicates tooth position.

Enamel is about 96% inorganic hydroxyapatite by weight; ameloblasts secrete and mineralize enamel and are lost after eruption.

Dentin is about 70% inorganic; dentinal tubules contain odontoblast processes and permit fluid movement.

Pulp zones from periphery are odontoblastic layer, cell-free zone of Weil, cell-rich zone, and central pulp; pulp stones are calcifications.

Principal periodontal ligament fibers are alveolar crest, horizontal, oblique, apical, and interradicular; oblique fibers resist axial occlusal forces.

Odontogenesis stages are bud, cap, and bell; enamel knot is a signaling center; Hertwig epithelial root sheath initiates root dentin formation.

Parotid gland is serous; submandibular gland is mixed with serous predominance; sublingual gland is mixed with mucous predominance.

Maxillary first permanent molar has three roots and four or five cusps; mandibular first permanent molar has two roots and five cusps.

Leukoplakia is a white patch that cannot be rubbed off and has no identifiable cause; dysplasia increases malignant transformation risk.

Oral squamous cell carcinoma is the most common oral malignancy; tobacco, betel quid, alcohol, and HPV16 are major risk factors.

Radicular cyst is the most common inflammatory odontogenic cyst; dentigerous cyst surrounds the crown of an unerupted tooth.

Odontogenic keratocyst has parakeratinized epithelium and basal palisading; it is locally aggressive and recurs.

Ameloblastoma is a benign but locally aggressive odontogenic tumor; histology shows reverse polarity and stellate reticulum.

Oral lichen planus shows Wickham striae and T-cell mediated basal damage; it has a small malignant transformation risk.

Pemphigus vulgaris is intraepithelial IgG against desmoglein 3; Nikolsky sign is positive and Tzanck smear shows acantholytic cells.

Mucocele commonly occurs on the lower lip from minor salivary duct obstruction; ranula is a floor-of-mouth mucocele.

Dental caries involves mutans streptococci and lactobacilli; fermentable carbohydrates lower plaque pH and promote demineralization.

Radiolucent structures include air, soft tissue, and cyst fluid; radiopaque structures include enamel, bone, metal, and calculus.

Lamina dura is the radiopaque alveolar bone lining the socket; loss of lamina dura suggests periapical or periodontal disease.

Cone beam CT gives three-dimensional bone imaging at lower dose than medical CT but has lower soft-tissue contrast.

Trigeminal neuralgia causes paroxysmal lancinating pain in V2 or V3; carbamazepine is first-line drug therapy.

Bell palsy is lower motor neuron CN VII weakness; herpes simplex virus is implicated and corticosteroids improve outcomes.

Biopsy is indicated for persistent oral ulcers, white or red patches, and any lesion suspicious for malignancy.

Fibrous dysplasia shows ground-glass bone; Paget disease may show cotton-wool skull patches; cherubism causes bilateral jaw expansion.

Sjogren syndrome causes dry eyes and mouth; labial salivary gland biopsy and anti-Ro/SSA antibodies support diagnosis.

Mandibular angle is a common fracture site; condylar fractures may cause anterior open bite and deviated opening.

Le Fort I is low maxillary; Le Fort II is pyramidal; Le Fort III is craniofacial disjunction through the nasofrontal suture and zygomatic arches.

Ludwig angina is bilateral submandibular, sublingual, and submental cellulitis; it can obstruct the airway and needs urgent drainage.

Inferior alveolar nerve block targets the pterygomandibular space; positive aspiration and lingual nerve involvement are recognized complications.

Cleft lip repair follows the rule of 10s: about 10 weeks, 10 pounds, and hemoglobin 10 g/dL; palate repair is often at 9-18 months.

Implant osseointegration is direct bone-to-implant contact without fibrous encapsulation; primary stability and favorable bone density improve success.

Incisional biopsy is used for large or suspicious lesions; excisional biopsy is used for small lesions and permits complete histologic diagnosis.

Odontogenic infection spreads along fascial planes; submandibular space involvement can extend to the lateral pharyngeal space and mediastinum.

Gingivitis is reversible inflammation confined to gingiva; periodontitis involves clinical attachment loss and alveolar bone loss.

Probing depth is distance from gingival margin to pocket base; clinical attachment level is distance from cementoenamel junction to pocket base.

Red complex periodontal pathogens are Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia.

Periodontitis staging describes severity and complexity; grading describes rate of progression and risk.

Bleeding on probing indicates active inflammation; suppuration and deep pockets increase risk of progression.

Nonsurgical therapy is scaling and root planing; systemic antibiotics are adjuncts, not substitutes, for mechanical debridement.

Smoking and poorly controlled diabetes are major risk factors for periodontitis progression.

Drug-influenced gingival enlargement is associated with phenytoin, nifedipine, and cyclosporine.

Guided tissue regeneration uses a barrier membrane to exclude epithelium and allow periodontal ligament and bone cells to repopulate.

Dental caries removal should preserve remineralizable dentin; enamel and dentin bonding rely on acid etching and smear-layer management.

Reversible pulpitis has provoked pain that resolves; irreversible pulpitis has spontaneous or lingering pain and usually needs pulp therapy.

Endodontic working length is the distance from a coronal reference point to the apical constriction, verified by apex locator and radiograph.

Sodium hypochlorite irrigation at 0.5-5.25% dissolves organic tissue and disinfects; EDTA removes the smear layer.

Chlorhexidine can be used as an irrigant but may form a precipitate with sodium hypochlorite; avoid mixing them.

Obturation uses gutta-percha with sealer; coronal seal prevents recontamination and improves endodontic success.

Maxillary first molars commonly have an MB2 canal; locating it improves endodontic success.

Avulsed permanent tooth should be replanted immediately if possible; milk or Hanks balanced salt solution is a suitable transport medium.

Composite polymerization shrinkage causes stress; C-factor is bonded surface area divided by unbonded surface area.

Complete denture balanced occlusion has contacts in centric and eccentric positions; it improves stability during function.

Centric relation is a maxillomandibular relationship with condyles in an anterior-superior position against the articular eminence; it is a reference for denture occlusion.

Reversible hydrocolloid alginate is used for preliminary impressions; vinyl polysiloxane is an elastomer for accurate final impressions.

Kennedy Class I has bilateral posterior edentulous areas; Class II is unilateral posterior; Class III is unilateral bounded posterior; Class IV is anterior bounded.

Removable partial denture rests transfer occlusal load to abutment teeth; major connectors connect components and distribute forces.

Porcelain-fused-to-metal crown uses a metal substructure and porcelain veneer; zirconia crowns provide high strength and acceptable esthetics.

Pontic design should permit cleaning; sanitation pontics are easy to clean but less esthetic.

Implant-supported prosthesis requires adequate bone volume and primary stability; osseointegration is direct bone contact.

Angle Class I has normal molar relationship; Class II has mandibular first molar distal to maxillary; Class III has mandibular first molar mesial.

SNA measures maxillary position relative to cranial base; SNB measures mandibular position; ANB estimates skeletal jaw discrepancy.

Cervical vertebral maturation stages estimate pubertal growth spurt and help time orthopedic treatment.

Orthodontic tooth movement uses controlled forces: tipping, translation, rotation, intrusion, and extrusion; excessive force causes hyalinization and root resorption.

Anchorage is resistance to unwanted tooth movement; maximum anchorage requires minimizing reaction forces on anchor teeth.

Functional appliances modify jaw growth and muscle function; headgear applies orthopedic force to the maxilla.

Clear aligners move teeth with sequential plastic trays; they require good compliance and are less effective for complex movements.

Retention after orthodontic treatment prevents relapse; fixed retainers and removable retainers are common options.

Primary teeth begin erupting around 6 months; first dental visit is by age 1 or within 6 months of first tooth eruption.

Early childhood caries affects primary maxillary incisors first; bottle feeding and frequent sugar exposure are major risk factors.

Fluoride varnish is a topical preventive agent; systemic fluoride is not recommended before 6 months and fluorosis risk depends on total intake.

Pulpotomy removes coronal pulp and preserves radicular pulp; pulpectomy removes all pulp and fills the canal with resorbable material.

Space maintainers preserve arch length after premature primary tooth loss; band-and-loop and lingual arch are examples.

Tell-show-do is a behavior guidance technique that reduces fear by explaining and demonstrating procedures.

Sealants protect susceptible pit and fissure surfaces; they are most effective when placed soon after permanent molar eruption.

Avulsed primary tooth is generally not replanted to avoid damage to the developing permanent tooth.

Incidence is new cases over a period; prevalence is all existing cases at a point or period; DMFT and dmft measure caries experience.

Cohort studies calculate relative risk; case-control studies calculate odds ratio; randomized trials best establish causality.

Screening sensitivity detects true positives; specificity detects true negatives; positive predictive value depends on prevalence.

Water fluoridation reduces caries; optimal concentration depends on climate; defluoridation reduces fluorosis risk.

Levels of prevention are primordial, primary, secondary, and tertiary; secondary prevention includes early detection and treatment.

Community periodontal index assesses periodontal status using sextants and selected index teeth.

Mean, median, and mode measure central tendency; standard deviation measures dispersion.

Dental utilization is influenced by cost, access, education, and perceived need; oral health education targets modifiable behaviors.