2,701 articles
Floppy eyelid syndrome
Floppy eyelid syndrome (FES), also called lax eyelid condition-related syndrome, is an underdiagnosed eyelid laxity disorder with easy upper-lid eversion, chronic papillary conjunctivitis, and strong association with obesity and obstructive sleep apnea.
Floppy iris syndrome
Intraoperative floppy iris syndrome (IFIS), also called floppy iris syndrome, is a triad of billowing iris, iris prolapse, and progressive miosis during cataract surgery, strongly linked to tamsulosin (Flomax) use for benign prostatic hyperplasia.
Flow limitation in the iliac artery
Flow limitation in the iliac artery (FLIA) is an exertional leg ischemia in endurance athletes, mainly cyclists, caused by endofibrosis, arterial kinking, or compression; diagnosed by provocative ABPI, Doppler, and NIRS testing.
FLOW-DCB trial
FLOW-DCB (NCT07852689) is a planned Korean multicenter randomized noninferiority trial comparing drug-coated balloon-based versus drug-eluting stent-only PCI in 100 adults with de novo coronary lesions, with distal FFR at 6 months as the primary outcome.
Fluid compartments
Fluid compartments: the body's water divided into intracellular fluid and extracellular fluid (plasma, interstitial, transcellular), about 42 L in a 70 kg man, governed by Starling forces and the revised glycocalyx model.
Fluid Therapy
Fluid therapy is a medical treatment that restores the volume and composition of body fluids to normal water-electrolyte balance, given intravenously, orally, by gavage, or under the skin.
Foix-Chavany-Marie syndrome
Foix-Chavany-Marie syndrome (FCMS), or bilateral anterior opercular syndrome, is a rare pseudobulbar palsy with anarthria, facio-pharyngo-glosso-masticatory paralysis, and preserved automatic movements, usually from bilateral opercular strokes.
Follicle-stimulating hormone
Follicle-stimulating hormone (FSH, follitropin) is an anterior pituitary glycoprotein gonadotropin with common alpha and unique beta subunits; it drives ovarian follicle growth via granulosa-cell FSHR and Sertoli-cell support of spermatogenesis, and is used in fertility treatment.
Follicular conjunctivitis
Follicular conjunctivitis, ICD-11 9A60.1, is conjunctival inflammation with lymphoid follicles, usually viral (adenovirus) or chlamydial, sometimes toxic from eye drops; follicles distinguish it from papillary bacterial or allergic conjunctivitis.
Follicular phase
Follicular phase: first phase of the menstrual cycle, from the first day of menstruation to ovulation, when FSH matures ovarian follicles and one dominant follicle releases an egg; typically 10-17 days and the main source of cycle length variability.
Fontan procedure
Fontan procedure: final palliative operation for single-ventricle congenital heart disease, connecting systemic venous return directly to the pulmonary arteries; staged after Norwood and Glenn, with venous hypertension and late liver, lymphatic, and thrombotic complications.
Fontanelle
Fontanelles (soft spots, fonticuli cranii) are the six membrane-covered gaps between skull bones in fetuses and infants, closing after birth; the anterior fontanelle closes around 4 to 26 months and signals raised pressure or dehydration when bulging or sunken.
Foot
Foot: terminal human lower-limb structure with 26 bones, 33 joints, three arches, and a windlass mechanism, evolved from a grasping ape-like organ for bipedal walking.
Foot drop
Foot drop (drop foot): inability to lift the front of the foot, usually from peroneal nerve injury or L5 radiculopathy; managed with AFOs, functional electrical stimulation, physiotherapy, and tendon transfer surgery.
Foramen magnum
Foramen magnum, the largest skull foramen, an oval opening in the occipital bone transmitting the medulla, vertebral arteries, and CN XI roots; key landmark in bipedalism and Chiari surgery.
Foramen ovale (heart)
Foramen ovale (heart): fetal opening between the right and left atria, also called the oval foramen, shunting blood past the lungs; normally closes at birth, persisting as a patent foramen ovale in about 25% of adults.
Forearm
The forearm, or zygopodium, is the segment of the upper limb between the elbow and wrist, containing the radius and ulna, which allow the hand to turn palm up or palm down.
Foreign body in conjunctival sac
Foreign body in conjunctival sac (ICD-10 T15.1, ICD-11 ND70.1): external material such as dust, metal, or glass lodged in the conjunctival sac between eyeball and eyelids; removed by irrigation or moist cotton applicator after anesthetic.
Foreign body in ear
Foreign body in ear (ICD-11 ND71): an object lodged in the external auditory canal, common in children (beads, food, toys) and adults (insects, hearing aid parts). Button batteries are urgent; removal uses irrigation, suction, or instruments.
Foreign body on external eye
Foreign body on external eye (ICD-11 ND70): superficially adherent or embedded objects on the cornea or conjunctival sac, causing pain, tearing, and photophobia; managed by irrigation, swab, spud, or needle removal, antibiotics, and no patching.
Foreskin
Foreskin (prepuce): the moveable fold of skin and mucosa covering the penis glans and meatus; non-retractable in infancy, retractable in 99% of boys by 17; distinct from phimosis and removed by circumcision.
Formication
Formication: tactile hallucination of insects crawling on or under the skin, from Latin formica (ant). Symptom of stimulant intoxication, menopause, neuropathy, and delusional infestation; not a delusion by itself.
Fossa ovalis (heart)
Fossa ovalis: oval depression on the lower interatrial septum of the right atrium, the closed remnant of the fetal foramen ovale; floor is septum primum, rim (limbus) is septum secundum; fusion fails in about 25% of people, leaving a patent foramen ovale.
Fractional flow reserve
Fractional flow reserve (FFR) is an invasive coronary physiology index, the distal-to-aortic pressure ratio during maximal hyperemia, with FFR ≤0.80 guiding revascularization of intermediate stenoses; introduced by Pijls and De Bruyne in the early 1990s and validated by DEFER, FAME, and FAME 2 trials.
Fracture of orbital floor
Fracture of orbital floor, or blowout fracture: break of the thin maxillary roof with intact inferior rim, causing diplopia, enophthalmos, and V2 numbness; repaired via transconjunctival, subciliary, subtarsal, or endoscopic approaches.
Framingham Heart Study
Framingham Heart Study, begun 1948 in Framingham, Massachusetts under the NHLBI: a longitudinal cohort study of 5,209 original participants, later six cohorts, that identified major cardiovascular risk factors and produced the Framingham risk score.
Frank–Starling law
Frank–Starling law (Starling's law of the heart): intrinsic cardiac mechanism whereby greater ventricular filling (preload) stretches myocardial fibers and increases stroke volume; named for Otto Frank (1895 frog heart) and Ernest Starling (1915 law of the heart).
Fraternal birth order and male sexual orientation
Fraternal birth order effect (FBOE): each older brother raises a man's odds of homosexuality by about 33%, attributed to the maternal immune hypothesis (H-Y antigens); pooled OBOR 1.47, challenged in 2023 as a statistical artefact.
Free energy principle
Free energy principle (FEP), Karl Friston's theory of self-organizing biological agents: they minimize variational free energy, a bound on sensory surprise, via perception and active inference; corollary of Bayesian brain ideas, criticized as unfalsifiable.
Frenulum
A frenulum (plural frenula, also frenum) is a small fold of tissue anchoring one movable body structure to another, found in the mouth, genitals, digestive tract, and brain.