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Femoral artery
Femoral artery (Arteria femoralis): main thigh artery, continuation of the external iliac artery under the inguinal ligament, becoming the popliteal artery at the adductor hiatus; largest branch profunda femoris; key site for catheterization and PAD.
Femoral nerve
The femoral nerve is a large lower limb nerve arising from the L2, L3, and L4 lumbar plexus roots and supplying the anterior thigh muscles.
Femoral triangle
Femoral triangle (Scarpa's triangle, trigonum femorale): wedge-shaped space in the superomedial thigh bounded by inguinal ligament, sartorius, and adductor longus; contains femoral nerve, artery, vein, canal (NAVEL); site for pulse, vascular access, hernias.
Femoral vein
Femoral vein (vena femoralis), formerly misnamed superficial femoral vein: the deep thigh vein continuing the popliteal vein through the adductor hiatus to become the external iliac vein; drains the lower limb, has one to six valves, and is a standard catheter access site.
Femur
Femur (thigh bone, os femoris): the longest, heaviest, strongest human bone, running hip to knee; ~128-degree neck-shaft angle, endochondral ossification from week 7, over 300,000 US hip fractures yearly.
Fencing response
Fencing response, or tonic posturing, is an involuntary posture after traumatic brain injury: one arm extends, the opposite flexes. Linked to the brainstem lateral vestibular nucleus; indicates moderate injury forces but not worse NFL recovery outcomes.
Fetal Development
Fetal development: the week-by-week growth of a human from zygote to blastocyst, embryo (weeks 5–10), and fetus until birth at 37–42 weeks, plus clinical growth monitoring.
Fever dream
Fever dreams are vivid, bizarre, often negative dreams occurring during fever (oral temperature 100.4°F/38°C or higher). Schredl's studies show they are more bizarre, emotionally intense, heat-themed, and lucid than normal dreams, likely because fever disrupts REM sleep.
Fibrinogen
Fibrinogen (coagulation factor I) is a 340-kDa plasma glycoprotein that thrombin converts to fibrin for blood clotting; also an acute-phase protein and studied cardiovascular risk marker, with concentrate therapies for congenital deficiency.
Fibro-adipose vascular anomaly
Fibro-adipose vascular anomaly (FAVA), a rare ISSVA-provisionally unclassified vascular malformation first described in 2014, causes painful fibrofatty intramuscular lesions with contractures, PIK3CA mutations, and frequent misdiagnosis as venous malformation.
Fibromuscular dysplasia
Fibromuscular dysplasia (FMD) is an idiopathic, non-inflammatory, non-atherosclerotic arteriopathy of medium arteries, mainly renal and cervicocranial, affecting women, causing stenosis, aneurysm, dissection, and hypertension.
Fibrous joint
Fibrous joint: a joint where bones are united by fibrous connective tissue with no joint cavity. Three types: skull sutures, tooth-socket gomphoses, and syndesmoses between parallel bones like the radius and ulna.
Fibula
The fibula, also called the calf bone, is the slim lateral bone of the lower leg. It bears no weight but stabilizes the ankle and forms the lateral malleolus.
Fick principle
The Fick principle states that an organ's blood flow equals its uptake of a substance divided by the difference in concentration between inflow and outflow blood.
Filarial lymphedema and elephantiasis
Filarial lymphedema is swelling of limbs, breasts, or genitals caused by filarial worms, beginning as reversible pitting edema and progressing over years to irreversible elephantiasis.
Filariasis due to Brugia malayi
Filariasis due to Brugia malayi, also called brugian filariasis, is lymphatic filariasis caused by the mosquito-borne nematode Brugia malayi, found mainly in India and Southeast Asia.
Filariasis due to Wuchereria bancrofti
Bancroftian filariasis, lymphatic filariasis due to Wuchereria bancrofti, a mosquito-borne nematode causing 90% of LF cases; lymphoedema, hydrocele, and a global MDA elimination program.
Filtering Surgery
Filtering surgery (glaucoma filtration surgery, trabeculectomy) creates a fistula draining aqueous humor to a subconjunctival bleb to lower IOP; developed from De Wecker's 1882 fistula to Cairns' 1968 guarded trabeculectomy, now alongside tube shunts and MIGS.
Fine motor skill
Fine motor skill: coordination of small muscles, bones, and nerves for small, precise hand movements such as pincer grasp and handwriting; also called manual dexterity. Covers corticospinal, cerebellar, and basal ganglia control, pegboard normative scores, developmental milestones, and stroke rehabilitation robotics.
Finger
Finger: one of five human hand digits, each with three phalanges (two in the thumb), moved by tendons and ligaments. Hox and SHH patterning constrains tetrapods to at most five true digits.
Fingerprint
Fingerprint: impression of friction ridges on fingers, formed in fetal development, unique and lifelong. Used for identification since ancient China; modern forensics (Galton, Henry, AFIS) and biometrics with measured error rates.
FIX-Chagas trial
FIX-Chagas (NCT05519046) is a randomized InCor Heart Institute trial in São Paulo comparing cardiac contractility modulation with CRT in 60 patients with Chagas cardiomyopathy, heart failure, and non-left bundle branch block.
Flaccid paralysis
Flaccid paralysis, also called acute flaccid paralysis (AFP), is loss of muscle tone from lower motor neuron lesions, caused by Guillain-Barré syndrome, poliomyelitis, acute flaccid myelitis, transverse myelitis, botulism, or myopathies, and tracked by WHO polio surveillance.
Flat feet
Flat feet, also known as pes planus, is a common condition in which the foot's arch is diminished or absent, and it usually needs no treatment.
Flavor
Flavor is the multisensory experience of eating, combining taste, retronasal smell, and trigeminal somatosensation, shaped by visual and sound cues; most people mistake it for taste alone and never notice the olfactory component.
Fleck corneal dystrophy
Fleck corneal dystrophy (FCD), or François-Neetens speckled corneal dystrophy, is a rare autosomal dominant PIKFYVE-related stromal corneal dystrophy with tiny non-progressive white flecks, normal vision, and no treatment required.
Flexibility (anatomy)
Flexibility (anatomy): joint range of motion and resistance to rotation, shaped by extracellular matrix, titin, and stretch tolerance; improved mainly by static, dynamic, and PNF stretching.
Flexor digitorum profundus muscle
Flexor digitorum profundus (FDP), deep forearm flexor muscle; flexes DIP joints of the four medial fingers, dual median/ulnar innervation, inserts on distal phalanges; site of jersey finger and quadrigia.
Flexor retinaculum of the hand
Flexor retinaculum of the hand, also called the transverse carpal ligament: fibrous band forming the carpal tunnel roof, attached to scaphoid, trapezium, pisiform, and hamate hook, retaining nine flexor tendons and the median nerve; released in carpal tunnel surgery.
Floater
Floater (eye floater, myodesopsia): a dark spot, thread, or cobweb drifting across vision, caused by vitreous strands casting retinal shadows. Usually harmless; sudden new floaters with flashes signal possible retinal tear.