2,701 articles
Tibia
Tibia (shin bone): the larger, medial of the two leg bones, second longest in the body after the femur. Forms the knee joint with the femur and the ankle joint with the fibula and talus; bears body weight.
Tibial nerve
Tibial nerve: terminal branch of the sciatic nerve (L4–S3) supplying motor and sensory innervation to the posterior leg and plantar foot; passes through the tarsal tunnel, dividing into medial and lateral plantar nerves; tarsal tunnel syndrome is its main entrapment.
Tibialis anterior muscle
Tibialis anterior (tibialis anticus), largest muscle of the leg's anterior compartment; dorsiflexes ankle and inverts foot; originates on lateral tibia and interosseous membrane, inserts on medial cuneiform and first metatarsal, innervated by deep fibular nerve (L4, L5).
Tibialis posterior muscle
Tibialis posterior (musculus tibialis posterior), deepest muscle of the leg's deep posterior compartment; originates from tibia, fibula, and interosseous membrane, inserts on navicular, cuneiforms, cuboid, and metatarsals 2-4; plantarflexes, inverts, and supports the medial arch; tibial nerve L4-L5.
Tickling
Tickling: touching the body to provoke laughter or squirming, divided into knismesis (light, feather-like) and gargalesis (heavy, laughter-inducing); self-tickle is suppressed by cerebellar prediction, and rats and great apes are ticklish too.
Tidal volume
Tidal volume (VT, TV) is the air moved in one normal breath, about 500 mL or 7 mL/kg ideal body weight in adults; a static lung volume in spirometry and, in ARDS ventilation, limited to 4–8 mL/kg predicted body weight.
Timrepigene emparvovec
Timrepigene emparvovec (BIIB111, AAV2-REP1) is an investigational AAV2 subretinal gene therapy delivering the CHM/REP1 gene for choroideremia; its phase 3 STAR trial missed the ≥15-letter BCVA endpoint but showed more ≥10-letter gains than controls.
Tinnitus
Tinnitus: perception of sound without an external source (ringing, buzzing, roaring), also called tinnitus aurium. Affects 10-25% of adults; linked to hearing loss, noise exposure, and medications; no FDA-approved drug treatment.
TNT trial (NCT00327691)
TNT (Treating to New Targets, NCT00327691) was a Pfizer-funded randomized trial of atorvastatin 80 mg versus 10 mg daily in 10,001 stable coronary disease patients, showing 22% fewer major cardiovascular events with intensive LDL lowering.
Toe
Toe: the five digits of the human foot; the hallux (great toe) has two phalanges and dedicated muscles, lesser toes share muscles; short toes and hallux adaptations reflect bipedal evolution; hallux valgus is the most common toe deformity.
Tongue
Tongue: muscular oral organ for chewing, swallowing, speech, and breathing; bears papillae with taste buds detecting five tastes; hypoglossal motor innervation; the regional tongue taste map is a myth.
Tonsil
Tonsil: lymphoid tissue of Waldeyer's ring (palatine, adenoid, tubal, lingual tonsils) guarding the pharynx; prone to tonsillitis, treated by tonsillectomy with modest proven benefit.
Tooth
Tooth: hard mineralized oral organ made of enamel, dentin, cementum, and pulp; develops via odontogenesis, cannot regenerate enamel, and is protected against cavities by fluoride and sealants.
Tooth Eruption
Tooth eruption: movement of teeth from alveolar bone to functional position in the mouth. Primary teeth erupt 4–10 months after birth; dental follicle and PTHrP signaling drive the process; teething symptoms affect about 70–80% of infants.
Torsion of spleen
Torsion of spleen (splenic torsion), twisting of the spleen on its vascular pedicle, usually in a wandering spleen; rare (about 500 cases), presenting with abdominal pain and mass, diagnosed by CT whirl sign, treated by splenopexy or splenectomy.
Total external ophthalmoplegia
Total external ophthalmoplegia (ICD-10 H49.3) is complete paralysis of the extraocular muscles with ptosis; acute causes center on Miller Fisher syndrome, chronic causes on mitochondrial CPEO.
Total Lung Capacity
Total lung capacity (TLC) is the lung gas volume at maximal inspiration, about 6 liters in healthy adults. Measured by plethysmography, gas dilution, or CT; reduced TLC defines restriction, elevated TLC indicates hyperinflation in COPD.
Totally endoscopic coronary artery bypass surgery
Totally endoscopic coronary artery bypass surgery, or TECAB, is a minimally invasive coronary bypass performed through chest ports with a robot, first performed in 1998 in Paris.
Touch
Touch (tactile sense, taction): the sensation of physical contact with objects, detected by mechanoreceptors in skin and mucous membranes; includes discriminative and affective (C-tactile) systems, haptics, and the somatosensory homunculus.
Toxoplasmic chorioretinitis
Toxoplasmic chorioretinitis (ocular toxoplasmosis, toxoplasma retinochoroiditis) is recurring Toxoplasma gondii inflammation of retina and choroid, a leading cause of posterior uveitis; antibiotics reduce recurrences but visual benefit is unproven.
Trabeculectomy
Trabeculectomy is a glaucoma operation that creates a small drainage channel in the eye to lower intraocular pressure, and is often described as the gold standard.
Trachea
Trachea (windpipe): midline cartilage-ringed airway from larynx to carina; 10-13 cm in adults, 16-20 C-shaped rings, trachealis muscle posteriorly, four wall layers, mucociliary clearance.
Tracheobronchial lymph nodes
Tracheobronchial lymph nodes sit at the tracheal bifurcation (superior and inferior, or carinal, groups), drain both lung lymphatic plexuses, the thoracic trachea, and esophagus, and correspond to IASLC stations 2, 4, 7, and 10 in lung cancer staging.
Trachoma
Trachoma, caused by Chlamydia trachomatis, is the leading infectious cause of blindness; controlled by the WHO SAFE strategy, with 33 countries validated as having eliminated it as a public health problem by 2026.
Tragus (ear)
Tragus (ear): the small cartilaginous fold of the auricle in front of the ear canal opening. First-arch derivative per classical and revised embryology; tragal pointer marks the facial nerve; common cartilage piercing site.
Transcranial direct-current stimulation
Transcranial direct-current stimulation (tDCS) is a non-invasive brain stimulation method delivering 1–2 mA constant current via scalp electrodes; used for depression (Level A evidence), pain, stroke, and Parkinson's disease, with HD-tDCS variants.
Transcranial Doppler
Transcranial Doppler (TCD) ultrasonography, introduced by Aaslid in 1982, is a noninvasive 2 MHz ultrasound test measuring blood flow velocity in basal brain arteries, used for vasospasm, stroke, sickle cell screening, and brain death confirmation.
Transcranial magnetic stimulation
Transcranial magnetic stimulation (TMS, rTMS) is a noninvasive brain stimulation technique introduced by Barker in 1985, using pulsed magnetic fields to depolarize cortical neurons; FDA-cleared for depression, OCD, and migraine, with seizure risk under 0.1%.
Transcutaneous pacing
Transcutaneous pacing (TCP, external pacing): emergency noninvasive cardiac pacing via skin electrodes for symptomatic bradycardia; a short-term bridge to transvenous pacing, ineffective in asystolic arrest; pioneered by Paul Zoll, re-introduced 1981 with 40 ms pulses and 80 cm2 electrodes.
Transitional epithelium
Transitional epithelium, or urothelium, is the distensible stratified epithelium lining the renal calyces, ureters, bladder, and proximal urethra, with umbrella cells, uroplakin plaques, and tight junctions forming a stretchable urine barrier.