2,701 articles
Cortical homunculus
Cortical homunculus, or sensory and motor homunculus (Latin 'little man'): distorted body maps on the primary somatosensory and motor cortices, first drawn by Wilder Penfield and Edwin Boldrey from 1937 electrical-stimulation studies of awake epilepsy patients.
Cortical interneuron
Cortical interneuron: GABAergic inhibitory neuron of the cerebral cortex, 20-30% of cortical neurons, in PV, SST, and 5HT3aR classes, born mainly in the ganglionic eminences.
Cortical Synchronization
Cortical synchronization, or neural phase synchronization, is the phase locking of cortical oscillations between brain regions, studied via PLV, coherence, and phase lag index in EEG and MEG as a mechanism for large-scale integration, memory, and attention, with volume conduction as its main measurement artifact.
Corticobasal degeneration
Corticobasal degeneration (CBD), also called corticobasal syndrome (CBS) in its clinical form, is a rare 4-repeat tauopathy causing asymmetric rigidity, apraxia, dystonia, and myoclonus, with onset around age 64, mean survival 6.5 years, and no disease-modifying treatment.
Corticobulbar tract
Corticobulbar tract (corticonuclear tract): descending pyramidal-tract pathway from the motor cortex through the internal capsule and brainstem to cranial nerve motor nuclei, bilaterally innervating most nuclei except the lower facial and hypoglossal nuclei.
Corticospinal tract
Corticospinal tract (pyramidal tract): major descending pathway for voluntary movement, from frontoparietal cortex through internal capsule to spinal cord; 75-90% of fibers cross at the medullary pyramidal decussation.
Corticotropin-releasing hormone
Corticotropin-releasing hormone (CRH, CRF, corticoliberin) is a 41-amino-acid hypothalamic peptide, isolated by Vale in 1981, that drives ACTH release via CRHR1/CRHR2 receptors in the HPA stress axis.
Cotton wool spots
Cotton wool spots (CWS) are fluffy yellow-white retinal lesions of accumulated axoplasmic debris in the nerve fiber layer, signaling ischemia from diabetes, hypertension, HIV, vein occlusion, or emboli; usually resolving in 6-12 weeks.
Coup contrecoup injury
Coup contrecoup injury: paired focal brain contusions at and opposite the site of a head blow, caused by brain-skull contact during rapid acceleration or deceleration; mechanisms include pressure gradients, cavitation, and rotation, distinguishing it from diffuse axonal injury.
Couvade syndrome
Couvade syndrome, also called sympathetic pregnancy, causes expectant fathers to experience pregnancy-like symptoms such as weight gain and nausea, which typically cease after the child's birth.
Cox maze procedure
Cox maze procedure (Cox-maze IV), a cardiac surgery devised by James L. Cox in 1987 that creates scar lesions in both atria to block atrial fibrillation signals; success 80-90%, gold standard surgical ablation.
Cramp
Cramp: sudden, involuntary, painful skeletal muscle contraction, self-resolving in seconds to minutes; common in calf, thigh, feet, hands; mechanisms debated (spinal vs peripheral); treated by stretching; quinine restricted.
Cranial nerves
Cranial nerves: twelve paired nerves (I–XII, plus controversial cranial nerve zero) emerging from the brain and brainstem, innervating head and neck structures, with nuclei organized in sensory and motor columns in the brainstem.
Craniopharyngioma
Craniopharyngioma, a rare benign sellar/suprasellar brain tumor from Rathke's pouch remnants; two distinct WHO 2021 entities, adamantinomatous (CTNNB1, children) and papillary (BRAF V600E, adults), treated by surgery, radiotherapy, and targeted drugs.
Craniotomy
Craniotomy: neurosurgical procedure temporarily removing a skull bone flap to reach the brain for tumor, hemorrhage, aneurysm, or seizure treatment; first wide approach by Wagner in 1889; bone replaced, unlike craniectomy.
Cremaster muscle
The cremaster muscle, Latin musculus cremaster, is a thin muscle layer in males that runs along the spermatic cord and raises the testis to regulate its temperature.
Crepitus
Crepitus: medical term for popping, cracking, grinding joint sounds or sensations, from gas cavitation, tendon snapping, or cartilage wear; also bony grating in fractures and subcutaneous crackling; common, usually benign without pain.
Creutzfeldt–Jakob disease
Creutzfeldt–Jakob disease (CJD), also called classic CJD, is a rare, always fatal human prion disease causing rapidly progressive dementia, about 1–2 cases per million yearly, mostly sporadic, distinct from variant CJD linked to BSE beef.
Crisscross heart
Crisscross heart (CCH), also called superoinferior ventricles or twisted atrioventricular connections, is a rare congenital malformation with crossed ventricular inflow streams from twisting of the heart about its long axis, prevalence about 1/125,000 live births.
Critical period
Critical period: a limited developmental window when experience is essential for normal brain development and its absence causes permanent change; classic model is Hubel and Wiesel's ocular dominance plasticity in cat visual cortex, distinct from broader sensitive periods.
Cross-dominance
Cross-dominance (crossed laterality, mixed dominance): dominant hand and dominant eye on opposite body sides. Affects marksmanship learning (86.1% vs 56.5% rifle qualification) but shows no reliable link to academic achievement or intelligence.
Cruciate ligament
The cruciate ligaments, or ligamenta cruciata, are the two crossed ligaments inside the knee, the anterior and posterior cruciate, which control front-to-back and rotational stability.
CSPPT trial
CSPPT (China Stroke Primary Prevention Trial), NCT00794885: 20,702 Chinese hypertensive adults randomized to enalapril 10 mg plus folic acid 0.8 mg or enalapril alone; folic acid cut first stroke 21% (HR 0.79).
CT pulmonary angiogram
CT pulmonary angiogram (CTPA, CT pulmonary angiography): contrast-enhanced CT timed to the pulmonary arteries, the standard test to diagnose acute pulmonary embolism; PIOPED II sensitivity 83%, specificity 96%, preferred over V/Q scanning.
CTO-PCI study
CTO-PCI study: percutaneous coronary intervention for chronic total coronary occlusions (blockages of at least 3 months), and the J-CTO, PROGRESS-CTO, CL, and CASTLE scoring systems predicting procedural success and wire-crossing difficulty.
Cubital fossa
Cubital fossa (antecubital fossa): triangular depression on the front of the elbow bounded by brachioradialis, pronator teres, and the inter-epicondylar line; contains radial nerve, biceps tendon, brachial artery, and median nerve; main venipuncture site.
Cushing reflex
Cushing reflex (vasopressor response, Cushing reaction): physiological response to acute intracranial pressure elevation, producing Cushing's triad of widened pulse pressure, bradycardia, and irregular respirations; proposed by Harvey Cushing in 1901.
Cutaneous lymphangiectasia
Cutaneous lymphangiectasia (acquired lymphangioma, lymphangiectasis) is dilation of superficial skin lymphatic vessels after obstruction or injury, causing frogspawn-like oozing vesicles, cellulitis risk, and treatments including CO2 laser, sclerotherapy, and excision.
Cuticle
Cuticle: the eponychium, the skin band sealing the nail plate to the proximal nail fold, and the outermost protective cell layer of a hair shaft; both barriers, damage causes paronychia or split ends.
Cutis marmorata telangiectatica congenita
Cutis marmorata telangiectatica congenita (CMTC, van Lohuizen syndrome) is a rare congenital capillary malformation causing persistent marbled skin, distinguished from physiologic cutis marmorata by failure to resolve with warming; GNA11 mosaicism, glaucoma risk.