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Bulb of vestibule
Bulb of vestibule (bulbus vestibuli, vestibular bulb): paired ~3 cm erectile tissue masses beside the vaginal opening, homologous to the male bulb of penis, engorging during arousal and attaching anteriorly to the clitoris.
Bulbar palsy
Bulbar palsy, also called progressive bulbar palsy (PBP), is lower motor neuron weakness of tongue, speech, and swallowing muscles from brainstem cranial nerve lesions; pseudobulbar palsy is its upper motor neuron, spastic counterpart.
Bulbospongiosus muscle
Bulbospongiosus (bulbocavernosus) muscle: paired pelvic floor muscle in the superficial perineal space; wraps penile bulb in males, vaginal orifice in females; innervated by pudendal nerve S2-S4; expels urine and semen, assists erection.
Bulbourethral gland
The bulbourethral glands, also called Cowper's glands, are a pair of pea-sized glands in the male reproductive system, below the prostate, that secrete alkaline pre-ejaculate, which neutralizes acidity and lubricates the urethra.
Bullous keratopathy
Bullous keratopathy is an eye condition in which blisters form in the cornea's surface layer because the corneal endothelium fails, often after cataract surgery or from Fuchs dystrophy.
Bundle branch block
Bundle branch block (BBB), left (LBBB) or right (RBBB), is a delay or block in the conduction pathway to one ventricle, causing wide QRS on ECG; LBBB signals heart disease and raises heart failure risk (RR 3.44), while management spans pacemakers, CRT, and conduction system pacing.
Bundle branches (heart)
The bundle branches are the two divisions of the heart's conduction system that carry the cardiac impulse from the bundle of His to the left and right ventricles.
Bundle of His
Bundle of His (atrioventricular bundle), discovered by Wilhelm His Jr. in 1893, is the 1.8 cm cardiac conduction strand linking the AV node to the bundle branches; target of His bundle pacing, now compared with left bundle branch pacing.
Bushy cell
Bushy cell: a principal neuron of the ventral cochlear nucleus with short bushy dendrites, two types (spherical, globular), endbulb of Held inputs, and projections for binaural sound localization.
Buttocks
Buttocks: the posterior pelvic prominences formed mainly by the gluteus maximus, medius, and minimus muscles. Key facts: gluteus maximus provides shape and hip extension; injections go in the upper outer quadrant; prominence is uniquely human.
C-reactive protein
C-reactive protein (CRP) is a pentraxin acute-phase protein made by hepatocytes, discovered in 1930 by Tillett and Francis; blood levels rise within 12–24 hours of inflammation and hsCRP above 3 mg/L marks cardiovascular inflammatory risk.
C9orf72
C9orf72, or chromosome 9 open reading frame 72, is a human gene on chromosome 9 whose GGGGCC repeat expansion, identified in 2011, is the most common genetic cause of ALS.
CA3 pyramidal cell
CA3 pyramidal cell: principal excitatory neuron of hippocampal CA3, also called cornu ammonis 3 pyramidal neuron. Defined by ~12,000 recurrent collateral synapses per rat cell, mossy fiber input, Schaffer collateral output to CA1, burst firing, and roles in pattern completion and memory.
Cadaver
Cadaver: a dead human body used for dissection, medical education, and research. Sources evolved from executed criminals and unclaimed bodies to donation programs; IFAA 2012 recommends donated bodies only.
Cajal-Retzius cell
Cajal-Retzius cells, also called CR cells, are transient reelin-secreting neurons of the developing cerebral cortex marginal zone, named after Ramón y Cajal and Retzius; they direct inside-out cortical layering and die by apoptosis after development.
Calcaneus
The calcaneus, also known as the heel bone or os calcis, is the largest tarsal bone, forming the heel, bearing most body weight, and anchoring the Achilles tendon.
Calcitonin
Calcitonin (thyrocalcitonin) is a 32-amino-acid peptide hormone from thyroid C cells, discovered by Copp in 1962, that lowers blood calcium by inhibiting osteoclastic bone resorption; used in Paget's disease, hypercalcemia, and osteoporosis.
Calcitonin gene-related peptide
Calcitonin gene-related peptide (CGRP), a 37-amino-acid neuropeptide from the calcitonin gene (alpha and beta isoforms), is a potent vasodilator whose CLR/RAMP1 receptor is the target of migraine drugs (gepants, monoclonal antibodies).
Calcium channel blocker
Calcium channel blocker (calcium antagonist): drug blocking L-type voltage-gated calcium channels in heart and vascular smooth muscle; classes dihydropyridine and non-dihydropyridine; used for hypertension, angina, arrhythmia; discovered mid-1960s from coronary dilator screening.
Calf (leg)
Calf (leg): posterior lower-leg muscle group of gastrocnemius, soleus, and plantaris (triceps surae) forming the Achilles tendon; plantarflexion, venous pump, strains, tennis leg.
Caloric reflex test
Caloric reflex test (caloric test, bithermal caloric testing): vestibular test irrigating the ear canal with warm and cool water or air to evoke nystagmus from each lateral semicircular canal separately; gold standard for unilateral vestibular hypofunction, introduced by Barany in 1906.
Cameron Health
Cameron Health, Inc., a San Clemente, California medical device company founded in 2001, developed the first commercially available subcutaneous ICD (S-ICD System) and was acquired by Boston Scientific in 2012 for $150 million plus milestones.
CaMKII in synaptic plasticity
CaMKII in synaptic plasticity: calcium/calmodulin-dependent protein kinase II, main postsynaptic density kinase. Autophosphorylation at Thr286 sustains activity after calcium entry through NMDA receptors, making it necessary and sufficient for LTP induction and a candidate molecular memory switch.
Camptodactyly-tall stature-scoliosis-hearing loss syndrome
CATSHL syndrome (camptodactyly-tall stature-scoliosis-hearing loss syndrome, OMIM 610474) is a rare FGFR3 loss-of-function disorder causing finger contractures, overgrowth, scoliosis, and sensorineural hearing loss.
Canadian Cardiovascular Society grading of angina pectoris
Canadian Cardiovascular Society (CCS) grading of angina pectoris, Campeau 1976: a four-class scale (I to IV) grading effort angina severity by the activity level provoking symptoms; widely used in guidelines, with known reproducibility limits.
Cancer-treatment-related lymphedema
Cancer-treatment-related lymphedema is chronic limb or trunk swelling caused by cancer treatment, especially lymph node surgery and radiation, affecting about 1 in 5 breast cancer patients.
Cannabinoid receptor
Cannabinoid receptors CB1 and CB2 are class A GPCRs mediating THC and endocannabinoid signaling; CB1 cloned 1990, CB2 1993, Gi/o-coupled, targets for pain, inflammation, and addiction drug development.
Capillary
Capillary: the smallest blood vessel, 5–20 µm wide, linking arterioles and venules; site of oxygen, nutrient, and fluid exchange. Discovered by Malpighi in 1660; fluid exchange follows the revised Starling principle with the endothelial glycocalyx.
Capillary endothelial cell
A capillary endothelial cell forms the single-cell-thick wall of a capillary, the smallest blood vessel and the main site of blood-tissue exchange, and adapts to the organ it serves.
Capillary leak syndrome
Capillary leak syndrome (Clarkson disease, SCLS): rare episodic disorder of capillary hyperpermeability causing hypotension, hemoconcentration, hypoalbuminemia; ~500 cases; MGUS in most; IVIG prophylaxis improves survival.