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Medical Dictionary


venation (ve-na′shun)
The arrangement and distribution of veins. [L. vena, vein]

1. The veins, venous. SEE ALSO: veno-. [L. vena, vein] 2. Combining form relating to venom. [L. venenum, poison]

venectasia (ve-nek-ta′se-a)
SYN: phlebectasia.

venectomy (ve-nek′to-me)
SYN: phlebectomy.

veneer (ve-ner′)
1. A thin surface layer laid over a base of common material. 2. In dentistry, a layer of tooth-colored material, usually porcelain or composite resin, attached to and covering the surface of a metal crown or natural tooth structure. [Fr. fournir, to furnish]

venenation (ven-e-na′shun, ve-ne-)
Poisoning, as from a sting or bite. [L. veneno, pp. -atus, to poison, fr. venenum, poison]

veneniferous (ven-e-nif′e-rus)
Conveying poison, as through a sting or bite. [L. venenifer, fr. venenum, poison, + fero, to carry]

venenosalivary (ven′e-no-sal′i-var-e)
Secreting a poisonous saliva, said of venomous reptiles. SYN: venomosalivary.

venenosity (ven-e-nos′i-te)
The state of containing poison or being poisonous. [L. venenosus, poisonous]

venenous (ven′e-nus)
SYN: poisonous. [L. venenosus]

venereal (ve-ner′e-al)
Relating to or resulting from sexual intercourse. [L. Venus (vener-), goddess of love]

venereology (ve-ner-e-ol′o-je)
The study of venereal disease. [venereal (disease) + G. logos, study]

venereophobia (ve-ner′e-o-fo′be-a)
Morbid fear of venereal disease. [venereal (disease) + G. phobos, fear]

venesection (ven-e-sek′shun)
SYN: phlebotomy. [L. vena, vein, + sectio, a cutting]

See veno-.

venin (ven′in)
Any poisonous substance found in snake venom. [see venom]

venipuncture (ven′i-punk-choor, ve′ni-)
The puncture of a vein, usually to withdraw blood or inject a solution.

John, English logician and philosopher, 1834–1923. See V. diagram.

veno-, veni-
The veins. SEE ALSO: vene- (1) . [L. vena]

venoclysis (ve-nok′li-sis)
SYN: phleboclysis. [veno- + G. klysis, a washing out]

venofibrosis (ve′no-fi-bro′sis)
SYN: phlebosclerosis.

venogram (ve′no-gram)
1. Radiograph of opacified veins. 2. SYN: phlebogram. [veno- + G. gramma, a writing]

venography (ve-nog′ra-fe)
Radiographic demonstration of a vein, after the injection of contrast medium. SYN: phlebography (2) . [veno- + G. grapho, to write] splenic portal v. SYN: splenoportography. transosseous v. radiographic demonstration of veins that drain a bone's marrow, by injection of contrast medium into the marrow at an appropriate point, as in vertebral v. or azygography by rib injection. vertebral v. radiographic demonstration of the epidural venous plexus by injection of contrast medium into the spinous process.

venom (ven′om)
A poisonous fluid secreted by snakes, spiders, scorpions, etc. [M. Eng. and O. Fr. venim, fr. L. venenum, poison] kokoi v. a potent neurotoxin found in the frog Phyllobates bicolor; it is a nonprotein compound with a molecular weight of approximately 400, and is lethal in microgram quantities. Russell's viper v. a v. derived from Russell's viper (Vipera russelli), which acts as an intrinsic thromboplastin; used in the laboratory evaluation of deficiencies of factor X or topically to arrest local hemorrhage in hemophilia.

venomosalivary (ven′o-mo-sal′i-var-e)
SYN: venenosalivary.

venomotor (ve′no-mo′ter)
Causing change in the caliber of a vein. [veno- + L. motor, a move]

venoperitoneostomy (ve′no-per-i-to-ne-os′to-me)
An obsolete operation involving insertion of the cut end of the saphenous vein into the peritoneal cavity in cases of ascites; the vein is inverted so that the valves prevent regurgitation of blood into the cavity while the ascitic fluid flows into the vein. [veno- + peritoneum + G. stoma, mouth]

venopressor (ve-no-pres′er)
Relating to the venous blood pressure and consequently the volume of venous supply to the right side of the heart.

venosclerosis (ve′no-skle-ro′sis)
SYN: phlebosclerosis.

venose (ve′nos)
Having veins; veiny. [L. venosus]

venosinal (ve′no-si′nal)
Pertaining to the vena cava and the atrial sinus of the heart.

venosity (ve-nos′i-te)
1. A venous state; a condition in which the bulk of the blood is in the veins at the expense of the arteries. 2. The unaerated condition of venous blood or of hypoxemic arterial blood.

venostasis (ve-no-sta′sis, ve-nos′ta-sis)
SYN: phlebostasis. [veno- + G. stasis, a standing]

venostat (ve′no-stat)
Any instrument for arresting venous bleeding. [veno- + G. statos, standing, stationary]

venostomy (ve-nos′to-me)
SYN: cutdown.

venotomy (ve-not′o-me)
SYN: phlebotomy.

venous (ve′nus)
Relating to a vein or to the veins. SYN: phleboid (2) . [L. venosus]

venovenostomy (ve′no-ve-nos′to-me)
The formation of an anastomosis between two veins. SYN: phlebophlebostomy. [veno- + veno- + G. stoma, mouth]

An opening into a cavity or canal, especially one through which the contents of such a cavity are discharged, as the anus. [O. Fr. fente, a chink, cleft]

venter (ven′ter) [TA]
1. SYN: abdomen. 2. [NA] SYN: belly (2) . 3. One of the great cavities of the body. 4. The uterus. [L. v. (ventr-), belly] v. anterior musculi digastrici [TA] SYN: anterior belly of digastric muscle. v. frontalis musculi occipitofrontalis [TA] SYN: frontal belly of occipitofrontalis muscle. v. inferior musculi omohyoidei [TA] SYN: inferior belly of omohyoid muscle. v. occipitalis musculi occipitofrontalis [TA] SYN: occipital belly of occipitofrontalis muscle. v. posterior musculi digastrici [TA] SYN: posterior belly of digastric muscle. v. superior musculi omohyoidei [TA] SYN: superior belly of omohyoid muscle.

ventilate (ven′ti-lat)
To aerate, or oxygenate, the blood in the pulmonary capillaries. SYN: air (2) . [L. ventilo, pp. -atus, to fan, fr. ventus, the wind]

ventilation (ven-ti-la′shun)
1. Replacement of air or other gas in a space by fresh air or gas. 2. Movement of gas(es) into and out of the lungs. SYN: oxidative metabolism, respiration (2) . 3. (V) In physiology, the tidal exchange of air between the lungs and the atmosphere that occurs in breathing. SEE ALSO: respiration. [see ventilate] airway pressure release v. mechanical v. in which patients being treated with continuous positive airway pressure have intermittent decreases rather than increases in airway pressure and volume. alveolar v. (VA) the volume of gas expired from the alveoli to the outside of the body per minute; calculated as the respiratory frequency (f) multiplied by the difference between tidal volume and the dead space (VT − VD); units: ml/min BTPS. artificial v. any means of producing gas exchange mechanically or manually between the lungs and the surrounding air, which is not performed entirely by the person's own respiratory system. SYN: artificial respiration. assist-control v. artificial positive-pressure v. by machine in which a full breath is produced automatically, following a patient's natural inspiratory effort. In the event that the patient does not initiate such an effort, the machine will provide a baseline, or “backup” respiratory rate. assisted v. application of mechanically or manually generated positive pressure to gas(es) in or about the airway during inhalation as a means of augmenting movement of gases into the lungs. SYN: assisted respiration. bag v. SYN: manual v.. continuous positive pressure v. (CPPV) SYN: controlled mechanical v.. controlled v. intermittent application of mechanically or manually generated positive pressure to gas(es) in or about the airway as a means of forcing gases into the lungs in the absence of spontaneous ventilatory efforts. SYN: controlled respiration. controlled mechanical v. (CMV) artificial v. in which all inspirations are provided by positive pressure applied to the airway, regardless of the patient's own efforts at breathing. In current clinical practice, this mode is almost never used. SYN: continuous positive pressure v., intermittent positive pressure v.. high-frequency v. mechanical v. using “jet” administration of breaths at frequencies anywhere from 300–3000 breaths per minute to avoid some complications of more conventional v.. intermittent mandatory v. (IMV) mechanical application of positive pressure volume at a predetermined frequency to the airway, interspersed between the patient's own natural breathing through the ventilator circuit. No attempt is made to time the machine's breaths with the patient's own. intermittent positive pressure v. (IPPV) SYN: controlled mechanical v.. inverse-ratio v. mechanical v. in which the time allowed by the machine for inspiration exceeds that allowed for expiration, which is opposite the situation in more standard modes of v.. liquid v. an experimental means of ventilating lungs suffering from severe injury, through use of O2 and CO2 dissolved in perfluorocarbons in a liquid, thus (theoretically) decreasing the incidence of atelectasis and other problems. mandatory minute v. mechanical v. in which the ventilator is configured to ensure a certain minute volume, but only if needed. manual v. intermittent manual compression of a gas-filled reservoir bag to force gases into a patient's lungs and thus maintain oxygenation and carbon dioxide elimination during apnea or hypoventilation. SYN: bag v.. maximum voluntary v. (MVV) the volume of air breathed when an individual breathes as deeply and as quickly as possible for a given time ( e.g., 15 s.). Usually extrapolated to what could be breathed over 1 minute. SYN: maximum breathing capacity. mechanical v. any mechanically assisted breathing, employing either positive or negative pressure devices. Some positive-pressure devices require intubation of the trachea and some require only a mask applied to the mouth or nose. For the past several decades, the standard way of mechanicaly ventilating a patient with respiratory failure has involved intubation of the trachea and either pressure- or volume-limited application of positive pressure to the lungs through the endotracheal tube; currently, the need for intubation in all cases is coming into question and many chronic respiratory failure patients can be adequately ventilated by noninvasive devices. negative pressure v. mechanical v. in which various devices that surround the thorax are used in such a way that the development of negative or subatmospheric pressure causes thoracic expansion and thus inhalation; the release of the negative pressure allows the thorax to relax and thus the lungs to exhale. This is the type of v. made famous by the “iron lung,” used in so many patients with poliomyelitis. Other such ventilators include the cuirass and the body suit. noninvasive positive pressure v. the application of positive pressure through a nasal or full-face mask encompassing the nose and mouth, which is cycled in a similar way to modes of v. in which more direct control of the patient's airway or trachea has been achieved. This type of v. is often used to temporize while treating the patient to avoid endotracheal intubation. permissive hypercapnic v. mechanical v. in which the level of carbon dioxide in the blood is allowed to rise well above normal values, to minimize the amount of mechanical support given to the patient, and thus minimize complications of that support, such as barotrauma. This mode of v. is used commonly in severe asthmatic patients, who, if ventilated more traditionally, would generate huge pressures in their airways, with resultant pneumothorax. pressure-controlled v. mechanical v. that is achieved regardless of the patient's spontaneous breathing, but that uses pressure as the major determining variable, along with rate and time, of how much air the patient receives. pressure-support v. mechanical ventilatory assistance in which each breath triggers a pressure-limited amount of support. The ventilator only provides support of each breath to a preset amount of pressure, thus the volume breathed can differ from breath to breath taken. proportional assist v. mechanical v. in which the ventilator, in synchrony with the patient's own breathing, gives support in proportion to the effort generated by the patient. This mode allows the patient to determine completely how much support is given by the machine. pulmonary v. respiratory minute volume, i.e., the total volume of gas per minute inspired (VI) or expired (VE) expressed in liters per minute; differs from alveolar v. by including the exchange of dead space gas. synchronized intermittent mandatory v. (SIMV) intermittent mandatory v. spontaneously initiated by the patient to increase tidal volume to a preset volume, and subsequently synchronized with the patient's respiratory cycle; if the patient makes no respiratory effort, the machine automatically delivers a preset number of breaths by itself. wasted v. that part of the pulmonary v. which is ineffective in exchanging oxygen and carbon dioxide with pulmonary capillary blood; calculated as physiologic dead space multiplied by respiratory frequency.

ventilation/perfusion mismatch
An imbalance between alveolar ventilation and pulmonary capillary blood flow.

ventilator (ven′til-a-tor)
SYN: respirator. [L. ventilo, to fan, fr. ventus,wind, + -ator, agent suffix] cuirass v. rigid breast plate that fits over the anterior portion of the chest and by application and release of negative pressure moves the chest wall, thus “breathing” for the patient.

An endosteal implant, usually made of titanium, utilized to provide support and fixation for a dental prosthesis by means of projections through the mucosa; also used to designate a family of implants.

ventrad (ven′trad)
Toward the ventral aspect; opposed to dorsad. [L. venter, belly, + ad, to]

ventral (ven′tral) [TA]
1. Pertaining to the belly or to any venter. 2. SYN: anterior (1) . 3. In veterinary anatomy, the undersurface of an animal; often used to indicate the position of one structure relative to another, i.e., situated nearer the undersurface of the body. [L. ventralis]

ventralis (ven-tra′lis) [TA]
SYN: anterior (1) . [L.]

ventral paraflocculus
A small hemisphere portion of the posterior lobe of the cerebellum (lobule IX) that is structurally associated with the tonsil of the cerebellum (also lobule HIX) and with the uvula (vermis lobule IX). SYN: paraflocculus ventralis.

ventricle (ven′tri-kl) [TA]
A normal cavity, as of the brain or heart. SYN: ventriculus (2) [TA] . [L. ventriculus, dim. of venter, belly] Arantius v. SYN: calamus scriptorius. cerebral ventricles lateral v., fourth v., third v., cavity of septum pellucidum. v. of cerebral hemisphere SYN: lateral v.. v. of diencephalon SYN: third v.. double outlet right v. a heterogeneous category of congenital abnormalities as yet unclassified. Basically both great arteries arise in whole or in part from the right v. or an infundibular chamber. Ventricular septal defect is nearly always present. Duncan v. SYN: cavity of septum pellucidum. fifth v. SYN: cavity of septum pellucidum. fourth v. [TA] a cavity of irregular tentlike shape extending from the obex rostralward to its communication with the sylvian aqueduct, enclosed between the cerebellum dorsally and the rhombencephalic tegmentum ventrally, having a rhomboid-shaped floor (rhomboid fossa) and a tentlike roof which in its caudal part is formed by the tela choroidea and the posterior medullary velum, in its middle part by the white matter of the cerebellum, and in its narrowing rostral part (recessus superior) by the anterior medullary velum. The fourth v. reaches its greatest width at the pontomedullary transition, where it expands laterally behind the cerebellar peduncles into the spoutlike lateral recess, and its greatest height at the fastigial recess, which reaches up into the cerebellar white matter. Direct communication of the brain's v. system and the subarachnoid space is established at the level of the fourth v. by a median opening in the tela choroidea, the medial aperture of Magendie's foramen, which opens into the cerebellomedullary cistern, and on both sides by the lateral aperture or foramen of Luschka, which connects the lateral recess with the interpeduncular cistern. SYN: ventriculus quartus [TA] , v. of rhombencephalon. laryngeal v. [TA] the recess in each lateral wall of the larynx between the vestibular and vocal folds and into which the laryngeal sacculus opens. SYN: ventriculus laryngis [TA] , laryngeal sinus, Morgagni sinus (3) , Morgagni v., sinus laryngeus. lateral v. [TA] a cavity shaped somewhat like a horseshoe in conformity with the general shape of the hemisphere; each lateral v. communicates with the third v. through the interventricular foramen of Monro, and expands from there forward into the frontal lobe as the anterior horn as well as caudally over the thalamus as the central part (cella media) or body which, behind the thalamus, curves ventrally and laterally, then forward into the temporal lobe as the inferior horn; from the apex of the curve a variably sized posterior horn extends back into the white matter of the occipital lobe. The large choroid plexus of the lateral v. invades the cella media and the inferior horn (but not the anterior and posterior horn) from the medial side. SYN: ventriculus lateralis [TA] , v. of cerebral hemisphere. left v. [TA] the lower chamber on the left side of the heart that receives the arterial blood from the left atrium and drives it by the contraction of its walls into the aorta. SYN: ventriculus sinister [TA] . Morgagni v. SYN: laryngeal v.. parchment right v. SYN: Uhl anomaly. v. of rhombencephalon SYN: fourth v.. right v. [TA] the lower chamber on the right side of the heart which receives the venous blood from the right atrium and drives it by the contraction of its walls into the pulmonary artery. SYN: ventriculus dexter [TA] . (right/left) ventricles of heart one of the two lower chambers of the heart. SYN: ventriculus cordis dexter/sinister. single v. congenital absence or near total absence of the ventricular septum. sixth v. SYN: Verga v.. sylvian v. SYN: cavity of septum pellucidum. v. of Sylvius SYN: cavity of septum pellucidum. terminal v. [TA] a dilation of the central canal of the spinal cord at the tip of the medullary cone. SYN: ventriculus terminalis [TA] . third v. [TA] a narrow, vertically oriented, irregularly quadrilateral cavity in the midplane, extending from the lamina terminalis to the rostral opening of the mesencephalic aqueduct. This v. communicates at its rostrodorsal corner with each of the two lateral ventricles through the left and right interventricular foramen of Monro. Its narrow roof is formed by the tela choroidea which is attached on either side to the tenia thalami; its lateral wall is formed by the medial surface of the thalamus and, below the hypothalamic sulcus, by the hypothalamus, which also forms its floor. In lateral profile, the third v. exhibits a number of recesses: in its floor, from before backward, 1) the preoptic recess in the acute angle between the base of the lamina terminalis and the dorsum of the optic chiasm, 2) the infundibular recess extending ventrally into the infundibulum but (in humans) not into the hypophysial stalk, and 3) the mamillary or inframamillary recess caused by the protrusion of the mamillary bodies into the v.. From its dorsocaudal corner, the pineal recess extends caudally into the pineal stalk. SYN: ventriculus tertius [TA] , v. of diencephalon. Verga v. an inconstant, horizontal, slitlike space between the posterior one-third of the corpus callosum and the underlying commissura fornicis (commissura hippocampi; psalterium) resulting from failure of these two commissural plates to fuse completely during fetal development; like the cavity of the septum pellucidum, the space is not a true v. in the sense that it did not develop from the central canal of the neural tube. SYN: cavum psalterii, cavum vergae, sixth v.. Vieussens v. SYN: cavity of septum pellucidum. Wenzel v. SYN: cavity of septum pellucidum.

ventricose (ven′tri-kos)
Bulging or swollen on one side or unequally.

ventricular (ven-trik′u-lar)
Relating to a ventricle, in any sense. SYN: ventricularis (1) .

ventricularis (ven-trik′u-la′ris)
1. SYN: ventricular. 2. SYN: thyroepiglottic part of thyroarytenoid (muscle). [Mod. L. fr. L. ventriculus]

ventricularization (ven-trik′u-lar-i-za′shun)
Transformation of an atrial phenomenon to simulate a ventricular one, especially of the atrial (or venous) pulse tracing in tricuspid regurgitation.

ventricular ponderance (ven-trik′7Macr;u-lar pon′der-ans)
A semiobsolete electrocardiographic term suggesting that one ventricle is either larger or thicker than the other.


ventriculitis (ven-trik-u-li′tis)
Inflammation of the ventricles of the brain. [ventricle + G. -itis, inflammation]

A ventricle. [L. ventriculus]

ventriculoatrial (VA) (ven-trik′u-lo-a′tre-al)
Relating to both ventricles and atria, especially to the sequential passage of conduction in the retrograde direction from ventricle to atrium.

ventriculocisternostomy (ven-trik′u-lo-sis′ter-nos′to-me)
An artificial opening between the ventricles of the brain and the cisterna magna. SEE ALSO: shunt (2) . [ventriculo- + L. cisterna, cistern, + G. stoma, mouth]

ventriculography (ven-trik-u-log′ra-fe)
1. Radiographic demonstration of the cerebral ventricles by direct injection of air or contrast medium; developed and described by Dandy in 1918. Cf.:pneumoencephalography. 2. Demonstration of the contractility of the cardiac ventricles by recording serially the distribution of intravenously injected radionuclide or that of radiographic contrast medium injected through an intracardiac catheter. [ventriculo- + G. graphe, a writing] radionuclide v. SYN: radionuclide angiocardiography.

ventriculomastoidostomy (ven-trik′u-lo-mas′toy-dos′to-me)
Operation for the establishment of a communication between the lateral cerebral ventricle and the mastoid antrum by means of a polythene tube for the relief of hydrocephalus. SEE ALSO: shunt (2) . [ventriculo- + mastoid, + G. stoma, mouth]

ventriculonector (ven-trik′oo-lo-nek′ter, -tor)
SYN: atrioventricular bundle. [ventriculo- + L. necto, to join]


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