vein

vein

 [vān]

a vessel through which blood passes from various organs or parts back to the heart, in the systemic circulation carrying blood that has given up most of its oxygen. Veins, like arteries, have three coats: an inner coat (tunica intima), middle coat (tunica media), and outer coat (tunica externa); however, in veins these are less thick and collapse when the vessel is cut. Many veins, especially superficial ones, have valves formed of reduplication of their lining membrane. See Appendix 2-6 and see also Plates.

afferent v's veins that carry blood to an organ.

allantoic v's paired vessels that accompany the allantois, growing out from the primitive hindgut and entering the body stalk of the early embryo.

cardinal v's embryonic vessels that include the pre- and postcardinal veins and the ducts of Cuvier (common cardinal veins).

emissary vein one passing through a foramen of the skull and draining blood from a cerebral sinus into a vessel outside the skull. See anatomic Table of Veins in the Appendices.

postcardinal v's paired vessels in the early embryo that return blood from regions caudal to the heart.

precardinal v's paired venous trunks in the embryo cranial to the heart.

pulp v's vessels draining the venous sinuses of the spleen.

subcardinal v's paired vessels in the embryo, replacing the postcardinal veins and persisting to some degree as definitive vessels.

sublobular v's tributaries of the hepatic veins that receive the central veins of hepatic lobules.

supracardinal v's paired vessels in the embryo developing later than the subcardinal veins and persisting chiefly as the lower segment of the inferior vena cava.

thebesian v's smallest cardiac veins; see anatomic Table of Veins in the Appendices.

trabecular v's vessels coursing in splenic trabeculae, formed by tributary pulp veins.

varicose v's see varicose veins.

vitelline v's veins that return the blood from the yolk sac to the primitive heart of the early embryo.

Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

vein

(vān), [TA]

A blood vessel carrying blood toward the heart; postnatally, all veins except the pulmonary carry dark unoxygenated blood.

Synonym(s): vena [TA]

[L. vena]

Farlex Partner Medical Dictionary © Farlex 2012

vein

(vān)

n.

1.

a. Anatomy Any of the membranous tubes that form a branching system and carry blood to the heart from the cells, tissues, and organs of the body.

b. A blood vessel of any kind; a vein or artery: felt the blood pounding in her veins.

c. Something that looks like a blood vessel, such as the hindgut of a shrimp.

2. Zoology One of the thickened cuticular ribs that form the supporting network of the wing of an insect and that often carry hemolymph. Also called nervure.

tr.v. veined, veining, veins

To supply or fill with veins.

---

vein′al adj.

The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

vein

(vān) [TA]

A blood vessel carrying blood toward the heart; all the veins except the pulmonary carry dark or deoxygenated blood.
Synonym(s): vena [TA] .

[L. vena]

Medical Dictionary for the Health Professions and Nursing © Farlex 2012

vein

1. (in higher animals) that part of the BLOOD CIRCULATORY SYSTEM carrying blood back to the heart from the tissues. Veins are thin-walled, but have the same basic structure as ARTERIES, although veins are usually larger than the corresponding artery. Veins, unlike arteries, will collapse when empty, and are provided with a series of oneway valves that aid in maintaining the flow of blood back to the heart, assisted by skeletal muscles when moving.
2. (in insect wings) the thickened parts of the CUTICLE that resemble a pattern of veins and enclose tubular airsacs (tracheae) and blood sinuses. Pumping blood into these veins early on in the adult stage causes the wings to take on their final form.
3. (in vascular plants) any of the vessels within the blade of each leaf (made up chiefly of vascular tissue) that are continuous with the VASCULAR BUNDLES of the stem. The patterns of such veins are distinctive in each plant and are often used in classification.

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

vein 

A tubular vessel that carries blood towards the heart. See artery.
anterior ciliary vein One of many veins that drains the ciliary body, the deep and superficial plexuses, the anterior conjunctival veins and the episcleral veins to empty into the vortex veins.
anterior facial vein Vein branching from the angular vein at the side of the nose and running obliquely downward and backward across the face. It crosses the mandible and joins the posterior facial vein to form the common facial vein, which opens into the internal jugular. The anterior facial vein drains the part of the eyelids anterior to the tarsus.
aqueous vein One of several veins serving as exit channels for the aqueous humour, which they carry from the canal of Schlemm to the episcleral, conjunctival and subconjunctival veins.
central retinal vein A vein formed by the junction of the superior and inferior retinal veins at about the level of the lamina cribrosa on the temporal side of the central retinal artery. After a short course within the optic nerve, it empties into the cavernous sinus, the superior ophthalmic vein and sometimes into the inferior ophthalmic vein. See central retinal artery; retinal vein occlusion.
conjunctival vein One of many veins that drains the tarsal conjunctiva, the fornix, and the major portion of the bulbar conjunctiva.
inferior ophthalmic vein Vein that commences as a plexus near the floor of the orbit, runs backward on the inferior rectus muscles and divides into two branches, one which runs to the pterygoid venous plexus and the other which joins the cavernous sinus, usually via the superior ophthalmic vein. The inferior ophthalmic vein receives tributaries from the lower and lateral ocular muscles, the conjunctiva, the lacrimal sac and the two inferior vortex veins.
palpebral vein One of the veins of the upper or lower eyelid that empties for the most part into the anterior facial vein as well as into the angular, supraorbital, superior and inferior ophthalmic, the lacrimal and the superficial temporal veins.
posterior ciliary vein See vortex vein.
superior ophthalmic vein Vein that is formed near the root of the nose by a communication from the angular vein soon after it has been joined by the supraorbital vein. It passes into the orbit above the medial palpebral ligament, runs backward to the sphenoidal fissure where it usually meets the inferior ophthalmic vein, and drains into the cavernous sinus. It has many tributaries: the inferior ophthalmic vein, the anterior and posterior ethmoidal veins, the muscular vein, the lacrimal vein, the central retinal vein, the anterior ciliary vein and two of the posterior ciliary veins (the superior ones).
vortex vein One of usually four (two superior and two inferior) veins which pierce the sclera obliquely on either side of the superior and inferior recti muscles, some 6 mm behind the equator of the globe. The two superior ones open into the superior ophthalmic vein and the two inferior open into the inferior ophthalmic vein. These veins drain the posterior uveal tract. Syn. posterior ciliary vein; vena vorticosa. See anterior ciliary vein.

Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann

vein

(vān) [TA]

Blood vessel carrying blood toward the heart; postnatally, all veins except the pulmonary carry dark unoxygenated blood.

[L. vena]

Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about vein

Q. I drink liquor a lot maybe 4x a week and I love drinking but after a couple days my veins star to hurt...Y? It runs in the familly alcohol and bud but I wish I could go a whole year withought poppin bottles.. what will be perscibed to a alki?

A. FROM ALL THAT DRINKING

Q. Are long flights dangerous? I'm flying next week to my vacation, and the flight is going to be rather long (almost 16 hours non-stop). Several years ago, my 75 years-old aunt had blood clot in her lung after a flight of similar length. I also heard that during flight the blood in the legs clots and that it can cause after that problems with the lungs and breathing. Does this mean it's dangerous for me to fly? Should I change my ticket to shorter connection flights?

A. Do other relatives of yours have blood clotting problems too, like your aunt? You should tell a doctor about the problem your aunt had and ask if it's genetic.

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