Vena comitans is Latin for accompanying vein. It refers to a vein that is usually paired, with both veins lying on the sides of an artery. They are found in close proximity to arteries so that the pulsations of the artery aid venous return

Venous return

Venous return is the rate of blood flow back to the heart. It normally limits cardiac output.Superimposition of the cardiac function curve and venous return curve is used in one hemodynamic model.-Physiology:...

. Because they are generally found in pairs, they are often referred to by their plural form: venae comitantes.

Venae comitantes are usually found with certain smaller arteries, especially those in the extremities. Larger arteries, on the other hand, generally do not have venae comitantes. They usually have a single, similarly sized vein which is not as intimately associated with the artery.

Examples of arteries and their venae comitantes:

• Radial artery
  Radial artery
  In human anatomy, the radial artery is the main blood vessel, with oxygenated blood, of the lateral aspect of the forearm.-Course:The radial artery arises from the bifurcation of the brachial artery in the cubital fossa. It runs distally on the anterior part of the forearm...
  
   and radial veins
  Radial veins
  In anatomy, the radial veins are venae comitantes that accompany the radial artery through the back of the hand and the lateral aspect of the forearm. They join the ulnar veins to form the brachial veins.They follow the same course as the radial artery....
  
  
• Ulnar artery
  Ulnar artery
  The ulnar artery is the main blood vessel, with oxygenated blood, of the medial aspect of the forearm. It arises from the brachial artery and terminates in the superficial palmar arch, which joins with the superficial branch of the radial artery...
  
   and ulnar veins
  Ulnar veins
  In anatomy, the ulnar veins are venae comitantes for the ulnar artery. They mostly drain the medial aspect of the forearm. They arise in the hand and terminate when they join the radial veins to form the brachial veins....
  
  
• Brachial artery
  Brachial artery
  The brachial artery is the major blood vessel of the arm.It is the continuation of the axillary artery beyond the lower margin of teres major muscle. It continues down the ventral surface of the arm until it reaches the cubital fossa at the elbow. It then divides into the radial and ulnar arteries...
  
   and brachial veins
  Brachial veins
  In human anatomy, the brachial veins are venae comitantes of the brachial artery in the arm proper. Because they are deep to muscle, they are considered deep veins. Their course is that of the brachial artery : they begin where radial veins and ulnar veins join...
  
  

Examples of arteries that do NOT have venae comitantes (i.e. those that have "regular" veins):

• Axillary artery
  Axillary artery
  In human anatomy, the axillary artery is a large blood vessel that conveys oxygenated blood to the lateral aspect of the thorax, the axilla and the upper limb...
  
   and the axillary vein
  Axillary vein
  In human anatomy, the axillary vein is a large blood vessel that conveys blood from the lateral aspect of the thorax, axilla and upper limb toward the heart...
  
  
• Subclavian artery
  Subclavian artery
  In human anatomy, the subclavian arteries are two major arteries of the upper thorax , below the clavicle . They receive blood from the top of the aorta...
  
   and the subclavian vein
  Subclavian vein
  The subclavian veins are two large veins, one on either side of the body. Their diameter is approximately that of the smallest finger.-Path:Each subclavian vein is a continuation of the axillary vein and runs from the outer border of the first rib to the medial border of anterior scalene muscle...
  
  

External links

• Photo of Venae comitantes of the brachial artery