The veins of a person have a diagram on their hands. Anatomy of the venous system

Anatomy of the venous system lower extremities is highly variable. An important role in assessing the data of instrumental examination in choosing the right method of treatment is played by knowledge of the individual characteristics of the structure of the human venous system.

In the venous system of the lower extremities, a deep and superficial network is distinguished.

deep venous network represented by paired veins accompanying the arteries of the fingers, foot and lower leg. The anterior and posterior tibial veins merge in the femoral-popliteal canal and form an unpaired popliteal vein, which passes into the powerful trunk of the femoral vein (v. femoralis). In the femoral vein, even before passing into the external iliac (v. iliaca externa), 5-8 perforating veins and the deep vein of the thigh (v. femoralis profunda), which carry blood from the muscles of the back of the thigh, flow. The latter, in addition, has direct anastomoses with the external iliac vein (v. iliaca externa), through the intermediary veins. In case of occlusion of the femoral vein, the thigh can partially flow through the deep vein system into the external iliac vein (v. iliaca externa).

Superficial venous network located in the subcutaneous tissue above the superficial fascia. It is represented by two saphenous veins - the great saphenous vein (v. saphena magna) and the small saphenous vein (v. saphena parva).

Great saphenous vein (v. saphena magna) starts from the internal marginal vein of the foot and throughout the entire length receives many subcutaneous branches of the superficial network of the thigh and lower leg. In front of the inner malleolus, it rises to the lower leg and, bending around the inner condyle of the thigh from behind, rises to the oval opening in the inguinal region. At this level, it flows into the femoral vein. The great saphenous vein is considered the longest vein in the body, has 5-10 pairs of valves, its diameter throughout is from 3 to 5 mm. In some cases, the great saphenous vein of the thigh and lower leg can be represented by two or even three trunks. 1-8 tributaries flow into the uppermost section of the great saphenous vein, in the inguinal region, often there are three branches that are of little practical importance: external genital (v. pudenda externa super ficialis), superficial epigastric (v. epigastica superficialis) and the superficial vein surrounding the ilium (v. cirkumflexia ilei superficialis).

Small saphenous vein (v. saphena parva) starts from the outer marginal vein of the foot, collecting blood mainly from the sole. Having rounded the outer ankle from behind, it rises along the middle of the back surface of the lower leg to the popliteal fossa. Starting from the middle of the lower leg, the small saphenous vein is located between the sheets of the fascia of the lower leg (N.I. Pirogov's canal), accompanied by the medial cutaneous nerve of the calf. And therefore, varicose veins of the small saphenous vein are much less common than the great saphenous vein. In 25% of cases, the vein in the popliteal fossa passes deep through the fascia and flows into the popliteal vein. In other cases, the small saphenous vein can rise above the popliteal fossa and flow into the femoral, great saphenous veins, or into the deep vein of the thigh. Therefore, before the operation, the surgeon must know exactly where the small saphenous vein flows into the deep one in order to make a targeted incision directly above the anastomosis. Both saphenous veins anastomose widely with each other by direct and indirect anastomoses and are connected through numerous perforating veins with the deep veins of the lower leg and thigh. (Fig.1).

Fig.1. Anatomy of the venous system of the lower extremities

Perforating (communicating) veins (vv. perforantes) connect deep veins with superficial ones (Fig. 2). Most perforating veins have suprafascial valves that move blood from superficial to deep veins. There are direct and indirect perforating veins. Straight lines directly connect the main trunks of the superficial and deep veins, indirect ones connect the saphenous veins indirectly, that is, they first flow into the muscular vein, which then flows into the deep vein. Normally, they are thin-walled, have a diameter of about 2 mm. With insufficiency of the valves, their walls thicken, and the diameter increases by 2-3 times. Indirect perforating veins predominate. The number of perforating veins on one limb ranges from 20 to 45. In the lower third of the lower leg, where there are no muscles, direct perforating veins predominate, located along the medial face of the tibia (Cocket area). About 50% of the communicating veins of the foot do not have valves, so blood from the foot can flow both from the deep veins to the superficial ones, and vice versa, depending on the functional load and the physiological conditions of the outflow. In most cases, perforating veins originate from tributaries, and not from the trunk of the great saphenous vein. In 90% of cases, there is incompetence of the perforating veins of the medial surface of the lower third of the leg.

The human venous system is a collection of various veins that provide full blood circulation in the body. Thanks to this system, all organs and tissues are nourished, as well as the regulation of the water balance in the cells and the removal of toxic substances from the body. According to the anatomical structure, it is similar to the arterial system, however, there are some differences that are responsible for certain functions. What is the functional purpose of the veins and what diseases can occur if the patency of blood vessels is impaired?

general characteristics

Veins are the vessels of the circulatory system that carry blood to the heart. They are formed from branched venules of small diameter, which are formed from a capillary network. The set of venules is transformed into larger vessels, from which the main veins are formed. Their walls are somewhat thinner and less elastic than those of arteries, since they are subjected to less stress and pressure.

The blood flow through the vessels is provided by the work of the heart and chest, when the diaphragm contracts during inspiration, forming a negative pressure. Valves are located in the vascular walls that prevent the reverse movement of blood. A factor contributing to the work of the venous system is the rhythmic contraction of the muscle fibers of the vessel, pushing the blood up, creating a venous pulsation.

The blood vessels that drain blood away from the tissues of the neck and head contain fewer valves because gravity makes circulation above the heart easier.

How is blood circulation carried out?

The human venous system is conditionally divided into a small and a large circle of blood circulation. The small circle is designed for thermoregulation and gas exchange in the pulmonary system. It originates from the cavity of the right ventricle, then the blood enters the pulmonary trunk, which consists of small vessels and ends in the alveoli. Oxygenated blood from the alveoli forms a venous system that flows into the left atrium, thereby completing the pulmonary circulation. A complete circulation of blood is less than five seconds.

The task of the systemic circulation is to provide all tissues of the body with blood enriched with oxygen. The circle originates in the cavity of the left ventricle, where high oxygen saturation occurs, after which the blood enters the aorta. The biological fluid saturates the peripheral tissues with oxygen, then returns to the heart through the vascular system. From most parts of the digestive tract, blood is initially filtered in the liver rather than moving directly to the heart.

Functional purpose

The full functioning of blood circulation depends on many factors, such as:

individual features of the structure and location of the veins;
gender;
age category;
lifestyle;
genetic predisposition to chronic diseases;
the presence of inflammatory processes in the body;
violations of metabolic processes;
actions of infectious agents.

If a person has risk factors that affect the functioning of the system, he should follow preventive measures, since with age there is a risk of developing venous pathologies.

Vessels contribute to the saturation of tissues with carbon dioxide

The main functions of venous vessels:

Blood circulation. Continuous movement of blood from the heart to organs and tissues.
transport of nutrients. They ensure the transfer of nutrients from the digestive tract to the bloodstream.
distribution of hormones. Regulation of active substances that carry out humoral regulation of the body.
excretion of toxins. The withdrawal of harmful substances and end products of metabolism from all tissues to the organs of the excretory system.
Protective. The blood contains immunoglobulins, antibodies, leukocytes and platelets, which protect the body from pathogenic factors.

Veins carry out general and local regulation of blood circulation

The venous system takes an active part in the spread of the pathological process, since it serves as the main route for the spread of purulent and inflammatory phenomena, tumor cells, fat and air embolism.

Structural features

The anatomical features of the vascular system lie in its important functional significance in the body and in the conditions of blood circulation. The arterial system, unlike the venous system, functions under the influence of the contractile activity of the myocardium and does not depend on the influence of external factors.

The anatomy of the venous system implies the presence of superficial and deep veins. Superficial veins are located under the skin, they start from the superficial vascular plexus or venous arch of the head, trunk, lower and upper extremities. Deeply located veins, as a rule, are paired, originate in separate parts of the body, accompany the arteries in parallel, from which they got the name "satellites".

The structure of the venous network consists in the presence of a large number of vascular plexuses and messages that provide blood circulation from one system to another. Veins of small and medium caliber, as well as some large vessels on the inner shell contain valves. The blood vessels of the lower extremities have a small number of valves, therefore, when they are weakened, pathological processes begin to form. The veins of the cervical, head and vena cava do not contain valves.

The venous wall consists of several layers:

Collagen (resist the internal movement of blood).
Smooth muscle (contraction and stretching of the venous walls facilitates the process of blood circulation).
Connective tissue (provides elasticity during body movement).

The venous walls have insufficient elasticity, since the pressure in the vessels is low, and the blood flow velocity is negligible. When the vein is stretched, outflow is difficult, but muscle contractions help the movement of fluid. An increase in blood flow velocity occurs when exposed to additional temperatures.

Risk factors in the development of vascular pathologies

The vascular system of the lower extremities is subjected to high stress during walking, running and prolonged standing. There are many reasons that provoke the development of venous pathologies. So, non-compliance with the principles of rational nutrition, when fried, salty and sweet foods predominate in the patient's diet, leads to the formation of blood clots.

Primarily, thrombus formation is observed in veins of small diameter, however, with the growth of a clot, its parts enter the main vessels, which are directed to the heart. In severe pathology, blood clots in the heart lead to its stop.

Hypodynamia contributes to stagnant processes in the vessels

Causes of venous disorders:

Hereditary predisposition (inheritance of a mutated gene responsible for the structure of blood vessels).
Changes in the hormonal background (during pregnancy and menopause, an imbalance of hormones occurs that affects the condition of the veins).
Diabetes mellitus (constantly elevated glucose levels in the bloodstream leads to damage to the venous walls).
Abuse of alcoholic beverages (alcohol dehydrates the body, resulting in a thickening of blood flow with further formation of clots).
Chronic constipation (increased intra-abdominal pressure, making it difficult for fluid to drain from the legs).

Varicose veins of the lower extremities is a fairly common pathology among the female population. This disease develops due to a decrease in the elasticity of the vascular wall, when the body is subject to intense stress. An additional provoking factor is excess body weight, which leads to stretching of the venous network. An increase in the volume of circulating fluid contributes to an additional load on the heart, since its parameters remain unchanged.

Vascular pathologies

Violation in the functioning of the venous-vascular system leads to thrombosis and varicose veins. The following diseases are most often observed in people:

Varicose veins. It is manifested by an increase in the diameter of the vascular lumen, but its thickness decreases, forming nodes. In most cases, the pathological process is localized on the lower extremities, but cases of damage to the veins of the esophagus are possible.
Atherosclerosis. The disorder of fat metabolism is characterized by the deposition of cholesterol formations in the vascular lumen. There is a high risk of complications, with damage to the coronary vessels, myocardial infarction occurs, and damage to the sinuses of the brain leads to the development of a stroke.
Thrombophlebitis. Inflammatory damage to the blood vessels, as a result of which there is a complete blockage of its lumen by a thrombus. The greatest danger lies in the migration of a thrombus throughout the body, as it can provoke severe complications in any organ.

Pathological dilation of veins of small diameter is called telangiectasia, which is manifested by a long pathological process with the formation of asterisks on the skin.

The first signs of damage to the venous system

The severity of symptoms depends on the stage of the pathological process. With the progression of damage to the venous system, the severity of manifestations increases, accompanied by the appearance of skin defects. In most cases, violation of the venous outflow occurs in the lower extremities, since they bear the greatest load.

Early signs of impaired circulation of the lower extremities:

strengthening of the venous pattern;
increased fatigue when walking;
painful sensations, accompanied by a feeling of squeezing;
severe swelling;
inflammation on the skin;
vascular deformity;
convulsive pain.

At later stages, there is increased dryness and pallor of the skin, which in the future may be complicated by the appearance of trophic ulcers.

How to diagnose pathology?

Diagnosis of diseases associated with venous circulation disorders consists in the following studies:

Functional tests (allow to assess the degree of vascular patency and the condition of their valves).
Duplex angioscanning (assessment of blood flow in real time).
Dopplerography (local determination of blood flow).
Phlebography (carried out by introducing a contrast agent).
Phleboscintiography (the introduction of a special radionuclide substance allows you to identify all possible vascular abnormalities).

Method of duplex scanning of venous circulation in the lower extremities

Studies of the state of superficial veins are carried out by visual inspection and palpation, as well as the first three methods from the list. For the diagnosis of deep vessels, the last two methods are used.

The venous system has a fairly high strength and elasticity, but the impact of negative factors leads to disruption of its activity and the development of diseases. To reduce the risk of pathologies, a person needs to follow the recommendations for a healthy lifestyle, normalize the load and undergo a timely examination by a specialist.

One of the constituent elements of the human circulatory system is a vein. Everyone who cares about their health needs to know what a vein is by definition, what is its structure and functions.

What is a vein and its anatomical features

Veins are important blood vessels that carry blood to the heart. They form a whole network that spreads throughout the body.

They are replenished with blood from the capillaries, from which it is collected and delivered back to the main engine of the body.

This movement is due to the suction function of the heart and the presence of negative pressure in the chest when inhalation occurs.

Anatomy includes a number of fairly simple elements that are located on three layers that perform their functions.

Valves play an important role in the normal functioning.

The structure of the walls of venous vessels

Knowing how this blood channel is built becomes the key to understanding what veins are in general.

The walls of the veins are made up of three layers. Outside, they are surrounded by a layer of mobile and not too dense connective tissue.

Its structure allows the lower layers to receive nutrition, including from the surrounding tissues. In addition, the fastening of the veins is carried out due to this layer as well.

The middle layer is muscle tissue. It is denser than the top, so it is he who forms their shape and maintains it.

Due to the elastic properties of this muscle tissue, the veins are able to withstand pressure drops without harming their integrity.

The muscle tissue that makes up the middle layer is formed from smooth cells.

In veins that are of the non-muscular type, the middle layer is absent.

This is characteristic of the veins passing through the bones, meninges, eyeballs, spleen and placenta.

The inner layer is a very thin film of simple cells. It is called the endothelium.

In general, the structure of the walls is similar to the structure of the walls of arteries. The width, as a rule, is greater, and the thickness of the middle layer, which consists of muscle tissue, on the contrary, is less.

Features and role of venous valves

Venous valves are part of the system that allows the movement of blood in the human body.

Venous blood flows through the body against the force of gravity. To overcome it, the muscular-venous pump comes into operation, and the valves, having filled up, do not allow the incoming fluid to return back along the vessel bed.

It is thanks to the valves that blood moves only towards the heart.

The valve is the folds that form from the inner layer, which consists of collagen.

They resemble pockets in their structure, which, under the influence of the gravity of the blood, close, holding it in the right area.

Valves can have from one to three valves, and they are located in small and medium sized veins. Large vessels do not have such a mechanism.

Failure of the valves can lead to stagnation of blood in the veins and its erratic movement. Due to this problem, varicose veins, thrombosis and similar diseases occur.

The main functions of the vein

The human venous system, whose functions are practically invisible in everyday life, if you do not think about it, ensures the life of the body.

The blood, dispersed to all corners of the body, is quickly saturated with the products of the work of all systems and carbon dioxide.

In order to remove all this and make room for the blood saturated with useful substances, the veins work.

In addition, hormones that are synthesized in the endocrine glands, as well as nutrients from the digestive system, are also carried throughout the body with the participation of veins.

And, of course, a vein is a blood vessel, so it is directly involved in regulating the process of blood circulation throughout the human body.

Thanks to her, there is a blood supply to each part of the body, during pair work with the arteries.

Structure and characteristics

The circulatory system has two circles, small and large, with their own tasks and features. The scheme of the human venous system is based precisely on this division.

Small circle of blood circulation

The small circle is also called pulmonary. Its job is to carry blood from the lungs to the left atrium.

The capillaries of the lungs have a transition to venules, which are further combined into large vessels.

These veins go to the bronchi and parts of the lungs, and already at the entrances to the lungs (gates), they combine into large channels, of which two come out of each lung.

They do not have valves, but go, respectively, from the right lung to the right atrium, and from the left to the left.

Systemic circulation

The large circle is responsible for the blood supply to each organ and tissue site in a living organism.

The upper part of the body is attached to the superior vena cava, which flows into the right atrium at the level of the third rib.

The jugular, subclavian, brachiocephalic and other adjacent veins supply blood here.

From the lower body, blood enters the iliac veins. Here the blood converges along the external and internal veins, which converge into the inferior vena cava at the level of the fourth lumbar vertebra.

All organs that do not have a pair (except the liver), blood through the portal vein first enters the liver, and from here into the inferior vena cava.

Features of the movement of blood through the veins

At some stages of movement, for example, from the lower extremities, the blood in the venous channels is forced to overcome gravity, rising almost one and a half meters on average.

This occurs due to the phases of breathing, when negative pressure occurs in the chest during inhalation.

Initially, the pressure in the veins located in the vicinity of the chest is close to atmospheric.

In addition, the contracting muscles push the blood, indirectly participating in the blood circulation process, raising the blood up.

Interesting video: the structure of a human blood vessel

To the superficial veins of the upper limb, vv. superficiales membri superioris, include the lateral and medial saphenous veins of the arm, v. cephalica et v. basilica.

Both veins start from the venous networks of the hand, rete venosum manus.

Superficial veins are more developed on the back of the hand.

On the palmar surface of the fingers there is a network of venous vessels formed by the palmar digital veins, vv. digitales palmares. This network is widely connected to the venous network of the rear of the fingers. At the base of the proximal phalanges, the veins of the palmar plexus of the fingers form the interhead veins, vv. intercapitulares, which pass through the interdigital folds to the rear of the hand.

On the palmar surface at the bases of the II-III-IV-V fingers, the interhead veins connect with each other and, forming an arc, flow into the palmar metacarpal veins, vv. metacarpales palmares.

The latter pass into the superficial and deep palmar venous arches, arcus venosi palmares superficialis et profundus. From them originate the ulnar and radial veins, vv. ulnares et vv. radiales related to deep veins.

Among the branches of the dorsal venous network, larger dorsal digital veins are distinguished, two on each finger, which follow in the longitudinal direction and, anastomosing with each other, form dorsal venous digital arches on the back of the middle of the proximal phalanges.

Vessels that drain blood from the veins of two adjacent fingers flow into vv. intercapitulares, connect with each other and form four dorsal metacarpal veins, vv. metacarpales dorsales. On the radial and ulnar sides of the hand, there is a continuation of the veins of the I and V fingers.

The remaining dorsal metacarpal veins drain into the 1st and 4th dorsal metacarpal veins.

The first dorsal metacarpal vein passes to the forearm and becomes the lateral saphenous vein of the arm, v. cephalica. The fourth dorsal metacarpal vein is called the medial saphenous vein of the arm. v. basilica.

Lateral saphenous vein of the arm, v. cephalica , is a direct continuation of the first dorsal metacarpal vein.

Starting at the back of the hand, it goes up, goes around the wrist joint and follows first along the radial edge of the forearm, and then, at the border of the lower and middle thirds, passes to its palmar surface, reaching the elbow bend.

Here the vein passes to the shoulder and goes first along the sulcus bicipitalis lateralis, and then along the groove between the deltoid and pectoralis major muscles, where it penetrates deep into the fascia. Having reached the subclavian region, v. cephalica takes the thoracoacromial vein, v. thoracoacromialis, and, perforating the medial section of the clavicular-thoracic fascia, flows into the axillary vein, v. axillaris.

Sometimes v. cephalica accompanies the accessory lateral saphenous vein of the arm, v. cephalica accessoria, located along the lateral edge of the forearm and flowing into it in the elbow area.

Medial saphenous vein of the arm, v. basilica , is a continuation of the 4th dorsal metacarpal vein. It goes up first along the back surface of the forearm, and then gradually passes to its palmar surface, along the medial edge of which it reaches the elbow bend.

Here the vein receives the intermediate vein of the elbow, v. intermedia cubiti, and, noticeably increasing in caliber, passes to the shoulder and goes to sulcus bicipitalis medialis.

Approximately at the level of the border of the lower and middle thirds of the arm v. basilica perforates the fascia of the shoulder and, continuing on its way, flows into the brachial veins, vv. brachiales.

Sometimes v. basilica only anastomoses with vv. brachiales, and itself follows along with the neurovascular bundle of the shoulder to the axillary cavity, where it flows into the axillary vein, v. axillaris.

Intermediate vein of elbow v. intermedia, starts from v. cephalica in the upper third of the forearm and, heading from the bottom up and medially, crosses obliquely the cubital fossa, falling into v. basilica. In the form of a single trunk is not always available.

On the palmar surface of the forearm between v. basilica and v. cephalica, there is a non-permanent intermediate vein of the forearm, v. intermedia antebrachii.

In the upper third of the forearm, this vein either passes along with v. intermedia cubiti, or its trunk bifurcates: one branch called the intermediate lateral saphenous vein, v. intermedia cephalica, goes to v. cephalica, the other is the intermediate medial saphenous vein, v. intermedia basilica, goes to v. basilica. In the elbow bend between v. intermedia cubiti there is a permanent anastomosis with deep veins.

In the distal forearm as v. cephalica, and v. basilica are connected to the deep palmar venous arch. In addition, v. basilica and v. cephalica in their course are widely interconnected by anastomoses both on the palmar and on the back surface of the forearm.

In medical practice, the superficial veins of the arm are often the site for various intravenous manipulations. The veins of the upper limb are divided into superficial and deep.

Superficial veins (rice. 49)

They are located under the skin, where they form venous networks. Of these, two saphenous veins of the arm are isolated: the head vein located laterally (v. cephalica) and medially - the main vein (v. basilica).

cephalic vein (v. cephalica) begins on the back of the hand, from where it follows to the radial side of the forearm, then passes to the shoulder, where it lies in the lateral groove outward from the biceps muscle, rises to the collarbone and flows into the axillary vein.

main vein (v. basilica) also begins on the back of the hand, rises along the ulnar side of the forearm to the shoulder, where it flows into the brachial vein.

In the region of the cubital fossa, between the head and main saphenous veins of the arm, there is a well-defined anastomosis - intermediate vein of the elbow (v. intermedianacubity).

Deep veins of the upper limb

They lie next to the arteries and have the same names. In addition, each artery, up to the brachial, is accompanied by two companion veins. From the deep veins of the hand, blood flows into the veins of the forearm, the ulnar and radial veins merge into the brachial, and the two brachial veins, merging, form one axillary vein. Each of these veins receives smaller veins in the corresponding area of the arm.

axillary vein unpaired, is the main collector of venous blood flowing from the upper limb. In addition to the brachial veins and the head vein of the arm, it receives the veins of the muscles of the shoulder girdle. (v. thoracoepigastrica) and chest muscles (v. thoracicalateralis). At the level of the outer edge of the 1st rib, the axillary vein continues into the subclavian vein.

subclavian vein passes in front of the subclavian artery, but is separated from it by the anterior scalene muscle and, merging behind the sternoclavicular joint with the internal jugular vein, together they form the brachiocephalic vein.

Veins of the chest

Venous blood from the walls and organs of the chest (with the exception of the heart) flows into semi-unpaired and unpaired veins.

Both veins begin in the lower part of the lumbar region, unpaired - to the right, semi-unpaired - to the left of the ascending lumbar veins. Here they anastomose widely with the lumbar veins, vv. lumbales, representing, as it were, a system of anastomoses between them. Heading further upward, the right and left ascending lumbar veins enter the chest cavity through a gap in the diaphragm. After that, they get the name: right - unpaired vein, v. azygos, and the left - semi-unpaired vein, v. hemiazygos.

unpaired vein, v. azygos, goes up along the right anterolateral surface of the thoracic spine and turns forward at the level of the body of the III thoracic vertebra. Having formed an arc with a convexity upwards, v. azygos is thrown through the right bronchus and immediately flows into the superior vena cava. Unpaired vein at the place of confluence with v. cava superior has two valves. Infused into an unpaired vein esophageal veins, vv.esophageae; bronchial veins, vv. bronchiales; posterior intercostal veins, vv. intercostales posteriores, semi-unpaired vein, v. hemiazygos.

semi-unpaired vein, v. hemiazygos, having entered the chest cavity, goes up the left lateral surface of the spinal column. At the level of the X-XII thoracic vertebrae, the semi-unpaired vein turns to the right, lies on the anterior surface of the spinal column behind the aorta and esophagus. The semi-unpaired vein crosses the anterior surface of the spinal column across and joins the unpaired vein at the level of the VIII thoracic vertebra. The semi-unpaired vein is shorter and somewhat thinner than the unpaired vein, and takes esophageal veins, vv. esophageae; mediastinal veins, vv. mediastinales; posterior intercostal veins, vv. intercostales posteriores And accessory semi-azygous vein, v. hemiazygos accessoria.

Accessory semi-unpaired vein, v. hemiazygos accessoria, is formed from 3-4 upper posterior intercostal veins of the left side and follows from top to bottom along the left lateral surface of the spinal column, flowing into v. hemiazygos or directly in v. azygos.