CARDIOVASCULAR SYSTEM
It consists of heart and blood vessels.
A. The heart
The heart is covered by 2 types of pericardial membranes. Fibrous pericardium and
serous pericardium.
Site of the heart: It lies behind the sternum and costal cartilages, extending from
the 2nd to the 6th costal cartilages. About 2/3 of the heart lies to the left and 1/3 of
the heart lies to the right of median plane.
Structure of the heart: The heart consists of 4 chambers; 2 atria and 2
ventricles:
1. Right Atrium:
- It receives the deoxygenated blood from all parts of the body by 2 large
veins (superior vena cava and inferior vena cava).
- It sends its blood to the right ventricle through the right atrioventricular
orifice (the tricuspid valve).
2. Right ventricle:
- It sends the deoxygenated blood through the pulmonary valve to the
pulmonary artery which divides into 2 branches for each lung where
oxygenation of blood occurs.
3. Left atrium:
- It receives the oxygenated blood from both lungs through 4 pulmonary
veins.
- It pumps blood to the left ventricle via the left atrioventricular orifice (the
mitral valve).
4. Left ventricle:
- It pumps its oxygenated blood to all parts of the body through the aortic
orifice (valve), to the aorta and its branches.
Valves of the heart: the heart contains 4 valves:
2. Tricuspid valve and Pulmonary valves in the right ventricle.
3. Mitral and aortic valves in the left ventricle.
B. Blood Vessels
I.Arteries:
- The artery is the blood vessel which carries the oxygenated blood from the heart to the
periphery.
- It carries oxygenated blood except the pulmonary artery, which carries deoxygenated
blood.
Arteries of the human body:
1. Aorta: It has three parts:
a- Ascending aorta: supply the heart.
b- Arch of aorta: it supplies head, neck, brain & upper limb.
c- Descending aorta: it supplies the thorax. It is continued in the abdomen as
abdominal aorta.
2. Arteries of abdomen and pelvis:
a- Abdominal aorta: It supplies the abdominal contents. It is divided into 2 common iliac
arteries.
b- Common iliac artery: it is divided into external and internal iliac arteries.
c- Internal iliac arteries: it supplies the pelvic viscera.
d- External iliac arteries: It continues in lower limbs as femoral arteries.
3. Arteries of lower limb:
a- Femoral artery: it supplies the front of the thigh and it continues as popliteal artery in
the back of knee.
b- Popliteal artery: it is divided into anterior and posterior tibial arteries.
c- Anterior tibial artery: it lies in front of the leg and passes on the dorsum of foot as
dorsalis pedis artery.
d- Posterior tibial artery: it passes in the back of the leg and is divides in the sole of
foot into medial and lateral planter arteries.
4. Arteries of Upper Limb:
a- Axillary artery:
It is the continuation of subclavian artery.
It lies in the axilla and passes in the arm as brachial artery.
b- Brachial artery:
It is the artery of the arm.
It divides in the cubital fossa into ulnar artery medially and radial artery laterally.
c- Ulnar artery: it descends on medial side of forearm (with ulnar nerve) and in the hand it
forms the superficial palmar arch.
d- Radial artery: it descends on the lateral side of forearm and its pulsation is felt on the front
of the lower end of the radius. It is continued in the hand as the deep palmar arch.
A
Arteries of the human body
II. Veins
- The vein is a blood vessel which carries the blood from the periphery to the heart. It
carries deoxygenated blood except the pulmonary veins, which carry oxygenated blood.
- Characters:
1. It has thin wall and wide lumen.
2. It does not pulsate.
3. It has low blood pressure.
4. Most of the veins especially those of the lower limbs contain valves which prevent the
reflux (back flow) of the blood by gravity.
Big veins of the human body:
1. Veins of Head and Neck
a. External jugular vein: superficial to sternomastoid muscle.
b. Internal jugular vein: deep to the sternomastoid muscle.
2. Veins of Thorax:
a. Brachiocephalic veins: formed by union of subclavian and internal jugular
veins.
b. Superior vena cava: formed by union of the right and left brachiocephalic
veins, and it ends into the right atrium of the heart.
3. Veins of and abdomen and pelvis:
a. Common iliac vein: It is formed in the abdomen by the union of external iliac
vein which drains the lower limb and internal iliac vein which drains the pelvis.
b. Inferior vena cava: the largest vein in the body, it begins by the union of the
two common iliac veins and.
4. Veins of the Upper Limb:
A- Superficial veins: They start by dorsal venous arch on the dorsum of the hand:
1. Basilic vein: On the medial side of forearm.
2. Cephalic vein: On the lateral side of forearm. In the cubital fossa, it is connected with
the basilic vein by the median cubital vein.
B- Deep veins:
1. Venae comitantes of radial, ulnar and brachial arteries.
2. Axillary vein.
5. Veins of Lower Limb:
A- Superficial veins:
1. Dorsal venous arch: on the dorsum of the foot.
2. Long saphenous vein: on the medial side of leg and knee to end in the femoral vein.
3. Short saphenous vein: on the lateral side of the leg to end in the popliteal vein.
A- Deep veins:
1. Popliteal vein: It lies in the back of the knee and is formed by the union of the vena
comitantes of the anterior and posterior tibial arteries.
2. Femoral vein: It lies in front of thigh, it is the continuation of the popliteal vein. It
enters the abdomen and continues as external iliac vein.
Veins of head, neck, thorax and upper limb