Blood Vessels: Main blood vessels and their branches -2

Location of Common Arteries and Veins

Names of Systemic Arteries

The Aorta and Its Branches

The aorta is the largest artery in the body. It extends upward and to the right from the left ventricle. Then it curves backward and to the left. It continues down behind the heart just in front of the vertebral column, through the diaphragm, and into the abdomen. It has four principal branches:

• The Ascending Aorta: It is the first portion of the aorta. It begins at the aortic valve.
• The Arch of the Aorta: It is located immediately beyond the ascending aorta.
•  The Thoracic Aorta: It is a continuation of the arch of the aorta. It is also called descending aorta
• The Abdominal Aorta: It is a continuation of the thoracic aorta in the abdominal cavity. It is the section between the diaphragm and the common iliac arteries.

Branches of the Ascending Aorta

The ascending Aorta has two branches near the heart that supply the all parts of the myocardium. They are:

• The left coronary arteries
• The right coronary arteries

Branches of the Arch of the Aorta

The arch of aorta gives off three large branches: the brachiocephalic trunk, the left common carotid and the left subclavian.

• The brachiocephalic trunk is a short artery. Its name means that is supplies the head and the arm.
• After extending upward, it divides into the right subclavian artery, and the right common carotid artery.
• The right subclavian artery supplies the right upper extremity and the right side of the head and neck.
• The right common carotid artery supplies the right side of the head and the neck.
•  The left common carotid artery is the second branch which extends upward from the highest part of the aortic arch. It supplies the left side of the neck and the head.
• The left subclavian artery extends under the left collar bone (clavicle) and supplies the left upper extremity.

Branches of the Thoracic Aorta

The third part of the aorta, the thoracic aorta, consists of parietal and visceral branches. They supply branches to the chest wall, to the esophagus, and to the bronchi and their treelike subdivisions in the lungs.

Parietal branches of the thoracic aorta include:

• Posterior intercostals arteries supply the intercostals, and deep muscles of the back.
• Subcostal arteries supply the same region of the posterior intercostals arteries
• Superior phrenic arteries supply the posterior part of the diaphragm

The visceral branches of the thoracic aorta include:

• Pericardial arteries supply the pericardium of the heart.
• Bronchial arteries supply the lungs, bronchi, and pleurae.
•  Esophageal arteries supply the oesophagus
• Mediastinal arteries supply the posterior mediastinum.

Branches of the Abdominal Aorta

The Abdominal aorta also consists of parietal and visceral branches that supply the abdominal viscera.

The visceral branches consist of:

• The celiac trunk that subdivides into three branches: the left gastric artery goes to the stomach, the splenic artery goes to the spleen, and the hepatic artery carries oxygenated blood to the liver.
• The superior mesenteric artery, the largest of these branches, carries blood to most of the small intestine as well as to the first half of the large intestine.
• The much smaller inferior mesenteric artery supplies the second one half of the large intestine.
• The suprarenal arteries supply the adrenal (suprarenal) glands.
• The renal arteries, the largest in this group, carry blood to the kidneys
•  The gonadal arteries (ovarian arteries in the female and testicular arteries in the male), supply the sex glands.

The parietal branches consist of:

• Inferior phrenic arteries supply the diaphragm.
•  Four pairs of lumbar arteries supply the lumbar vertebrae, spinal cord, and muscle and skin of the lumbar region of the back.
• Median sacral arteries supply the sacrum and coccyx.

Arteries of the Pelvis and the Lower Limbs

The abdominal aorta finally divides into two common iliac arteries. Both of these vessels extend into the pelvis, where each one subdivides into an internal and an external iliac artery.

The internal iliac vessels then send branches to the pelvic organs, including the urinary bladder, the rectum, and some of the reproductive organs.

The external iliac arteries continue into the thigh as the femoral arteries. These vessels give of branches in the thigh and then become the popliteal arteries, which subdivide below the knee. The subdivisions include the tibial arteries, fibular arteries, and dorsalis pedis, which supply the leg and the foot.

Other Sub-branches of Systemic Arteries

Just as the larger branches of a tree give off limbs of varying sizes, so the arterial tree has a multitude of subdivisions. Hundreds of names might be included, but we shall mention only other For example, each common carotid artery gives off branches to the thyroid gland and other parts of the head. The hand receives blood from the subclavian artery, which becomes the axillary structures in the neck before dividing into the external and internal carotid artery, which supplies in the axilla. The longest part of this vessel, the brachial artery, is in the arm proper. It subdivides into two branches near the elbow: the radial artery, which continues down the thumb side of the forearm and wrist, and the ulnar artery, which extends along the medial or little finger side into the hand.

Major Veins of the Systemic Circulation

Two terminal systemic veins, the superior and interior venacava, along with their other veins, drain blood and return to the heart.

The Superior Venacava

The superior venacava receives blood from the regions superior to the diaphragm except from the pulmonary circuit. It is formed by the union of the right and left brachiocephalic veins and empties into the right atrium.  It drains the head, neck, chest, and the upper limbs. The largest veins of the upper limbs are the cephalic, the basilic, and the median cubital veins.

The Inferior Venacava

The inferior venacava, which is much longer than the superior vena cava, returns the blood to the heart from all body regions below the diaphragm. It begins in the lower abdomen the by the union of the two common iliac veins. It then ascends along the back wall of the abdomen, receiving venous blood draining from the pelvis, kidney and lower limbs. Just before it penetrates the diaphragm, it is joined by the hepatic veins, which transport blood from the liver, and then it enters the inferior aspect of the right atrium of the heart. The saphenous veins of the lower extremities are the longest veins of the body.

Drainage into the inferior vena cava is more complicated than drainage into the superior vena cava. The large veins below the diaphragm may be divided: into two groups:

• The right and left veins that drain paired parts and organs.
• They include the iliac veins from near the groin, four pairs of lumbar veins from the dorsal part of the trunk and from the spinal cord, the testicular veins from the testes of the male and the ovarian veins from the ovaries of the female, the renal and suprarenal veins from the kidneys and adrenal glands near the kidneys, and finally the large hepatic veins from the liver.
• For the most part, these vessels empty directly into the inferior vena cava.
• The left testicular in the male and the left ovarian in the female empty into the left renal vein, which then take this blood to the inferior venal cava; these veins thus constitute exceptions to the rule that the paired veins empty directly into vena cava.
• Unpaired veins that come from the spleen and from parts of the digestive tract (stomach and intestine) and empty into a vein called the portal vein.
• Unlike other veins, which empty into the inferior vena cava, the hepatic portal vein is part of a special system that enables blood to circulate through the liver before returning to the heart.