- The blood vessels which carry oxygenated blood away from the heart and supply blood to various body parts collectively constitute the arterial system.
- The major blood vessels arising from the left ventricle is called a systemic aorta.
- This aorta branches off to form many smaller arteries, which in turn branch off many times into arterioles.
- The aorta runs upwards and sharply curves or arches downwards. The upward running portion of aorta is called the ascending aorta, and the downward curving aorta is called a descending aorta.
1. Ascending aorta: It gives off:
- Coronary arteries: There are two coronary arteries (right and left) arising from the very base of the aorta. They supply oxygenated blood to the walls of the heart.
2. Aortic arch gives off the following arteries:
a. Innominate artery or Brachiocephalic trunk:
b. Left common carotid artery:
c. Left subclavian artery:
- Innominate (Brachiocephalic) artery: It is about 4 to 5 cm long, which soon divides into two branches to form right common carotid artery and the right subclavian artery.
- Right common carotid artery: It runs upwards on the side of the trachea and enters the neck and head. It divides into external and internal carotids that supply blood to the right side of the head and face.
- Right subclavian artery: It gives off the following arteries:
- Vertebral artery: It supplies to the head and parts of the right shoulder.
- Right axillary artery: It supplies blood to the scapular region.
- Right brachial artery: It supplies blood to the arm.
- Right radial artery: It supplies to the fore arm, elbow joint, radius and muscles of raidial side of forearm.
- Right ulnar artery: It supplies to the ulna, forearm, muscles of ulnar side of forearm.
- Left common carotid artery: It arises directly from the aorta. It runs upwards on the side of the neck (trachea). It divides into the external and internal carotid arteries.
- The internal carotid artery supplies blood to most parts of the brain. It also supplies blood to the eyes, forehead and nose.
- The external carotid artery branches off further to supply blood to various body parts as follows:
- Superior thyroid artery: It supplies blood to thyroid gland and adjacent muscles.
- Lingual artery: It supplies to the tongue, floor of the mouth etc.
- Facial artery: It supplies to the facial parts of the mouth.
- Occipital artery: It supplies to the posterior part of the head.
- Temporal artery: It supplies to the frontal, temporal and parietal parts of the scalp.
- Maxillary artery: It supplies to the muscles of the mouth.
- Left subclavian artery: It arises directly from the aorta and divides in the same ways as right subclavian branch of the innominate artery. It supplies blood to the similar body parts as done by the right subclavian artery but to the left side.
- Vertebral artery: It supplies to the neck and parts of the left shoulder.
- Left axillary artery: It supplies to the scapular region.
- Left brachial artery: It supplies to the upper forearm, humerus and elbow joint. Brachial artery in the anterior elbow is site used for measurement of blood pressure.
- Left radial artery: It supplies to the fore arm, elbow joint, radius and muscles of raidial side of forearm.
- Left ulnar artery: It supplies to the ulna, forearm, muscles of ulnar side of forearm.
3. Thoracic aorta:
The thoracic segment of the descending aorta (also called thoracic aorta) gives off several pairs of small arteries and supplies blood to the following parts:
a. Bronchial arteries (unpaired): They supply to the bronchi, bronchioles and connective tissues in the lungs.
b. Oesophagial arteries (unpaired): They supply to the oesophagus.
c. Intercostal arteries:
- Dorsal branch (9 pairs): They supply to the spinal cord, muscles and skin of back.
- Posterior intercostal arteries (1 pair below rib 12):
- Muscular branch: It supplies to the chest muscles.
- Cutaneous branch: It supplies to the skin of thorax.
- Mammary branch: It supplies to the mammary glands of breasts.
d. Superior phrenic arteries: They supply to the diaphragm.
4. Abdominal aorta:
After piercing the diaphragm, the descending arch of aorta becomes abdominal aorta and gives off a number of paired and unpaired arteries to supply to different body parts as follows:
a. Inferior phrenic arteries: They supply to the diaphragm and the lower oesophagus.
b. Celiac artery (trunk): It is unpaired and originates immediately below the diaphragm and gives off three branches:
- Left gastric artery: It supplies blood to the stomach.
- Common hepatic artery: It supplies blood to the liver, gall bladder, pancreas and the pyloric stomach.
- Splenic artery: It supplies blood to the parts of the pancreas, stomach, omentum and the spleen.
c. Superior mesenteric artery (unpaired) : It is a thick and long unpaired artery which further branches off as:
- Inferior pancreaticoduodenal artery: It supplies blood to the head of pancreas and duodenum.
- Jejunal and ileal arteries: Supply to the small intestine.
- Ileocolic artery: Supplies to the lower ileum, appendix, ascending and part of transverse colon.
- Right colic and middle colic arteries: Supply to the transverse and ascending colon.
d. Inferior mesenteric artery (unpaired): It further branches off as:
- Left colic artery: Supplies to transverse and descending colon.
- Sigmoid artery: Supplies to descending and sigmoid colon.
- Superior rectal artery: Supplies blood to the rectum and anal region.
e. Renal arteries: A pair of renal arteries supply blood to a pairs of kidneys. Renal arteries also give off suprarenal arteries which supply blood to the suprarenal (adrenal) glands.
f. Gonadal arteries: A pair of gonadial arteries supply blood to the gonads. They are called testicular arteries in males and ovarian arteries in females.
g. Lumbar arteries (4 or 5 pairs): Supply blood to the skin, muscle and vertebrae of the lumbar region of back, spinal cord and meninges of lower back. They also supply to the caudal equina.
h. Median sacral (middle) artery: Supplies to the sacrum and coccyx.
i. Common iliac arteries: There are two large branches; left and right iliac arteries which are formed by the bifurcation of aorta at its lower end. Each common iliac artery divides into external and internal iliac arteries.
- The internal iliac artery supplies blood to pelvic viscera, including urinary bladder, prostate gland, uterus, vagina, rectum etc.
- The external iliac artery continues downwards to the lower limb
j. Femoral artery: Supplies to the skin and muscles of thigh, medial adductors and hamstrings.
k. Popliteal artery: Supplies to the knee joint
l. Anterior tibial artery: Supplies to the knee joint and the muscles and skin in front of leg, and ankle joint.
m. Dorsal pedal artery: Supplies to the muscles, skin and joints (including ankle) on the dorsal side of foot.
n. Posterior tibial artery: Supplies to lateral leg, knee joint, muscles and skin on back of leg, ankle joint, muscles of fibula, heel and toes.
References:
- Vidyarthi, R.D and Pandey, P.N. 1998. A Textbook of Zoology, S. Chand and Company Ltd., New Delhi
- Seeley, R.R., Stephens, T.D. and Tate, P.1992. Anatomy and Physiology, second edition, Mosby Year Book, London