Arteries are the large vessels that carry blood away from the heart.
Human body circulation is divided into two types – pulmonary and systemic.
Arteries of pulmonary system carry deoxygenated from the right ventricle to the lungs to get it oxygenated by lungs. This blood is then returned to the left atrium of the heart by pulmonary vein and then passed to the left ventricle and from thereon to the systemic circulation.
Systemic arteries have a common trunk – the aorta which receives blood from the left ventricle.
Aorta is a large trunk that commences at the left ventricle and goes all the way to the abdomen. Throughout main arteries emerge from the aorta to supply different regions of the body and further branch for a wider reach.
In their distributions, the arteries may communicate by forming the anastomosis, often to reinforce or enrich the circulation of a particular region.
The arteries further give off branches which further divide into smaller branches called arterioles which in their turn open into a close-meshed network of microscopic vessels, termed capillaries. The capillaries are the places where tissue oxygen and nutrition is exchanged. , the true deliverers of oxygen and nutrients to the cells.
The capillary vessels further form venules which then gradually drain to larger veins and finally the large venous trunk – vena cava and return the deoxygenated blood to the right atrium of the heart.
Arteries are found in all parts of the body, except in the hairs, nails, epidermis, cartilages, and cornea.
The article is an overview of the arterial system and specific arteries are discussed separately in detail.
Pulmonary Trunk and Branches
The pulmonary trunk is a vessel that arises from the right ventricle of the heart, extends upward, and divides into the right and left pulmonary arteries that carry deoxygenated blood to the lungs.
It arises from the conus arteriosus of the right ventricle and is wholly contained within the pericardium along with aorta.
The right pulmonary artery is longer and larger than the left.
The aorta begins at the upper part of the left ventricle, ascends for a short distance and arches backward and to the left side. From thereon, it descends thorax and passes into the abdominal cavity through the aortic hiatus in the diaphragm.
Opposite the lower border of L4 [fourth lumbar vertebra], it divides into dividing into the right and left common iliac arteries.
It begins at the upper part of the base of the left ventricle. At the origin, it has three small dilatations called the aortic sinuses lying opposite to segments of the valve.
Th aorta ascends to join the aortic arch where the caliber of the aorta increases. This dilatation is called the bulb of the aorta.
Branches of Acending Aorta
- Two coronary arteries, which supply the heart
It forms two curvatures
- convexity upward
- Convexity forward and to the left.
It runs backward and its left side is in contact with the left lung and pleura.
- Brachiocephalic trunk
- Largest branch
- Divides further into right common carotid and right subclavian
- Left common carotid artery
- Left subclavian artery.
Descending thoracic aorta
It is the part of the aorta till aortic hiatus [roughly lower border of T12] and is contained in the posterior mediastinum.
In the beginning, it is on the left of the vertebral column but goes to midline gradually with the descent.
- Visceral branches
- Mediastinal arteries
- Parietal branches
- Subcostal arteries
- Superior phrenic artery
- Posterior intercostals arteries
It begins at the aortic hiatus of the diaphragm [lower border of T12 vertebra],
It descends in front of the vertebral column and ends on the body L4 vertebra, slightly left to the midline.
It ends by dividing into two common iliac arteries.
- Celiac artery
- Superior mesenteric
- Inferior mesenteric
- Middle suprarenal
- Ovarian arteries
- nferior phreni
- Middle sacral
- Common iliac arteries.
Arteries of Head and Neck
Two common carotid arteries are main suppliers to head and neck. Right common carotid is branch of brachiocephalic trunk behind the sternoclavicular joint whereas the left is from the highest part of the arch of the aorta.
Each artery passes obliquely upward, from behind the sternoclavicular articulation. At the level of the upper border of the thyroid cartilage, where it divides into the external and internal carotid arteries.
External carotid supply the exterior of the head, the face, and the greater part of the neck whereas internal carotid supplies majorily within the cranial and orbital cavities.
External carotid artery
It begins at the level of the upper border of the thyroid cartilage, curve slightly to pass upward and forward and then back to space behind the neck of the mandible.
- Superior thyroid
- Posterior auricular
- Ascending pharyngeal
- Superficial temporal
- Maxillary larger branch The maxillary artery is the larger of the 2 terminal branches of the external carotid; it supplies the deep structures of the face and may be divided into mandibular, pterygoid, and pterygopalatine portions.
Internal carotid artery
It supplies the anterior part of the brain, the eye and its appendages, and few branches to forehead and nose.
The vessels is divided into four parts- cervical, petrous [within petrous part of the temporal bone], cavernous [within cavernous sinus], and cerebral.
- Cervical portion of -no branches.
- Petrous portion
- Caroticotympanic artery
- Artery of the pterygoid canal
- Cavernous portion
- Anterior meningeal
- Cerebral portion
- Ophthalmic artery
- Anterior cerebral
- Middle cerebral
- Posterior communicating
Some authors divide this artery into seven parts.
Circle of Willis
An extensive anastomosis is present in the base of the brain and is called cerebral arterial circle (of Willis). It is formed by
- Anterior cerebral arteries [from internal carotid] connected together by the anterior communicating artery.
- Posterior cerebral arteries [ branches of the basilar artery which formed by joining of two vertebral arteries] that are connected on either side with the internal carotid by the posterior communicating artery.
Anterior cerebral artery
The anterior cerebral artery arises from the internal carotid at the medial extreme of the lateral sulcus of the brain.
It goes forward and medially above the optic nerve, across the anterior perforated substance, to the start of the longitudinal fissure.
Here, it connects to connected opposite counterpart the anterior communicating artery and participates in the formation of the circle of Willis.
Thereon, both the vessels run side by side in the longitudinal fissure, curve around the genu of the corpus callosum to turn back and continue to end by anastomosing with the posterior cerebral arteries.
Middle cerebral artery
The middle cerebral artery is the largest branch of the internal carotid artery that first runs on lateral sulcus and then backward and upward on the surface of the insula.
It divides into a number of branches for the lateral surface of the cerebral hemisphere.
- Anterolateral ganglionic
- Inferior lateral fronta
- Ascending frontal
- Ascending parietal
- Temporal arteries.
Posterior cerebral artery
Posterior cerebral is a branch of the basilar artery [which is formed by joining vertebral arteries].
- Posteromedial ganglionic branches, which pierce the posterior perforated substance and supply the medial surface of the thalami and the walls of the third ventricle.
Anterior choroidal artery
A small but constant branch that arises from the internal carotid, near the posterior communicating artery. It is distributed to the hippocampus, fimbria, tela choroidea of the third ventricle, and choroid plexus.
Arteries of Upper Limbs
Subclavian artery is the origin of the vessel dedicated for the upper limb. On right it is a branch of brachiocephalic trunk and on left, it is a branch of arch of the aorta.
Its extent is to the outer border of the first rib. After this it continues as axillary artery till lower border of axilla and then termed the brachial artery which finally divides into the radial and ulnar arteries.
The branches of the subclavian artery are
- Vertebral artery
- Ascends and enters the skull through the foramen magnum
- Unites with the vessel of the opposite side to form the basilar artery
- Thyrocervical trunk
- Internal thoracic artery
- Divides at the level of the sixth intercostal space into the musculophrenic and superior epigastric arteries
- Costocervical trunk
- Dorsal scapular artery.
It is the continuation of the subclavian artery in the axilla. It starts at the outer border of the first rib and continues as brachial artery after the lateral axillary fold.
From first part
- Highest thoracic
From the second part,
- Lateral thoracic
From third part
- Posterior humeral circumflex
- Anterior humeral circumflex.
It commences at the lower margin of the tendon of the teres major. It travels downward, initially medial and then gets in front of the bone. Its bifurcation lies midway the arm to end about 1 cm below the elbow.
Here it branches into the radial and ulnar arteries. At first, the brachial artery lies medial to the humerus, but as it runs down the arm, it gradually gets in front of the bone
- Profunda brachii
- Superior ulnar collateral
- Nutrient artery
- Inferior ulnar collateral
- Muscular branches.
The radial artery is a terminal branch of the brachial artery that starts below the flexion crease of the elbow and passes along the radial side of the forearm to the wrist.
- Branches in forearm
- Radial recurrent
- Palmar carpal
- Superficial palmar
- Branches in the wrist group
- Dorsal carpal
- First dorsal metacarpal
- Branches in hand
- Hand group
- Princeps pollicis
- Radialis indicis
- Deep palmar arch
It is the larger of the terminal branches of the brachial artery and begins a little below the bend of the elbow.
- Forearm branches
- Anterior ulnar recurrent artery
- Posterior ulnar recurrent artery
- Common interosseous artery
- Muscular artery
- Wrist branches
- Palmar carpal artery
- Dorsal carpal artery
- Hand branches
- Superficial palmar arch
- Contribution to the deep palmar arch
Arteries of Trunk [Branches of Abdominal Aorta]
It is a short thick trunk that arises from the front of the aorta, just below the aortic hiatus of the diaphragm.
- Left gastric artery
- Common hepatic artery [ further branches into gastroduodenal and proper hepatic arteries]
- Splenic artery
- Pancreatic branches
- Short gastric arteries
- Left gastro-omental
Superior mesenteric artery
It is a large vessel that arises below the celiac artery and supplies
- the whole length of the small intestine [, except the superior part of the duodenum]
- Ascending part of the colon
- Proximal two-thirds of the transverse colon
. Its branches are the inferior pancreaticoduodenal, intestinal, middle colic, ileocolic, and right colic arteries.
Inferior mesenteric artery
- Distal third of the transverse colon
- Whole of the descending colon
- Sigmoid colon
- Greater part of the rectum
- Left colic
- Superior rectal arteries
These arise immediately below the superior mesenteric artery.
The right is longer and left is higher.
small inferior suprarenal branches to the suprarenal gland, the ureter, and the surrounding cellular tissue and muscles.
Common iliac arteries are terminal branches of the abdominal aorta at L4 level.
They diverge from the termination of the aorta, pass downward and laterally, and divide into 2 branches, the external iliac and internal iliac arteries.
External iliac supplies the lower limb.
Internal iliac supplies the viscera and muscles of the pelvis, buttock, the external genitalia, and the medial side of the thigh. It is also called hypogastric artery.
Branches of common iliac artery
- Small branches to the peritoneum, the psoas major, the ureters, and the surrounding areolar tissue
- Iliolumbar or supernumerary renal arteries[ [occaisonally]
Branches of external iliac artery
- Inferior epigastric (immediately above the inguinal ligament)
- Deep iliac circumflex, before passing beneath the inguinal ligament
Branches of Internal Iliac Artery
From the anterior trunk – umbilical, obturator, uterine, vaginal, inferior vesical, middle rectal, internal pudendal, and inferior gluteal
From the posterior trunk – iliolumbar, lateral sacral, and superior gluteal
Arteries of Lower Limbs
It is the direct continuation of the external iliac that runs as a single trunk from the inguinal ligament to the lower border of the popliteal fossa starting its course anterior to the femur and then going medialward and finally posterior to lower end of femur.
The femoral artery begins immediately behind the inguinal ligament and ends at the junction of the middle and lower thirds of the thigh, where it passes through an opening in the adductor magnus to become the popliteal artery.
- Superficial epigastric
- Superficial iliac circumflex
- Superficial external pudendal
- Highest genicular
- Deep external pudendal
- Muscular branches
- Profunda femoris arteries [Further branches into lateral femoral circumflex, medial femoral circumflex, perforating, and muscular branches.
It is the continuation of the femoral and extends from the opening in the adductor magnus and vertically downward to the lower border of the popliteus, where it divides into the anterior and posterior tibial arteries.
- Muscular branches
- Genicular arteries
Anterior tibial artery
This artery begins at the bifurcation of the popliteal, at the lower border of the popliteus.
It typically passes anterior to the popliteus muscle and then through an oval opening at the superior aspect of the interosseus membrane. The artery then descends between the tibialis anterior and extensor digitorum longus muscles.
It continues as the dorsalis pedis artery at the level of the anterior aspect of the ankle.
- Posterior tibial recurrent
- Anterior tibial recurrent
- Anterior lateral malleolar
- Muscular branches
- Anterior medial malleolar arteries.
The dorsalis pedis is the continuation of the anterior tibial. It passes forward from the ankle joint along the tibial side of the dorsum of the foot to the proximal part of the first intermetatarsal space
Divides into the first dorsal metatarsal and the deep plantar branches.
Posterior tibial artery
it is the other terminal branch of the popliteal artery and travels in the posterior compartment of the leg.
- Fibular artery – travels down to divide into lateral calcaneal arteries
- Posterior medial malleolar
- Nutrient artery
- Muscular branches
- Medial calcaneal
- Lateral plantar artery
- Medial plantar artery
Histology of Artery
Arteries are composed of three coats from inside out
- Endothelial coat or tunica intima
- Muscular coat or tunica media
- Connective tissue coat or tunica adventitia
The 2 inner coats can be very easily separated from the external coat.
Arterial sheaths are formed by fibroareolar investments, which form their sheaths. The vessel is loosely connected with its sheath by delicate areolar tissue, and the sheath usually encloses the accompanying veins, and sometimes a nerve.
Blood supply of arteries is by nutrient vessels called the vasa vasorum. these arise from a branch or neighboring vessels and are distributed to the external coat. Nerve fibers from the sympathetic nervous system supply the arteries.
On larger vessels, these form plexus and the branches are distributed principally to the muscular tissue of the middle coat.
These fibers cause the contraction and relaxation of this tissue, to regulate the amount of blood sent to any part.
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