Vascularization

Combo Gratuito - COVID-19

Temos o compromisso com a educação, por isso estamos liberando o material rico sobre o Sistema Cardiovascular, contendo Apostila, Banco de Questões e Palavras cruzadas. Receba AGORA no seu e-mail.

VASCULARIZATION NERVOUS SYSTEM

The nervous system is made up of noble and highly specialized structures, which require for its metabolism a permanent and high supply of glucose and oxygen. The brain's oxygen and glucose consumption is very high, which requires a very intense blood flow. Decreases in circulating blood glucose and oxygen concentration or, on the other hand, suspension of blood flow to the brain are not tolerated for a very short period.

Stopping brain circulation for more than seven seconds leads to loss of consciousness. After about five minutes, lesions appear that are irreversible, as, as is well known, nerve cells do not regenerate.

The cerebral blood flow is very high, being surpassed only by that of the kidney and the heart. It is estimated that in a minute the brain circulates an amount of blood approximately equal to its own weight.

Arterial Vascularization of the Brain

Willis Polygon:

The brain is vascularized through two systems: Vertebro-Basilar (vertebral arteries) and Carotid (internal carotid arteries). These are specialized arteries for brain irrigation. At the base of the skull these arteries form an anastomotic polygon, the Willis Polygon, from which the main arteries for cerebral vascularization come out.

Internal and Vertebral Carotid Arteries
Internal and Vertebral Carotid Arteries
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

The vertebral arteries anastomose to originate the basilar artery, lodged in the basilar gutter. It divides into two posterior cerebral arteries that supply the posterior inferior surface of each of the cerebral hemispheres.

The internal carotid arteries originate on each side a middle cerebral artery and an anterior cerebral artery.

The anterior cerebral arteries communicate through a branch between them which is the anterior communicating artery.

The posterior cerebral arteries communicate with the internal carotid arteries through the posterior communicating arteries.

WILLIS POLYGON & #8211; SCHEME
 
WILLIS POLYGON - SCHEME
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.
WILLIS POLYGON & #8211; SCHEME
WILLIS POLYGON - SCHEME

 

Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.
BRAIN ARTERIES & #8211; BOTTOM VIEW
 
BRAIN ARTERIES - LOWER VIEW
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

Internal Carotid Artery (Carotid System)

Common carotid bifurcation branch, the internal carotid artery, after a more or less long pathway through the neck, enters the cranial cavity through the carotid canal of the temporal bone. It then punctures the dura and arachnoid and, at the beginning of the lateral sulcus, is divided into two terminal branches: the middle and anterior cerebral arteries. The internal carotid artery when blocked can lead to irreversible brain death. Carotid artery clogging is a serious, and unfortunately common, occurrence. Clinically, the internal carotid arteries and their branches are often referred to as the anterior circulation of the brain.

PREVIOUS VIEW OF PREVIOUS CEREBRAL AND MEDIUM ARTERIES
 
PREVIOUS VIEW OF PREVIOUS CEREBRAL AND MEDIUM ARTERIES
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.
AVERAGE CEREBRAL ARTERY
AVERAGE CEREBRAL ARTERY

 

Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

Vertebral and Basilar Artery (Vertebra-Basilar System)

The vertebral arteries run upward toward the brain from the subclavian arteries near the back of the neck. They pass through the transverse foramina of the first six cervical vertebrae, pierce the atlanto-occipital membrane, the dura and arachnoid, and enter the skull through the foramen magnum. They then run along the ventral face of the bulb and, approximately at the level of the bulb-pontine sulcus, fuse to form a single trunk, the basilar artery. The vertebral arteries also originate the posterior inferior spinal and cerebellar arteries.

The basilar artery runs through the basilar sulcus of the bridge and terminates anteriorly, bifurcating to form the right and left posterior cerebral arteries. The basilar artery gives rise, in addition to the posterior cerebral arteries, to the following arteries: superior cerebellar, anterior inferior cerebellar and labyrinth artery, thus supplying brain areas around the brainstem and cerebellum. The vertebra-basilar system and its branches are often referred to clinically as the posterior circulation of the brain.

REAR AND PREVIOUS BRAIN ARTERY
REAR AND PREVIOUS BRAIN ARTERY

 

Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.
SCHEME OF BRAIN ARTERIES
SCHEME OF BRAIN ARTERIES

 

Below is a schematic summary of brain vascularization:

Venous Vascularization of the Brain

The brain veins, in general, do not follow the arteries, being larger and larger than the arteries. They drain into the dural sinuses, from where blood converges to the internal jugular veins, which receive virtually all brain venous blood.

The external and internal jugular veins are the two main veins that drain blood from the head and neck. The external jugular veins are more superficial and drain to the subclavian veins the blood from the posterior neck and head. The deep internal jugular veins drain the anterior portion of the head, face and neck. They are responsible for draining most of the blood from the various venous sinuses of the skull. The internal jugular veins on either side of the neck join the subclavian veins to form the brachiocephalic veins, which carry blood to the superior vena cava.

The brain veins are arranged in two systems: superficial venous system and deep venous system. Although anatomically distinct, the two systems are joined by numerous anastomoses.

Superficial Venous System - Drain the cortex and the underlying white matter. Formed by superficial (superior and inferior) cerebral veins that flow into the dural sinuses.

Deep Venous System Drain blood from regions deeper in the brain, such as the striated body, inner capsule, diencephalon, and much of the white medullary center of the brain. The most important vein of this system is the great cerebral vein or Galenic vein, to which all the blood from the deep venous system of the brain converges.

VENOUS VASCULARIZATION OF THE BRAIN
 
VENOUS VASCULARIZATION OF THE BRAIN
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.
VENOUS VASCULARIZATION OF THE BRAIN
 
VENOUS VASCULARIZATION OF THE BRAIN
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

 

Structures of
Nervous system
Nervous tissue

Spinal cord

Brainstem

Cerebellum

Diencephalon

Telencephalon

Meninges and CSF

Peripheral Nervous System