Vein of Galen
Encyclopedia
The great cerebral vein is one of the large blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...

s in the skull
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...

 draining the cerebrum
Telencephalon
The cerebrum or telencephalon, together with the diencephalon, constitutes the forebrain. The cerebrum is the most anterior region of the vertebrate central nervous system. Telencephalon refers to the embryonic structure, from which the mature cerebrum develops...

 (brain). It is also known as the "vein of Galen" (VG), named for its discoverer, the Greek physician Galen
Galen
Aelius Galenus or Claudius Galenus , better known as Galen of Pergamon , was a prominent Roman physician, surgeon and philosopher...

. However, it is not the only vein with this eponym.

Anatomy

The great cerebral vein of Galen is considered a deep/internal cerebral vein. The internal cerebral veins are formed by the union of the thalamostriate vein and the choroid
Choroid
The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye, containing connective tissue, and lying between the retina and the sclera. The human choroid is thickest at the far extreme rear of the eye , while in the outlying areas it narrows to 0.1 mm...

 vein at the interventricular foramen. The deep/internal group of cerebral veins can be seen on the superior surfaces of the caudate nuclei and thalami just under the corpus callosum
Corpus callosum
The corpus callosum , also known as the colossal commissure, is a wide, flat bundle of neural fibers beneath the cortex in the eutherian brain at the longitudinal fissure. It connects the left and right cerebral hemispheres and facilitates interhemispheric communication...

. The veins at the anterior poles of the thalami merge posterior to the pineal gland
Pineal gland
The pineal gland is a small endocrine gland in the vertebrate brain. It produces the serotonin derivative melatonin, a hormone that affects the modulation of wake/sleep patterns and seasonal functions...

 to form the Great Cerebral Vein of Galen. Most of the blood in the deep cerebral veins collects into the great cerebral vein. This comes from the inferior side of the posterior end of the corpus callosum
Corpus callosum
The corpus callosum , also known as the colossal commissure, is a wide, flat bundle of neural fibers beneath the cortex in the eutherian brain at the longitudinal fissure. It connects the left and right cerebral hemispheres and facilitates interhemispheric communication...

 and empties into the straight sinus located in the midline of the tentorium. Unlike the arteries, the cerebral veins have anastomoses. With extensive anastomoses, a slow occlusion of a venous channel rarely produces more than transitory effects.

There are both superficial/external and deep/internal cerebral veins
Internal cerebral veins
The internal cerebral veins drain the deep parts of the hemisphere and are two in number; each is formed near the interventricular foramen by the union of the terminal and choroid veins....

, the great cerebral vein being a deep/internal vein as mentioned above) in the brain. As there are similarities, there are also differences between these two types of veins in the brain. The superficial veins at the dorsal parts of the hemispheres run upward and medially and empty into the large superior sagittal sinus
Sagittal sinus
Sagittal sinus can refer to:* Superior sagittal sinus* Inferior sagittal sinus...

 in the upper margin of the falx cerebri
Falx cerebri
The falx cerebri, also known as the cerebral falx, so named from its sickle-like form, is a strong, arched fold of dura mater which descends vertically in the longitudinal fissure between the cerebral hemispheres....

. The superior sagittal sinus
Superior sagittal sinus
The superior sagittal sinus , within the human head, is an unpaired area along the attached margin of falx cerebri. It allows blood to drain from the lateral aspects of anterior cerebral hemispheres to the confluence of sinuses...

 divides into two parts called the transverse sinuses where the falx cererbri meets the tentorium cerebelli. The sigmoid sinus
Sigmoid sinus
The sigmoid sinuses , within the human head, are two areas beneath the brain which allow blood to drain inferiorly from the posterior center of the head. They drain from the transverse sinuses and converge with the inferior petrosal sinuses to form the internal jugular vein...

, which continues the transverse sinus, empties into the jugular vein
Jugular vein
The jugular veins are veins that bring deoxygenated blood from the head back to the heart via the superior vena cava.-Internal and external:There are two sets of jugular veins: external and internal....

 at the jugular foramen
Jugular foramen
The jugular foramen is a large aperture in the base of the skull. It is located behind the carotid canal and is formed in front by the petrous portion of the temporal, and behind by the occipital; it is generally larger on the right than on the left side....

. The internal jugular vein
Jugular vein
The jugular veins are veins that bring deoxygenated blood from the head back to the heart via the superior vena cava.-Internal and external:There are two sets of jugular veins: external and internal....

 leaves the skull and travels downward to the neck.

The veins of the brain have very thin walls and contain no valves. They emerge in the brain and lie in the subarachnoid space
Subarachnoid space
In the central nervous system, the subarachnoid cavity is the interval between the arachnoid membrane and pia mater....

. They pierce the arachanoid matter and the meningeal layer in the dura and drain into the cranial venous sinuses.

Malformations

Most conditions associated with the great cerebral vein are due to congenital defects. Vein of Galen aneurysmal malformations (VGAM) are the most common form of symptomatic cerebrovascular malformation in neonates and infants. The presence and locations of angiomas are very variable and do not follow any predictable pattern. The congenital malformation develops during weeks 6-11 of fetal development as a persistent embryonic prosencephalic vein of Markowski; thus, VGAM is actually a misnomer. The vein of Markowski actually drains into the vein of Galen.

Absence

Absence of the great cerebral vein is a type of malformation. The veins of the deep structures of the brain normally drain through the Galenic system. In the absence of the great cerebral vein, the veins from the diencephalon and the basal ganglia drain laterally into the transverse sinus instead of conjoining in the midline through the Galenic drainage system. Absence of the great cerebral vein is quite rare. It is detected in infancy. Most patients die in the neonatal period or in early infancy.

Thrombosis

Thrombosis of the great cerebral vein is a form of stroke due to a blood clot in the vein. It affects just 3 to 8% of patients, predominantly women. Patients may present with consciousness problems, headaches, nausea, visual defects, fatigue, disturbance of eye movements and pupillary reflexes, or coma. Thrombosis of the cerebral vein is often deadly but can be survived. Risk factors include oral contraceptives, pregnancy, and the puerperium.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK