Emissary veins
Encyclopedia
The emissary veins are valveless vein
s which normally drain external veins of the skull
into the dural venous sinuses
. However, because they are valveless, pus can flow into the skull through them as well, making them a possible route for transmission of extracranial infection to get into the skull.
One important emissary vein communicates from outside the skull through the sphenoidal emissary foramen
inferior to the zygomatic arch
with the cavernous sinus
on the inside of the skull. This is an important route for spread of infection because cranial nerves
III, IV, V1, V2, and VI and the internal carotid pass through the cavernous sinus. Subsequent infection or inflammation in the cavernous sinus can result in damage to any of the cranial nerves that pass through it or meningitis
. Also, rupturing the emissary veins will result in a subdural hematoma
which will compress the brain.
There are also emissary veins passing through the Foramen Ovale,Jugular Foramen,Foramen Lacerum and Hypoglossal canal.
Vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...
s which normally drain external veins of 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...
into the dural venous sinuses
Dural venous sinuses
The dural venous sinuses are venous channels found between layers of dura mater in the brain...
. However, because they are valveless, pus can flow into the skull through them as well, making them a possible route for transmission of extracranial infection to get into the skull.
One important emissary vein communicates from outside the skull through the sphenoidal emissary foramen
Sphenoidal emissary foramen
In the base of the skull, in the great wings of the sphenoid bone, medial to the foramen ovale, a small aperture, the sphenoidal emissary foramen, may occasionally be seen opposite the root of the pterygoid process. When present, it opens below near the scaphoid fossa...
inferior to the zygomatic arch
Zygomatic arch
The zygomatic arch or cheek bone is formed by the zygomatic process of temporal bone and the temporal process of the zygomatic bone , the two being united by an oblique suture; the tendon of the Temporalis passes medial to the arch to gain insertion into the coronoid process...
with the cavernous sinus
Cavernous sinus
The cavernous sinus , within the human head, is a large collection of thin-walled veins creating a cavity bordered by the temporal bone of the skull and the sphenoid bone, lateral to the sella turcica.-Contents:...
on the inside of the skull. This is an important route for spread of infection because cranial nerves
Cranial nerves
Cranial nerves are nerves that emerge directly from the brain, in contrast to spinal nerves, which emerge from segments of the spinal cord. In humans, there are traditionally twelve pairs of cranial nerves...
III, IV, V1, V2, and VI and the internal carotid pass through the cavernous sinus. Subsequent infection or inflammation in the cavernous sinus can result in damage to any of the cranial nerves that pass through it or meningitis
Meningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
. Also, rupturing the emissary veins will result in a subdural hematoma
Subdural hematoma
A subdural hematoma or subdural haematoma , also known as a subdural haemorrhage , is a type of haematoma, a form of traumatic brain injury. Blood gathers within the outermost meningeal layer, between the dura mater, which adheres to the skull, and the arachnoid mater, which envelops the brain...
which will compress the brain.
See also
- Occipital emissary veinOccipital emissary veinThe occipital emissary vein is a small emissary vein which passes through the condylar canal....
There are also emissary veins passing through the Foramen Ovale,Jugular Foramen,Foramen Lacerum and Hypoglossal canal.