Structure
There are also emissary veins passing through the foramen ovale, jugular foramen, foramen lacerum, and hypoglossal canal.[ citation needed ]
| Emissary veins | |
|---|---|
| Details | |
| Identifiers | |
| Latin | vena emissaria |
| TA98 | A12.0.00.033 A12.3.05.301 |
| TA2 | 4872 |
| FMA | 50790 |
| Anatomical terminology | |
The emissary veins connect the extracranial venous system with the intracranial venous sinuses. They connect the veins outside the cranium to the venous sinuses inside the cranium. They drain from the scalp, through the skull, into the larger meningeal veins [ citation needed ] and dural venous sinuses. They may also connect to diploic veins within the skull. [1]
Emissary veins have an important role in selective cooling of the head. They also serve as routes where infections are carried into the cranial cavity from the extracranial veins to the intracranial veins.
There are several types of emissary veins including the posterior condyloid, mastoid, occipital and parietal emissary veins. [1]
There are also emissary veins passing through the foramen ovale, jugular foramen, foramen lacerum, and hypoglossal canal.[ citation needed ]
Because the emissary veins are valveless, they are an important part in selective brain cooling through bidirectional flow of cooler blood from the evaporating surface of the head. In general, blood flow is from external to internal [2] but the flow can be altered by increased intracranial pressure.
One notable emissary vein, the vein of Vesalius, travels through the sphenoidal emissary foramen inferior to the zygomatic arch, connecting the pterygoid plexus with the cavernous sinus. [3] This is an important route for the spread of infection as cranial nerve VI and the internal carotid pass through the cavernous sinus, with cranial nerves III, IV, V1, and V2 passing alongside the lateral wall of the sinus. Subsequent infection or inflammation in the cavernous sinus can result in septic cavernous sinus thrombosis, with resultant damage to the cranial nerves contained within, as well as further spread of the infection leading to meningitis. [4]
Rupture of an emissary vein can result in a subgaleal hemorrhage, a rare but serious injury most often seen as a complication of vacuum extraction. [5]
Cranial nerves are the nerves that emerge directly from the brain, of which there are conventionally considered twelve pairs. Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck, including the special senses of vision, taste, smell, and hearing.
The danger triangle of the face which consists of the area from the corners of the mouth to the bridge of the nose, including the nose and maxilla. Due to the special nature of the blood supply to the human nose and surrounding area, it is possible for retrograde infection from the nasal area to spread to the brain, causing cavernous sinus thrombosis, meningitis, or brain abscess.
The foramen magnum is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblongata, passes through the foramen magnum as it exits the cranial cavity. Apart from the transmission of the medulla oblongata and its membranes, the foramen magnum transmits the vertebral arteries, the anterior and posterior spinal arteries, the tectorial membranes and alar ligaments. It also transmits the accessory nerve into the skull.
In neuroanatomy, dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. The other two meningeal layers are the arachnoid mater and the pia mater. It envelops the arachnoid mater, which is responsible for keeping in the cerebrospinal fluid. It is derived primarily from the neural crest cell population, with postnatal contributions of the paraxial mesoderm.
The foramen lacerum is a triangular hole in the base of skull. It is located between the sphenoid bone, the apex of the petrous part of the temporal bone, and the basilar part of the occipital bone.
The posterior cranial fossa is the part of the cranial cavity located between the foramen magnum, and tentorium cerebelli. It is formed by the sphenoid bones, temporal bones, and occipital bone. It lodges the cerebellum, and parts of the brainstem.
The falx cerebri is a large, crescent-shaped fold of dura mater that descends vertically into the longitudinal fissure between the cerebral hemispheres of the human brain, separating the two hemispheres and supporting dural sinuses that provide venous and CSF drainage to the brain. It is attached to the crista galli anteriorly, and blends with the tentorium cerebelli posteriorly.
The cavernous sinus within the human head is one of the dural venous sinuses creating a cavity called the lateral sellar compartment bordered by the temporal bone of the skull and the sphenoid bone, lateral to the sella turcica.
The sigmoid sinuses, also known as the pars sigmoid, are paired dural venous sinuses within the skull that receive blood from posterior transverse sinuses.
The pterygoid plexus is a fine venous plexus upon and within the lateral pterygoid muscle. It drains by a short maxillary vein.
The trigeminal ganglion is the sensory ganglion of each trigeminal nerve. The trigeminal ganglion is located within the trigeminal cave, a cavity formed by dura mater.
The occipital vein is a vein of the scalp. It originates from a plexus around the external occipital protuberance and superior nuchal line to the back part of the vertex of the skull. It usually drains into the internal jugular vein, but may also drain into the posterior auricular vein. It drains part of the scalp.
The lateral parts of the occipital bone are situated at the sides of the foramen magnum; on their under surfaces are the condyles for articulation with the superior facets of the atlas.
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. Vesalius was the first to describe and illustrate this foramen, and is also called the foramen Vesalius. Other names include foramen venosum and canaliculus sphenoidalis.
Cavernous sinus thrombosis (CST) is the formation of a blood clot within the cavernous sinus, a cavity at the base of the brain which drains deoxygenated blood from the brain back to the heart. This is a rare disorder and can be of two types–septic cavernous thrombosis and aseptic cavernous thrombosis. The most common form is septic cavernous sinus thrombosis. The cause is usually from a spreading infection in the nose, sinuses, ears, or teeth. Staphylococcus aureus and Streptococcus are often the associated bacteria.
This article describes the anatomy of the head and neck of the human body, including the brain, bones, muscles, blood vessels, nerves, glands, nose, mouth, teeth, tongue, and throat.
The inferior petrosal sulcus is the groove containing the inferior petrosal sinus.
Sinus pericranii (SP) is a rare disorder characterized by a congenital epicranial venous malformation of the scalp. Treatment of this condition has mainly been recommended for aesthetic reasons and prevention of bleeding.
The venous plexus of hypoglossal canal is a small venous plexus surrounding the hypoglossal nerve as it passes through the hypoglossal canal. The plexus connects with the occipital sinus (intercranially), inferior petrosal sinus (intercranially), internal jugular vein (extracranially), condylar vein, and paravertebral venous plexus.
The marginal sinus is a dural venous sinus surrounding the margin of the foramen magnum inside the skull, accommodated by the groove for marginal sinus. It usually drains into either the sigmoid sinus, or the jugular bulb. It communicates with the basilar venous plexus anteriorly, and the occipital sinus posteriorly ; it may form extracranial communications with the internal vertebral venous plexuses, or deep cervical veins.
