Sphenoidal emissary foramen

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Sphenoidal emissary foramen
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Sphenoid bone. Upper surface. (Sphenoidal emissary foramen labeled at left, fourth from bottom.)
Gray193.png
Base of the skull. Upper surface. (Sphenoid is yellow, and sphenoidal emissary foramen is labeled at bottom of sphenoid.)
Details
Identifiers
Latin foramen venosum
TA98 A02.1.05.037
TA2 623
FMA 53157 54785, 53157
Anatomical terms of bone

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 (it is often absent) 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. [1] Other names include foramen venosum and canaliculus sphenoidalis.

Contents

Importance

If at all present, the sphenoidal emissary foramen gives passage to a small vein (vein of Vesalius) that connects the pterygoid plexus with the cavernous sinus. The importance of this passage lies in the fact that an infected thrombus from an extracranial source may reach the cavernous sinus. [2] The mean area of the foramen is small, which may suggest that it plays a minor role in the dynamics of blood circulation in the venous system of the head. [3]

Structure

The sphenoidal emissary foramen varies in size in different individuals, and is not always present on both sides of the sphenoid bone (one on each great wing of the sphenoid). In a study conducted under 100 skulls, the sphenoidal emissary foramen was only present in 17% of the cases, and it was always single. [3]

In another study, the differences between the right and the left side as well as the differences between the male and the female sex were noted. Out of the 70 sides observed (35 skulls total), the sphenoidal emissary foramen was present in 32.85% of the cases (20.0% right side, 12.85% left side). The incidence of bilateral and unilateral sphenoidal emissary foramen was 22.85% (8 out of 35 skulls) and 20% (7 out of 35 skulls) respectively. Regarding the differences between the male and the female sex, no remarkable differences were observed, although the occurrence of the foramen was more in females compared to males (found in 13 sides in females and in 10 sides in males). [2]
The skulls with one foramen were most frequent; those with two followed it and those with 3 (sphenoidal emissary) foramina were least frequent. [4] Lang (1983) reported that the sphenoidal emissary foramen was present in about 40% of his material. It was found on the right side in 49% of the cases and in 36% of the cases on the left. [5]

In the newborn, the foramen is about 1.0 mm in length, in the adults at the right side about 2 mm and at the left side 1.4 mm. The width increases from 1.0 to 1.14 mm at the right side and from 1.0 to 1.3 mm at the left side. [6]

Asymmetry

Though the sphenoidal emissary foramen is small and variable, it is consistently symmetrical. In a study in which 50 high-resolution CT scans of the base of the skull were reviewed, the significance of asymmetry was investigated. In a large number of cases, the foramen was remarkably symmetric, and where there was asymmetry, it signified abnormality in four of the six cases. Abnormal causes of asymmetry included invasion by nasopharyngeal melanoma, angiofibroma, carotid-cavernous fistula with drainage through the emissary veins, and neurofibromatosis. Thus, for the usually symmetric sphenoidal emissary foramina, asymmetry is more likely the result of a pathologic process than a normal variant. [7] Ginsberg, Pruett, Chen and Elster did not find that asymmetry indicated disease in a study under 123 CT studies. [8]

Related Research Articles

<span class="mw-page-title-main">Foramen ovale (skull)</span> Hole in the sphenoid bone of the skull

The foramen ovale is a hole in the posterior part of the sphenoid bone, posterolateral to the foramen rotundum. It is one of the larger of the several holes in the skull. It transmits the mandibular nerve, a branch of the trigeminal nerve.

<span class="mw-page-title-main">Sphenoid bone</span> Bone at the front of the skull

The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the basilar part of the occipital bone. The sphenoid bone is one of the seven bones that articulate to form the orbit. Its shape somewhat resembles that of a butterfly or bat with its wings extended.

<span class="mw-page-title-main">Palatine bone</span> Bone of the facial skeleton

In anatomy, the palatine bones are two irregular bones of the facial skeleton in many animal species, located above the uvula in the throat. Together with the maxillae, they comprise the hard palate.

<span class="mw-page-title-main">Internal carotid artery</span> Artery of the human brain

The internal carotid artery is an artery in the neck which supplies the anterior circulation of the brain.

<span class="mw-page-title-main">Middle meningeal artery</span> Artery supplying the meninges

The middle meningeal artery is typically the third branch of the first portion of the maxillary artery. After branching off the maxillary artery in the infratemporal fossa, it runs through the foramen spinosum to supply the dura mater and the calvaria. The middle meningeal artery is the largest of the three (paired) arteries that supply the meninges, the others being the anterior meningeal artery and the posterior meningeal artery.

<span class="mw-page-title-main">Foramen lacerum</span> Triangular hole in the base of the skull

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 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 and dural venous sinuses.

<span class="mw-page-title-main">Cavernous sinus</span> Sinus in the human head

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.

<span class="mw-page-title-main">Foramen spinosum</span> Hole in the sphenoid bone of the skull

The foramen spinosum is a small open hole in the greater wing of the sphenoid bone that gives passage to the middle meningeal artery and vein, and the meningeal branch of the mandibular nerve.

<span class="mw-page-title-main">Foramen rotundum</span> Hole in the sphenoid bone of the skull

The foramen rotundum is a circular hole in the sphenoid bone of the skull. It connects the middle cranial fossa and the pterygopalatine fossa. It allows for the passage of the maxillary nerve (V2), a branch of the trigeminal nerve.

<span class="mw-page-title-main">Pterygopalatine fossa</span> Fossa in the skull

In human anatomy, the pterygopalatine fossa is a fossa in the skull. A human skull contains two pterygopalatine fossae—one on the left side, and another on the right side. Each fossa is a cone-shaped paired depression deep to the infratemporal fossa and posterior to the maxilla on each side of the skull, located between the pterygoid process and the maxillary tuberosity close to the apex of the orbit. It is the indented area medial to the pterygomaxillary fissure leading into the sphenopalatine foramen. It communicates with the nasal and oral cavities, infratemporal fossa, orbit, pharynx, and middle cranial fossa through eight foramina.

<span class="mw-page-title-main">Sphenoid sinus</span> One of the four paired paranasal sinuses

The sphenoid sinus is a paired paranasal sinus occurring within the body of the sphenoid bone. It represents one pair of the four paired paranasal sinuses. The pair of sphenoid sinuses are separated in the middle by a septum of sphenoid sinuses. Each sphenoid sinus communicates with the nasal cavity via the opening of sphenoidal sinus. The two sphenoid sinuses vary in size and shape, and are usually asymmetrical.

<span class="mw-page-title-main">Greater wing of sphenoid bone</span> Large part of the skull front behind the eye socket

The greater wing of the sphenoid bone, or alisphenoid, is a bony process of the sphenoid bone, positioned in the skull behind each eye. There is one on each side, extending from the side of the body of the sphenoid and curving upward, laterally, and backward.

<span class="mw-page-title-main">Middle cranial fossa</span>

The middle cranial fossa is formed by the sphenoid bones, and the temporal bones. It lodges the temporal lobes, and the pituitary gland. It is deeper than the anterior cranial fossa, is narrow medially and widens laterally to the sides of the skull. It is separated from the posterior cranial fossa by the clivus and the petrous crest.

<span class="mw-page-title-main">Infratemporal fossa</span> Cavity that is part of the skull

The infratemporal fossa is an irregularly shaped cavity that is a part of the skull. It is situated below and medial to the zygomatic arch. It is not fully enclosed by bone in all directions. It contains superficial muscles, including the lower part of the temporalis muscle, the lateral pterygoid muscle, and the medial pterygoid muscle. It also contains important blood vessels such as the middle meningeal artery, the pterygoid plexus, and the retromandibular vein, and nerves such as the mandibular nerve (CN V3) and its branches.

<span class="mw-page-title-main">Pterygoid canal</span>

The pterygoid canal is a passage in the sphenoid bone of the skull leading from just anterior to the foramen lacerum in the middle cranial fossa to the pterygopalatine fossa.

<span class="mw-page-title-main">Sphenoidal process of palatine bone</span> Thin, compressed plate

The sphenoidal process of palatine bone is a thin, superomedially directed plate of bone. It is smaller and more inferior compared to the orbital process of palatine bone.

<span class="mw-page-title-main">Parietal foramina</span>

A parietal foramen is an opening in the skull for the parietal emissary vein, which drains into the superior sagittal sinus. Occasionally, a small branch of the occipital artery can also pass through it. It is located at the back part of the parietal bone, close to the upper or sagittal border. It is not always present, and its size varies considerably. Parietal foramina tend to be symmetrical, with the same number on each side.

<span class="mw-page-title-main">Body of sphenoid bone</span>

The body of the sphenoid bone, more or less cubical in shape, is hollowed out in its interior to form two large cavities, the sphenoidal sinuses, which are separated from each other by a septum.

<span class="mw-page-title-main">Base of skull</span> Inferior area of the skull, composed of the endocranium and lower parts of the skull roof

The base of skull, also known as the cranial base or the cranial floor, is the most inferior area of the skull. It is composed of the endocranium and the lower parts of the calvaria.

References

PD-icon.svgThis article incorporates text in the public domain from page 150 of the 20th edition of Gray's Anatomy (1918)

  1. Raval, BB; Singh, PR; Rajguru, J (February 2015). "A morphologic and morphometric study of foramen vesalius in dry adult human skulls of gujarat region". Journal of Clinical and Diagnostic Research. 9 (2): AC04-7. doi:10.7860/JCDR/2015/11632.5553. PMC   4378719 . PMID   25859437.
  2. 1 2 Gupta N, Ray B, Ghosh S (2005). "Anatomic characteristics of foramen vesalius". Kathmandu University Medical Journal. 3 (10): 155–8. PMID   16415612.
  3. 1 2 Reymond J, Charuta A, Wysocki J (2005). "The morphology and morphometry of the foramina of the greater wing of the human sphenoid bone". Folia Morphologica Warszaw. 64 (3): 188–93. PMID   16228954.
  4. Kodama K, Inoue K, Nagashima M, Matsumura G, Watanabe S, Kodama G (1997). "Studies on the foramen vesalius in the Japanese juvenile and adult skulls". The Hokkaido Journal of Medical Science. 72 (6): 667–74. PMID   9465318.
  5. "Illustrated Encyclopedia of Human Anatomic Variation: Opus V: Skeletal Systems: Cranium - Sphenoid Bone". Illustrated Encyclopedia of Human Anatomic Variation. Retrieved 2006-04-09.
  6. Lang J, Maier R, Schafhauser O (1984). "Postnatal enlargement of the foramina rotundum, ovale et spinosum and their topographical changes". Anatomischer Anzeiger. 156 (5): 351–87. PMID   6486466.
  7. Lanzieri CF, Duchesneau PM, Rosenbloom SA, Smith AS, Rosenbaum AE (1988). "The significance of asymmetry of the foramen of Vesalius". American Journal of Neuroradiology. 9 (6): 1201–4. PMC   8331922 . PMID   3143245.
  8. Ginsberg LE, Pruett SW, Chen MY, Elster AD (February 1994). "Skull-base foramina of the middle cranial fossa: reassessment of normal variation with high-resolution CT". American Journal of Neuroradiology. 15 (2): 283–91. PMC   8334600 . PMID   8192074.

See also