Foramen spinosum

The foramen spinosum is a hole located in the greater wing of the sphenoid. It is located posterolateral to the foramen ovale and anterior to the sphenoidal spine. It allows the passage of the middle meningeal artery, middle meningeal vein and usually the meningeal branch of the mandibular nerve (sometimes it passes through the foramen ovale).

Foramen spinosum
The inner surface of the sphenoid bone, with the foramen spinosum labelled at the left, second from the bottom.
The inner surface of the base of the skull, with the sphenoid bone yellowed. The foramen spinosum is visible at the bottom right of the bone.
Details
Identifiers
LatinForamen spinosum
TA98A02.1.05.038
TA2624
FMA53156
Anatomical terms of bone

The foramen spinosum is often used as a landmark in neurosurgery, due to its close relations with other cranial foramina. It was first described by Jakob Benignus Winslow in the 18th century.

Structure

The foramen spinosum is a foramen in the sphenoid that connects the middle cranial fossa to the infra temporal fossa. It is located posterolateral to the foramen ovale and anterior to the sphenoidal spine.

Variation

The foramen spinosum varies in size and location. The foramen is rarely absent, usually unilaterally, in which case the middle meningeal artery enters the cranial cavity through the foramen ovale.[1] It may be incomplete, which may occur in almost half of the population. Conversely, in a minority of cases (less than 1%), it may also be duplicated, particularly when the middle meningeal artery is also duplicated.[2][1]

The foramen may pass through the sphenoid bone at the apex of the spinous process, or along its medial surface.[2]

Development

In the newborn, the foramen spinosum is about 2.25 mm long and in adults about 2.56 mm. The width of the foramen extends from 1.05 mm to about 2.1 mm in adults.[3] The average diameter of the foramen spinosum is 2.63 mm in adults.[4]

The earliest perfect ring-shaped formation of the foramen spinosum was observed in the eighth month after birth and the latest seven years after birth in a developmental study of the foramen rotundum, foramen ovale and foramen spinosum. The majority of the foramina in the skull studies were round in shape.[4] The sphenomandibular ligament, derived from the first pharyngeal arch and usually attached to the spine of the sphenoid bone, may be found attached to the rim of the foramen.[2][5]

Animals

In other great apes, the foramen spinosum is found not in the sphenoid but in parts of the temporal bone such as the squamous part, found at the sphenosquamosal suture, or absent.[2][6]

Function

The foramen spinosum permits the passage of the middle meningeal artery, middle meningeal vein, and the meningeal branch of the mandibular nerve.[2][7]:763

Clinical significance

Due to its distinctive position, the foramen is used as an anatomical landmark during neurosurgery. As a landmark, the foramen spinosum reveals the positions of other cranial foramina, the mandibular nerve and trigeminal ganglion, foramen ovale, and foramen rotundum. It may also be relevant in achieving haemostasis during trauma surgery.[2]

History

The foramen spinosum was first described by the Danish anatomist Jakob Benignus Winslow in the 18th century. It is so-named because of its relationship to the spinous process of the greater wing of the sphenoid bone. However, due to incorrectly declining the noun, the literal meaning is "hole full of thorns" (Latin: foramen spinosum). The correct, but unused name would, in fact, be foramen spinae.[2]

Additional images

See also

  • Foramina of skull

References

This article incorporates text in the public domain from page 150 of the 20th edition of Gray's Anatomy (1918)

  1. "Illustrated Encyclopedia of Human Anatomic Variation: Opus V: Skeletal Systems: Cranium – Sphenoid Bone". Illustrated Encyclopedia of Human Anatomic Variation. Retrieved 2006-04-10.
  2. Krayenbühl, Niklaus; Isolan, Gustavo Rassier; Al-Mefty, Ossama (2 August 2008). "The foramen spinosum: a landmark in middle fossa surgery" (PDF). Neurosurgical Review. 31 (4): 397–402. doi:10.1007/s10143-008-0152-6. PMID 18677523. S2CID 37126697.
  3. 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.
  4. Yanagi S (1987). "Developmental studies on the foramen rotundum, foramen ovale and foramen spinosum of the human sphenoid bone". The Hokkaido Journal of Medical Science. 62 (3): 485–96. PMID 3610040.
  5. Ort, Bruce Ian Bogart, Victoria (2007). Elsevier's integrated anatomy and embryology. Philadelphia, Pa.: Elsevier Saunders. p. Elsevier’s Integrated Anatomy and Embryology. ISBN 978-1-4160-3165-9.
  6. Braga, J.; Crubézy, E.; Elyaqtine, M. (1998). "The posterior border of the sphenoid greater wing and its phylogenetic usefulness in human evolution". American Journal of Physical Anthropology. 107 (4): 387–399. doi:10.1002/(SICI)1096-8644(199812)107:4<387::AID-AJPA2>3.0.CO;2-Y. PMID 9859876.
  7. Drake, Richard L.; Vogl, Wayne; Tibbitts, Adam W.M. Mitchell; illustrations by Richard; Richardson, Paul (2005). Gray's anatomy for students. Philadelphia: Elsevier/Churchill Livingstone. ISBN 978-0-8089-2306-0.

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