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.[3] 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.[3][4]
The foramen may pass through the sphenoid bone at the apex of the spinous process, or along its medial surface.[4]
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 variesfrom 1.05 mm to about 2.1 mm in adults.[5] The average diameter of the foramen spinosum is 2.63 mm in adults.[6] It is usually between 3 and 4 mm away from the foramen ovale in adults.[7]
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.[6] 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.[4][8]
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.[4]
^ abMoore, Keith L.; Dalley, Arthur F.; Agur, Anne M. R. (2018). Clinically Oriented Anatomy (8th ed.). Wolters Kluwer. pp. 841–844. ISBN978-1-4963-4721-3.
^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. PMID6486466.
^ abYanagi 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. PMID3610040.
^Ort, Bruce Ian Bogart, Victoria (2007). Elsevier's integrated anatomy and embryology. Philadelphia, Pa.: Elsevier Saunders. p. Elsevier’s Integrated Anatomy and Embryology. ISBN978-1-4160-3165-9.{{cite book}}: CS1 maint: multiple names: authors list (link)
^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. ISBN978-0-8089-2306-0.