title: Clinical anatomy of the orbitomeningeal foramina: variational anatomy of the canals connecting the orbit with the cranial cavity.
abstract: OBJECTIVE
  In addition to the optic canal and the superior orbital fissure, orbits are connected with the cranial cavity via inconstant canals including the orbitomeningeal foramen. This study has been carried out in order to define many anatomical and radiological details of the orbitomeningeal foramen that are relevant in the clinical practice.
  
  
  METHODS
  Almost 1000 skulls and 50 computerized tomographies were examined to determine incidence, number, length, and caliber of the orbitomeningeal foramen as well as the topography of their orbital and cranial openings. A retrospective study of angiographies carried out on more than 100 children was performed to look for arteries candidate to run through the orbitomeningeal foramen.
  
  
  RESULTS
  Orbitomeningeal foramina were detected in 59.46% of skulls and in 54% of individuals by computerized tomography. Orbits with two to five foramina were found. Canals were classified as M-subtype or A-subtype depending on their cranial opening. Large foramina, with the caliber ranging between 1 and 3 mm, were found in 12.17% of orbitomeningeal foramen-bearing orbits. By computed tomography the average caliber measured 1.2 ± 0.3 and 1.5 ± 0.5 mm (p < 0.005) at the orbital and cranial openings, respectively (p < 0.005). Angiographies showed meningo-lacrimal and meningo-ophthalmic arteries, meningeal branches of the lacrimal and supraorbital arteries, and some unidentified arteries that could pass through the orbitomeningeal foramina.
  
  
  CONCLUSIONS
  Orbitomeningeal foramina are a common occurrence. When large they may house important arteries that can be the source of severe bleedings during deep dissection of the lateral wall of the orbit. Orbital surgeons should be aware of their existence.
authors.affiliation: Department of Molecular Medicine, Institute of Human Anatomy, University of Padova, Via A. Gabelli 65, 35127, Padua, Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: Macchi
authors.affiliation: Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100, Siena, Italy.
authors.forename: Marì
authors.initials: M
authors.lastname: Regoli
authors.affiliation: Unit of Neuroimaging and Neurointervention (NINT), Azienda Ospedaliera Universitaria Senese (AOUS), University of Siena, Policlinico "Santa Maria alle Scotte", Siena, Italy.
authors.forename: Sandra
authors.initials: S
authors.lastname: Bracco
authors.affiliation: Gut Health and Food Safety Institute Strategic Program, Institute of Food Research, Norwich, UK.
authors.forename: Claudio
authors.initials: C
authors.lastname: Nicoletti
authors.affiliation: Section of Radiology, Euganea Medica Center, Via Colombo 3, Sant'Agostino Di Albignasego, 35127, Padua, Italy.
authors.forename: Aldo
authors.initials: A
authors.lastname: Morra
authors.affiliation: Department of Molecular Medicine, Institute of Human Anatomy, University of Padova, Via A. Gabelli 65, 35127, Padua, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Porzionato
authors.affiliation: Department of Molecular Medicine, Institute of Human Anatomy, University of Padova, Via A. Gabelli 65, 35127, Padua, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: De Caro
authors.affiliation: Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100, Siena, Italy. eugenio.bertelli@unisi.it.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Bertelli
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D063405:Anatomic Variation; D000792:Angiography; D002648:Child; D005260:Female; D006801:Humans; D007765:Lacrimal Apparatus / Q000098:blood supply / Q000000981:diagnostic imaging; D008297:Male; D008576:Meningeal Arteries / Q000000981:diagnostic imaging; D008578:Meninges / Q000033:anatomy & histology*; D008875:Middle Aged; D009880:Ophthalmic Artery / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D009915:Orbit / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D010256:Paranasal Sinuses / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D012886:Skull / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Meningo-lacrimal artery; Meningo-ophthalmic artery; Orbit; Orbital surgery; Orbitomeningeal foramen