title: The lumbar mamillo-accessory foramen: a study of 203 lumbosacral spines.
abstract: We have examined 203 lumbar and sacral skeletal specimens and have noted the frequent occurrence of a mamillo-accessory foramen, formed by the ossification of the mamillo-accessory ligament. The dorsal ramus of the lumbar nerve passes through this foramen. At the L5 level, this foramen is found frequently: in 26% of the cases on the left side and in 13.5% on the right. In some cases it is seen as a simple, deep notch. It is found much less frequently at L4 and almost never seen above. It is equally rare at the sacral level where it is formed by a narrowing and closure of the groove between the zygapophyseal joint and the sacral lateral mass. The authors propose that these bony foramina are a manifestation of osteoarthritic changes and that they could, in certain cases, irritate or compress the dorsal ramus along its passage.
authors.affiliation: Department of Anatomy, UER Pitié-Salpêtrière, University of Paris V, France.
authors.forename: J Y
authors.initials: JY
authors.lastname: Maigne
authors.forename: R
authors.initials: R
authors.lastname: Maigne
authors.forename: H
authors.initials: H
authors.lastname: Guerin-Surville
mesh_terms: D006801:Humans; D008022:Ligaments / Q000033:anatomy & histology / Q000473:pathology; D008159:Lumbar Vertebrae / Q000033:anatomy & histology*; D009999:Ossification, Heterotopic; D012447:Sacrum / Q000033:anatomy & histology*