title: The superficial anulus fibrosus ligament. An incipient description of a separate ligament between the lumbar anterior longitudinal ligament and the intervertebral disc.
abstract: A previously unknown ligament, the superficial anulus fibrosus ligament (SAFL), situated on the ventral part of the L5 intervertebral disc (ID) was observed and described from autopsy material. Twenty-eight cadaveric specimens from 12 black and 16 white persons aged 17-30 years were studied during routine forensic autopsies. The anterior longitudinal ligament was separated from the ID and the ventral part of the SAFL was visualized. The SAFL samples were removed, measured and studied with both conventional histology and examination by transmission electron microscopy. The SAFL was a completely separate ligament at the level of the L5-S1 ID situated between the anterior longitudinal ligament and the anulus fibrosus of the ID. The fibers of the ligament were vertically oriented. A difference in distance between the L5-S1 vertebral bodies ventrally was noted in the two groups studied (18.7 +/- 1.2 mm in the black vs. 15.2 +/- 1.0 mm in the white, p < 0.001), indicating a difference in the ventral thickness of the intervertebral disc. Also, there was a difference in the length (black: 17.7 +/- 1.6 mm vs. white: 14.1 +/- 1.1), thickness (black: 3.3 +/- 0.3 mm vs. white: 2.1 +/- 1.9), and the cross-sectional area (black: 58.2 +/- 6.7 mm(2) vs. white: 26.5 +/- 2.7 mm(2), p < 0.001) of the SAFL. Conventional light microscopy revealed no obvious differences. However, transmission electron microscopy revealed notably larger collagen fibril diameter in black than white subjects. In conclusion, the interbody distances were greater in the black group, indicating a greater intervertebral disc thickness, compared to that of the white. Furthermore, the SAFL was significantly longer and thicker in the black than in the white group. Albeit unsubstantiated, these race-specific macroscopic findings may have implications for understanding the etiology of various low back stress problems.
authors.affiliation: Department of Medical Anatomy, The Panum Institute, University of Copenhagen, Copenhagen, Denmark.
authors.forename: P
authors.initials: P
authors.lastname: Hanson
authors.forename: K
authors.initials: K
authors.lastname: Qvortrup
authors.forename: S P
authors.initials: SP
authors.lastname: Magnusson
mesh_terms: D000293:Adolescent; D000328:Adult; D044383:Black People; D002102:Cadaver; D006801:Humans; D007403:Intervertebral Disc / Q000033:anatomy & histology; D008022:Ligaments / Q000033:anatomy & histology* / Q000648:ultrastructure; D008159:Lumbar Vertebrae / Q000033:anatomy & histology; D008854:Microscopy, Electron; D013131:Spine / Q000033:anatomy & histology* / Q000648:ultrastructure; D044465:White People