A morphometric study of the lumbar foramen. Influence of flexion-extension movements and of isolated disc collapse.
The authors undertook a morphometric study of the intervertebral foramina in anatomic specimens of spines unaffected by degenerative lesions. They studied the variations in shape and size of 38 intervertebral foramina during flexion-extension movements and following an isolated disc collapse. The cast technique takes into account the bony prominences, the bulge of the disc anteriorly and of the capsulo-ligamentous structures posteriorly. In flexion, all the diameters of the foramina are maximal. In full extension all the diameters decrease significantly: the pedicles come closer together, the disc bulges posteriorly and the ligamentum flavum is pushed forward by the superior articular process of the underlying vertebra. A disc collapse of 4 mm decreases all the diameters, and in this case lumbar extension results in a sufficient decrease of foraminal diameter to threaten the nerve root.
Laboratoire d'Anatomie, CHU Cochin Port-Royal, Paris, France.
M A
MA
Mayoux-Benhamou
M
M
Revel
C
C
Aaron
G
G
Chomette
B
B
Amor
D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000209:etiology* / Q000473:pathology; D008159:Lumbar Vertebrae / Q000033:anatomy & histology* / Q000473:pathology / Q000502:physiology; D008297:Male; D009068:Movement