L5-S1
Medical abbreviation · Anatomy
| Stands for | Fifth lumbar and first sacral vertebrae (lumbosacral junction) |
|---|---|
| Categories | Medical |
L5-S1 stands for Fifth lumbar and first sacral vertebrae (lumbosacral junction), an anatomy abbreviation.
Junction between the lowest lumbar vertebra and the sacrum, where the mobile spine meets the rigid pelvis. Together with L4-L5 it accounts for the great majority of lumbar disc herniations, and an L5-S1 herniation usually compresses the S1 nerve root, causing sciatica down the back of the leg and a reduced ankle reflex.
Example: L5-S1 extrusion with left S1 radiculopathy; absent left Achilles reflex.
Usage notes
Isthmic spondylolisthesis, a slip after a stress fracture of the pars interarticularis, most often occurs at L5-S1 and is common in young gymnasts and football linemen. Sacral slope and pelvic incidence measured at this junction guide spinal alignment surgery. Also written L5/S1.
Related abbreviations
More anatomy abbreviations
- ICS – Intercostal space
- IJ – Internal jugular (vein)
- IMA – Inferior mesenteric artery
- IT band – Iliotibial band
- L-spine – Lumbar spine
- L4-L5 – Fourth and fifth lumbar vertebrae (intervertebral level)
- LCL – Lateral collateral ligament
- LE – Lower extremity
- LLQ – Left lower quadrant
- LN – Lymph node
- LUQ – Left upper quadrant
- MAL – Midaxillary line
See all 70 anatomy abbreviations →
This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.