Related Experiment Video
Updated: Jul 11, 2026

A Mobile Outside-in Technique of Transforaminal Lumbar Endoscopy for Lumbar Disc Herniations
Published on: August 7, 2018
Twelfth Rib Length as a Predictor of Anatomic Variations in the Lumbosacral Plexus Associated With Atypical
Hidaka Anetai1, Juri Teramoto2,3, Takafumi Ono4
1Department of Physical Therapy, Faculty of Health Science, Juntendo University, Tokyo, Japan.
Study Design:
A combined clinical and cadaveric observational study.
Objectives:
To investigate whether anatomic variations in the lumbosacral plexus (LSP) are associated with diagnostic discrepancies in lumbar disc herniation (LDH) and to corroborate clinical findings with anatomic evidence.
Summary Of Background Data:
LDH is typically diagnosed based on clinical neurological symptoms and the level of the compressed spinal nerve root (the responsible lesion) identified by magnetic resonance imaging. However, in some patients, radiculopathy symptoms do not always align with the responsible lesion, complicating the diagnosis. This discrepancy may be linked to anatomic variations in the LSP, although the exact cause remains unclear. LSP roots may exhibit cranio-caudal deviations, which tend to be associated with shorter or longer 12th ribs, providing a potential basis for investigation.
Methods:
We examined 12th rib length in 144 patients with LDH at Juntendo University Hospital and investigated the relationship between LSP branch deviations and 12th rib length in 29 Japanese cadavers, donated to Juntendo University School of Medicine.
Results:
Of the total, 102 cases showed matching radiculopathies and responsible lesions (matched group), whereas 42 cases exhibited discrepancies (mismatched group). The mismatched group was subdivided into: 19 cases with radiculopathy at a lower level than predicted by the responsible lesion (lower-level radiculopathy type) and 23 cases with radiculopathy at a higher level (higher-level radiculopathy). These types were significantly associated with shorter and longer 12th ribs, respectively, suggesting cranial and caudal deviations in LSP branches, confirmed by anatomic examination.
Conclusion:
These findings suggest that contradictory neurological symptoms in LDH may be largely due to cranio-caudal deviations in the LSP and its branches. Furthermore, the 12th rib length may help predict these anatomic variations, potentially improving diagnostic accuracy in LDH.
Related Concept Videos
Spinal Nerves: Anatomy
There are 31 bilateral pairs of spinal nerves, each emerging from the spinal cord through the intervertebral foramina—openings between adjacent vertebrae. These nerves are...
Spinal Nerves: Plexus I
The Cervical Plexus
The cervical plexus, formed by the anterior rami of the first four...
Spinal Nerves: Plexus II
The Lumbar Plexus
The lumbar plexus is situated within the lumbar region of the back and is primarily formed by the first four lumbar spinal nerves (L1 to L4). This plexus extends its branches into several nerves, including the...
Herniated Intervertebral Disc l: Introduction
Degenerative Disc Disease ll: Pathophysiology

