Citation, DOI & article data
The conus medullaris is the terminal end of the spinal cord.
After the cord terminates, the nerve roots descend within the spinal canal as individual rootlets, collectively termed the cauda equina. The conus medullaris most commonly terminates at the L1/2 intervertebral disc level in children and adults 1-3.
Extending from the conus is a delicate strand of fibrous tissue called the filum terminale that acts to give longitudinal support to the cord.
The termination of the conus medullaris has been reported from mid-T11 to mid-L3 vertebral body levels and the average termination varies from study-to-study 1-3 but a level at or above the L2/3 intervertebral disc level can be considered normal and a level at L3 vertebral body is equivocal and can be a normal variant or the result of a tethered cord 1. On fetal MRI, the vertebral bodies can be difficult to accurately count, but the kidneys may be used as a reference; a normal conus should not terminate below the lower margin of normally positioned kidneys.
- 1. Wilson DA, Prince JR. John Caffey award. MR imaging determination of the location of the normal conus medullaris throughout childhood. AJR Am J Roentgenol. 1989;152 (5): 1029-32. doi:10.2214/ajr.152.5.1029 - Pubmed citation
- 2. Soleiman J, Demaerel P, Rocher S et-al. Magnetic resonance imaging study of the level of termination of the conus medullaris and the thecal sac: influence of age and gender. Spine. 2006;30 (16): 1875-80. Pubmed citation
- 3. Kesler H, Dias MS, Kalapos P. Termination of the normal conus medullaris in children: a whole-spine magnetic resonance imaging study. Neurosurg Focus. 2007;23 (2): E7. doi:10.3171/FOC-07/08/E7 - Pubmed citation