What is the anatomy of cauda equina?

Updated: Jun 14, 2018
  • Author: Segun Toyin Dawodu, JD, MD, MS, MBA, LLM, FAAPMR, FAANEM; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

The spinal cord tapers and ends at the level between the first and second lumbar vertebrae in an average adult. The most distal bulbous part of the spinal cord is called the conus medullaris, and its tapering end continues as the filum terminale. Distal to this end of the spinal cord is a collection of nerve roots, which are horsetail-like in appearance and hence called the cauda equina (Latin for horse's tail). (See the image of cauda equina anatomy below.)

Illustration demonstrating the relevant anatomy of Illustration demonstrating the relevant anatomy of the cauda equina region

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These nerve roots constitute the anatomic connection between the central nervous system (CNS) and the peripheral nervous system (PNS). They are arranged anatomically according to the spinal segments from which they originated and are within the cerebrospinal fluid (CSF) in the subarachnoid space with the dural sac ending at the level of second sacral vertebra.


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