The cauda equina () is a bundle of spinal nerves and spinal nerve rootlets, consisting of the second through fifth lumbar nerve pairs, the first through fifth sacral nerve pairs, and the coccygeal nerve, all of which arise from the lumbar enlargement and the conus medullaris of the spinal cord. The cauda equina occupies the lumbar cistern, a subarachnoid space inferior to the conus medullaris. The Nerve that compose the cauda equina innervate the Pelvic cavity and human leg to include motor innervation of the , , , foot, internal anal sphincter and external anal sphincter. In addition, the cauda equina extends to sensory innervation of the perineum and, partially, parasympathetic innervation of the bladder.
Structure
In
adulthood, the cauda equina is made of
Vertebral column spinal nerve roots.
Development
In
Human, the
spinal cord stops growing in
Infant. At birth the end of the spinal cord is about the level of the third
lumbar vertebrae, or L3. Because the
Bone of the
vertebral column continue to grow, by about 12 months of age the end of the cord reaches its permanent position. Typically this is at the level of L1 or L2 (closer to the head),
ranging due to normal
anatomical variations anywhere from the twelfth thoracic vertebra (T12) to L3. Individual spinal nerve roots arise from the cord as they get closer to the head, but as the differential growth occurs, the top end of the nerve stays attached to the spinal cord while the lower end of the nerve exits the
spinal column at its proper level. This results in a "bundle"-like structure of
nerve fibers that extends
caudally, within the spinal column, from the end of the spinal cord, gradually declining in number further down as individual pairs leave the spinal column.
Clinical significance
Needle insertion
The cauda equina exists within the lumbar cistern, a gap between the arachnoid membrane and the
pia mater of the spinal cord, called the subarachnoid space. Cerebrospinal fluid also exists within this space. Because the spinal cord terminates at level L1/L2,
lumbar puncture (or colloquially, "spinal tap") is performed from the
lumbar cistern between two
Vertebra at level L3/L4, or L4/L5, where there is no risk of accidental injury to the spinal cord, when a sample of CSF is needed for clinical purposes.
Cauda equina syndrome
Cauda equina syndrome, a rare disorder affecting the bundle of nerve roots (cauda equina) at the lower (lumbar) end of the spinal cord, is a surgical emergency.
Cauda equina syndrome occurs when the
Nerve root in the lumbar spine are compressed, disrupting sensation and movement.
Nerve roots that control the function of the
bladder and
bowel are especially vulnerable to damage. It can lead to permanent
paralysis, impaired bladder and/or bowel control, loss of
sexual sensation, and other problems if left untreated. Even with immediate treatment, some patients may not recover complete function.
Cauda equina syndrome most commonly results from a massive disc herniation in the lumbar region.
Radiculopathy
The cauda equina is vulnerable to being compressed, causing a
radiculopathy.
History
The cauda equina was named after its resemblance to a horse's tail () by the
French language anatomist Andreas Lazarus (André du Laurens) in the 17th century.
See also
-
Saladin, Kenneth S. Anatomy and Physiology The Unity of Form and Function
-
Smith's Anesthesia for infants and children. 8th edition, Chapter 1, Page 8.
External links
- Cauda Equina Syndrome UK Charity social network
