Title: Spinal cord
Content:  filum terminale, which anchors the spinal cord to the coccyx. The cauda equina ("horse's tail") is a collection of nerves inferior to the conus medullaris that continue to travel through the vertebral column to the coccyx. The cauda equina forms because the spinal cord stops growing in length at about age four, even though the vertebral column continues to lengthen until adulthood. This results in sacral spinal nerves originating in the upper lumbar region. For that reason, the spinal cord occupies only two-thirds of the vertebral canal. The inferior part of the vertebral canal is filled with cerebrospinal fluid (CSF) and the 
Title: Cauda equina
Content:  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 nerves that compose the cauda equina innervate the pelvic organs and lower limbs to include motor innervation of the hips, knees, ankles, feet, 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.
Title: Cauda equina syndrome
Content:  After the conus medullaris (near lumbar vertebral levels 1 (L1) and 2 (L2), occasionally lower), the spinal canal contains a bundle of nerve fibers (the cauda equina or "horse-tail") that branches off the lower end of the spinal cord and contains the nerve roots from L1–L5 and S1–S5. The nerve roots from L4–S4 join in the sacral plexus which affects the sciatic nerve, which travels caudally (toward the feet). Compression, trauma or other damage to this region of the spinal canal can result in cauda equina syndrome. The symptoms may also appear as a temporary side-effect of a sacral extra-dural injection.
Title: Cauda equina
Content:  In adulthood, the cauda equina is made of lumbosacral spinal nerve roots.
Title: Cauda equina
Content:  In humans, the spinal cord stops growing in infancy and the end of the spinal cord is about the level of the third lumbar vertebra, or L3, at birth. Because the bones of the vertebral column continue to grow, by about 12 months of age, the end of the cord reaches its permanent position at the level of L1 or L2 (closer to the head). However, due to normal anatomical variations, the final cord end position may occur anywhere from T12 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 from the end of the spinal cord, gradually declining in number further down as individual pairs leave the spinal column.
Title: Spinal disease
Content:  Cauda equina syndrome is a rare syndrome that effects the spinal nerves in the region of the lower back called the cauda equine (Latin for "horses tail"). Injury to the cauda equine can have long lasting ramifications for the individual. Symptoms include lower back pain, bladder disturbances, bowel dysfunction, and anesthesia or paresthesia between the thighs. In order to prevent progressive neurological changes surgery can be a viable option.
Title: Spinal cord
Content:  the L1/L2 vertebral level, forming a structure known as the conus medullaris. Although the spinal cord cell bodies end around the L1/L2 vertebral level, the spinal nerves for each segment exit at the level of the corresponding vertebra. For the nerves of the lower spinal cord, this means that they exit the vertebral column much lower (more caudally) than their roots. As these nerves travel from their respective roots to their point of exit from the vertebral column, the nerves of the lower spinal segments form a bundle called the cauda equina. There are two regions where the spinal cord enlarges: 
Title: Cauda equina
Content:  The cauda equina exists within the lumbar cistern, a gap between the arachnoid membrane and the pia matter 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 vertebrae 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.
Title: Neuromere
Content:  column below the conus medullaris. The cauda equina forms as a result of the fact that the spinal cord stops growing in length at about age four, even though the vertebral column continues to lengthen until adulthood. This results in the fact that sacral spinal nerves actually originate in the upper lumbar region. The spinal cord can be anatomically divided into 31 spinal segments based on the origins of the spinal nerves. Each segment of the spinal cord is associated with a pair of ganglia, called dorsal root ganglia, which are situated just outside the spinal cord. These ganglia contain cell bodies of sensory neurons. Axons of 
Title: Cauda equina
Content:  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 roots 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. A disc herniation occurs when one of 

Question: where does the spinal cord become cauda equina?
Answer: L1 or L2.
the conus medullaris.