<s>[INST] context: The cauda equina is a structure within the lower end of the spinal column, that consists of nerve roots and rootlets from above.
Because the spinal cord stops growing in infancywhile the bones of the spine continue growing, the spinal cord in adults ends at about the level of the vertebra L1, and at birth at L3.
To get through the intervertebral foramen at the correct segment, the roots must travel down the length of the spine, thus gaining an oblique course.
Thai is why the spinal nerves are more &more oblique as we trace them from supero-inferiorly. For e.g., L-5 spinal nerve is more oblique as compared to T-5. Also, L-5 will be more in length as compared to T-5
Clinical relevance
Cauda equina syndrome is a serious neurologic condition in which there is compression of the contents of the spinal canal below the termination (conus) of the spinal cord.
Any lesion which compresses the cauda equina may cause dysfunction of the nerves although the commonest is a central disc prolapse.
Other causes include protrusion of the vertebra into the canal if weakened by infection or tumor and an epidural abscess or hematoma.
Signs include weakness of the muscles innervated by the compressed roots (often paraplegia), sphincter weaknesses causing urinary retention and post-void residual incontinence as assessed by catheterizing after the patient has voided.
Also, there may be decreased rectal tone; sexual dysfunction; saddle anesthesia; bilateral leg pain and weakness; and bilateral absence of ankle reflexes.
Pain may, however, be wholly absent; the patient may complain only of lack of bladder control and of saddle-anaesthesia, and may walk into the consulting-room. [/INST] question: A 26-year-old woman experiences severe back pain from an automobile accident. CT scan shows that the L5 vertebral foramen is completely obliterated by the collapsed L5 laminae and pedicles. In this injury, which of the following structures is crushed | options: A: Cauda equine B: Vertebral artery C: Filum terminale D: Denticulate ligament | answer: A </s>