Conus medullaris

Looks like

The tapered lower end of the spinal cord, at the level of the first or second lumbar vertebra in adults; below it only the nerve roots of the cauda equina continue.

What it does

Holds the last cord segments that control the bladder, bowel and sexual function.

Keeping it well

A lumbar puncture is done below it, at L3–L4, so the needle meets only floating roots. Compression here (conus syndrome) causes early bladder and bowel failure and saddle numbness — an emergency.

Related conditions

• Amyloidosis (AL and ATTR)
• Amyotrophic lateral sclerosis
• B12 & folate deficiency
• Bone metastases and spinal cord compression
• Botulism
• Cauda equina syndrome
• Chiari malformation and syringomyelia
• Chickenpox (varicella)
• Chronic neuropathic pain
• Chronic pain syndrome
• Fibromyalgia
• Friedreich's ataxia
• Guillain-Barré syndrome
• Lyme disease
• Multiple sclerosis
• Myasthenia gravis
• Neck pain and cervical spondylosis
• Neurogenic bladder
• Neuromyelitis optica spectrum disorder
• Peripheral neuropathy
• Poliomyelitis
• Rabies
• Restless legs syndrome
• Shingles (herpes zoster)
• Spina bifida & neural tube defects
• Spinal cord injury
• Spinal muscular atrophy
• Tetanus
• Tick-borne encephalitis
• Vitamin B1, C and other deficiencies