Nervous System

Spinal Cord

Why do physicians perform a spinal tap at the fourth lumbar vertebra (L4)?

A spinal tap, also called a lumbar puncture, is the withdrawal of a small amount of cerebrospinal fluid from the subarchnoid space in the lumbar region of the vertebral column. Since the spinal cord ends at the level of the first or second lumbar vertebra, a needle can be inserted into the subarchnoid space at the fourth lumbar vertebra with little risk of injuring the spinal cord. The cerebrospinal fluid may be tested and examined for infection. Cerebrospinal fluid is also withdrawn to reduce pressure caused by swelling of the brain or spinal cord following injury or disease.


This is a web preview of the "The Handy Anatomy Answer Book" app. Many features only work on your mobile device. If you like what you see, we hope you will consider buying. Get the App