Describe the physiology of cerebrospinal fluid (CSF). (70% of marks) Describe the anatomy relevant to the performance of a lumbar puncture. (30% of marks)
Most candidates performed well in this question. The physiology of cerebrospinal fluid (CSF)
required candidates to write about CSF formation, circulation and absorption, compare the
composition of CSF to plasma and describe normal volumes and pressures. The functions of
CSF also need to be listed. Some candidates described the displacement of CSF when
intracranial pressure rises as a function of CSF. No marks were given for this.
The best approach to the anatomy of a lumbar puncture was to describe the lumbar
intervertebral space at which the lumbar puncture is done and then describe the anatomical
structures that the needle would traverse from the skin to the subarachnoid space.
Mentioning the indications for a lumbar puncture was not required.