Final answer:
A normal sulcus generally measures 3 mm or less, with deviations potentially indicating pathological conditions.
Step-by-step explanation:
A common measurement for a normal sulcus is 3 mm or less. In medicine, the term sulcus refers to the indents or "valleys" found in the cortical surface of the brain.
These sulcal patterns help to increase the surface area of the cerebral cortex and are significant in distinguishing various regions of the brain.
A sulcus that is deeper than 3 mm might indicate underlying pathological conditions. For instance, in neuroimaging, a widening of the sulcal spaces may be associated with brain atrophy.