A student traces the efferent pathway of the hippocampal formation as described in the circuit of Papez. After fibres leave the hippocampus via the fimbria and fornix and synapse in the mammillary body, which structure carries the next limb of the circuit?

• A Mammillotegmental tract to the reticular formation
• B Anterior commissure to the cingulate gyrus
• C Stria terminalis to the septal nuclei
• D Mamillothalamic tract (bundle of Vicq d'Azyr) to the anterior nucleus of the thalamus ✓

Explanation

The Papez circuit runs: hippocampus, fornix, mammillary body, mamillothalamic tract, anterior thalamic nucleus, cingulate gyrus, cingulum, back to entorhinal cortex. The bundle of Vicq d'Azyr is the correct name for this tract and is a favourite exam fact. The mammillotegmental tract also arises from the mammillary bodies but projects caudally to the tegmentum and is not part of the limbic loop, which kills option A. The stria terminalis connects the amygdala to the hypothalamus and belongs to the amygdaloid circuit instead.

Reference: Snell's Clinical Neuroanatomy, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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