Posterior BrainStem showing Pineal gland

The pineal gland is situated posterior to the third ventricle and rests in a depression between the two superior colliculi, which are part of the posterior (dorsal) surface of the midbrain (the most superior part of the brainstem). The pineal gland itself is not considered part of the brainstem but rather part of the epithalamus region of the diencephalon (forebrain).

Superior Colliculi

The gland sits nestled in the groove between the paired superior colliculi, which are located on the dorsal aspect of the midbrain's tectum (or quadrigeminal plate).

Third Ventricle

The pineal gland is attached by a short stalk to the posterior wall of the third ventricle. A small extension of the third ventricle, the pineal recess, projects into this stalk.