Because of its location deep within the brain, the thalamus is neighbored by several structures and also portions of the ventricular system. Anteriorly, the thalamus extends forward to contact the interventricular foramen, which connects the lateral and third ventricles (eFig. 9.28). Together, the thalamic nuclear masses and the ventrally located hypothalamus comprise the lateral walls of the third ventricle. Immediately lateral to the thalamus is the posterior limb of the internal capsule (eFig. 9.29). Related to the dorsal aspect of the thalamus is the body of the lateral ventricle, and extending caudally is the midbrain portion of the brainstem (eFig. 9.28). Across the midline of the third ventricle, the two thalamic masses are interconnected by the interthalamic adhesion.