Thalamus. (a) Medial view. The thalamus forms the superior part of the lateral wall of the third ventricle. The hypothalamic sulcus is the border between the thalamus above and hypothalamus below. (b) Superolateral view of the position of the thalamus in the lateral ventricle. The thalamus is located in the center of the lateral ventricle at the upper end of the brainstem. The anterior thalamic nucleus (tubercle) forms the posterior edge of the foramen of Monro. (c) Superior view. The upper margin of the thalamus forms the lateral parts of the floor of the lateral ventricle. The stria terminalis and thalamostriate vein run along the striathalamic sulcus. (d) The fornix wraps around the medial edge of the thalamus, and the caudate nucleus wraps around the lateral edge of the thalamus. (e) Posterolateral view. The left thalamus was removed to expose the subthalamic nucleus and red nucleus. The pulvinar is the posterolateral part of the thalamus.