system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Floor of body of lateral ventricle is formed by
assistant
The correct answer is  Floor of body of lateral ventricle is formed by 

Caudate nucleus
Thalamostriate vein
Thalamus upper  surface 
Body of fornix upper surface

Rostrum of corpus callosum forms floor, septum pellucidum forms medial wall, and genu of corpus callosum forms anterior wall of anterior horn of lateral ventricle.