This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neuroanatomy 1, Subject name: Anatomy
All are seen in the floor of third ventricle except? 
Select and explain. 
A. Mammillary body, B. Oculomotor nerve, C. Optic chiasma, D. Tuber cinereum
B: Oculomotor nerve
Answer: B: Oculomotor nerve 
Explanation: Boundaries of 3rd ventricle: LATERAL WALL - Thalamus, Hypothalamus FLOOR - Mammillary body , tegmentum pa of mid brain , tuber cinereum ,infundibular stalk , optic chiasma. ROOF - Fornix ANTERIOR - lamina terminalis , anterior commissure POSTERIOR - pineal body , posterior commissure Extra edge Septum pellucidum Thin ,triangular,veical double membrane separating the anterior horns of the left and right lateral ventricles of the brain. Extends between corpus callosum and the fornix.