Which areas of the brain make up the brain stem?
The brain stem comprises the medulla, the pons and the midbrain, according to Kandel's extremely authoritative Principles of Neural Science. This is equivalent to the midbrain and the hindbrain minus the cerebellum, which is probably where the confusion stems from.


  Kandel, E. R., Schwartz, J. H., &amp; Jessell, T. M. (Eds.). (2000). Principles of neural science (Vol. 4, pp. 1227-1246). New York: McGraw-Hill.