Q.Give reason - Injury to medulla oblongata may prove fatal.

The hindbrain is made of the pons varolii, cerebellum and medulla oblongata. The pons varolii, a rounded bulge on the underside of the brain stem, carries a fibre band linking the cerebrum, cerebellum, medulla and spinal cord, plus several nuclei of its own. The cerebellum, the brain's second-largest part (two hemispheres joined by a central vermis, mostly white matter under a thin cortex whose branching pattern in section is the arbor vitae, with over 30 million cortical neurons and three pairs of cerebellar peduncles connecting it to the rest of the CNS), is an important regulatory centre for equilibrium, posture, balance, muscle tone and the smooth moderation of voluntary movement; all its own output is involuntary, even though learning a new skilled movement may initially involve it. The medulla oblongata, the conical posterior brain part continuing directly into the spinal cord, controls vital involuntary functions -- heartbeat, respiration, vasomotor activity, peristalsis -- as well as reflexes like coughing, sneezing, swallowing and vomiting; because these functions are vital, injury to the medulla can prove fatal. Its cavity, the fourth ventricle (metacoel), carries CSF-secreting choroid plexuses draining through the paired foramina of Luschka and the median foramen of Magendie.