View the ventral side of the brain: o. Locate the optic nerve, optic chiasm, olfactory bulb

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1 BRAIN DISSECTION Identify External Structures: Cerebral hemispheres, brain stem, cerebellum Gyri, sulci, fissures (longitudinal and transverse fissures) Locate lobes of the cerebrum View the ventral side of the brain: o Locate the optic nerve, optic chiasm, olfactory bulb Identify Internal Structures: Make a sagittal section through the longitudinal fissure, corpus callosum, and midline of the cerebellum. o Identify white & gray matter o A thin membrane ventral to the corpus callosum separates the lateral ventricles. Pierce this membrane and probe the cavity of the lateral ventricle o Locate the third ventricle o Locate thalamus, hypothalamus, and epithalamus o Locate the midbrain, pons, and medulla o Locate the cerebellum and view the arbor vitae Questions: 1) What structure increases surface area of the cerebrum? 2) What does the longitudinal fissure separate? 3) What does the transverse fissure separate? 4) Describe at least 1 main function of each lobe of the cerebrum. 5) Discuss functions of each part of the diencephalon. 6) Discuss functions of the brain stem. 7) Where is the reticular formation located?

2 8) Name 2 main functions of the reticular formation. 9) How would damage to the cerebellum affect someone? Critical Thinking Questions: 10) Robert, a brilliant computer analyst, suffered a blow to his anterior skull from a falling rock while mountain climbing. Shortly thereafter, it was obvious to his coworkers that his behavior had undergone a dramatic change. Although previously a smart dresser, he was now unkempt. One morning, he was observed defecating into the wastebasket. His supervisor ordered Robert to report to the company s doctor immediately. Which region of Robert s brain was affected by the cranial blow? 11) Mrs. Jones has had a progressive decline in her mental capabilities in the last five or six years. At first her family attributed her occasional memory lapses, confusion, and agitation to grief over her husband s death six years earlier. When examined, Mrs. Jones was aware of her cognitive problems and was shown to have an IQ score approximately 30 points less than would be predicted by her work history. A CT scan showed diffuse cerebral atrophy. The physician prescribed an acetylcholinesterase inhibitor and Mrs. Jones showed slight improvement. What is Mrs. Jones s problem? Why did the acetylcholinesterase inhibitor help? 12) A brain tumor is found in a CT scan of Mr. Smith s head. The physician is assuming that it is not a secondary tumor (not a product of metastasis) because an exhaustive workup has revealed no signs of cancer elsewhere in Mr. Smith s body. Is the brain tumor more likely to have developed from nerve tissue or from neuroglia? Why? 13) A police officer has just stopped Sally on suspicion of driving while intoxicated. The officer asks Sally to walk the yellow line on the road and then to place the tip of her index finger on the tip of her nose. How would these activities indicate Sally s level of sobriety? Which part of her brain is being tested by these activities?

3 14) Infants have little to no control of the movements of their head. One of the consequences of this is that they are susceptible to shaken-baby syndrome. Shaken-baby syndrome is caused by vigorous shaking of an infant or young child by the arms, legs, chest, or shoulders. Forceful shaking can cause brain damage leading to intellectual disability, speech and learning disabilities, paralysis, seizures, hearing loss, and even death. What areas of the brain might be affected in this syndrome, resulting in each of these symptoms? 15) While working in the ER, you admit two patients who were in an auto collision. One is dead on arrival, having sustained a severed spinal cord at the level of C 2. The other patient suffered a similar injury but at the level of C 6 and is still alive. Explain briefly, in terms of the origin and function of the phrenic nerves, why one injury was fatal and the other was not. 16) An elderly gentleman has just suffered a stroke. He is able to understand verbal and written language, but when he tries to respond, his words are garbled. What cortical region has been damaged by the stroke? 17) Following a train accident, a man with an obvious head injury was observed stumbling about the scene. An inability to walk properly and a loss of balance were quite obvious. What brain region was injured? 18) A young man has just received serious burns, resulting from standing with his back too close to a bonfire. He is muttering that he never felt the pain. Otherwise, he would have smothered the flames by rolling on the ground. What part of his CNS might be malfunctioning?

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