1. part of the brain anterior to the cerebellum and between the medulla and rest of the midbrain 2. chemical messenger, released at the end of a nerve cell 3. essential, distinguishing tissue of an organ or system 4. thin, delicate inner membrane of the meninges 5. organ that receives a nervous stimulation and passes it on to afferent nerves 6. phagocytic glial cell 7. large, interlacing network of nerves 8. nerves outside the brain and spinal cord including cranial and spinal nerves 9. involuntary, autonomic nerves that regulate normal body functions such as heart rate, breathing, and gastrointestinal muscles 10. glial cell that forms the myelin sheath covering axons