The Brain Exhibit
Human Brain Anatomy
The brain weighs about 3 pounds and has three main parts: the cerebrum, the cerebellum and the brain stem. When removed from the skull, the human brain is as soft as Jello. For preservation, brains are treated with chemicals such as formaldehyde. These were carefully dissected and encased in plastic blocks. The brains not encased in plastic blocks were hardened with liquid plastic in a process called plastination.
These brains have been collected from autopsies performed by the Department of Pathology and Laboratory Medicine at the University of Tennessee Health Science Center and from cadavers donated to the Department of Anatomy, University of Tennessee at Knoxville and UTHSC.
Horizontal Section of a Human Brain
The dark area in the brain stem, marked by an arrow, is called substantia nigra. Many of the cells in this area would be lost in patients with Parkinson's disease.
Comparing Animal Brains
In general, larger animals tend to have larger brains. However, larger brains do not always equate to intelligence and thinking ability. If the ratio of body weight to brain weight were considered, the squirrel monkey's brain is larger than a human brain. The squirrel monkey, a small South American monkey, may be clever, but it is not a great thinker. Intelligence and cognitive ability are functions of density, number of neurons and surface area of the brain. The size of various areas of the brain is also important. The neocortex, is the area of the brain which controls social relationships, and reasoning. It makes up 16 percent of the brain in insect-eaters and 80 percent in humans.
Brain Diseases Awareness and Prevention
The brain is surrounded by three protective coverings known as the meninges. These are the pia mater, the arachnoid layer and the dura mater. The pia mater adheres to the brain; the dura mater lines the inside of the skull and the arachnoid layer lies in between the pia and dura mater. Head injuries may cause bleeding between these layers. The use of automobile seat belts and bicycle helmets can reduce many of these injuries. Increased blood pressure may cause hemorrhage deep inside the brain.
- Meningitis: Infection of the meninges is known as meningitis. Vaccines may prevent meningitis. Infection of the meninges by bacteria, viruses, or fungi causes meningitis resulting in high fever, headache, and stiff neck. The specimen illustrates the thickened and opaque meninges, characteristic of bacterial meningitis.
- Subdural Hemorrhage or Hematoma: Injuries to the head often result in bleeding under the membranes covering the brain. Bleeding under the dura mater is called subdural hemorrhage or hematoma. Wearing a seat belt can help reduce the impact on the brain during an automobile accident. In this specimen a subdural hematoma is marked by an arrow.
- Cerebral Hemorrhage: The dark clot on the left side of this specimen is a "cerebral hemorrhage," a bleed in the substance of the brain. Hypertension (high blood pressure) can cause this type of hemorrhage, which the patient expresses as a stroke. Check your blood pressure regularly and consult a physician if it is increased.
- Cancer: Cancer from many organs can spread to the brain. This specimen shows spread of lung cancer to the brain. The arrows show the cancer tissue. Smoking is one of the main causes of lung cancer.
The Brain Exhibit
For scheduling information contact:
930 Madison Avenue
Memphis, TN 38163
Phone (901) 448-6353
Fax (901) 448-6979