Nervous+System

Dylan Baxter- Nervous system [complete]

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Billy Ripple =)

Fetal Pig - Nervous System 1. Remove the skin and muscles from the head and carefully remove the bone and cartilage from the skull. Use a scalpel to remove skin and muscles and sharp-pointed scissors to chip away the skull bone bit by bit. Be patient, this process may take a while. 2. Note the membranes, the meninges, which cover the brain. The outermost layer is called the dura mater. Remove the dura mater and note the finer layer called the pia mater. 3. Locate the cerebrum. This is the largest part of the brain and has two hemispheres separated by a long fissure (creating left and right halves). The surface of the cerebrum has small hills, called gyri, and valleys called sulci. The cerebrum mainly functions with sensory and motor functions and is also associated with memory and reasoning. In the pig, it is much smaller than in the human. The longitudinal fissure separates the right and left hemispheres. 4. Locate the corpus callosum. This whitish band connects to two hemispheres. You may need to separate (pull apart) the brain to find this band. 5. Find the cerebellum, which is a large mass that lies behind the cerebrum. The cerebellum functions in coordination and balance. The transverse fissure separates the cerebrum from the cerebellum. The cerebellum also has a right and left side, separated by a fissure called the vermis. 6. The medulla oblongata is located at the posterior part of the brain and is connected to the spinal cord. 7. Locate the lobes of the brain. The frontal lobe is found toward the anterior just in front of the central sulcus. It functions for thinking and problem-solving. The parietal lobe is located behind the central sulcus, and it is concerned with perception of stimuli. The occipital lobe is at the back of the brain and controls many aspects of vision. The temporal lobe is located below the lateral fissure and functions in hearing and memory. Locate all the fissures and lobes on the pig's brain. 8. Use a scalpel to cut away the skin and muscles the cover the vertebral column of the pig. Gradually shave away the bones with the scalpel until the spinal cord is exposed. 9. Find the cerevical enlargement (near the neck) and the lumbar enlargement (near the lower back). These areas of the spinal cord are enlarged because of the many nerves that enter and leave this area (to go to the arms and legs) 10. Observe the spinal nerves. There are 33 pairs of spinal nerves which are divided into 8 cervical (neck), 14 thoracic (upper back), 7 lumbar (lower back) and 4 sacral (tail). You may not be able to find every single one, but careful dissection of the specimen should expose a few of them in each area. 11. When you've found a good example of a spinal nerve, note the small bulb associated with it. This is the dorsal root ganglion, which encases the nerve cells. Trace this nerve as far as you can into the body.