The purpose of the sheep brain dissection is to familiarize you with the threedimensional structure of the brain and teach you one of the great methods of studying the brain, while looking at its structure. The sheep brain will emphasize the human brain, observations that indicate that there are many similarities between the sheep brain and the human brain. Even the differences are instructive and help us to learn about the brain. Being able to locate important structures in the sheep brain was a great benefit to understanding how the structures are related to each other in the human brain. If the same structure exists in both brains, they are in the same relative location.
Materials
Dissection pan
Sheep Brain
Dissection kit:
Brain scalpel
Probe
Gloves
Before beginning the dissection of the sheep brain we needed to know the terms used to specify the location and relative location of various brain structures. All these terms are both absolute and relative. Let me explain that. Let us take lateral. It both means at the side of the brain, and closer to the side. So some structure that is quite in the middle can be lateral to another structure that is even closer to the middle of the brain. To summarize,anterior or rostral mean in the front or towards the front. Posterial or caudal is at or towards the back Lateral means on the side or towards the side. Medial is at or towards the middle. Dorsal means on top, in the brain and head only, and ventral means on the bottom, in the brain and head only.
In addition to the direction, the brain as a three dimensional object can be divided into three planes. There is the frontal or coronal planes which divides front from back. It can divide the brain and any location as long as it divides the brain from front to back.Next are the saggital planes which divides the left from the right of the brain. In the figure below, the most important saggital plane is illustrated the mid-saggital plane. However, as with the frontal planes, any plane that is parallel to the mid-saggital plane, is also a saggital plane. The last planes are the horizontal planes that divide the brain in to top and bottom portions.
My first examine on the exterior of the entire brain. I was able to see one or two of the three layers of the meninges, the dura mater, the arachnoid layer, and the pia mater. The meninges are the protective coverings, which enclose the brain and spinal cord. The dura mater, the tough outer layer, will have been mostly removed when the brains were prepared for the dissection; however, some of the dura may stay on the brain. The arachnoid layer, the middle layer, and pia mater, the inner layer, are still likely to cover the brain. The pia mater follows the gyri and sulci and most likely is still on your specimen and may be indistinguishable from the brain. Blood vessels are between the arachnoid layer and the pia mater.
My group dissected the mid-saggital cut on the brain. Which means we cut the brain from the middle going from the front of the brain to the back. When looking in the inside we noticed the cerebellum. We noticed the pattern of grey and white matter. To us it resembled a tree or bush and is called as a result the arborvitae. Then we had to cut it in sections going from the outside in from front to back, on one side of the brain we already cut.
Our Brain Dissection
After we were done we went to look at everyone elses brain dissection. My favorite was probably Sarah's and Nicole's brain, they cut theres from front to back.
If you look on the side of the brain there is some of the dura, the extra skin that was on top of the brain.
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