Sheep Brain Dissection (Virtual)
1. The sheep brain is enclosed in a tough outer covering called the dura mater. You can still see some structures on the brain before you remove the dura mater. Take special note of the pituitary gland and the optic chiasma. These two structures will likely be pulled off when you remove the dura mater.
2. This image shows the ventral surface of the sheep's brain with most of the dura mater removed. The pituitary gland and the optic chiasma are still intact.
(A = pituitary gland, B = optic chiasma, C = olfactory bulb)
3. On this image, the dura matter has been completely removed, you can still see the optic chiasma but the pituitary gland is missing. The infundibulum (pituitary stalk) is now visible in the center. Careful dissection also reveals two other large nerves: the oculomotor nerves (C.2). Often these two nerves are removed with the dura mater, but in this image they are still intact.
4. If you flip the brain over to the other side, you can see the cerebellum, it will be loosely attached to the cerebrum in most cases. If you did not carefully remove the dura mater you may have accidentally pulled the entire cerebellum away from the brain. The lobes of the brain are visible, as well as the transverse fissure, which separates the cerebrum from the cerebellum. The convolutions of the brain are also visible as bumps (gyri) and grooves (sulci).
5. The gap between the cerebrum and the cerebellum at the transverse fissure can reveal some internal parts of the brain. In this image, a student is bending the cerebellum down to show the superior and inferior colliculi (circled).
6. You can also push the colliculi down to show the pineal body from this side.
7. Using a scalpel and the longitudinal fissure as a guide, the brain is separated into the left and the right hemisphere. In the image below, a student is using forceps to show the lateral ventricle.
8.The image below shows a cleanly separated brain with the major internal structures visible.
Related Pages: Sheep Brain Dissection Lab Guide | Sheep Brain Labeling | Cranial Nerves Coloring |