Human Anatomy and Physiology I.docx - Human Anatomy and...

Human Anatomy and Physiology I
Lab 10 The nervous system
Sheep brain dissection
Lab Exercises 10-1
The sheep brain is quite similar to the human brain except for proportion. The sheep has a
smaller cerebrum. Also, the sheep brain is oriented anterior to posterior (more horizontally), while
the human brain is oriented superior to interior (more vertically.)
Materials
Dissection tools and tray, lab gloves, preserved sheep brain.
Figure 10-11. The major structures of a sheep brain cut along the longitudinal
fissure.
Examining the external sheep brain.
1. The tough outer covering of the sheep brain is the dura mater, the outermost meninges membrane
covering the brain. Remove the dura mater to see most of the structures of the brain, but remove
it carefully, so as to leave all the other structures beneath it intact. Removing the dura mater from
the cerebellum at the back of the brain can be tricky. Look for areas on the side of the brain that
you can snip to peel the dura mater off.

2. Note the second meninges membrane, the arachnoid mater, below the dura mater.
3. The cerebrum half is missing the longitudinal fissure – which divides the brain into nearly
symmetrical left and right hemispheres. But the transverse fissure is clearly visible.
4. The surface of the cerebrum is covered with large folds of tissue called gyri. The grooves
between the gyri are sulci. The deeper sulci are often called fissures. The fissures are used as