Nervous System and Sheep Brain, Lab Report Example

Introduction

During this week of lab activities, the key objectives were to examine the brain and its cranial nerves. The lab utilized several different approaches this week.  Information from the lab manual, the brain model, the preserved human brain, and the sheep brain all provided a different perspective on the brain.  Of all the information, the dissection of a sheep’s brain will be most useful for me. Identifying structures from a model or picture doesn’t compare to seeing what the structures actually look like.  I think that these laboratory exercises will prove challenging in identifying each structure, but will also be very informative about just how complex the brain is.

Procedures:

In order to learn more about the brain and its cranial nerves, the lab had several activities to perform. Gross Anatomy of the Brain and Cranial Nerves activity one required us to examine a brain and identify its external structures using a model of the human brain and the figures shown in the manual.  These structures included the outside of the cerebral hemispheres, the diencephalon, the brain stem, the cerebellum. Gross Anatomy of the Brain and Cranial Nerves activity two required us to also use the brain model, figures in the lab manuals, and the preserved human brain to identify the internal brain structures. These structures included internal areas of the cerebral hemispheres, the diencephalon, the brain stem, the cerebellum.  Gross Anatomy of the Brain and Cranial Nerves activity three involved dissection of a sheep’s brain to examine the outer and inner structures of the brain.

Materials:

Gross Anatomy of the Brain and Cranial Nerves materials included a dissectible human brain model, three dimensional model of ventricles, preserved human brain, coronally sectioned human brain slice, materials for cranial nerve testing, preserved sheep brain, dissecting tray and instruments, disposable gloves, and the video tape: The Human Nervous System: The Brain and Cranial Nerves.

Methods:

Gross Anatomy of the Brain and Cranial Nerves activity one, first step was to read the information about the brain in the lab manual. Secondly, use the preserved brain or slices to identify the structures of the cerebral hemispheres. Thirdly, use the brain model and figures in the lab manual to compare to other structures of the preserved brain.  Next, use the turn the brain model identify the external structures, such as the olfactory bulbs, optic nerves, pituitary glands, and mammillary bodies. After that, continue to examining the brain, identifying structures, such as the pons and medulla. Continue turning the brain to identify the large cauliflower shaped cerebellum. Gross Anatomy of the Brain and Cranial Nerves activity two, first step take the brain model apart to identify the gray matter that contains the cell bodies of cerebral neurons. Step two, examine deeper into the white matter to identify the corpus callosum. Continue examining deeper to identify clusters of basal nuclei.   Next, locate and identify the pituitary gland. Also, identify the optic chiasma of the optic pathway to the brain. After that, trace the short midbrain from the mammillary bodies to the rounded pons. Now, trace the rounded pons to the medulla oblongata below and identify its structures. Lastly, examine the internal structures of the cerebellum. Gross Anatomy of the Brain and Cranial Nerves activity three, step one was to bring all the materials I needed to my dissecting area. Secondly, put on my gloves. Next, turn the sheep brain so that its left lateral side is showing and place the sheep brain on the dissecting tray to observe the fragments of the dura mater. Using the dissecting knife, cut the dura mater longitudinally along the fissure and force the cerebral hemispheres apart, exposing the corpus callosum. Next, examine the superior surface of the brain and identify the arachnoid mater.  After that, turn the brain so that the ventral surface is facing upward, and identify the olfactory bulb, the optic nerves and its parts, the stalk of the pituitary, the mammillary body, the cerebral peduncles, and the large oculomotor nerves. Continuing on posteriorly, identify the vestibulocochlear nerves, the glossopharyngeal nerves, the vagus nerves, accessory nerves, and the hypoglossal nerves. Then, gently force the cerebrum and cerebellum apart to identify the pineal gland and the corpora quadridgemina. Following that, place the ventral side of the brain down and make a cut completely through from top to bottom. Lastly, identify the thalamus, white matter, and other internal structures.

Results     

The results of Gross Anatomy of the Brain and Cranial Nerves activity one was identification of external structures, such as the olfactory bulbs, optic nerves, pituitary glands, mammillary bodies, pons, medulla, and cerebellum.

The results of Gross Anatomy of the Brain and Cranial Nerves activity two were identification of gray matter, basal nuclei, pituitary gland, and medulla oblongata. The basal nuclei was identified as specks of gray embedded in the white matter.

The results of activity three Gross Anatomy of the Brain and Cranial Nerves was identification of both exterior and interior structures in the sheep’s brain. It was difficult to identify some of the structures, however some of the structures were easily identifiable, such as the medulla oblongata.

Questions

A sheep’s olfactory bulbs are significantly larger than humans.

Sense of smell is more important to sheep than humans.

The depth of fissures in cerebral hemispheres are smaller than humans.

It is part of vision and hearing processes.

Conclusion               

This week of laboratory activities showed just how complex and amazing the brain is. It is composed of so many little parts that have big functions. Each part has a function and is well protected under many layers. This lab involved comparing diagrams, models, and actual brains. I concluded from these activities that the brain is definitely the most important part of the body. It is the control center for so many functions of the body. That’s why just a bump to the head can have such a major effect on the entire body.