Brain Dissection Lab Report

In class today, we performed a dissection and identification process on a sheep brain. We began by using the forceps to remove the meninges, or the 3 layers of tissue that protect the brain and spinal cord, to see all the different sections of the brain more clearly. We then cut the brain longitudinally to observe the medial plane of the brain. Lastly, we used the scalpel to make a cross sectional cut of the cerebrum to expose the grey and white matter. The different areas of the brain are identified and labeled with pins and sketches.

The cerebrum, labelled with the yellow pin, is responsible for higher brain function like thought and action. The cerebellum, marked with the green pin, receives information from the sensory system and regulates motor movement. The brainstem, marked with the red pin, regulates heart rate, breathing, sleeping, and eating. The anterior part of the brain is marked with the white pin while the posterior portion is marked with black. 

A myelin layer increases the speed at which impulses propagate along the myelinated fiber. 

The thalamus, marked with the yellow pin, relays and processes sensory and motor information.

The optic nerve, marked with the green pin, transfers visual info from retina to the brain via electrical impulses.The medulla oblongata, marked with the red pin, relays sensory info to the thalamus and regulates visceral functions like cardio, respiration, and digestion. The pons, which has a blank pin, relays sensory information to the cerebellum and thalamus and acts as a subconscious somatic and visceral motor center. The midbrain, which has a blue pin, is associated with vision, hearing, motor control, alertness, and temperature regulation. The corpus callosum, marked with a white pin, integrates functions between the cerebral cortex on one side of the brain to the same region on the other side. The hypothalamus, marked with a black pin, is a center for controlling emotions, autonomic functions, and hormone production.

Grey matter is the darker tissue of the brain and spinal cord, consisting of mainly nerve cell bodies and branching dendrites. White matter is composed of bundles of myelinated nerve cell processes or axons which connect areas of grey matter and carry nerve impulses between neurons. Myelinated means that the axon is covered by the myelin sheath, thus increasing the speed of the impulse. Unmyelinated means that the axon is not covered by the myelin sheath, thus reducing the speed of the impulse. 

Sheep Eye Dissection Lab

From the anterior view of the sheep eye, the eyelid, cornea, sclera, and fatty tissue are visible. The posterior view of the eye presents the optic nerve, the extrinsic muscle, and more fatty tissue, which covers the entire outer area of the eye. In the internal posterior view, the vitreous humor, retina, and choroid can be observed. The internal anterior view shows the ciliary body, lens, pupil, and iris.

The sclera is the tough and thick white outer cover of the eyeball. It is covered with a layer of fatty tissue and muscle tissue. The choroid brings blood, oxygen, and nourishment to the eye. The cornea, which is the cloudy and tough cover over the iris and is located just behind the the pupil's opening, helps to protect the eye and focus light. The cornea is cloudy due to the cataract condition, which prevents or reduces the amount of light that reaches the cornea. The iris, which is the brown colored part of the eye controls the amount of light that penetrates the eye. The lens, which is the clear structure that adjust the eye's focus and is responsible for about 20% of the eye's focusing, was surrounded by the ciliary body. The ciliary body encircles the lens and controls its shape with muscles.





The optic nerve is a bundle of nerve fibers that carry information from the retina to the brain for processing. The pupil is the oval shaped hole that allows light to enter the eye. In humans, the pupil is circular. The retina is the layer of light sensitive cells that line the inner eyeball. The retina contains rods, which are photoreceptor cells that respond to dim light. The vitreous humor is the clear gel that fills the space between the lens and the retina of the eyeball.




The tapetum lucidum, which reflets light back into the retina, is the iridescent blue, shiny, and reflective material located directly behind the retina and is part of the choroid layer in nocturnal animals. Although humans lack the tapetum, animals use this to see in the dark, which is why animal eyes glow occasionally glow in pictures with flash.

Relate & Review: The Woman With a Hole In Her Brain

The woman in the article was missing her cerebellum, which is responsible for motor memory and body control. The cortex took over the responsibilities of the cerebellum and she was able to survive with only a few issues. Another part of the brain, the pons, is the portion that lies above the medulla oblongata and below the midbrain. It transmits sensory info and motor impulses from the brain. It also controls the subconscious somatic and visceral motor centers. An injury to the pons can result in coma, sleep or sensory disturbances, and increase levels of anxiety and stress. A severe injury or absence of the pons would result in death, so a person cannot live without his or her pons.

The Clay Brain

In class today, we created brain models out of clay to showcase the different components of the brain. One model was of the left hemisphere from the right looking at the sagittal plane. The second was a lateral view of the right cerebral hemisphere. each part is differentiated with different colors of clay.