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.