1. The Central Nervous System (Brain & Spinal Cord)
LABORATORY EIGHT
The Central Nervous System
(Brain & Spinal Cord)

2. Nervous Tissue
Neurons: functional cells that transport electrical impulses
Neuroglia: non-conductive cells
Schwann cells
Dandrites transmit information into the soma and axon conveys impulses away from the soma.
Myelin is a fatty substance that insulates larger neurons, allows nerve impulses to be conducted at a faster rate. In PNS, Myelin is produced by Schwann cells and in the CNS by oligodendrocytes.

3. Human Brain
Transverse fissure

4. Human Brain – Right Half
Septum pellucidum
Fornix
Choroid Plexus
Optic Chiasma
Corpora quadrigemina
Mammilary body
Cerebral aqueduct
Fourth ventricle

5. Human Brain Ventricles
Ventricles are a complex series of spaces within the hemispheres of brain.
The ventricles and their associated capillary networks, the choroid plexus produce and house CSF
CSF circulates through the ventricles, the subarachnoid space and the central canal of the spinal cord.
The brain ventricle model in the lab is like you have solidified the CSF in this mold of brain ventricles.
Looks like a dragon: Wings: lateral ventricles, head & body: third ventricle, tail: fourth ventricle
Site of massa intermedia

6. Cerebral Meninges (Three layers of protective connective Tissue in CNS)
Cerebrospinal fluid (CSF): cushions and nourishes the brain and spinal cord
The pia matter is in direct contact with the surface of the brain and spinal cord. It is a thin transparent membrane that serves to attach blood vessels to the surface of the CNS

7. Dura Mater in Cerebral Meninges (Fig 8.15, p140)
Modified in two areas:
Falx cerebri – penetrates longitudinal fissurebetween brain hemispheres
Tentorium cerebelli – penetrates transverse fissure that separates the cerebrum from the cerebellum

8. Spinal Cord Meninges

9. Cross-Section of Spinal Cord (Also study fig 8.12, p138)
Dorsal gray horn
White matter
Ventral gray horn
Central Canal

10. Electroencephalogram
EEG is a record of the electrical activity that takes place in the brain
Brain waves are characterized by their frequency (cycle per second) - Fig 8.16, p140
Alpha (8-13 cps): relaxed with eyes closed
Beta (14-25 cps): alert, performing a task
Theta (4-7 cps): normal in children, but abnormal in adult - indicates emotional/mental imbalances
Delta (<4 cps): deep sleep
Report 8C, p149
You do not need to know the frequency of each brain waves, but you need to be able to identify each related graph and to know when each of the brain waves are likely to occur.

11. Laboratory Report P145, Q1 & P146, Q2 - bottom of the page Table 8.1
On Fig 8.3 and Fig 8.5, draw a thick black line that crosses thalamus
Table 8.1
Compare the size of characteristics in question to the rest of the brain of the same species; e.g., the size of the cerebellum of human compare to the rest of the human brain

12. Sheep Brain Dissection Google search under “image” for Sheep brain dissection
Each lab pair should obtain a sheep brain, dissection tools, and a tray
Choose a sheep brain with intact pituitary gland
Note the 1800 relationship between the cerebrum, cerebellum, and spinal cord
Identify the superficial structures listed under 8B Procedure, step 1 (p134) and step 3 (p136)
Identify the longitudinal fissure and transverse fissure, but the central and lateral fissures can not be identified on the sheep brain
Grasp the sheep brain gently by the cerebral hemispheres and the cerebellum, and separate them at the transverse fissure to see the corpora quadrigemina (superior & inferior colliculi) & pineal body (step 5, p137)
To prepare for pituitary gland removal, carefully cut Trigeminal V cranial nerve, 1cm above its attachment site to the brain
When removing the pituitary gland, look underneath it to make sure no cranial nerve is attached
If you see a string structure attached to the pituitary gland from one side and to the floor of the brain from another side, clip it with a pair of scissors closer to the pituitary gland
Identify cranial nerves I, II, III, IV, V, VI and XI
Section the sheep brain by placing it ventral side up.
Make a long, smooth, midsagittal cut. Be sure to completely divide the brain in half
Identify the structures listed under step 2, p135
Observe the prepared coronal section of the sheep brain and identify the assigned structure on step 7, p137
Take half of the dissected brain home, and return them to the lab when done.
Sulci: shallow grooves
Gyri: raised areas or folds (notice how convoluted the brain is)
Fissure: deep grooves
superior & inferior colliculi – babies butt & toilet seat
Pineal gland: up above the crack of the babies butt
Ventral cut: cut through longitudinal fissure, optic chiasma, mammillary body (little breast), pons, and right through the vein on medulla oblangata
Wrap the sheep brain in a damp paper towel and de-glove on it
Store it at room temperature, in dark, away from children’s reach