LABORATORY Seven
The Central Nervous System
(Brain & Spinal Cord)
Nervous Tissue
• Neurons: functional
cells that transport
electrical impulses
• Neuroglia: nonconductive cells
– Schwann cells
Human Brain
Transverse fissure
Human Brain – Right Half
Septum pellucidum
Fornix
Choroid Plexus
Optic Chiasma
Corpora quadrigemina
Mammilary body
Cerebral aqueduct
Fourth ventricle
Human Brain Ventricles
Ventricles are a complex series of spaces within the hemispheres of brain
which produce and house CSF.
Site of massa intermedia
Dura Mater in Cerebral Meninges
• Modified in two areas:
– Falx cerebri – penetrates longitudinal fissure
between brain hemispheres
– Tentorium cerebelli – penetrates transverse
fissure that separates the cerebrum from the
cerebellum
Spinal
Cord
Meninges
Cross-Section of Spinal Cord
Dorsal gray horn
White matter
Ventral gray horn
Central Canal
Human Spinal Cord Model
Conus medullaris – letter ‘d’
Filum terminale – letter ‘e’
Cauda equina – around letter ‘e’
Sheep Brain Dissection
Google search under “image” for Sheep brain dissection
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Each lab pair should obtain a sheep brain, dissection tools, and a tray
Choose a sheep brain with intact pituitary gland if possible!
Note the 1800 relationship between the cerebrum, cerebellum, and spinal cord
Identify the superficial structures
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
To prepare for pituitary gland removal, carefully cut Trigeminal cranial nerve V, 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 assigned structures
Observe the prepared coronal section of the sheep brain and identify the assigned
structures
Take half of the dissected brain home, and return them to the lab when done.