VAN 121: Veterinary Gross Anatomy-II (2+2)

BRAIN - MENINGES

Note

• Study details of the structure of brain by referring to concerned volume of the lecture notes.
• A specimen of brain with the meninges is given for dissection and a sagittal section of the brain is given for reference only.

Dissection 

• Slit open the dura mater carefully with the scissors, starting from the anterior end and extending aong the ventro lateral aspect on either side till the upper part of the dura mater can be removed from the brain.
• While removing, note a sickle shaped fold lodged in the longitudinal fissure of the brain, the falx cerebri and another crescentic fold in the transverse fisure between the cerebrum and the cerebellum, thetentorium cerebelli.
• Now carefully remove the lower part of the dura with the diaphragm sellae at the base of the brain retaining the cranial nerves as for as for as possbile on the brain for later examination.
• Note in the diaphragm sellae the openings for the stalk of the pituitary gland centrally and for the emergent artery of the rete mirabile cerebri and the oculomotor nerves on either side.
• Study the dura mater and the venous sinuses enclosed between its two layers.
• Examine the arachnoid membrane and study the location of the subarachnoid cisterns.
• The piamater closely invests the brain dipping into all the sulci.
• The chorioid plexuses of the fourth ventricle can be seen between the cerebellum and the medulla oblongata.
• The rete mirabile cerebri can be noted between the layers of the diaphragm sellaef as also the arterial circle (circle of Willis) formed from the emergent artery in either side on the base of the brain.