Sheep Brain Dissection Lecture Notes

Introduction to Sheep Brain Dissection

• Focus on the pituitary gland, also known as 'hypothesis'.
• Tools used: knife, probe, pickup, scissors.

Orientation of the Brain

• Inferior surface: bottom part of the brain.
• Superior surface: top part of the brain.
• Anterior (rostral): towards the nose.
• Posterior: towards the back.

Meninges of the Brain

• Dura Mater: outermost layer, tough (removed in this dissection).
• Arachnoid: middle glistening layer, spider web-like projections.
• Pia Mater: innermost layer, soft surface of the brain.

Brain Anatomy

• Gyri: Hills in the brain surface.
• Sulci: Valleys in the brain surface.
• Cerebrum: main part of the brain.
• Cerebellum: back part of the hindbrain.
• Spinal Cord: part of the central nervous system.

Notable Fissures

• Medial Longitudinal Fissure: separates the two hemispheres.
• Sylvian Sulcus (Lateral Fissure): located on the lateral side.

Key Structures

• Pituitary Gland: often pulled out with dura.
• Cranial Nerves: includes olfactory tract, optic nerve (optic chiasum), cranial nerve 3 (oculomotor), cranial nerve 4 (trochlear), cranial nerve 5 (trigeminal), and others.

Brain Lobes

• Temporal Lobes: lateral parts, like earmuffs.
• Frontal Lobe: front part of the brain.
• Parietal Lobe: upper middle part.
• Occipital Lobe: back part of the brain.

Dissection Steps

• Coronal Cuts: slices for anterior and posterior views.
• Gray vs. White Matter: gray matter contains unmyelinated structures, white matter contains myelinated tracts.
• Corpus Callosum: connects two hemispheres.

Ventricular System

• Lateral Ventricles: right (1st), left (2nd).
• Third Ventricle: connects lateral ventricles through cerebral aqueduct to the fourth ventricle.
• Fourth Ventricle: located near the cerebellum.

Brain Stem Components

• Midbrain
• Pons: middle, looks pregnant.
• Medulla Oblongata

Sagittal Cuts

• Mid-sagittal Cut: divides into right and left sides.
• Arbor Vitae: tree-like white matter in the cerebellum.

Final Notes

• Ensure all structures are reviewed.
• Proper cleanup and storage of tools.