Sheep Brain Dissection

Students examine a sheep brain to identify major external and internal structures. The activity includes removing the dura mater, separating hemispheres along the longitudinal fissure, and locating key features such as the corpus callosum, ventricles, colliculi, pineal gland, cerebellar arbor vitae, gyri, and sulci.

• Follow instructions provided in the links below.

Sheep Brain Dissection - Center for Science Education - Great Diseases:

Sheep brain dissection- Ren Hartung:

📄 Sheep Brain Dissection - LibreTexts: [https://bio.libretexts.org/Bookshelves/Human_Biology/Human_Anatomy_Lab/11%3A_The_Central_Nervous_System_(Brain)/11.07%3A_Sheep_Brain_Dissection]]

📄 Lab: Sheep Brain Dissection - Elizabeth Moretz: https://elizabethmoretz.weebly.com/uploads/4/4/5/6/44567783/sheep_brain_dissection.pdf

📄 Virtual Sheep Brain Dissection - The Biology Corner: [[https://www.biologycorner.com/2020/12/27/brain-dissect-virtual/

• Compare a sheep brain to a human brain model or 3D digital atlas to highlight differences in proportion and orientation.
• Prepare thin sagittal or coronal sections (under instructor supervision) to visualize ventricles and deeper nuclei.
• Relate external skull features to brain orientation by discussing foramen magnum position in quadrupeds versus bipeds.
• Integrate a functional mapping exercise that links identified structures to sensory, motor, or integrative roles.

• Wear gloves and a lab coat; tie back hair and avoid loose clothing.
• Use scalpels and scissors with care; always cut on the tray with the specimen resting flat (never cut while holding the specimen).
• Handle preserved tissues and fluids as potential chemical irritants; avoid skin and eye contact and work in a well-ventilated area.
• Dispose of tissues as biological waste and blades in approved sharps containers; follow local protocols.
• Sanitize the workspace and instruments after the lab; wash hands thoroughly.
• Be mindful of latex sensitivity; provide nitrile gloves as needed.

• Why is the sheep cerebrum proportionally smaller than the human cerebrum? (Sheep rely more on midbrain and olfactory processing, whereas humans have expanded cortical areas for higher cognition.)
• How does spinal cord orientation differ between sheep and humans, and what skull feature reflects this? (Sheep have a more horizontal cord and a posterior foramen magnum; humans have a vertical cord and a centrally located foramen magnum.)
• What is the function of the corpus callosum observed in the midline cut? (It contains commissural fibers that connect the left and right cerebral hemispheres.)
• What is the optic chiasma and why is it ventrally located? (It is where optic nerves partially cross; it lies near the base of the brain along the visual pathway.)
• Why might the pituitary gland be missing after dura removal? (It is attached by a slender stalk and often tears away with the dura.)
• What do gyri and sulci accomplish? (They increase cortical surface area, allowing more neurons within a limited skull volume.)
• How do white matter and gray matter differ in appearance and function? (White matter is lighter due to myelinated axons for rapid signaling; gray matter contains neuron cell bodies for processing.)
• Where are the superior and inferior colliculi located and what are their roles? (On the dorsal midbrain; superior colliculi coordinate visual reflexes and inferior colliculi process auditory reflexes.)