Biology 12 Block _____ / Name: ______

S H E E PB R A I N L A B

Purpose: To study the structure and function of the mammalian (sheep) brain.

References: "Nelson Biology 12" (chapter 9), dissection charts, models, internet, other texts.

Instructions - External Anatomy:

1.  Working in groups of two or three, select a sheep brain. The brain will be cut in half longitudinally (sagitally). Lay the brain flat on the dissecting tray so as to view the external surface.

2.  Identify the external structures indicated below on the brain. Then draw an external anatomy diagram with all the following structures labelled.

cerebellum, cerebral hemisphere, spinal cord, medulla oblongata, temporal lobe,
parietal lobe, frontal lobe, occipital lobe

3.  Complete the table for the major external brain regions.

STRUCTURE / FUNCTION
Frontal lobe
Temporal lobe
Occipital lobe
Parietal lobe
Cerebellum
Medulla oblongata
Cerebral hemisphere

4.  Observe the convolutions and fissures (indentations) on the surface of the brain. Define the following terms:

Sulcus (singular) / Sulci (plural)
Gyrus (singular) / Gyri (plural)

5.  Why does the brain have these sulci and gyri? ______

6.  What is the general name for the 3 protective membranes that cover the brain?
______

7.  Which one of these membranes might be found closely adhering to the sheep brain?
______

Instructions - Internal Anatomy:

1.  Turn the brain over in the dissecting tray so the internal structures are visible.

2.  Identify the internal structures indicated below on the brain. Then label the internal anatomy diagram with all the structures. (Note: the pituitary gland is usually not visible on the sheep brain)

corpus callosum, medulla oblongata, pituitary gland, ventricle, pons, sulci, gyri, cerebral cortex, thalamus, hypothalamus, cerebellum, pineal gland

3.  Complete the table for the major internal brain structures.

STRUCTURE / FUNCTION
Corpus callosum
Cerebral cortex
Thalamus
Hypothalamus
Pons
Pituitary gland
Pineal gland

Instructions - Pin Labelling / Worksheet Completion:

1.  Obtain FIVE dissecting pins. Choose any five structures, internal or external, and gently place a pin in each region of the sheep brain. Be very accurate in your placement.

2.  Bring your sheep brain with pins inserted to your teacher for a group evaluation. You will be evaluated on correct placement of your pins and the ability to state the function of each part (without use of worksheets). Your teacher will also ask you to identify THREE other structures and functions.

3.  After your evaluation, wash off the pins, return the brain to the bin, wash all equipment including the dissection tray and then wash your hands.

4.  Your external diagram, internal diagram handout and this handout are due Monday.