Laboratory 10: Sheep Brain Dissection

 

During this exercise you will examine the brain from a number or perspectives.

 

1.         To do so you should be familiar with the appropriate anatomical terms describing the three-dimensional position of the brain.

a.         Dorsal

b.         Ventral

c.         Medial

d.         Lateral

e.         Distal and proximal

f.          Anterior and posterior

g.         Rostral and caudal

 

2.         You will first conduct a gross anatomical examination the brain from the dorsal, ventral and medial perspectives. From the dorsal surface you should identify:

 

 

a.         Cerebral hemispheres (right/left)

b.         Hemispheric lobes

            i.          Frontal

            ii.          Parietal

            iii.         Occipital

            iv.         Temporal

c.         Gyrus and sulcus

d.         Superior longitudinal fissure

e.         Cerebellum

f.          Corpus callosum (deep to superior longitudinal fissure)

g.         Lateral fissure

h.         Central sulcus

 

            From the ventral surface you should identify:

 

 


            a.         Olfactory bulbs

            b.         Meninges

                        i.          Dura

                        ii.          Pia (Translucent layer covering the surface of the brain)

            c.         Pituitary gland

            d.         Optic chiasm

            e.         Optic tract

            f.          Stalk of pituitary (hypophysis/tuber cinerium)

            g.         Hypothalamus (Found under hypophysis and includes mammillary bodies)

            h.         Mammillary bodies

            i.          Brain stem

                        i.          Pons

                        ii.          Medulla

                        iii.         Cerebellum

            j.          Spinal cord

 

            From the medial perspectives you should identify:

 


            a.         Lateral fissure

b.         Central sulcus

c.         Precentral gyrus

d.         Postcentral gyrus

 

 

3.         You will then examine the brainstem from the dorsal view. You should identify:

 

 

 

            a.         Cerebellum

            b.         Vermis (not covered)

            c.         Cerebellar penduncles

            d.         4th ventricle

            e.         Quadrigemina

                        i.          Superior and inferior colliculi

            f.          Pineal gland

 

4.         You will then examine the medial surface of the brain after sectioning on a mid-sagittal plane. You should identify:

 


            a.         Corpus callosum

            b.         Lateral ventricle

            c.         Fornix

            d.         3rd ventricle

            e.         4th ventricle

            f.          Thalamus

            g.         Superior colliculus

            h.         Inferior colliculus

            i.          Pineal gland

            j.          Hypothalamus

            k.         Optic chiasm

            l.          Mammillary body

            m.        Cerebellum

            n.         Pons

            o.         Medulla

            p.         Spinal cord

 

5.         You will then remove the cerebral hemisphere and cerebellum from one of the sectioned halves. Examine the brainstem and identify structures previously        viewed in the earlier exercises.

 


6.         You will then section the removed hemisphere horizontally through the lateral ventricle. You should identify:

 

            a.         Lateral ventricle

            b.         Corpus callosum

 

7.         You will then cut 5 horizontal sections, approximately one inch apart, in the other half of the brain (i.e., the sagittal section containing the hemisphere and    cerebellum). View which sections the previously identified structures appear.