Brain Dissection

Question 1

identify the dorsal surface features

Answer 1

i) cerebral hemisphere

ii) cerebellum

iii) caudal aspect of brain stem continuing into the spinal cord

iv) longitudinal fissure: a fold of dura mater (the falx cerebri) would usually extend down into the longitudinal fissure, containing the dorsal sagittal sinus

v) obliquely orientated transverse fissure: dividing the cerebellum from the occipital lobes of the cerebral hemispheres

Question 2

identify theses structures

Answer 2

vi) large rostral and small caudal colliculi of the roof of midbrain
vii) origin of CN IV (trochlear) (only CN to leave the dorsal surface of the brain)
viii) pineal gland (forming part of the epithalamus and particularly well developed in animals where daylight length in breeding)

Question 3

what is this structures

Answer 3

ix) the corpus callosum: lying at bottom of fissure (usually with the free margin of the falx cerebri situated immediately above)

Question 4

what are these structures

Answer 4

x) fourth ventricle
xi) choroid plexus of the fourth ventricle
xii) medial aspect of cerebellar peduncles

Question 5

what are the cranial nerves

Answer 5

Question 6

what are the cranial nerves

Answer 6

Question 7

what is this structure

Answer 7

basilar artery

Question 8

what is this structure

Answer 8

ii) pons

iv) cerebral peduncles running obliquely from the main bulk of the cerebral hemispheres to the pons

v) hypophysis cerebri (pituitary gland) the dark structures which may be present on either side of the gland are the cavernous sinuses (containing the rete mirabile cerebri)

Question 9

what are these structures

Answer 9

vi A) the position of the olfactory bulb

vi B) olfactory peduncle (“stalk”)

vi C) rhinal sulcus (“groove”)

Question 10

what are these structures

Answer 10

i) lateral ventricles
ii) hippocampus
iii) choroid plexus of lateral ventricle

Question 11

what are these structures

Answer 11

iv) course of optic tract from the optic chiasm to the lateral geniculate nulceus of thalamus (curves round the lateral aspect of the cerebral peduncle)
v) lateral geniculate nucleus (thalamic nucleus situated laterally)
vi) optic radiations into the cerebral cortex

Question 12

what are these structures

Answer 12

iv) course of optic tract from the optic chiasm to the lateral geniculate nulceus of thalamus (curves round the lateral aspect of the cerebral peduncle)
v) lateral geniculate nucleus (thalamic nucleus situated laterally)
vi) optic radiations into the cerebral cortex

Question 13

what are these structures of a midline sagittal incision

Answer 13

vii) corpus callosum
viii) pineal gland (epiphysis)
ix) interthalamic adhesion
x) circular third ventricle
xi) mesencephalic aqueduct connecting the third and fourth ventricles
xii) tectum (“roof”)
xiii) tegmentum (“floor”)
xiv) fourth ventricle
xv) continuation of the 4th ventricle into the central canal of the spinal cord
xvi) interventricular foramen leading from lateral to third ventricle
xvii) lateral recess connecting the fourth ventricle to subarachnoid space

Question 14

what are these structures

Answer 14

xviii) corpus callosum
xix) corona radiata (white matter structure comprising a sheet of motor and association fibres which converge from all parts of the cerebral cortex to form the cerebral peduncle)
xx) caudate nucleus and most of the thalamus lie medial to fibres of corona radiata