DIENCEPHALON The diencephalon is the bridge between brain stem and cerebral hemispheres. It consists of tissue surrounding the third ventricle and it is limited laterally by the posterior limb of the internal capsule. 1. The diencephalon is limited anteriorly by the Posterior commissure Third ventricle Foramen of Monro and lamina terminalis Hypothalamic sulcus Right! No, the answer is C. The posterior commissure is the posterior limitation of the diencephalon and the lateral wall of the third ventricle is the medial border. 2. The diencephalon is divided into a dorsal part (thalamus) and ventral (hypothalamus) by the Posterior commissure Hypothalamic sulcus Third ventricle Anterior commissure Foramen of Monro Very good! No, the answer is B. The hypothalamic sulcus is a groove that can be seen in the wall of the third ventricle that extends from the foramen of Monro anteriorly to the aqueduct of Sylvius posteriorly. 3. The diencephalon is supratentorial has 4 subdivisions evolved from the prosencephalon contains the basal ganglia Right! No, the answer is ABC. The basal ganglia is not a part of the diencephalon. They are large masses of gray matter, deep in the cerebral hemispheres, lateral and anterior to the thalamus. 4. The 4 subdivisions of the diencephalon include thalamus epithalamus hypothalamus temporal lobe Very good! No, the first three foils are correct. The temporal lobe is not a subdivision of the thalamus. The ventral thalamus is another subdivision. The diencephalon has 4 regions all with thalamus in their names. 5. The epithalamus contains the stria medullaris thalami habenular nuclei pineal gland pituitary gland Right! No, the first three foils are correct The epithalamus is dorsal to the thalamus. The stria medullaris is a band of fibers carrying impulses from the septal area to the habenular nuclei. The habenular nuclei send fibers via the habenulointerpeduncular tract to the interpeduncular nucleus in the midbrain. The pineal is often calcified in the adult, thus seen as a midline structure on skull films. 6. The thalamus is the largest structure in the diencephalon contains the tuber cinereum is a relay and integrating station contains the subthalamic nucleus Right! No, the answer is B. The tuber cinereum is part of the hypothalamus and the subthalamic nucleus is part of the ventral thalamus. 7. The nuclei of the thalamus are in lateral wall of III ventricle include the pulvinar may fuse in the midline (massa intermedia) make the anterior end of the thalamus broad and the posterior end narrow Very good! No, the first three foils are correct. An interthalamic adhesion sometimes forms in the third ventricle. The shape of the thalamus is the reverse of that in the fourth foil. The anterior nucleus is narrow and posteriorly the pulvinar and geniculate bodies are broad. 8. The Y shaped internal medullary lamina divides the thalamus into anterior area medial area lateral area ventral area Very good! No, the first three foils are correct. There is no major ventral division of the thalamus. The anterior area contains only the anterior nucleus. The medial division contains the midline and dorsomedial nuclei. The lateral division is divided into dorsal and ventral tiers, containing 5 and 3 nuclei respectively. 9. The ventral posterior lateral nucleus receives trigeminal fibers from the head second order neurons from the spinothalamic tract visual information from the optic tract axons from medial lemniscal pathways from trunk and limbs Right! No, the second and fourth foils are correct. The trigeminal thalamic fibers from the head end in the ventral posterior medial nucleus. Visual fibers from the optic tract terminate in the lateral geniculate nucleus ( or body ). 10. The medial geniculate body projects from the ventral surface of the pulvinar sends efferents to the cortex by way of the anterior limb of the internal capsule receives auditory afferent fibers via the brachium of the inferior colliculus receives visual fibers from the optic tract. Right! No, the first and third foils are correct. Efferent auditory fibers leave the medial geniculate, pass through the auditory radiation of the POSTERIOR limb of the internal capsule. Visual fibers go to the lateral geniculate body. 11. The lateral geniculate body efferent fibers terminate in the calcarine cortex of the occipital lobe efferent fibers pass through the posterior limb of the internal capsule some fibers loop around the temporal horn (Meyer's loop) is considered a part of the basal ganglia Right. No, the first and third foils are correct! 12. The ventral lateral nucleus of the thalamus integrates and transmits sensory information receives collateral fibers from the red nucleus receives input from the globus pallidus receives fibers from the dentate nucleus of the cerebellum Very good. No, the second and last foils are correct. The ventral lateral as well as the ventral anterior nucleus of the thalamus integrate and transmit information to the motor cortex. The ventral anterior nucleus receives input from the globus pallidus. 13. The subthalamus contains subthalamic nucleus fields of Forel zona incerta internal capsule Right. No, the first three foils are correct. The internal capsule is not a part of the subthalamus but it is the lateral and ventral boundries of this region. 14. The subthalamic nuclei are ventral to the zona incerta have no interconnecting pathway across the midline receive a small input from substantia nigra are involved with emotions Right. No, the first and third foils are correct. The subthalamic nuclei are interconnected via the supramaxillary commissure. The nucleus seems to be involved with movement. Lesions of the subthalamic nucleus in man causes hemi ballismis, an involuntary violent flinging movement of contralateral limbs. 15. Regarding the fields of Forel the lenticular fasciculus is H2 field of Forel the thalamic fasciculus is H1 field of Forel they are fiber bundles carrying pallidal and cerebral efferents to the thalamus they are fiber bundles ventral to the subthalalmic nucleus Right. No, the first three foils are correct. The fiber bundles of the fields of Forel are dorsal to the subthalamic nucleus. 16. The zona incerta consists of fiber bundles connecting cerebellum with thalamus is a rostral continuation of mesencephalic reticular formation receives the spinothalamic pain fibers is sandwiched between the lenticular fasciculus and thalamic fasciculus Right. No, the second and last foils are correct. 17. The hypothalamus lies ventral to the hypothalamic sulcus has neurosecretory nuclei includes the mammillary bodies is divided into medial and lateral divisions by the fornix Right. No, all the foils are correct. 18. The supraoptic nucleus is above the optic tract sends fibers (along with paraventricular nucleus fibers) to posterior pituitary sends neurosecretory material down the fibers to posterior pituitary sends vasopressor and oxytocin to anterior pituitary Right. No, the first three foils are correct. The supraoptic andparaventricular nuclei have neurosecretory cells that produce vasopressen (ADH) and oxytocin which is transported down fibers to posterior pituitary lobe where they are stored. 19. A lesion of the supraoptic nucleus may cause excessive retention of urine excessive excretion of urine urine of high specific gravity diabetes insipidus Right. No, the second and fourth foils are correct. Pitression or antidiuretic hormone (ADH) increases reabsorption of water from the distal convoluted tubules of the kidney. Thus, a lesion of the supraoptic nucleus would reduce ADH, causing increased urinary output of a low specific gravity, known as diabetes insipidus. 20. Oxytocin is believed produced by the paraventricular nucleus of the hypothalamus is used to induce labor causes contraction of the uterus travels down fibers through the pituitary stalk to the posterior lobe of the pituitary Right No, all foils are correct. 21. The mammillary bodies are in rostral hypothalamus receives its major input from the fornix sends neurosecretory material to the pituitary receives premotor cortex fibers by way of the median forebrain bundle Very good. No, the second and last foils are correct. The mammillary bodies are two ventral spherical masses protruding from the caudal hypothalamus. Two way communication with the anterior nucleus of the thalamus occurs by way of the mammillothalamic tract. 22. The main source of descending hypothalamic fibers to the brain stem is the preoptic region posterior hypothalamic nucleus paraventricular nucleus supraoptic nucleus Right No, the first and third foils are correct. The majority of fibers from the posterior hypothalamic nucleus descend as the dorsal longitudinal fasciculus (in the periaqueductal gray) to end on autonomic and motor nuclei in the brainstem tegmentum. 23. The hypothalamus is involved with motor function autonomic regulation sensory perception and conscious evaluation feeding and drinking behavior Right. No, the second and last foils are correct. In addition, the hypothalamus appears to play a role in the sleep-wakefulness cycle.