lecture 15 Flashcards
diencephalon is covered by what? what do these two structures form?
- covered by telencephelon
- together, make cerebrum
the diencephalon is a _____ extension of the _____
rostral, brainstem
the diencephalon has widespread connections to:
motor, sensory and limbic pathways (diverse)
how many and what are the divisions of the diencephalon?
epithalamus, thalamus, subthalamus, hypothalamus
4
describe the location of the divisions of the diencephalon
- thalamus is located in the centre of the brain, below the lateral ventricles (2 lobes)
- epithalamuc sits on either side of the 3rd ventricle (innermost part of the thalamus), on top of the thalamus, below lateral ventricles
- hypothalamus sits below and infront of the thalamus at the bottom of the 3rd ventricle
- subthalamus sits on either side of the hypothalamus, below the thalamus
what are the external landmarks of the diencephalon?
- optic chiasm
- optic tract
- caudal border of mammillary bodies
describe the optic chiasm as an external landmark
forms the anterior boundary of the hypothalamus
describe the optic tract as an external landmark
forms the lateral boundary of the hypothalamus
describe the mammillary bodies as an external landmark
part of the hypothalamus, form its posterior boundary
what are the internal landmarks of the diencephalon from a coronal section?
- internal capsule
- 3rd ventricle
- tegmentum of the midbrain
- floor of body of lateral ventricles
describe the internal capsule as an internal landmark
forms the lateral borders of the diencephalon
(contact w thalamus, subthalamus and hypothalamus)
(fibres of nerve bundles running along outside)
describe the 3rd ventricle as an internal landmark
forms the medial boundary of the diencephalon
contact w epithalamus, thalamus and hypothalamus, doesnt pass all the way through the hypothalamus tho
describe the tegmentum as an internal landmark
forms the inferior boundary of the diencephalon
describe the lateral ventricles as an internal landmark
forms the superior and dorsal boundaries of the diencephalon (contact w epithalamus and thalamus)
what are the internal landmarks of the diencephalon from a sagittal section?
- anterior commissure to optic chiasm
- mammillary bodies to pineal gland
describe the anterior commissure as an internal landmark
white matter tract of crossing nevre fibres that sits at the anterior wall of the 3rd ventricle (top of the hypothalamus)
describe the mamillary bodies as an internal landmark
pair of small round bodies located at the posterior of the hypothalamus (roughly same level as optic chiasm)
where is the epithalamus located?
posterior to thalamus (thalamus forms its anterior boundary)
what does the epithalamus contain?
- pineal gland
- habenular nuclei
describe the pineal gland in relation to the epithalamus
- the base of the pineal stalk is formed from the habenular nuceli and posterior commisures
- hangs btwn lobes
what is the function of the pineal gland
production and secretion of melatonin (controls carcadian rhythm - sleep)
describe the habenular nuclei in relation to the epithalamus
small group of nuclei located in the epithalamus
what is the function of the habenular nuclei?
functions as a center for the integration of smell, visceral and somatic efferent pathways
(i.e., connects limbic system to the midbrain)
input for the habenular nuclei?
stria medullaris
output for the habenuclar nuclei?
habenular interpeduncular tract
where is the hypothalamus located?
- inferior to thalamus
- projects anterior to thalamus
- at bottom of 3rd ventricle
- anterior boundary = optic chiasm
- lateral boundary = optic tract
- posterior boundary = mammillary bodies
what does the hypothalamus contain?
- mammillary bodies
- infundibulum (pituitary stalk)
what is the overall function of the hypothalamus?
visceral control center
what are the four general functions of the hypothalamus?
(1) visceromotor (automatic) control area
(2) viscerosensory control area
(3) regulatory area for hormone release from ant pit
(4) endocrine role
describe the hypothalamus as an area for visceromotor control
- controls automatic centers of the brain stem involved in HR, BP, breathing and digestive functions
- controls somatic motor patterns associated with emotions
describe the hypothalamus as an area for vicersosensory control
- regulates water balance and thirst
- regulates body temp (functions as thermostat)