35: Hypothalamus Flashcards
Hypothalamus function
Regulates basic drives, emotional behavior, homeostasis, and endocrine function
Examples of homeostasis regulated by hypothalamus
Food intake, fluid and electrolyte balance, body temp, sexual and reproductive behavior, circadian rhythm
Embryological origin of hypothalamus
Diencephalon
Rostral hypothalamus vs caudal
Rostral: optic chiasms
Caudal: tegmentum and PAG in midbrain
What do the walls of the hypothalamus form?
Floor and walls of third ventricle
Infundibular stalk
Connects hypothalamus + post pit
Three notable areas of the hypothalamus
- Mammillary bodies
- Tuber cineureum
- Median eminence
Mammillary bodies location
Posterior hypothalamus, next to cerebral peduncles
Tuber cinereum
Swelling between mammillary bodies + optic chiasm
Median eminence
From tuber cinereum -> narrows into infundibulum
What divides hypothalamus into its lateral and medial zones?
Columns of the fornix
Lesion to lateral zone nuclei
Decrease in feeding, weight loss
Anterior area of medial zone function
Range of visceral/somatic function, temp regulation
Lesion of SON and PVN
diabetes insipidus: increased H2O uptake and increased urination
Damage to SCN
Modulation or abolishment of circadian rhythm
Lesion to ventromedial nucleus
Excessive eating and weight gain
Stimulation vs lesion of dorsomedial nucleus
Stimulation: sham rage
Lesion: decreased aggression and feeding
Mammillary body lesion
Inability to process short-term events into long-term memories
Overall blood supply to hypothalamus
Small perforating A’s of Circle of Willis
Blood supply to anteromedial group vs posteromedial group of hypothalamus
Anteromedial: ACA + ACoA
Posteromedial: PCA + PCoA
What does the rostral vs caudal portion of the PCoA supply?
Rostral: tuberal region
Caudal: mammillary region
What do MFB and DLF stand for?
MFB: medial forebrain bundle
DLF: dorsal longitudinal fasciculus
Connection between mammillary bodies + medial zone -> PAG and RF
Enables hypothalamus to influence emotional aspect of behavior
Two tracts that interact between hypothalamus and pituitary
- Supraopticohypophyseal tract
2. Tuberoinfundibular tract
Where are oxytocin and ADH stored before being released into capillary plexus to the post pit?
Herring bodies
Tuberoinfundibular tract
PVN -> pituitary, conveying releasing hormones
Lesion in anterolateral medulla
Disrupts hypothalamomedullary fibers -> symp outflow to face and head (Horner’s syndrome) or body
