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What does the hypothalamus do?

Controls visceral, autonomic, endocrine, and emotional function. 


Where is the hypothalamus located?

It extends from the anterior perforated substance and optic chiasm to the optic tracts and the mamillary bodies. 


What are the 4 major structures within the hypothalamus

1. Pre-optic area 2. Medial hypothalamic area 3. Lateral hypothalamic area 4. Median eminence


Features of the lateral hypothalamic area

Contains the lateral hypothalamic nucleus


Features of the median eminence

Funnel like extension of the tuber cinereum. Region where the CNS interacts with the pituitary. 


Features of the medial hypothalamic area.

The medial hypothalamic area is continuous with the periaqueductal gray. It contains the supraoptic, tuberal and mamillary regions - which correspond to the anterior, middle and posterior regions respectively.


Supraoptic region of the hypothalamus. 

AKA the anterior region of the medial hypothalamus. Contains the 1. paraventricular and supraoptic nuclei which secrete oxytocin and vasopressin. 2. anterior hypothalamic nucleus. 3. suprachiasmatic nucleus - biologic clock with afferent input from the retinas.


Tuberal region of the hypothalamus

Region where the fornix separates the hypothalamus into the medial and lateral positions.


Mamillary region

Contains the mamillary bodies and the posterior hypothalamic nuclei. 


General input to the hypothalamus

1. Pyriform cortex --> amygdala --> stria terminalis --> hypothalamus and hippocampus. 2. Closed loop: CG ---> entorhinal cortex --> hippocampus --> hypothalamus --> anterior thalamic nucleus back to the cingulate gyrus.


Sources of hypothalamic input

1. Medial forebrain bundle 2. Fornix 3. Stria terminalis 4. Mamillary peduncle 5. Dorsal longitudinal fasciculus 6. Retinohypothalamic tract 7. Nucleus solitarius


Medial forebrain bundle

Sends information related to basic emotional drives and smell. From the basal olfactory areas, septal nuclei, periamygdala, and subiculum to the lateral preoptic and lateral hypothalamic areas.



Brings information from the hippocampus to the mamillary bodies. 


Stria terminalis

Also brings information related to emotional drive and smell. It arises from the amygdala and travels within the terminal sulcus between the thalamus and the caudate to the anterior and pre-optic nuclei. 


Mamillary peduncle

Brainstem reticular formation to the lateral mamillary nucleus. 


Dorsal longitudinal fasciculus

Midbrain's central gray --> periventricular hypothalamus. 


Retinohypothalamic tract

Involved in circadian rhythms Runs from the retinal ganglion cells to both suprachiasmatic nuclei.


Nucleus solitarius 

The rostral portion of the nucleus solitarius is involved in taste and projects fibers to the medial hypothalamus The caudal portion of the nucleus solitarius is involved in visceral sensation and projects fibers to the lateral hypothalamus.


What are the major hypothalamic output tracts?

1. Mamillothalamic 2. Dorsal longitudinal fasciculus 3. Medial forebrain bundle 4. Stria terminalis 5. Mamillotegmental tract 6. Descending autonomic projections 7. Supraoptichypophyseal tract 8. Tuberohypophyseal tract


Output of the mamillothalamic tract

Mamillary bodies to the anterior thalamic nucleus.


Output of the dorsal longitudinal fasciculus

Mamillary bodies to the midbrain tegmentum and central gray. 


Output of the medial forebrain bundle

Lateral hypothalamus to the hippocampus


Output of the stria terminalis

Runs from the hypothalamus to the amygdala


Output of the mamillotegmental tract

Mamillary bodies to the midbrain ventral and dorsal tegmentum


Output of the descending autonomic projections

Paraventricular, lateral hypothalamic, posterior hypothalamic nuclei to the dorsal motor nucleus of 10, nucleus solitarius, nucleus ambiguous, medulla and the spinal intermediolateral cell column. 


Output of the supraoptichypophyseal tract

Supraoptic and paraventricular nuclei to the posterior pituitary gland. Leads to the release of the oxytocin, vasopressin, cholecystokinin, enkephalins, and angiotensin. 


Output of the tuberohypophyseal tract

Arcuate nucleus of the tuber region to the median eminence and the infundibular stem. Releases hormones into the fenestrated capillaries of the portal hypophyseal tract.


Seven basic roles of the hypothalamus

1. Parasympathetic -> anterior and ventromedial hypothalamic nuclei. 2. Sympathetic -> Posterior and lateral hypothalamic nuclei. 3. Decreases body temperature -> anterior hypothalamic nuclei 4. Increases body temperature -> posterior hypothalamic nuclei 5. Satiety center -> Medial hypothalamic nucleus 6. Feeding center --> Lateral hypothalamic nucleus 7. Arousal center --> Posterior hypothalamic nucleus


Where is the pituitary gland located

Within the sella turcica of the sphenoid bone


Components of the pituitary gland

1. Adenohypophysis 2. Neurohypophysis