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.
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.
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.
Brainstem reticular formation to the lateral mamillary nucleus.
Dorsal longitudinal fasciculus
Midbrain's central gray --> periventricular hypothalamus.
Involved in circadian rhythms Runs from the retinal ganglion cells to both suprachiasmatic nuclei.
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