The Hypothalamus

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The diencephalon | Main Anatomy Index | The visual system

Last updated 30 March 2006

The Hypothalamus

Robinson, S. University of NSW, Neuroanatomy (ANAT 2007) tutorial. 1 September 1998.

Click here to go to the Hypothalamus under "The Diencephalon".

 

General Functions of the Hypothalamus

  1. Hypothalamic neurons measure blood temperature, osmolarity and hormone levels.
  2. The hypothalamus integrates the ANS especially during emotional responses.
  3. It also regulates endocrine functions of the adenohypophysis (anterior pituitary) by releasing neurohormones into the hypophyseal portal system.
  4. It regulates the function of the kidneys, uterus and mammary glands by releasing vasopressin (anti-diuretic hormone, ADH) and oxytocin into the bloodstream.

 

Borders of the Hypothalamus

Rostral Lamina terminalis
Caudal Posterior margin of the mammillary bodies
Dorsal Hypothalamic sulcus
Medial 3rd ventricle
Lateral Subthalamus and internal capsule
Ventral Optic chiasm, tuber cinereum, mammillary bodies and neurohypophysis (posterior pituitary)
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Organisation of the Hypothalamus

 

Anterior Nuclear Group

Preoptic nucleus Controls the parasympathetic nuclei
Supraoptic nucleus Synthesis and secretion of vasopressin. Lesions of this nucleus can cause diabetes insipidus.
Suprachiasmatic nucleus Receives retinal input and projects to the pineal gland. This controls circadian rhythms.
Anterior nuclei Some (esp. INAH3) are larger in male heterosexuals, due to circulating androgens in perinatal life which "rescues" neurons from programmed cell death. It is involved in response to temperature and sexual preference.
Paraventricular nucleus Synthesis and secretion of oxytocin (milk ejection reflex and uterine contractions). It also regulates food intake.

 

Tuberal Nuclear Group

Dorsomedial nucleus Both of these may be involved with the paraventricular nucleus in inhibiting eating and drinking (satiety centre). Lesions of these nuclei can cause eating disorders.
Ventromedial nucleus
Arcuate nucleus Function is unknown.

 

Posterior Nuclear Group

Posterior nucleus Regulates the body's response to cold and controls the sympathetic nervous system.
Mammillary nuclei They are part of the limbic system. They are prone to damage in chronic alcoholism. Korsakoff's patients have amnesia, but can recall if a hint is provided. This suggests that the mammillary bodies code memories so that they can be retrieved.
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Connections

Main Afferent Pathways

 

Medial Forebrain Bundle

 

Stria Terminalis

 

Fornix

 

Main Efferent Pathways

Mammillothalamic Fasciculus

 

Hypothalamic-Reticular Pathway

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Michael Tam (c) 1998