QS Study

Connections of Hypothalamus

The hypothalamus is an important part of the central nervous system which controls the autonomic nervous system and endocrine system. It plays a key role in regulating pituitary function. It is a part of the brain that contains a number of small nuclei with a mixture of functions. It is located below the thalamus and is part of the limbic system.

The main afferent and efferent connections of the hypothalamus are given below:

Afferent Connections:

These various nuclei of hypothalamus bring a lot of afferent input/connections which are:

  • Visceral and somatic inputs through ascending tracts
  • Olfactory pathway or olfactory tract (medial forebrain bundle)
  • Corticohypothalamic (from neocortex, i.e. frontal lobe) tract
  • Hippocampus (via fornix)
  • From tegmentum of midbrain

Afferent Pathways

Medial and spinal lemnisci, reticular formation –

  • Origin: Viscera and somatic structure
  • Destination: Hypothalamic nuclei

Medial forebrain bundle –

  • Origin: Olfactory mucous membrane
  • Destination: Hypothalamic nuclei

Corticohypothalamic fibers –

  • Origin: Frontal lobe of the cerebral cortex
  • Destination: Hypothalamic nuclei

Hippocampohypothalamic fibers (Limbic system)

  • Origin: Hippocampus
  • Destination: Nuclei of mammillary body

Amygdalohypothalamic fibers

  • Origin: Dorsomedial and midline nuclei of the thalamus
  • Destination: Hypothalamic nuclei

Tegmental fibers –

  • Origin: Tegmentum of midbrain
  • Destination: Hypothalamic nuclei

Connections of Hypothalamus 1

Fig: Important Afferent and Efferent Connections of Brainstem

Efferent Connections:

  • Hypothalamohypophyseal tract
  • Mammillothalamic tract (connects mammillary body to anterior thalamic nuclei)
  • mammillotegmental tract (connects the mammillary body to tegmentum present in the midbrain)
  • Connected to vital centers in brainstem motor neurons in spinal cord.

Efferent Pathways –

Mammillothalamic tract –

  • Origin: Nuclei of mammillary body
  • Destination: an Anterior nucleus of the thalamus

mammillotegmental tract –

  • Origin: Nuclei of mammillary body
  • Destination: Reticular formation in the tegmentum of the midbrain

Descending fibers in reticular formation to the brainstem and spinal cord –

  • Origin: Preoptic, anterior, posterior and lateral nuclei of the hypothalamus.
  • Destination: Craniosacral parasympathetic and thoracolumbar sympathetic.
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