Connections of the hypothalamus

graph TD
A[Ascending somatosensory pathways] --> B(Thalamus)
A --> C
B <--> C(Hypothalamus)
D[Neocortex] <--> C
E[Limbic system] <--> C
F[Olfactory impulses] --> C
G[Visual inputs] --> C
C <--> H[Visceral centres in brainstem and spinal cord]
C --> I[Neuro-endocrine influence on hypophysis cerebri]

• Has afferent and efferent connections in the form of
Nervous connections
• Afferent

Function	Origin	Pathway	Destination
Somatic	Skin	Collateral branches of the lemniscal afferent fibers	ㅤ
Gustatory	Tongue	Dorsal longitudinal fasciculus (brainstem)	Nucleus of solitary tract
Visceral	Visceral organs	Median forebrain bundle (spinal cord)	Reticular formation
Circardian rhythm	Optic chiasm	Retinohypothalamic	Suprachiasmatic nucleus
Olfaction	- Anterior olfactory areas - septal areas - tegmentum of the midbrain	Medial forebrain bundle	midbrain, pons and medulla
ㅤ	Frontal lobe	Corticohypothalamic fibers - direct - indirect: through Thalamus (medial, dorsal, midline nuclei) --> periventricular fibres (so called because they travel just subjacent to the ependyma)	ㅤ
Limbic system-Short term memory (papez circuit)	Hippocampus	Hippocampohypothalamic fibers (fornix)	Mammillary body
ㅤ	Amygdaloid complex	Amygdalohypothalamic fibers (ventral amydalofugal pathway/stria terminalis/direct pathway)	Hypothalamus - Lateral nucleus - Ventromedial nucleus
ㅤ	dorsomedial and midline thalamic nuclei	Thalamohypothalamic fibers	ㅤ
ㅤ	midbrain	Tegmental fibers	ㅤ


• Efferent tracts

Function	Origin	Pathway	Destination
Autonomic control	Preoptic, anterior, posterior, and lateral nuclei of hypothalamus	To brain stem (reticular formation): dorsal longitudinal fasciculus To Spinal cord: Medial forebrain bundle	Craniosacral parasympathetic and thoracolumbar sympathetic outflows
Limbic system	Nuclei of mammillary body	Mammillothalamic tract	Anterior nucleus of thalamus; relayed to cingulate gyrus
Unknown in human but in animals regulating visceral function and processing spatial information	Nuclei of mammillary body	Mammillotegmental tract	Reticular formation in tegmentum of midbrain
ㅤ	Hypothalamic nuclei	Multiple pathways	Limbic system



 





 
Bloodstream & CSF
• Control of pituitary gland by the Hypothalamus
• Bioactive peptides made by nuclei in hypothalamus release into capillaries or CSF (neurosecretion)
• Control of Neurohypophysis (Post. Pituitary)
• Vasopressin (antidiuretic hormone, ADH)

• Origin
• Supraoptic nucleus
• Tract
• Supraopticohypophyseal tract
• Terminate
• Posterior pituitary

• Oxytocin

• Origin
• Paraventricular (magnocellular part) nucleus
• Tract
• Paraventriculohypophyseal tract
• Terminate
• Posterior pituitary

• Control of the Adenohypophysis by the Hypothalamus
• The cells of the arcuate (infundibular) nucleus produce releasing factors that travel along their axons (Tuberohypophyseal tract) and are released into the capillaries → releasing factors enter anterior pituitary through the hypothalamohypophyseal portal system → release of appropriate hormones.
Hypothalamic regulatory hormone	Presumed nuclear origin
GHRH	Infundibular/arcuate nucleus
GHIH (Somatostain)	Suprachiasmatic nucleus
Prolactin releasing hormone	Arcuate nucleus
Prolactin inhibiting hormone	?
Corticotrophin releasing hormone	Paraventricular nuclei
TRH	Paraventricular and dorsomedial nuclei
LHRH	Preoptic and anterior nuclei