Anatomy of the Hypothalamus

Introduction

• The diencephalon is the caudal part of the forebrain, located between the telencephalon and the midbrain.
• Comprises:
  • Hypothalamus
  • Thalamus
  • Epithalamus
  • Subthalamus
• Known as the head ganglion of the autonomic nervous system.

Location

• Base of the brain
• Below the third ventricle
• Above the optic chiasm and pituitary gland
• Intersection of cortex, cerebellum, and brainstem

Neurons and Pathways

• Small neurons in the tuberal area of the anterior hypothalamus produce hypothalamic-releasing hormones.
• Afferent pathways include:
  • Brainstem
  • Thalamus
  • Basal ganglia
  • Cerebral cortex
  • Olfactory areas
• Key connections:
  • Dorsal longitudinal fasciculus with brainstem reticular centers
  • Autonomic nervous system and thalamus
  • Hypothalamoneurohypofacial tract connects paraventricular and supraoptic nuclei to the posterior pituitary

Pituitary Gland

• Connects via pituitary stalk at the median eminence
• Located outside the dura mater
• Divided into:
  • Anterior pituitary (adenohypophysis) from Radke's pouch
  • Posterior pituitary (neurohypophysis) from neural ectoderm

Functions of Hypothalamus

• Central control for autonomic nervous system and endocrine function
• Produces hormones for anterior and posterior pituitary

Hypothalamic Nuclei

• Grouped into:
  • Anterior region: Lateral preoptic, medial preoptic, superoptic, paraventricular, anterior hypothalamic, and suprachiasmatic nuclei
  • Tuberal region: Dorsomedial, ventromedial, and arcuate nuclei
  • Posterior region: Mammillary, posterior, and tuberomammillary nuclei
• Lateral nucleus spans all three regions.

Surrounding Structures

• Anterior boundary: Anterior commissure, lamina terminalis, subcalisole area
• Posterior boundary: Mammillary bodies, posterior perforated substance, cerebral peduncle, cerebral aqueduct of Sylvius
• Inferior aspect: Supraoptic recess, pituitary stalk and gland, tuber cinereum
• Superior boundary: Hypothalamic sulcus, thalamus, choroid plexus of third ventricle, foramen

Vascular Supply

• Supplied by anterior and posterior branches of the Circle of Willis
• Receives blood from superior hypophyseal artery branches
• Hypothalamic arteries connect to pituitary gland's capillary plexus
• Venous drainage to cavernous sinus -> superior and inferior petrosal sinuses -> transverse sinus -> sigmoid sinus -> internal jugular vein

Conclusion

• This concludes the video on module 1 of the hypothalamus anatomy.