General
- Part of diencephalon—pars ventralis diencephali.
Relations
- Most part of hypothalamus is hidden
- However, some parts of the hypothalamus can be seen on the external (ventral) surface of the brain.
- These visible parts of hypothalamus are located in the interpeduncular fossa
- They form the floor of third ventricle
- Boundaries of Hypothalamus
- Superiorly
- Thalamus
- separated by the hypothalamic sulcus
- Medially
- Lateral wall of the third ventricle below the level of the hypothalamic sulcus.
- Laterally
- internal capsule,
- (in the posterior part) with the ventral thalamus (subthalamus).
- Posteriorly
- Merges with the ventral thalamus and through it, with the tegmentum of the midbrain.
- Anteriorly
- Extends up to the lamina terminalis, and merges with certain olfactory structures in the region of the anterior perforated substance.
- Inferiorly
- Forms structures in the floor of the third ventricle.
- Tuber cinereum
- A hollow eminence of gray matter
- Has no BBB
- Enhances normally after contrast administration
- Contains median eminence which contains the arcuate and infundibular nucleus
- Between Optic chiasm and mamillary body
- Infundibulum
- Mamillary bodies
Subdivisions of Hypothalamus
- 2 medial and lateral zones:
- Structure lying between the medial and lateral zones. Mamillothalamic tract, fasciculus retroflexus and column of the fornix
- Medial zone
- Periventricular
- Intermediate
- Lateral zone
- 4 anteroposterior regions:
- Preoptic region
- Adjacent to the lamina terminalis
- Anterior to the optic chiasma
- The preoptic region differs from the rest of the hypothalamus in being a derivative of the telencephalon
- Lamina terminalis also belongs to the telencephalon
- Supraoptic (or chiasmatic) region
- Lies above the optic chiasma
- Tuberal (or infundibulotuberal) region
- Consist of infundibulum, the tuber cinereum, and the region above it
- Mamillary (or posterior) region
- consists of the mamillary bodies and the region above them
Nuclei of the hypothalamus
- Preoptic nucleus: is resting on the lamina terminalis
- Ventral medial nucleus: largest and most prominent
- Lateral nucleus: diffuse collection of cells that extend through the supraoptic, tuberal, and mamillary regions in the lateral zone.
- Hypothalamic nucleus: from anterior to posterior
- Lateral: Hunger and thirst centre
- Medial:
Preoptic area | Supraoptic areaAnterior hypothalamic | Tuberal (infundibulo-tuberal) areaIntermediate hypothalamic area | Mammillary areaPosterior hypothalamic area |
Preoptic nucleus | Lateral | ㅤ | Lateral |
ㅤ | Supraoptic Nuclei ADH | Lateral Tuberal | ㅤ |
ㅤ | ㅤ | Tuberoammillary | ㅤ |
Preoptic area | Supraoptic area Anterior hypothalamic | Tuberal (infundibulo-tuberal) area Intermediate hypothalamic area | Mammillary area Posterior hypothalamic area |
Preoptic nuclei Sexual hormone (LHRH) Parasympathetic | Paraventricular nuclei Oxytocin | Dorsomedial nuclei Integrator for satiety centre | Posterior nuclei Sympathetic |
Suprachiasmatic Circardian | Anterior nuclei Parasympathetic | Ventromedial Nuclei Satiety centre | Mamillary bodies Memory |
ㅤ | Supraoptic Nuclei ADH | Arcuate nuclei Ant pituitary hormone | ㅤ |