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Hypothalamus

Dr Yuranga Weerakkody and Dr Frank Gaillard et al.

The hypothalamus is located, as the name would suggest, below the thalamus, and is intimately associated with both the limbic system and the pituitary gland.

Boundaries

Its boundaries are in some places poorly defined (outlined in blue in figure 1):

anterior - lamina terminalis, with optic chiasm at its lower border and anterior commissure above
superior - an imaginary line drawn between the anterior and posterior commissures
posterior - an imaginary line sloping antero-inferiorly from the posterior commissure to the mamillary bodies
inferior (floor) - infundibular stalk, tuber cinereum and mamillary bodies (from front to back)

Fiber tracts

postcommissural fornix (running posterior to the anterior commissure vertically down to end in the mamillary bodies)
principle mamillary bundle - originates in the mamillary body and runs superiorly a short distance before dividing into:
- mamillothalamic tract (aka Vicq d'Azyr's bundle) - which terminates in the anterior thalamic neucleus
- mamillotegmental tract (smaller)

Nuclei

The hypothalamus is really a collection of nuclei arranged symmetrically around its floor and lateral walls, and can be divided into medial and lateral areas.

Medial area

supraoptic (anterior)
- supraoptic nucleus (medial part)
- suprachiasmatic nucleus
- medial preoptic nucleus
- paraventricular nucleus
- anterior nucleus
tuberal
- dorsomedial nucleus
- ventromedial nucleus
mamillary (Posterior)
- mamillary nuclei
- posterior nucleus

Lateral area

supraoptic (anterior)
- latateral preotpic neucleus
- supraoptic nucleus (lateral part)
- lateral nucleus (anterior part)
tuberal
- lateral nucleus (tuberal part)
- lateral tuberal nuclei
mamillary (posterior)
- lateral nucleus (posterior part)