Hypothalamus
The Hypothalamus is a small part of the diencephalon inferior to the thalamus. It contains ~ a dozen nuclei and is split into 4 major regions: Mammillary, Tuberal, Supraoptic, Preoptic. Function : The Hypothalamus is one of the major regulators of homeostasis. Sensory impulse from both somatic and visceral senses arrive at the hypothalamus as do receptors for vision, taste, and smell. Osmotic pressure is monitored in the hypothalamus as well as glucose levels, certain hormone concentrations, and the temperature of blood. In addition, the hypothalamus has important connections with the Pituitary Gland and produces a variety of hormones.
Epithalamus
This region is located superior/posterior to the thalamus consisting of the Pineal Gland and Habenuclar Nuclei. The Pineal Gland is the size of a prune and protrudes from the posterior midline of the 3 rd ventricle. It is considered part of the endocrine system because it secretes the hormone melatonin which is thought to contribute to the body’s biological clock which is controlled by the hypothalamus. Melatonin is liberated during darkness more than light and therefore it is thought to induce sleepiness.
The Habenuclar Nuclei is involved in olfaction, especially emotional responses to odors.
Hypophysis
The hypophysis, or pituitary gland, rests within a recess of the floor of the cranial cavity called the sella turcica (part of the sphenoid bone). It is stabilized in position by a fold of dura mater. Functions of the diencephalon include reproductive functions and integrate smell, vision and taste with autonomic functions. It is responsible for rest wake cycles, digestion, temperature, water balance and blood sugar levels.
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