VAN 121: Veterinary Gross Anatomy-II (2+2)

Pineal body and hypothalamus

PINEAL GLAND AND HYPOTHALAMUS

Pineal gland 

• It is a small ovoid or fusiform gland situated dorsally in a deep depression between the thalami and the corpora quadrigemina.
• It is attached to the postero-superior quadrant of the third ventricle by a hollow stalk, which is a small recess of the third ventricle.
• Immediately under the posterior part of the stalk is a short transverse band of white mater called the posterior commissure.

Hypothalamus

• The term hypothalamus does not refer to any single structure anatomically.
• It includes the wall of the third ventricle below the thalamus, optic chiasma, tuber cinerium, infundibulum, mamillary body, subthalamic nuclei, posterior perforated substance etc.
• The hypothalamus is functionally important as it contains centres of the sympathetic and parasympathetic systems regulating visceral activities; centres for regulation of body temperature, fat, carbohydrate and water metabolism, centre for sleep rhythm etc.
• Neurons in the hypothalamus are also concerned in the regulation of secretion of hormones in the pars anterior of the pituitary through secretion of chemical mediators or releasing factors into the blood stream (Hypophyseal portal circulation).
• In addition, other neurons in the hypothalamus are responsible for secretion of the posterior pituitary hormones which are conveyed by the axons of these neurons through the hypothalamo-hypophyseal tract to the pars nervosa, where they are released in to the blood stream.  Click to see the functional areas of hypothalamus