In this video, we will be discussing about the anatomy of hypothalamus. The diencephalon makes up the caudal part of the forebrain between the telencephalon and the midbrain. It consists of the hypothalamus, thalamus, epithalamus and the subthalamus.
It is the principal autonomic center of the brain and it is also called as the head ganglion of the autonomic nervous system. The hypothalamus is located at the base of the brain, below the third ventricle and just above the optic chiasm and pituitary gland. This location can be thought of as the intersection of the cortex the cerebellum, and the brainstem.
Most of the cell bodies of the small neurons containing hypothalamic-releasing hormones are located in the tuberal area in the anterior part of the hypothalamus. Afferent pathways to the hypothalamic nuclei arise from the brainstem, thalamus, basal ganglia, cerebral cortex, and olfactory areas. Different pathways include the dorsal longitudinal fasciculus connecting the hypothalamus to the brainstem reticular centers, connections to the autonomic nervous system and the thalamus, and the hypothalamoneurohypofacial tract that connects the paraventricular and supraoptic nuclei which produce antidiuretic hormone to the nerve terminals in the median eminence and to the posterior pituitary. The pituitary stock which connects the median eminence to the pituitary gland passes through an opening in the dura surrounding the brain.
The pituitary gland lies outside the dura It rests in the cilla tarsica below the optic chiasm and is divided into anterior and posterior portions, each with a distinct embryology, anatomy, and function. The anterior pituitary, or the adenohypophyse, arises from the Radke's pouch from the oral cavity and the posterior pituitary, or The neurohypophyse arises from neural ectoderm at the floor of the forebrain. The hypothalamus functions as the central control center for the autonomic nervous system and endocrine function. Its nuclei produce releasing hormones for the anterior pituitary and the hormones that are released by the posterior pituitary.
posterior pituitary, the hypothalamic nuclei. These nuclei have been grouped into three different groups, the anterior region, the tuberal region, and the posterior region. The anterior region comprises of lateral preoptic nucleus, medial preoptic nucleus, superoptic nucleus, paraventricular nucleus, anterior hypothalamic nucleus and the suprachiasmatic nucleus, while the tubular region comprises of dorsomedial hypothalamic nucleus, ventromedial nucleus and arcuate nucleus. The posterior region comprises of mammillary nuclei, posterior nucleus and tuberomammillary nucleus. The lateral nucleus is present in all the three regions.
Now let's try to understand the relationship of hypothalamus to its surrounding structures. Hypothalamus is bound anteriorly by the anterior commissure in the lamina terminalis. The subcalisole area with its gyrus is also related anterior to the thalamus but it is just beyond the anterior commissure and the lamina terminalis. Posteriorly, hypothalamus is bound by the mammillary bodies, the posterior perforated substance, cerebral peduncle, and the cerebral aqueduct of sylveus.
On the inferior aspect, from anterior to posterior, the hypothalamus is bound by the supraoptic recess and crest, the pituitary stock and gland, and the tuber cinerium. Superiorly, we can appreciate hypothalamic sulcus and more superior to it are the thalamus, the choroid plexus of the third ventricle, and the foreneck. Now how about the vascular supply to hypothalamus? The anterior and posterior branches of the circle of bilis provide arterial blood supply to the hypothalamus.
The hypothalamus also receives arterial supply from the hypothalamic branches of the superior hypophyseal artery. The hypothalamic arteries have anastomotic connections to the primary and secondary capillary plexus of the pituitary gland. The plexus drains venous blood to the cavernous sinus.
which then drains to the superior and inferior petrosal sinuses. The superior petrosal sinus drains into the transverse sinus to form the sigmoid sinus. Eventually, the sigmoid sinus merges with the inferior petrosal sinus and becomes the internal jugular vein. That concludes our video on the module 1 of hypothalamus.
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