02. Pituitary and Hypothalamus I

Pituitary Master endocrine gland Small gland Situated at the base of the brain in the hypophyseal fossa Infundibulum p...

Pituitary

1. Master endocrine gland
2. Small gland
3. Situated at the base of the brain in the hypophyseal fossa
4. Infundibulum pierces the diaphragma sellae to attach to the floor of the 3^rd ventricle

Relations

Superiorly	Diaphragma sellae Optic chiasma Tuber cinerium Infundibular recess
Lateral	Cavernous sinus cranial nerves are damaged in lateral enlargement :3rd, 4th,5th & 6th cranial nerves can be damaged)
Inferior	Sphenoid sinus (change in shape due to pituitary lesions) Hypophyseal fossa Venous channels

1. Neurohypophysis
2. Adenohypophysis

	Neurohypophysis	Adenohypophysis
Embriologically	Diencephalon	Ectodermal (Rathke’s pouch)
Morphologically	Posterior lobe (Continuous with the 3rd ventricle) More GLIAL cells	Anterior lobe (Separated from primitive oral cavity) More EPITHELIAL cells
Functionally	ADH, Oxytosin	GH, ACTH, FSH, LH, TSH, Prolactin
Blood supply	Superior & inferior hypophyseal arteries	Portal vessels (starts & ends with capillaries ) Carry hormone releasing factors from the hypothalamus
	Veins drain to near by dural sinuses

Applied anatomy

Symptoms due to pressure effects ( Tumors)	Symptoms due to hormonal effects
Pressure on optic chiasma Bitemporal hemianopia	Acromegaly (increased GH)
Hypothalamic syndrome	Cushing syndrome (decreased ACTH)
Enlarged sella tursica (pituitary fossa enlarged)	Prolactinoma (increased Prolactin secretion )
Pressure upon 3rd ventricle (increased ICP)	Hypopituitarism (less hormone secretion)

Hypothalamus

General features	Functions	Applied anatomy
Part of diencephalon Forms the floor & the lateral wall of the 3rd ventricle	Endocrine control	DI – Decreased ADH level
Head ganglion of the autonomic systems	Neurosecretion	Diencephalic autonomic epilepsy Salivation Sweating Flushing
2 major nuclei Supra optic Para ventricular	Autonomic effects Anterior – parasympathetic Posterior – sympathetic	Hyper glycaemia
	Regulation of food & water intake	Sleep disturbances
	Temperature regulation	Obesity – Frolic’s syndrome
	Sexual behavior & reproduction
	Act as a biological clock Controls the circadian rhythm of hormone secretion
	Emotional control

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