Pituitary Gland Anatomy Lecture Notes (Fall 2023) PDF

F A C U L T Y O F M E D I C I N E B M S 303 F A L L 2 0 23 Pituitary gland Dr.Waleed Nasr  THE PITUITARY GLAND (HYPOPHYSIS CEREBRI) ❑The master of endocrine glands ❑It is a small (size of a pea) oval structure attached to the und...

F A C U L T Y O F M E D I C I N E B M S 303 F A L L 2 0 23 Pituitary gland Dr.Waleed Nasr  THE PITUITARY GLAND (HYPOPHYSIS CEREBRI) ❑The master of endocrine glands ❑It is a small (size of a pea) oval structure attached to the undersurface of the brain (hypothalamus) by the infundibulum.  Sulcus chiasmaticus Tuberculum sellae (optic chiasma) ❑Pituitary gland lies in the hypophyseal fossa ❑ It is connected to hypothamus by infundibulum (pituitary stalk) ❑Weight : 0.5 gm Dorsum sellae It lies within the pituitary fossa of the sphenoid bone  PITUITARY GLAND SAGITTAL SECTION OF HEAD & NECK Pituitary gland https://lh3.googleusercontent.com/EEbsZ2_tBqNVfudzfdFkEcqBwnayGKR4DouHOb https://lh3.googleusercontent.com/SBkcyjnZDShCbXD_4ply Sphenoidal air sinus Relations of pituitary gland: Prof Azza Kamal/ Genitourinary & Endocrine Module it is covered superiorly diaphragma sellae of dura mater. Inferiorly, the pituitary is separated from the floor of the fossa by a venous sinus  On each side: cavernous sinus & its contents Cavernous sinus Pituitary https://lh3.googleusercontent.com/eHPnEi9e5LHTSSAI The pituitary has two major parts, the Neurohypophysis and adenohypophysis, which differ in their origin, structure and function Lobes of Pituitary Gland (1) Anterior Lobe ➔ adenohypophysis (2) Posterior Lobe ➔ neurohypophysis 1) Anterior lobe: consists of 3 parts: 1- Pars distalis 2- Pars intermedia 3-Pars tuberalis : upward extension from pars distalis that encircles the infundibulum https://lh3.googleusercontent.com/mLwZ5hkNBiP66hKjC  Lobes of the Pituitary gland 2) Posterior Lobe: 1- Pars nervosa : lies posterior to anterior lobe 2-Infundibulum: connection between pituitary &hypothalamus https://lh3.googleusercontent.com/mLwZ5hkNBiP66hKjC  highly vascular. It consists of epithelial cells of Adenohypophysis varying size and shape arranged in cords or irregular follicles, between which lie thin-walled vascular sinusoids Pituitary gland TSH FSH ACTH LH gonadotropic hormones. Prolactin and growth hormone. Neurohypophysis Axons arising from groups of hypothalamic Neurones terminate in the neurohypophysis. They form the neurosecretory hypothalamohypophysial tract and terminate near the sinusoids of the posterior lobe. The neurohormones stored in the main part of the neurohypophysis are vasopressin (antidiuretic hormone; ADH), which controls reabsorption of water by renal tubules and oxytocin, which promotes the contraction of uterine smooth muscle in childbirth and the ejection of milk from the breast during lactation The neurohypophysis is a diencephalic downgrowth connected with the hypothalamus The adenohypophysis is an ectodermal derivative of the stomatodeum Arteries and veins of the pituitary gland Inferior hypophyseal artery: Arises from internal carotid artery (ICA) inside the cavernous sinus and supplies the posterior lobe. Superior hypophyseal artery: Several arteries arise from ICA after leaving the cavernous sinus, they supply the infandibulum. Hypothalamo-hypophyseal portal system of veins supplies the anterior lobe and carries the hormone- releasing factors from the cells of hypothalamus down to the anterior lobe. Large veins drain the gland into the cavernous sinus. https://lh3.googleusercontent.com/3gU0DwzxeB1Im https://lh3.googleusercontent.com/4hUox8d9jEJE81LlG  Effects of Pituitary Tumors 1) Upward pressure : compressing optic chiasma leading to bitemporal hemianopia 2) Lateral pressure on cavernous sinus leading to congestion of eye & 3) Endocrinal disturbances Questions: 1. The Pituitary gland lies in: a) Sella turcica b) Posterior cranial fossa c) Ant cranial fossa d) Infra temporal fossa