ANATOMY ANATOMY OFOF

THE PITUITARY GLAND THE PITUITARY GLAND

OBJECTIVESOBJECTIVES

At the end of the lecture, students should At the end of the lecture, students should be able to:be able to:

Describe the positionposition of the pituitary gland.

List the structures relatedthe structures related to the pituitary gland.

Differentiate between the lobes of the the lobes of the glandgland.

Describe the blood supply the blood supply of pituitary of pituitary gland gland & the hypophyseal portal systemhypophyseal portal system..

PITUITARY GLANDPITUITARY GLAND(HYPOPHYSIS CEREBRI)(HYPOPHYSIS CEREBRI)

It is referred to as the master of endocrine glandsmaster of endocrine glands.

It is a small oval structure 1 cm in diameter.

PITUITARY GLANDPITUITARY GLAND

X-RAY SKULL: LATERAL VIEWSAGITTAL SECTION OF HEAD

& NECK

Hypophyseal fossa

Sphenoidal air sinus

Pituitarygland

It lies in the middle cranial fossaIt is well protected in sella turcica (hypophyseal fossa) of body of sphenoid

Sella turcica

POSITION

it lies between optic chiasma optic chiasma (anteriorly) & mamillary bodies mamillary bodies (posteriorly).

Mamillary body

Optic chiasma

Body of sphenoid

A fold of dura mater (Diaphragma sellae) covers the pituitary gland & has an opening for passage of infundibulum (pituitary stalk) connecting the gland to hypothalamus.

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SUPERIORSUPERIOR: : Diaphragma sellae

INFERIOR: INFERIOR: Sphenoidal air sinuses

LATERAL:LATERAL: Cavernous sinuses

SUBDIVISIONS OF PITUITARY GLANDSUBDIVISIONS OF PITUITARY GLAND

The gland is subdivided into:

1) Anterior lobe (Adenohypophysis): it is the it is the True gland, Secretes hormones

2) Posterior lobe (Neurohypophysis): connected to hypothalamus through hypothalamo-hypophyseal tracthypothalamo-hypophyseal tract, Stores hormones secreted by hypothalamic nuclei

Hypothalamo-hypophyseal tract

BLOOD SUPPLY OF PITUITARY GLANDBLOOD SUPPLY OF PITUITARY GLAND

ARTERIES: ARTERIES: Superior & inferior hypophyseal arteries (branches of internal carotid artery)

VEINS:VEINS: Hypophyseal veins drain into Cavernous Sinuses.

DISTRIBUTION OF ARTERIESDISTRIBUTION OF ARTERIES

Superior hypophyseal: Superior hypophyseal: supplies infundibulum & forms a capillary network from which vessels pass downward & form sinusoids into the anterior lobe of pituitary gland (hypophyseal portal system).(hypophyseal portal system).Inferior hypophysealInferior hypophyseal: : supplies posterior lobe of pituitary gland.

a hypothalamo-hypophseal portal vessel

Hormone-releasing & Hormone-releasing & inhibiting factors inhibiting factors produced by hypothalamus use Hypophyseal Portal System of vessels to reach the Anterior lobe of pituitary gland

ANTERIOR LOBE

The neurohypophysis receives The neurohypophysis receives a nerve supply from some of a nerve supply from some of the hypothalamic nuclei the hypothalamic nuclei ((supraoptic supraoptic & & paraventricularparaventricular) )

The axons of these nuclei The axons of these nuclei convey convey their neurosecretion neurosecretion to the Posterior lobe of pituitary gland through Hypothalamo-Hypophyseal tract from where it passes into the blood stream.

POSTERIOR LOBE

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