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Pituitary and suprarenal Gland

Dr. Lubna Nazli

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Objectives

• Site, size of pituitary and suprarenal

• Divisions of pituitary

• Relations of pituitary and suprarenal

• Development of pituitary and suprarenal

• Blood supply

• Applied anatomy

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Site

• The pituitary gland lies in the hypophyseal fossa of the sphenoid and is connected to the hypothalamus by the infundibulum, or pituitary stalk.

• The dura covering the superior aspect of the gland forms the diaphragma sellae.

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Size

It is a neuroglandular body suspended from floor of III ventricle.

The gland is about :• 12mm transversely• 8mm in

anteroposterior diameter.

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Divisions

The major divisions of the gland are:

• anterior lobe, or adenohypophysis.

• posterior lobe, the neurohypophysis.

These 2 parts are different in development, function and structure.

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Parts of each lobe

• Adenohypophysis – pars distalis – pars intermedia – pars tuberalis

• Neurohypophysis – pars nervosa – pituitary stalk – median eminence

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Relations

• In front: ant intercavernous sinus

• Behind: post intercavernous sinus

• Below: sphenoidal air sinus

• Above: optic chiasma

• On each side: cavernous sinus

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E. Sphenoid Sinus

F. Pituitary Gland

G. Cavernous Sinus

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DEVELOPMENT

The pituitary gland is derived from two sources.

• The anterior lobe is an up growth of ectoderm from the roof of the stomodeum

• The posterior lobe is a down growth of neuroectoderm from the diencephalon.

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• In the middle of the fourth week, a diverticulum, Rathke's pouch, grows upwards from the roof of the mouth towards the developing brain.

• As the upgrowth contacts a downgrowth from the brain, the infundibulum, it begins to pinch off from its connection with the stomodeum.

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Hormones of anterior pituitary:

• Growth hormone• Prolactin• Thyrotrophic hormone• Gonadotrophic

hormone (FSH & LH)• ACTH• MSH

Hormones of posterior pituitary:

• Vasopressin or anti-diuretic hormone

• Oxytocin

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Arterial supply and venous drainage

• The arteries of the pituitary gland arise from the internal carotid arteries as the inferior and superior hypophyseal arteries.

• The inferior hypophyseal arteries mainly supply the pars nervosa before forming short portal vessels to supply the pars distalis.

• The superior hypophyseal arteries supply the floor of the hypothalamus, the median eminence.

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• What are capillary plexuses?

• Portal vessels?

• Hypothalamo-hypophyseal tract?

• Venous drainage : into the cavernous and intercavernous sinuses.

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• The capillary plexus formed by the superior hypophyseal artery in the median eminence form into long portal vessels which run down in the pituitary stalk to form a capillary plexus in the pars distalis.

• In the median eminence the capillary plexus receives secretions from releasing factor cells.

• The blood is drained from the pituitary by inferior hypophyseal veins into the dural venous sinuses.

Hypothalamic Control of the Posterior Pituitary

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Hypothalamic Control of the Anterior Pituitary

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Clinical Anatomy

• Upward growth of pituitary tumors may press on the optic chiasma.

• Typical visual field defects would be bitemporal hemianopia, and upper quadrantopia.

• Tumors can grow up into the third ventricle causing hydrocephalus.

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• Rapid lateral expansion, perhaps due to haemorrhage may compress the third, fourth or sixth cranial nerves.

• Headache may be present from stretch of the meninges. Surgery to remove pituitary tumors is usually performed through the sphenoidal sinus.

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Disturbance of endocrine functions

• Gigantism & acromegaly ( GH )

• Cushing’s syndrome (ACTH )

• Diabetes insipidus (ADH)

Suprarenal gland

• Triangular endocrine glands over the kidneys. • each gland weighs about (4.5 g) • consists of an inner medulla which produces the

catecholamine hormones (Epinephrine and Norepinephrine)

• outer cortex which secretes the steroid hormones (Aldosterone, Cortisol and Androgens)

Relations

Right suprarenal gland

• posteriorly: related to the diaphragm

• Inferiorly: related to the upper pole of right kidney

• Posteriomedially: related to IVC

Relations

The left Suprarenal gland

• Inferiorly: related to the upper pole of left kidney

• Posteriorly: related to the diaphragm

• Anteriorly: related to the stomach, spleen , pancreas and to the lesser sac

Blood Supply

Arteries:a) Sup suprarenal artery - from inf phrenic (abd

aorta)

b) Mid suprarenal - from aorta directly

c) Inf suprarenal - from renal artery

• Veins– R suprarenal vein –> IVC– L suprarenal vein –> L renal vein –> IVC

Innervation.

• The celiac plexus and splanchnic nerves supply branches.

• Most of the fibers are preganglionic sympathetic and synapse directly with the cells of the medulla.

Development of suprarenal gland

• The cortex develops from the mesoderm

• The medulla develops from neural crest cells and contains sympathetic cells which secretes catecholamines

Clinical Anatomy

• Addison's disease

• Cushing's disease

Addison's disease Also known as chronic adrenal insufficiency, or hypocortisolism. An endocrine disorder in which the body produces insufficient amounts

of adrenal steroid hormones (glucocorticoids and often mineralocorticoids

symptoms and signChronic fatigue that gradually worsens Muscle weakness Weight loss and loss of appetite Nausea, diarrhea, or vomiting Areas of hyperpigmentation

Cushing's syndrome

Cushing's syndrome (also called hypercortisolism or hyperadrenocorticism) is an endocrine disorder caused by high levels of cortisol in the blood. Cortisol is released from the adrenal gland in response to ACTH being released from the pituitary gland in the brain.

Cushing’s syndrome

Symptoms •Weight gain particularly of the trunk and face •Moon face•Sweating•Telangiectasia (dilation of capillaries),•Purple or red striae on the(trunk, buttocks, arms, legs )•Hirsuitism•Buffalo hump •Reduced libido, impotence, amenorrhoea•Infertility. •Psychosis. Depression and anxiety