RADIOLOGY ANATOMY OF THE PITUITARY GLAND Dr fahad

RADIOLOGY ANATOMY OF THE PITUITARY GLAND Dr. fahad albadr

ANATOMY OF THE PITUITARY GLAND

OBJECTIVES At the end of the lecture, students should be able to: q Describe the position of the pituitary gland. q List the structures related to the pituitary gland. q Differentiate between the lobes of the gland

PITUITARY GLAND (HYPOPHYSIS CEREBRI) q. It is referred to as the master of endocrine glands q. It is a small oval structure 1 cm in diameter.

PITUITARY GLAND X-RAY SKULL: LATERAL VIEW SAGITTAL SECTION OF HEAD & NECK Pituitary gland Hypophyseal fossa Sphenoidal air sinus

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

Optic chiasma Mamillary body Body of sphenoid q it lies between optic chiasma (anteriorly) & mamillary bodies (posteriorly).

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.

IMPORTANT RELATIONS q. SUPERIOR: Diaphragma sellae q INFERIOR: Sphenoidal air sinuses q. LATERAL: Cavernous sinuses

SUBDIVISIONS OF PITUITARY GLAND Hypothalamo-hypophyseal tract The gland is subdivided into: 1) Anterior lobe (Adenohypophysis): it is the True gland, Secretes hormones 2) Posterior lobe (Neurohypophysis): connected to hypothalamus through hypothalamo-hypophyseal tract, tract Stores hormones secreted by hypothalamic nuclei

BLOOD SUPPLY OF PITUITARY GLAND ARTERIES: Superior & inferior hypophyseal arteries (branches of internal carotid artery) VEINS: Hypophyseal veins drain into Cavernous Sinuses.

DISTRIBUTION OF ARTERIES a hypothalamohypophseal portal vessel §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). §Inferior hypophyseal: supplies posterior lobe of pituitary gland.

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

POSTERIOR LOBE §The neurohypophysis receives a nerve supply from some of the hypothalamic nuclei (supraoptic & paraventricular) §The axons of these nuclei convey their neurosecretion to the Posterior lobe of pituitary gland through Hypothalamo. Hypophyseal tract from where it passes into the blood stream.

NORMAL PITUITARY GLAND v The gland is composed of two parts: ØAnterior lobe (adeno hypophysis) ØPosterior lobe (neuro hypophysis) v Normal size: ØWeight: 0. 5 g ØHeight: 4 -12 mm ØAnterior posterior: 5 -16 mm

INDICATIONS FOR IMAGING THE PITUITARY GLAND v. Hormonal dysfunction § Cushing syndrome § Growth abnormalities e. g. Growth hormone deficiency, acromegaly v. Visual abnormalities vheadache

v. What is best modality to image the pituitary gland ? A. B. C. D. E. X ray CT scan MRI US Nuclear medicine

v. What is best modality to image the pituitary gland ? A. X ray B. CT scan C. MRI D. US E. Nuclear medicine

CT scan MRI

CT scan MRI

X RAY

1 2 3 4 5 6

1 2 3 4 5 6 1 -Optic sulcus 2 - Anterior clinoid process 3 -Floor of sella turcia (Pituitary fossa) 4 - Posterior clinoid process 5 - Dorsum sella 6 - Sphenoid sinus

MRI

4 3 5 2 6 1

4 3 1 - pituitary gland 2 - sphenoid sinus 3 - optic chiasm 4 - hypothalamus 5 - pituitary stalk 6 - claivus 5 2 6 1

NORMAL PITUITARY ADENOMA

3 2 1 4 5 6

3 2 1 4 5 6

Optic chiasm Pituitary stalk Carotid artery Cavernous sinus Pituitary gland Sphenoid sinus

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