1. Pituitary Gland Dr. Lubna Nazli Asst. Prof Anatomy RAKMHSU Dt: 15/4/08
Time: 8.30 – 9.30 am

2. Objectives Site, size Divisions Relations Development Blood supply
Applied anatomy

3. 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 sella.

5. Size
It is a neuroglandular body suspended from floor of III ventricle.
The gland is about :
12mm transversely
8mm in anteroposterior diameter.

6. 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.

7. Parts of each lobe Adenohypophysis Neurohypophysis pars distalis
pars intermedia
pars tuberalis
Neurohypophysis
pars nervosa
pituitary stalk
median emminence

8. Relations In front: ant intercavernous sinus
Behind: post intercavernous sinus
Below: sphenoidal air sinus
Above: optic chiasma
On each side: cavernous sinus

9. E. Sphenoid Sinus F. Pituitary Gland G. Cavernous Sinus

10. 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.

11. 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.

13. Hormones of anterior pituitary:
Growth hormone
Prolactin
Thyrotrophic hormone
Gonadotrophic hormone (FSH & LH)
ACTH
MSH

14. Hormones of posterior pituitary:
Vasopressin
Oxytocin

15. 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.

17. 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.

18. 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.

19. 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.

20. Disturbance of endocrine functions
Gigantism & acromegaly ( GH )
Cushing’s syndrome (ACTH )
Diabetes insipidus (ADH)