- Situated below the 3rd ventricle
- Lies in the pituitary fossa of the sella turcica of the sphenoid
bone
- Covered by fold of dura mater know as the diaphragma sellae
- Connected to brain by infundibulum
- Divided into anterior and posterior lobes
Anterior lobe
- Consists of pars anterior and pars intermedia
- Blood supply reaches lobe via the infundibulum
- Transports hormones from the hypothalamus
- Cells are classified as chromophils or chromophobes
- Chromophils are either basophilic or eosinophilic
Posterior lobe
- Downgrowth of the floor of the 3rd ventricle
- Nerve fibres extend from hypothalamus to the posterior pituitary
Relations of the pituitary
- Gland is overhung by anterior and posterior clinoid processes,
dorsum sellae and diaphragma sellae
- Infundibulum passes posterior to optic chiasma
- Superior to optic chiasma is the anterior communicating artery
- Cavernous sinus lies on each side of the gland
- In the lateral wall of each cavernous sinus lies
- III, IV, ophthalmic branch of V, VI cranial nerve
- Internal carotid artery
Pituitary enlargements
- Symptoms of pituitary tumours occur due to:
- Endocrine effects
- Pressure on adjacent structures
- Visual changes include
- Bitemporal hemianopia
- III nerve palsy
- Palsies of IV and VI nerves are rare
- Proptosis
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