The pituitary gland, also known as the hypophysis cerebri, is an important endocrine gland of human body. The hormones produced by this gland influence the activities of many other endocrine glands, and for this reason it is often referred to as “The Master Endocrine Gland”. It is obviously vital to life.
The pituitary gland is situated in the Sella turcica of the Sphenoid bone, and is attached to the undersurface of the brain via its infundibulum. It is covered by a dural fold called Diaphragma sellae, which has a central aperture for the infundibulum. Owing to its location, the gland is well protected.
Pituitary gland is a small oval structure about the size of a pea and weighing about 0.5 grams. It is functionally connected to the hypothalamus via a small tube like structure called the Infundibulum or Pituitary Stalk.
The pituitary gland is divided into two lobes, which have different embryologic origin;
- Anterior lobe or Adenohypophysis: It arises from an invagination of the oral ectoderm that forms Rathke’s pouch
- Posterior lobe or Neurohypophysis: It originates from neuroectoderm and develops as an extension of the hypothalamus.
- Superiorly: Diaphragma sella, Optic chiasma
- Inferiorly: Sphenoid bone
- Laterally: Cavernous sinus
- Posteriorly: Dorsum sellae, Basilar artery, Pons
The arterial blood supply is derived from the superior and inferior hypophyseal arteries, branches of the internal carotid artery.
The venous drainage is into the intercavernous sinuses.
The pituitary gland secretes a number of hormones. The hormones secreted from the anterior pituitary are different from those secreted by the posterior pituitary.
Hormones of anterior pituitary:
- Growth hormone (GH), also known as “somatotropin”
- Thyroid stimulating hormone (TSH)
- Adrenocorticotropic hormone (ACTH)
- Prolactin (PRL), also known as “Luteotropic hormone”
- Luteinizing hormone (LH)
- Follicle stimulating hormone (FSH)
- Melanocyte-stimulating hormones (MSH), also known as “intermedins”
Hormones of posterior pituitary
Unlike the anterior pituitary, the posterior pituitary doesn’t actually synthesize any hormone. It just stores and secretes two hormones synthesized in the hypothalamus. These are;
- Antidiuretic hormone, also known as “vasopressin”