Pituitary Blood Supply: What Artery Keeps It Alive?

Understanding the pituitary gland’s vital function requires a deep dive into its intricate blood supply. The Sella turcica, a saddle-shaped depression in the sphenoid bone, provides a bony housing for this crucial endocrine organ. The question of what artery is inside pituitary gland is directly related to the effectiveness of hormone regulation. Therefore, exploring the vascular architecture that sustains the pituitary is critical for healthcare professionals.

Image taken from the YouTube channel Institute of Human Anatomy , from the video titled REAL Human Pituitary Gland .

Pituitary Blood Supply: Deciphering the Arterial Lifeline

Understanding the blood supply to the pituitary gland is crucial for comprehending its function and diagnosing related disorders. The gland’s intricate hormonal control relies on a complex network of arteries and veins. This explanation will detail the primary arterial supply, specifically focusing on answering the question: "what artery is inside pituitary gland?"

The Pituitary Gland: A Brief Overview

Before delving into the blood supply, a quick overview of the pituitary gland itself is necessary. The pituitary, often called the "master gland," is a small, pea-sized endocrine gland located at the base of the brain, nestled within a bony structure called the sella turcica. It’s divided into two main lobes:

• Anterior Pituitary (Adenohypophysis): This lobe produces and releases several crucial hormones, including growth hormone, prolactin, adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH).
• Posterior Pituitary (Neurohypophysis): This lobe stores and releases hormones produced by the hypothalamus, namely antidiuretic hormone (ADH or vasopressin) and oxytocin.

The Primary Arterial Supply to the Pituitary Gland

The pituitary gland receives its blood supply primarily from branches of the internal carotid artery. These branches form a rich network that ensures adequate perfusion of both the anterior and posterior lobes. The two main arterial branches contributing to this supply are:

• Superior Hypophyseal Artery (SHA)
• Inferior Hypophyseal Artery (IHA)

It is important to note that the IHA irrigates mostly the posterior pituitary, and although branches from SHA do penetrate both parts of the gland, SHA irrigates mostly the anterior pituitary.

The Superior Hypophyseal Artery (SHA)

The SHA is the dominant arterial supplier to the pituitary gland, particularly the anterior lobe.

• Origin: Arises from the internal carotid artery near the cavernous sinus.
• Path: It runs along the pituitary stalk and divides into branches that supply:
  • The median eminence of the hypothalamus
  • The pituitary stalk itself
  • The anterior pituitary gland
• Significance: The SHA gives rise to the hypophyseal portal system, a unique vascular network that connects the hypothalamus to the anterior pituitary. This system is crucial for the transport of releasing and inhibiting hormones from the hypothalamus to regulate the anterior pituitary’s hormonal secretions.

The Inferior Hypophyseal Artery (IHA)

The IHA primarily supplies the posterior lobe (neurohypophysis) of the pituitary gland.

• Origin: Arises from the internal carotid artery within the cavernous sinus.
• Path: It courses medially along the inferior aspect of the pituitary gland.
• Target: It supplies primarily the posterior pituitary, as well as small contributions to the pituitary stalk.
• Significance: While it doesn’t directly participate in the hypophyseal portal system, the IHA provides essential blood flow for the function of the posterior pituitary, ensuring the release of ADH and oxytocin.

Answering: What Artery is Inside Pituitary Gland?

Given the intricate vascular network, the answer to "what artery is inside pituitary gland?" is both the superior and inferior hypophyseal arteries—or, more accurately, branches of these arteries. They penetrate both lobes to different degrees.

• Anterior Pituitary: Primarily supplied by branches of the superior hypophyseal artery.
• Posterior Pituitary: Primarily supplied by the inferior hypophyseal artery.
• These branches form a complex network of arterioles and capillaries within the gland, delivering oxygen and nutrients to the pituitary cells.

The Hypophyseal Portal System

The hypophyseal portal system deserves special mention because it plays a critical role in the function of the anterior pituitary.

1. The SHA supplies the capillary plexus of the median eminence.
2. Hypothalamic neurons release hormones into this capillary plexus.
3. These capillaries converge into portal venules.
4. Portal venules travel down the pituitary stalk.
5. The portal venules then branch into a secondary capillary plexus within the anterior pituitary.
6. Hypothalamic hormones reach the anterior pituitary cells, stimulating or inhibiting the release of pituitary hormones.

This system allows for direct and targeted communication between the hypothalamus and the anterior pituitary, ensuring precise control of hormone secretion.

Venous Drainage

The venous drainage of the pituitary gland follows a path distinct from the arterial supply.

• Venous blood collects into small veins within the pituitary gland.
• These veins drain into the cavernous sinus, a large venous sinus located on either side of the pituitary gland.
• The cavernous sinus then empties into other venous sinuses, ultimately draining into the internal jugular vein.

Clinical Significance

Understanding the pituitary gland’s blood supply is vital in diagnosing and treating various conditions:

• Pituitary Tumors: Tumors can disrupt the normal blood flow to the pituitary, leading to hormone deficiencies or excesses.
• Sheehan’s Syndrome: Postpartum hemorrhage can cause pituitary infarction (tissue death due to lack of blood supply), resulting in hypopituitarism (underactivity of the pituitary gland).
• Empty Sella Syndrome: Compression of the pituitary gland due to increased cerebrospinal fluid pressure can impair blood flow.
• Surgery: Knowledge of the arterial supply is crucial during pituitary surgery to minimize damage to the gland and surrounding structures.

So, next time you’re thinking about how the pituitary gland manages all those important hormones, remember the crucial question: what artery is inside pituitary gland? Hopefully, this gave you some clarity and you can use this knowledge to impress your friends at your next trivia night! Keep exploring and stay curious!