Overview
This lecture provides an overview of the pituitary gland's anatomy, its location, structure, relationship with surrounding bones and brain regions, and its connection to the hypothalamus.
Pituitary Gland Anatomy
- The pituitary gland is located in the midline at the base of the brain, sitting within a bony cavity called the sella turcica of the sphenoid bone.
- It has two main lobes: the anterior lobe (adenohypophysis) which is larger, and the posterior lobe (neurohypophysis) which is smaller.
- The lobes originate from different embryological tissues and join during development, separated by Rathke's cleft.
- Rathke’s cleft can sometimes persist as a Rathke’s cleft cyst.
- The pituitary stalk (infundibulum) connects both lobes to the hypothalamus above.
- The optic chiasm is located just above the pituitary gland, explaining visual symptoms in pituitary tumors.
Surrounding Structures
- The sella turcica is bounded anteriorly by the tuberculum sellae and posteriorly by the dorsum sellae.
- The cavernous sinus, containing the internal carotid artery, lies lateral to the sella turcica in the paracellar region.
- The pituitary stalk travels upward to connect to the floor and lateral walls of the third ventricle.
Hypothalamic-Pituitary Connection
- The hypothalamus, which controls the pituitary gland, is divided into three regions: anterior, tuberal (infundibular), and posterior (mammillary).
- The anterior hypothalamus regulates release of hormones like oxytocin and vasopressin via the posterior pituitary.
- The posterior hypothalamus and other nuclei play key roles in body homeostasis and autonomic function.
- Lesions of the hypothalamus can severely impact bodily regulation.
Key Terms & Definitions
- Pituitary gland — Master endocrine gland beneath the brain, controlling other glands.
- Adenohypophysis — Anterior pituitary lobe, secretes multiple hormones.
- Neurohypophysis — Posterior pituitary lobe, releases oxytocin and vasopressin.
- Rathke’s cleft/cyst — Developmental space/cyst between anterior and posterior lobes.
- Infundibulum — Pituitary stalk connecting pituitary to hypothalamus.
- Sella turcica — Saddle-shaped cavity in the sphenoid bone housing the pituitary.
- Cavernous sinus — Venous sinus lateral to the pituitary; contains carotid artery.
- Hypothalamus — Brain region controlling the pituitary and many homeostatic functions.
Action Items / Next Steps
- Review the anatomy of the pituitary gland, sella turcica, and hypothalamic regions.
- Prepare for discussion on pituitary tumors and their clinical significance.