Topics

Topic

design image
Posterior lobe pituitary gland

The posterior lobe of the pituitary gland, also known as the neurohypophysis, is the smaller and more posterior part of the pituitary gland. It is primarily composed of axonal projections from the hypothalamus and specialized glial cells called pituicytes. Unlike the anterior pituitary, the posterior lobe does not synthesize hormones but rather stores and releases hormones (mainly oxytocin and vasopressin/antidiuretic hormone) that are produced in the hypothalamic nuclei. The neurohypophysis plays a vital role in maintaining water balance, parturition, and lactation through hormone release into systemic circulation. Its anatomical location within the sella turcica and its intimate relationship with the hypothalamus and pituitary stalk make it a key structure in endocrine and neuroimaging studies.

Synonyms

  • Neurohypophysis

  • Pars nervosa (main component)

  • Posterior pituitary

Function

  • Storage and release of vasopressin (antidiuretic hormone, ADH) and oxytocin (both produced in the hypothalamus)

  • Regulation of water balance via ADH

  • Facilitation of uterine contraction and milk ejection via oxytocin

Arterial Supply

  • Mainly supplied by the inferior hypophyseal arteries (branches of the internal carotid artery)

  • Additional minor contribution from the superior hypophyseal arteries

Venous Drainage

  • Venous blood drains into the hypophyseal veins

  • Hypophyseal veins ultimately drain into the cavernous sinus

MRI Appearance

  • T1-weighted: Posterior lobe appears as a bright/high signal (“posterior pituitary bright spot”) due to neurosecretory granules containing vasopressin.

  • T2-weighted: Typically iso- to mildly hyperintense compared to brain parenchyma.

  • FLAIR: Usually isointense to mildly hyperintense; the bright spot may be less conspicuous.

  • Post-contrast T1: May show mild homogeneous enhancement due to vascularity, but the posterior lobe bright spot is best appreciated on non-contrast T1.

CT Appearance

  • Appears as a soft tissue density structure in the posterior part of the pituitary fossa

  • Not distinctly differentiated from the anterior lobe on non-contrast CT

  • May enhance homogeneously with contrast, but less conspicuous than on MRI

MRI images

posterior lobe pituitary gland mri 3t axial image

MRI images

posterior lobe pituitary gland mri 3t sagittal image