Posterior Pituitary

Overview

Introduction

• Function 
  • to secrete oxytocin and vasopressin into systemic circulation
    • recall that the posterior pituitary (or neurohypophysis) have their neuronal cell bodies in the hypothalamus 
• Anatomy 
  • embryology
    • derived from an evagination of the floor of the forming ventricular system
  • the pituitary gland resides within the sella turcica
    • underneath the sella turcica is the sphenoid sinus allowing
      • a transphenoidal surgical approach to access the pituitary fossa
    • the pituitary fossa is laterally bounded by the cavernous sinus 
  • the pituitary gland lies inferiorly to the optic chiasm
    • pituitary tumors compressing the optic chiasm results in a
      • bitemporal hemianopia 
• Clinical correlate 
  • central diabetes insipidus 
    • secondary to vasopressin (ADH) deficiency and can result from
      • neurosurgery
      • head trauma
      • malignancy affecting the pituitary-hypothalamic region
  • syndrome of inappropriate ADH 
    • secondary to ADH excess and can results from
      • meningitis
      • head trauma
      • pulmonary disorders (e.g., pneumonia and small cell lung cancer)
      • medication side effects (e.g., selective-serotonin reuptake inhibitors, carbamazepine, and cyclophosphamide)
      • ADH-secreting tumors