Detailed definition
The pituitary gland sits in the sella turcica at the base of the skull and connects to the hypothalamus via the pituitary stalk. The anterior pituitary (adenohypophysis) produces six main hormones: growth hormone (GH), prolactin, ACTH (regulating cortisol), TSH (regulating thyroid), and the gonadotropins FSH and LH (regulating ovary or testis). The posterior pituitary (neurohypophysis) stores and releases oxytocin and vasopressin made in the hypothalamus. In menopause, the gonadotropic axis is the relevant story: as ovarian inhibin B and estradiol fall, negative feedback on the pituitary diminishes, and FSH and LH rise to characteristic postmenopausal levels. The pituitary itself is functioning normally; it is responding to the loss of ovarian feedback.
Why it matters in menopause
Knowing the pituitary is the source of FSH and LH (and that elevated postmenopausal levels reflect intact pituitary function responding to ovarian failure) helps distinguish ovarian causes of amenorrhea (high FSH/LH) from pituitary causes (low or normal FSH/LH).