. Chordate anatomy. Chordata; Anatomy, Comparative. 534 CHORDATE ANATOMY Pituitary Gland. The human pituitary gland is a flattened oval body, its longest diameter averaging lo to 12 mm., located at the base of the brain near the optic chiasma, where it is attached by a stalk to the lower end of the infundibulum. Lodged in a cavity, the sella turcica, in the sphenoid bone, the pituitary is as safe from injury as possible. (Fig. 296) Like the suprarenals, the pituitary is formed of two elements of diverse origin and function. The chief parts are a larger anterior glandular lobe, and a smaller po
. Chordate anatomy. Chordata; Anatomy, Comparative. 534 CHORDATE ANATOMY Pituitary Gland. The human pituitary gland is a flattened oval body, its longest diameter averaging lo to 12 mm., located at the base of the brain near the optic chiasma, where it is attached by a stalk to the lower end of the infundibulum. Lodged in a cavity, the sella turcica, in the sphenoid bone, the pituitary is as safe from injury as possible. (Fig. 296) Like the suprarenals, the pituitary is formed of two elements of diverse origin and function. The chief parts are a larger anterior glandular lobe, and a smaller posterior nervous lobe partly surrounded by the anterior lobe. Between the two major lobes are two smaller glandular masses, the pars intermedia and the pars tuberalis. Blood is richly supplied from the adjacent arterial circle, while numerous veins drain the CORPORA QUADRIGEMIN/^ PINEAL ORGAN ! POST commissure; | THIRD "'^"'â ^"'^' "^ -' MAS. INTERMEDIA,^, CHORlOIDurT '{ CORPUS ' ' CALLOSUM FORNIX. MEDULLA OPTIC CHIASMA'^ INFUNDIBULUM MAMMILLARY BODY SPHENOID BONE ^^POSTERIORIlobE of PITUITARY ^^ INTERIOR J Fig. 2g6.âA median section of the human brain-stem, showing the relations of the pituitary gland. (After Sobotta.) blood into the venous circle and the basilar plexus of veins. Nerves are supplied from the carotid plexus and the infundibulum. In the pars intermedia some colloid-filled foUicles resembUng those of the thyroid occur among the cell cords. The cells of the posterior lobe are chiefly neuroglia cells with numerous connective-tissue fibers. One of the important functions of the anterior lobe is the stimulation of growth. Enlarged pituitary in early life is accompanied by excessive growth of bone. Deficient secretion, on the other hand, produces a certain type of dwarf, the ateliotic dwarf or "; After the growth of the long bones has ceased, as in the normal adult, it is of course impossible to stimulate further growth in height.
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