Hemi section of head and neck showing nose and pharynx
This sagittal section of the head and neck region shows the Pituitary gland.
The pituitary gland, or the hypophysis cerebri, is a reddish-grey, ovoid structure, with an average adult weight of 500 mg. Superiorly, it is continuous with the hypothalamus through a narrow stalk known as the infundibulum. It is located in the body of the sphenoid bone and is in close relation with the optic chiasma above and the sphenoidal air sinus below. The pituitary gland has two major parts, the neurohypophysis and adenohypophysis. The neurohypophysis is made up of nerve fibres derived from the cells of the hypothalamus. The adenohypophysis is made up of clusters of cells. These cells secrete hormones that act up on the endocrine glands of our body. The tumour of the pituitary can compress the optic chiasma leading to visual defects such as hemianopia. The other structure that can be appreciated in this specimen is the cavity of the third ventricle.
Sphenoidal air sinus:
The sphenoidal air sinus is present in the body of the sphenoid bone. It makes the skull lighter. Its secretion is drained into the spheno-ethmoidal recess in the lateral wall of nose. Its infection leads to sinusitis.
Cavity of the third ventricle:
The cavity of the third ventricle is a slit-like cavity between the two thalami. Above, it is continuous with the lateral ventricles through the interventricular foramen (of Monro) and posteroinferiorly with the fourth ventricle through the cerebral aqueduct (of Sylvius). The choroid plexus (blood capillaries) within the ventricle produces the cerebrospinal fluid.