Abstract: To investigate the anatomical characteristics of the internal wall of the cavernous sinus. MethodsTwenty skull specimens were prepared to observe the anatomical characteristics of the internal wall of the cavernous sinus. Coronal, sagittal or axial sections were made in 18 of them. All were observed under an microscope. ResultsThere was no membrane existing at the internal wall of the cavernous sinus. The pituitary capsule interfaced the pituitary and the cavernous segment of the internal carotid artery. Of the coronal and axial sections, 4 pituitary glands protruded into the upper compartment of ICA like a tongue and 4 pituitary glands were tightly contacted with ICA. Of the sagittal sections, ICA was found when the pituitary gland and the pituitary capsule were removed. ConclusionsPituitary adenomas have the inclination to invade the cavernous sinus because of anatomical defects, and invasive pituitary adenomas should be cautiously diagnosed.

Key words: Internal wall of cavernous sinus, Internal carotid artery, Pituitary capsule, Pituitary adenomas