Terminology of the prostate and related structures

The various studies of J.E. McNeal (1968ndash;1977) established with precision the different sites of predilection for prostatic carcinomas, benign prostatic hypertrophy (BPH), and inflammation, making the division of the prostate into right, left, and middle lobes and isthmus inadequate for their description. Unfortunately, his positional terms for the sites (peripheral, central, transition, and preprostatic) are not based on the usual parameters and cannot be directly related to those of other workers. Nevertheless, the International Federation of Associations of Anatomists' Federative Committee on Anatomical Terminology has made recommendations in Terminologia Anatomica, based on his findings but modified to take some account of those of Tisell and Salander (1975 Scand J Urol Nephrol 1975 9:185-191). The use of the term lobe is confined to the right and left lobes and the variable middle lobe. The term lobule is used for the subdivisions, which are named from the anatomical position. Thus each side has a superomedial, an anteromedial, an inferoposterior, and an inferolateral lobule. Also necessary to describe a site of predilection is a peri-urethral gland zone. In ultrasound diagnosis, the trapezoid area is important: its upper limit is the rectoperinealis, its anterior limit is the intermediate part of the urethra, its lower limit is the anoperinealis, and its posterior limit is the anorectal junction. Confusion at the bladder neck is resolved by recognizing that the position of the internal urethral orifice varies with functional state of the bladder: while it is filling the orifice lies above the base of the prostate; when voiding begins, the orifice descends to the base of the prostate; between the filling internal orifice and the emptying internal orifice is the bladder neck part of the urethra.