THE URETHRA.
This is about an inch and a half in length, and is lodged in the upper wall of the vagina in its course downward and forward, beneath the arch of the os pubis, to the meatus urinarius. It is lined by mucous membrane, which is disposed in longitudinal folds, and is continuous internally with that of the bladder, and externally with the vulva; the mucous membrane is surrounded by a proper coat of elastic tissue, to which the muscular fibres of the detrusor urinæ are attached. It is to the elastic tissue that is due the remarkable dilatability of the female urethra, and its speedy return to its original diameter. The meatus is encircled by a ring of fibrous tissue, which prevents it from distending with the same facility as the rest of the canal; hence it is sometimes advantageous in performing this operation, to divide the margin of the meatus slightly with the knife.