Fig. 11.—Lateral section of rectum; normal curve. R. Rectal pouch. C. cul-de-sac of the rectum. E. S. External sphincter. I. S. Internal sphincter. H. Hilton’s white line. P. Position of prostate gland.
A digital examination reveals, in the normal state, a soft, velvety, unbroken mucous membrane, the parts pliable and yielding, with no reflex excitability of the sphincters. The position and sensibility of the uterus should be noted in the female, and size of the prostate gland in the male of advanced years.
The first three or three and a half inches of the rectum can be brought within reach of the finger. Explorations farther up will require a rectal sound and a long tubular speculum. Nine-tenths of all rectal ailments are found within the first two inches. Therefore, few general practitioners will ever be called upon to treat anything beyond the reach of the finger or the scope of a common speculum.
All hemorrhoids of any appreciable size, or other tumorous growths in the same vicinity, will show at defecation and can be treated while the parts are extruded. All abrasions, ulcerations, indurations, etc, are discoverable by the sense of touch. Hence, it will be seen that the uses of the speculum are narrowed down to a few in number. Namely: in that of bringing to view for observation and treatment diseased surfaces previously located; small, soft hemorrhoids and other minor affections which may have escaped detection by a careful digital examination.
Then, in view of the foregoing facts, and in consideration of the anatomical formation of the parts, being a collapsable tube, highly sensitive and extremely difficult of accessibility, quite unlike the vaginal canal, which is closed at one end, more capacious and dilatable, and designed by nature to be approached from the exterior, a speculum should be so constructed as to not only be easy of introduction and withdrawal, but to exclude all the surface except a limited portion, and permit the greatest amount of available light possible to fall on the exposed part shown in situ.
The greatest barrier to the successful use of a speculum is the unruly external sphincter and the excessive mobility of the mucous and muco-cutaneous surfaces. The upper margin of the external sphincter terminates beneath the junction or the skin with the mucous membrane, which place also marks the beginning of the internal sphincter and its junction with the external muscle by a more dense connective tissue, sometimes appearing as a white line at the muco-cutaneous junction called the white line of Hilton.
According to Dr. Andrews, Hilton has demonstrated that the locality where the two muscles join by the intervention of this fibrous ring forming the anal verge, the junction of the skin and mucous membrane, and the exit of the branches of the pudic nerve, is identical.
Fig. 12.—Author’s Rectal Speculum.