Abstract
Two muscles, one voluntary the other involuntary, and an inch or more apart, exist at the bladder-neck, both functioning as sphincters. This dual musculature is explained by the emergence of the ejaculatory ducts between them. If both these muscles are open when semen is discharged, secretion may escape into the bladder or to the exterior; also any urine in the bladder would flow out. The internal sphincter is usually tightly contracted during ejaculation. Instances are given in which the internal sphincter is paralysed or injured, e.g. after operation, in prostatic hypertrophy, and in certain nervous diseases. Two instances are reported of direct injury to this localized area, with the result, in all cases, that ejaculation failed. In prostatic hypertrophy the internal sphincter is dilated by the growing adenoma, and at operation it is further stretched and perhaps cut across. Continence then depends on the external sphincter. Two cases are reported in which the external sphincter had previously been paralysed, total incontinence resulting.
Recent work on the trigonal muscle; its function in opening the internal sphincter. Influence of this muscle on prostatic enlargement.
In central nervous disease the dilatation of the internal sphincter resulting in funnel-neck is very common. Series of cases of nervous disease examined in order to determine the frequency of this sign are reported. Other cases occurring apart from nervous disease are also reported.
The part played by the sphincters in ejaculation is discussed and illustrated by reports of further cases of paralysis of the sphincter. It is shown that in the normal way the external sphincter weakens during coitus, and especially during ejaculation, but when the internal sphincter is paralysed no weakening is evident. Penile erection is associated with spasm of the internal sphincter, and spasm of the internal sphincter is produced by irritation, e.g. vesical stone may produce priapism.
The varying types of adenoma bear different relationship to the internal sphincter. The view that submucosal glands give rise to prostatic enlargement is supported. The influence of prostatic enlargement on the internal sphincter is discussed.