Musculature of the prostate gland.

Abstract

SUMMARY The pattern of prostatic musculature may be outlined as follows: 1 The ureters enter the bladder, give rise to the trigonal musculature, and contribute elements to the bladder musculature. 2 The fibres of the trigonal muscle decussate in the midline and veer ventrally, giving rise to the internai sphincter and contributing fibres to the fibromuscular plate encircling the internai urethral orifice. 3 The internai sphincter surrounds the internai urethral orifice and decussates ventrally to the urethra, contributing elements to the urethra, external sphincter and prostatic parenchyma. 4 Henle's muscle arises from the puboprostatic muscle and in association with the external sphincter surrounds the urethra just distal to the prostate. It then passes ventrally and superiorly to insert into the glandular capsule of the prostate, the prostatic parenchyma and the tri go ne. 5 The ventral component of bladder musculature arises from the pubo-vesical ligament, the lateral true ligament of the bladder, and the fascial capsule of the prostate. The dorsal component arises from the glandular capsule of the prostate, the tendinous yoke under the uvula, and the prostatic parenchyma. 6 The longitudinal musculature of the urethra arises principally from the fibromuscular plate, but is also supplemented by elements from the glandular capsule, internai sphincter and prostatic parenchyma. 7 The double layered prostatic glandular capsule is contributed to by or gives rise to most of the muscular elements associated with the prostate gland, except the ventral longitudinal bladder musculature. 8 The external sphincter is formed by the distal prolongation of the anteriorly decussating fibres of the internai sphincter, and is separated from the deep perineal sphincter by the superior levator fascia. 9 The prostatic parenchymal musculature consists of ramifying septa extending between the middle third of the prostatic urethra and the prostatic glandular capsule. 10 Several prominent muscle groups envelop neuromuscular elements associated with the prostate gland and radiate into the adjacent supporting fascial structures.