Handa 9781496386441 Full Sample Chap 1

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SECTION I  Preparing for Surgery

Bladder

Urogenital sphincter muscle

1

Bulbocavernosus muscle

2

3

Schematic

Vagina Levator ani

of circular

Uterus

I

muscle coat

Bartholin gland

Outer longitudinal fibers

Outer longitudinal fibers Urogenital sphincter muscle Inner longitudinal fibers

1

Trigonal sphincter muscle

Urethra

Bladder

Circular fibers

Vagina

Ureter

Urogenital sphincter

2

Rectum

Triangular ligament

Urethra

Vagina

Pelvic fascia

Urogenital sphincter

3

Sphincter

Urethra

Vagina

Urogenital sphincter

x2

FIGURE 1.25  Lateral view of the pelvic organs showing detailed anatomy of the urethra and bladder. Insets demonstrate composition of the smooth muscle fibers of the bladder and bladder neck (top right) and the striated urogenital sphincter complex (left side insets). The compressor urethra is not seen. (The original illustration is in the Max Brödel Archives in the Department of Art as Applied to Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA. Used with permission.)

to the umbilicus by the median umbilical ligament (rem- nant of urachus). The bladder lies against the pubic bones laterally and inferiorly and abuts the obturator internus and levator ani. Posteriorly, it rests against the vagina and cervix. These relations are discussed further in consideration of the pelvic planes and spaces. The blood supply of the bladder comes from the superior vesical artery, which comes off the patent part of the umbilical artery and inferior vesical artery, which is either an independent branch of the internal pudendal artery or arises from the vaginal artery. The nerve supply to the bladder is derived from the vesical plexus, a component of the inferior hypogastric

its structure. It passes through the bladder base in an intramural portion for a little less than a centimeter. This region of the bladder, where the urethral lumen traverses the bladder base, is called the vesical neck. In its distal two thirds, the urethra is fused with the vagina (see FIG. 1.25 ), with which it shares a com- mon embryologic derivation from the urogenital sinus. From the vesical neck to the perineal membrane, which starts at the junction of the middle and distal thirds of the urethra, the urethra has several layers. An outer, circularly oriented skeletal muscle layer (urogeni- tal sphincter) mingles with some circularly oriented smooth muscle fibers. Inside this layer is a longitudinal layer of smooth muscle that surrounds a remarkably vascular submucosa and nonkeratinized squamous epithelium that responds to estrogenic stimulation. The proximal urethral lumen is lined by a urothelial layer.

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plexus. Urethra

The urethral lumen begins at the internal urethral ori- fice (meatus) and has a series of regional differences in

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