Anatomic Considerations

The pelvic cavity, covered by the visceral peritoneal layer, is composed of the pelvic organs in the middle with vessels and nerves laterally. It is divided by fasciae developed from vascular sheaths. There are three groups (Fig. 8-228):

1. The visceral pelvic fascia is oriented in a sagittal plane and is composed of two symmetric fasciae. It courses along the lateral borders of the pelvic organs and the medial borders of the vessels, thinning as it extends anteriorly. In the axial plane it can be seen only posteriorly as a thin continuous line enveloping the perirectal fat (Fig. 8-229).

2. The second group is oriented in a frontal plane and is composed of two fasciae originating from the genital artery sheaths and from the inferolateral extension of the peritoneal layer of the cul-de-sac. The anterior one separates the urinary bladder and genital tract; the posterior one, the genital tract from the rectum. Generally, there is a paucity of fat at these sites and the fasciae are not imaged.

3. The umbilicovesical fascia, located anterior to the peritoneum and posterior to the transversalis fascia, has a triangular configuration with its apex at the umbilicus. It is on a more cephalad plane than the anterior portion of the visceral pelvic fascia (Fig. 8-228a,b). Inferiorly, its base joints the pubovesical ligament medially, blends with the pelvic visceral fascia laterally, and then with the parietal pelvic fascia lining the pelvic muscles in continuity with the transversalis fascia. It courses around the anterior part of the bladder and surrounds the urachus. These superior edges are occupied by the obliterated umbilical arteries, extending anteriorly from the internal iliac arteries. The obliterated urachus is often visible in the axial plane as a median fold. The lateral segment of the umbilicovesical fascia including the obliterated umbilical arteries covered by the peritoneum is identifiable as a thin line (Fig. 8-229). Below the peritoneal reflection, the umbilicovesical fascia extends to the pelvic floor on each side of the urinary bladder, but here it is too thin to be demonstrated by CT.

The anterior extraperitoneal fat of the pelvis is divided by the umbilicovesical fascia into three spaces (Figs. 8-229 and 8-230):

Umbilicovesical Fascia

Fig. 8—228. The extraperitoneal paravesical pelvic spaces.

(a) Axial diagram in a female. The upper lateral border of the umbilicovesical fascia surrounds the obliterated umbilical arteries (arrowhead). While diagrammatically shown together here, the umbilicovesical fascia is on a more cephalad plane than the anterior part of the visceral pelvic fascia.

(b) Frontal diagram in a male.

(c) Sagittal diagram in a male. Star = space of Retzius.

(d) Sagittal oblique view.

Fig. 8—228. The extraperitoneal paravesical pelvic spaces.

(a) Axial diagram in a female. The upper lateral border of the umbilicovesical fascia surrounds the obliterated umbilical arteries (arrowhead). While diagrammatically shown together here, the umbilicovesical fascia is on a more cephalad plane than the anterior part of the visceral pelvic fascia.

(b) Frontal diagram in a male.

(c) Sagittal diagram in a male. Star = space of Retzius.

(d) Sagittal oblique view.

Ub = urinary bladder Ut = uterus Re = rectum Pr = prostate Ii = internal iliac artery

1 = umbilicovesical fascia

2 = visceral pelvic fascia

3 = muscles lined by parietal pelvic fascia

4 = obliterated urachus

5 = transversalis fascia

6 = pubovesical ligament A = prevesical space

B = perivesical space C = genital space D = perirectal space E = paravesical space

Fig. 8—229. The prevesical (A), perivesical (B), perirectal (D), and paravesical (E) spaces and landmarks shown by axial CT in a male (a) and in a female (b).

The obliterated urachus (4) is visible anterior to the urinary bladder (Ub). Only the posterior part of the visceral pelvic fascia (2) can be seen on these images. Re = rectum; Ii = internal iliac artery; Ut = uterus; arrowhead = obliterated umbilical artery; 1 = umbili-covesical fascia; 3 = peritoneal layer.

Umbilicovesical FasciaPerivesicle Space

Fig. 8—230. The prevesical space.

Tl-weighted sagittal MR image in a female shows the prevesical space with abundant fat (A) and the space of Retzius (asterisk). The low-signal intensity line is composed of the obliterated urachus and the umbilicovesical fascia.

1. The prevesical space lies anterior and lateral to the umbilicovesical fascia, deep to the transversalis fascia, and inferiorly to the posterior part of the pubic bone. It is a huge potential compartment that extends superiorly, becoming progressively thinner as it approaches the umbilicus, and communicates with the properitoneal fat and the posterior pararenal space around the abdominal wall and flanks. Its fat is more abundant anteroinferiorly, especially behind the pubis, where the prevesical space is also called the retropubic space or space of Retzius. This space has posterior extensions surrounding the urinary bladder laterally. It is limited laterally by the thin anterior portion of the visceral pelvic fascia and then by the perineal muscles.

2. The paravesical space lies between the lateral pelvic wall lined by the parietal pelvic fascia and the visceral pelvic fascia. Superiorly, it is limited by the peritoneum. This compartment's fatty tissue has a large tortuous venous network and loose connective tissue.

3. The perivesical space is bounded by the umbilicoves-ical fascia, within the confines of which lie the bladder, urachus, and obliterated umbilical arteries. It is a thin space with little fat. A small amount of fat is present between the peritoneum and the dome of the bladder. Posterior to the bladder, the supravaginal portion of the cervix and anterior portion of the vagina are continuous with the perivesical space in women. In men, there is similar continuity with the prostate and seminal vesi-cles.284

An additional space in the pelvis is the perirectal space. It is limited by the posterior part of the visceral pelvic fascia, which is thick at this level. It continues into the abdominal extraperitoneal spaces.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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