Surgical Anatomy of the Psarp Approach

The most important factor for postoperative continence is adequate surgical technique. It is therefore necessary to mention the anatomical sections of a PSARP approach performed by Huber et al. in 1983 [17]. His preparations in a human cadaver with normal pelvic anatomy correspond with the recent PSARP procedure in children with ARM (Fig. 25.2).

In newborn babies, the anatomical situation is similar to that in adults, but is more difficult to demonstrate, especially under surgical conditions. However, the nerve supply inside the ailerons latéraux, the lateral fascial wings, shows the same course and density [3] (Fig. 25.3). These postganglionic extramural cho-linergic nerve fibers running from the pelvic plexus are responsible for the propulsive rectal evacuation and descend from segments S2 to S4. They should only be cut inside Waldeyer's fascia and directly on the rectal wall.

Unfortunately, in patients with ARM the anatomical structures of the rectum, anorectal sphincters, and their nerve supply are frequently not well developed. This includes malformations of the intramural plexus, pelvic fascia, and the blood supply to the blind pouch (see CD Chap. 6 and Chap. 7).

In piglets with anal atresia, the ailerons latéraux appear to be less well developed and the nerve sup-

Table 25.2 Physiological factors contributing to anorectal continence. ARRP Anorectal resting pressure profile

Anatomical site

Physiological factor

Rectum

Propulsive bowel motility Compliance (adaptation reaction)

Pelvic floor

Anorectal angle Resting tone and contractility of striated muscle complex Sensibility: feeling of fullness

Internal anal sphincter

Resting tone (70-80% of ARRP) Internal sphincter relaxation reflex

External anal sphincter

Resting tone and voluntary contractility of muscle fibers Fine continence (hem-orrhoidal plexus) Rectosphincteric reflex

Anorectum

Discrimination Warning period

Prostate Inferior Anal Nerve

Fig. 25.2 A The external anal sphincter (8), the urogenital diaphragm (4), the puborectalis muscle (5) as part of the levator ani muscles (2), and the pudendal nerves (9) running lateral into Alcock's canal, as well as branches of the pudendal artery and the inferior rectal nerves (9). The external anal sphincter is innervated by the pudendal nerves; however, the levator ani muscles and the upper part of the puborectalis muscle are innervated by branches of the sacral plexus laying on the inner surface of the pelvic floor. Sacrospinal ligament (7), coccygeal muscle (3). B The pelvic floor is opened and the levator ani (10) and sphincter muscles cut (8). The internal muscle fibers of the levator muscles can be seen inserting into the longitudinal muscle layer of the rectum (11). The sacrotuberal ligament (2) is cut as well and elevated. The inferior rectal nerves and the inferior rectal artery (7) are visible. Here, the pudendal nerves can be seen more closely (4), passing into Alcock's canal (3) after having left the pelvis. Very important are the rectal fas-

cias (15) and next to them, the lateral rectal wings (also called "ailerons latéraux" (16), the lateral fixation of the rectum. Ischial spines (5), sacrospinal ligament (6), anococcygeal ligament (12/13). C After having removed the sacrum, the rectal fascias (2) can be demonstrated. Only the dorsal part of the rectal fascia is called Waldeyer's fascia (3). Laterally, the rectal fascia passes over into the internal parietal pelvic fascia. meso-sigmoid (5), rectum (1). D This is the most important view for PSARP. It shows branches of the medial rectal artery (5), the venous plexus (6), and the parasympathetic splanchnic nerves (the erigentes and pelvic nerves). They run together with the sympathetic nerve fibers of the inferior hypogastric plexus of the pelvic sympathetic trunk inside the ailerons lateraux to the rectum (7). The endarteries and the tiny endings of the nerve fibers are passing through Waldeyer's perirectal fascia into the muscular wall of the rectum. Pouch of Douglas (8) (reproduced from Huber et al 1993) [17]

Anatomy Sympathetic Trunk
Fig. 25.3 Anatomical situation in female newborn. A Pudendal nerve supply to the anus and lateral wings in a female newborn. B Magnification of lateral wings (ailerons lateraux) after removing the fascia
Surgical Anatomy Female
Fig. 25.4 Anatomical situation in a female piglet with imperforate anus. A Piglet with imperforate anus. B Blind pouch in the piglet with a poor nerve supply. C Blind pouch (above vagina) opened
Piglets Imperforate Anus
Fig. 25.5 A Insertion of Waldeyer's fascia (W.F.) in a patient with intermediate anal atresia. B Waldeyer's perirectal fascia incised (green arrow)
Waldeyer FasciaRectal Artery Anatomy

Fig. 25.6 Course of the erigentes nerve, according to Stephens 1988 [2]. A Normal situation. B Intermediate type imperforate anus with rectourethral fistula. C High-type anorectal malformation (ARM). P---C Pubococcygeal line

Surgical Anatomy Rectum

Fig. 25.7 A-D Variations of arterial supply to the rectum and rectosigmoid according to van Lanz and Wachsmuth 1982 [22]. A Normal course of rectal arteries in 88% of patients. B Bilateral middle rectal arteries (4.8%). C Only the left branch coming from superior rectal artery (4.8%). D Only the right branch coming from superior rectal artery (2.4%). E Branches of inferior mesenteric artery to the rectosigmoid. A Artery

Fig. 25.7 A-D Variations of arterial supply to the rectum and rectosigmoid according to van Lanz and Wachsmuth 1982 [22]. A Normal course of rectal arteries in 88% of patients. B Bilateral middle rectal arteries (4.8%). C Only the left branch coming from superior rectal artery (4.8%). D Only the right branch coming from superior rectal artery (2.4%). E Branches of inferior mesenteric artery to the rectosigmoid. A Artery ply seems to be poorer (Fig. 25.4). Likewise, the nerve supply of the external anal sphincter seems to be less dense, which might be explained by the purely reflex-controlled fecal continence of these animals [3]. Contribution of the ailerons latéraux to fixation of the rectum in the small pelvis might account for stronger development in men, particularly in adults.

Essentials of Human Physiology

Essentials of Human Physiology

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