Anteriorly: Fascia propria of the rectum Posteriorly: Presacral fascia Laterally: Lateral rectal ligament Inferiorly: Rectosacral ligament

(Fig.10.8).

Above it is continuous with retroperitoneum

The rst description of anal glands was given by Haller in 1751 [5]. Chiari further described these glands in 1878. Chiari suggested that infection of these anal glands caused an anal stula [5]. Herrman and Desfosses further supported this in 1880 [5].

Seow Cheon, in his publication, described the position of the anal glands [7]. These glands are present at varying depths in the anal canal wall. They are predominantly present in the posterior half of the anal canal, explaining the internal open­ing present posteriorly in most stulas. Anal glands in 80% of the cases are present in submucosa. It extends to conjoined longitudinal muscles in 7–8% cases, to internal sphincter in 8%, intersphincteric space in 2% cases, and in 1% cases, anal glands penetrate the external anal sphincter [7] (Fig.10.10).

As stated earlier, most anal ducts have their outlet posteriorly in the anal canal. The direc­tion of these glands is usually caudal, rarely lat­eral or cephalad. This explains perianal abscess being the common presentation of anorectal abscesses [6].

The intersphincteric abscess ruptures between the supercial and deep part of an external anal sphincter into a deep anterior anal space (Fig.10.15). In females, deep anterior space and its suppurative conditions might extend to the rectovaginal septum, which is an occasional rea­son for the lower rectovaginal stula [16]. The management of this abscess will be explained in the next chapter.

the septum of an ischiorectal fossa.

Most of the rectal and anal canal anatomy has been illustrated by nineteenth and twentieth­century researchers [17]. Based on these studies, pararectal spaces and para-anal spaces have been dened. Potential spaces of clinical importance include the ischiorectal fossa, which contains the nerves, fat, and inferior rectal arteries. The ischio­rectal space is separated from a perianal space by an intermuscular septum formed from the con­joined longitudinal muscles. The septum prevents infection from the perianal space to the ischiorec­tal space and separates the internal hemorrhoidal plexus from the external hemorrhoidal plexus. The perianal space contains external hemor­rhoidal plexus and is the typical site for throm­bosed external hemorrhoids. The perianal abscess and intersphincteric tracts are other common conditions in this space. The intersphincteric space is considered the genesis of the perianal abscess as most of the anal glands end here. The submucosal space contains the internal hemor­rhoidal plexus.

To understand the clinical signicance of anal glands as a potential source of infection, one must realize their existence [5, 6]. It is well­known that intestinal tracts are a natural lodging for some pathogenic and nonpathogenic organ­isms [6]. It is commonly recognized that any alteration in bowel habits or irritation is respon­sible for pathological conditions in the anorectal region [19]. Trauma can occur in the anorectal region due to overdistention of the anal canal by a hard motion or chronic diarrhea. Both the

exterior and anterior commissures of an anal canal are weak areas and prone to trauma [19]. Posteriorly, the external anal sphincter bers give the least support, and anteriorly few circu­lar bers give support [19]. As anal glands are concentrated more posteriorly, the pathogenic gut organisms can enter through the traumatic mucosa, making the posterior abscesses and stulas most common [19]. Another source of infection through the mucosa is blood-borne due to disease in other body parts [19]. As mentioned above, anal glands are in the inter­sphincteric and submucosal spaces. They act as a nidus of infection, leading to an abscess and subsequent stula formation. John A. Eglitis in 1961 [5, 6] has reported that the intermus­cular portion of these glands are usually dis­tended in pear-shaped sacks, which measure

0.91×1.28×2.1mm, and their location makes them liable to the possibility of the narrow duct of the gland getting obstructed with subse­quent cyst formation. Scarborough, in 1941 [6], reported that the anal glands are not free from malignancy and described primary carcinoma as originating from rudimentary remains of the anal glands. The existence, variation, position, number, and the course of these anal glands make their removal mandatory while operating on patients for an abscess and stula-in-ano [6].