The Anal Canal | pakhane ki jagah | Anatomy | Length, Zone, and Arrangements

The anal canal ( pakhane ki jagah, maqad ka rasta ) is the terminal part of the large intestine that is below the level of the pelvic diaphragm, between the rectum and the anus. It is situated between the right and left ischioanal fossas in the anal triangle of the perineum. It acts as the bowel’s final functional part, controlling excrement release through two muscular sphincter complexes. The anus is the terminal part of the anal canal’s aperture. The transformation of its internal surface from a mucous membrane layer (endodermal) to skin-like tissue distinguishes the anal canal ( pakhane ki jagah, maqad ka rasta ) from the rectum (ectodermal) Canal anesthetic.

The colorectal zone, which is lined by uninterrupted glandular mucosa, is the proximal zone of the anal canal. The squamous zone, which is lined by continuous squamous mucosa, is the distal zone. The transition zone is located in the middle and includes a variety of epithelia. The anal valves, anal sinuses, and bases of anal columns are all part of the dentate line, which runs along the anal canal ( pakhane ki jagah, maqad ka rasta ). The extent of the specialized mucosa, i.e., the transitional zone and squamous zone down to the perianal skin, determines the histologic anal canal. When orienting biopsies from this region, the dentate line is an important anatomical landmark.

Anal Canal ( pakhane ki jagah, maqad ka rasta ) Arrangement:

From the anorectal junction to the anus, the anal canal ( pakhane ki jagah maqad ka rasta )in humans is around 2.5 to 4 cm long. It’s pointing backward and downwards. The lumen is close in the shape of an anteroposterior slit by inner involuntary and outer voluntary sphincters. The canal is separated from the rectum by transitioning from endodermal to skin-like ectodermal tissue along the internal surface.

Anal Canal ( pakhane ki jagah, maqad ka rasta ) Segments:

The upper and lower parts of the canal are historically distinguishing the pectinate line:

Area Columnar (upper zone):

Simple columnar epithelium lines the mucosa.

Longitudinal folds or elevations of tunica mucosa are joined inferiorly by anal valves, folds of the mucous membrane.

The superior rectal artery is the source of this supply (a branch of the inferior mesenteric artery)

Zone At the Bottom:

A white line known as Hilton’s line divides the area into two smaller zones:

Hemorrhagic zone, with stratified squamous non-keratinized epithelium lining it.

Zone Hut is a stratified squamous keratinized epithelium that blends in with its perianal skin.

The inferior rectal artery is the source of this supply (a branch of the internal pudendal artery)

Zone Separation Line:

The anal verge is a transitional region between the anal canal epithelium and the perianal skin at the distal end of the anal canal.  There is no confusion with the anal canal’s pectinate line, which separates the upper and lower areas. The anal gland secretes lymph and accumulated feces from the colon lining. In certain species, gland expungement can be regularly performed every 24–36 months to avoid infection and the development of fistulas around the anal canal ( pakhane ki jagah, maqad ka rasta ).

Length of the Anal Canal ( pakhane ki jagah, maqad ka rasta ):

The distance travels the parallel borders of the anal canal until they form the diverging walls of the distal rectum is referred to as anal canal length. The average length of the anal canal in women is 16 mm (range: 6 to 26 mm) and 22 mm (range: 10 to 38 mm) at rest. The canal lengthens to a mean of 19 mm (range, 9 to 26 mm) in women and 28 mm (capacity, 12 to 45 mm) in men during lifting (squeezing). The canal shortens slightly during straining, and in young women, it measures 14 mm (range, 6 to 20 mm), and in young men, it measures 17 mm (range, 9 to 27 mm).

The Anal Canal’s Upper Reaches:

When it passes through a muscular pelvic diaphragm, the anal canal interacts with the rectum. There are 5 to 10 rectal columns in the upper region, each with a small artery and vein. Hemorrhoids enlarge the terminal portions of the blood vessels that supply the rectal and anal areas; they are vulnerable to enlargement. The upper mucous membrane is similar to the rest of the large intestine in that it contains mucus-producing and absorptive cells.

The Anal Canal’s Lower Reaches:

Tiny concentric circular folds of the mucous membrane known as anal valves connect the lower portions of the anal columns. Little anal sinuses open to lymph ducts and glands between the valves; these may become abscessed and infected, particularly in people who have chronic diarrhea, constipation, or diabetes. The anal canal’s internal wall is lining wet, soft skin with no hair or glands at first, then a rough layer of skin with hair and glands. Circular and longitudinal muscle layers exist in both the upper and lower parts of the anal canal, allowing the channel to expand and contract.  The anal opening is keratinized skin with many folds when acquired. The folds will enable the skin to stretch without tearing when open. Perspiration glands are found in the skin around the anal opening but not directly adjacent.

Constriction of Muscles:

Two muscular constrictions that control fecal passage make up the lower anal canal and the anal opening. The internal sphincter is set on the canal’s inner surface. The external sphincter is a voluntary muscle layer surrounding the anal canal ( pakhane ki jagah, maqad ka rasta ) and an anal opening on the outside. Except during the early years of life, it can expand and contract at will when it is not entirely forming. Nerves cause sphincter reactions and pain sensations in the anal canal. The lower channel is susceptible to heat, cold, and cutting. So, if you are facing any issues, feel free to contact us.