Anorectal junction and anal canal

Hirschsprung's disease (congenital megacolon)

Deficiency of ganglion cells in Meissner's submucosal plexus and Myenteric plexus of Auerbach (failure of migration of the neural crest cells to the Myenteric plexus).Associated with down syndrome and Chagas disease. 90% restricted to the rectum. Bowel is dilated proximal to the defect , inability of peristalsis to push the stool beyond the aganglionic segment. Presents with fecal retention and abdominal distention; this is a functional, not anatomical obstruction. Diagnosis is by rectal biopsy.

Internal hemorrhoids (Piles)

Increased intra-abdominal pressure, pregnancy, chronic constipation, and other conditions may lead to prolapses of the rectal mucosa, containing the superior rectal veins (internal rectal venous plexus). Occur above the pectinate line and are usually accompanied by painless bleeding, due to autonomic innervation of the upper sections of the anal canal.

external Hemorrhoids

Predisposing factors similar to those of internal hemorrhoids may cause blood clots (thromboses) in the external rectal venous plexus (inferior rectal veins). These clots, which are covered by the skin, are known as external hemorrhoids. They occur below the pectinate line and are painful due to somatic innervation by the inferior rectal branch of the pudendal nerve.

a routine method used to examine the anatomical and mucosal covering of the large intestine. First, barium sulfate solution is pumped into the large intestine through the anus to fill the colon. After taking X-rays in various positions, the patient is asked to defecate, and then a bit of air is pumped into the large intestine through the anus. The highly detailed X-ray images made after this procedure reveal the anatomy of the large intestine, including many mucosal abnormalities, polyps, tumors, diverticulae, or other abnormalities

What is barium enema (with double contrast)?

inserting suppositories into the anal canal in newborns and infants is an effective way to deliver the proper dosage of a drug in a relatively short time- especially compared to oral administration- since it is almost immediately absorbed through the inferior rectal veins into the IVC, making its way quickly through the circulatory system. If necessary, suppositories may also be given to adults under certain conditions

Why are drugs sometimes administered into the anus (suppository)?

rectal examination to palpate the prostate gland is commonly performed. Such examination gives an initial idea about the size of the prostate gland. A benign prostatic hyperplasia (BPH), prostatic cancers, or other benign conditions may cause difficulties with micturition and lead to more frequent urination, since the bladder cannot empty properly

Why might a rectal examination be done in males having problems with micturition?

somatic; inferior rectal (anal) nerve- a branch of the pudendal nerve; external anal sphincter

________ innervation of the anal canal inferior to the pectinate line via the _______ ________ _________, sends motor fibers (efferent) to the ________ _______ _______.

external anal sphincter

a voluntary sphincter made of striated muscle fibers surrounded the lower part of the anal canal.It is attached to the perineal body anterior and to the coccyx through the anococcygeal ligament.

internal anal sphincter

an involuntary muscle that is actually the continuation of the inner circular muscle of the intestines, surrounds the upper two-thirds of the anal canal

external rectal venous plexus

are beneath the skin in the lower sections of the anal canal

Crohn's disease

chronic granulomatous inflammatory bowel disease. Discontinuous(skip areas), involving both ileum and the colon. Infectious or immunologic or psychologiccauses. Crampy pain in R. lower quadrant, fever, diarrhea, rectal bleeding...

Abscesses

develop in the ischioanal fossa, which may get large and even invade the contralateral side.They need incisions and drinage. One should avoid injuring the inferior rectal nerve and vessels or risk paralyzing the external anal sphincter.

proctoscopy

examination of the rectum and anus with a proctoscope

inferior hypogastric plexus

for the rectum and superior part of the anal canal, the parasympathetic nerves run into the ______ _________ ________.

portal hypertension due to liver cirrhosis

in ________ _________, these veins may be dilated and engored with blood

anal columns; superior rectal artery and vein

in a coronal section, the interior vein of the anal canal exhibits six to ten roll-shaped longitudinal folds, the ______ ________, which contain the terminal branches of the _______ ______ ______ and _______.

Diverticulosis/diverticulitis

in sigmoid colon or elsewhere in the colon, in older people (over 55y) could be a change due to age and still considered to be normal, however, if infection or inflammation proceeds (diverticulitis) is pathologic.

sphincteric incontinence

injury to the nerves to the external sphincter with the ischioanal fossa results in _______ ___________ when peristaltic waves reach the anus

ulcerative colitis

is a chronic relapsing ulceroinflammatory disease, involvingprimarily the rectum and left colon. Infectious or immunologic or psychologic causes. Patient is a young adult with fever, left side abdominal pain, bloody diarrhea, rectalbleeding, continuous (no skip regions), crypt abscess ...

superficial inguinal lymph nodes

lymphatics inferior to the pectinate line drain into the:

sacral or internal iliac lymph nodes

lymphatics of the inferior portion of the rectum drain into:

pararectal and sacral lymph nodes; inferior mesenteric lymph nodes; lumbar lymph nodes

lymphatics of the superior portion of the rectum enter the ______ and _______ lymph nodes, moving through to the __________ _______ lymph nodes and finally to the ______ lymph nodes

internal iliac, common iliac, and lumbar lymph nodes

lymphatics superior to the pectinate line drain into the:

prolapse of the rectum

may occur through anus due to trauma (child birth) and age.

prolapse of the rectum

may occur through the anus due to trauma (eg. childbirth) and age

Cancers of the rectum

metastasize to liver (hematogenous metastasis)through the superior rectal vein into the inferior mesenteric and portal veins.Metastasis to surrounding: anterior: to urinary bladder, prostate, seminal vesicles (male)and to uterus and vagina in female. Posteriorly, to sacral nerve plexus. Laterally to the ureter.

peristalsis; internal anal sphincter

parasympathetic innervation to the muscles results in _______, but inhibits the ________ _______ ________.

anorectal junction; anal valves

the ______ ________ is at the superior end of these columns, and _____ ______ join the inferior ends of the columns

sensory (afferent)

the _______ fibers are only sensitive to stretching, and are also involved in reflexes

superior, middle and inferior rectal veins; portacaval anastomosis

the _______, _________, and __________ ________ veins make several anastomotic connections along the wall of the anal canal- important connections between the portal and systemic veins, called the _________ __________

pelvic splanchnic nerves (the S2, 3, and 4)

the ________ ________ nerves are responsible for the parasympathetic innervation of the rectum and superior section of the anal canal

middle and inferior rectal veins; internal pudendal vein; IVC

the ________ and ______- _______ veins (drain the lower part of the anal canal), along with the _______ ________ vein, drain into the internal iliac vein, which then drains into the ________

2cm; puborectalis muscle

the internal anal sphincter is about ____ cm high and lies inferior to the ________ ________.

pectinate line

the lower ends of the anal valves form an irregular line called the _______ ______, creating the border between the upper and lower part of the anal canal

sympathetic and parasympathetic nerves

the rectum and superior section (to the pectinate line) of the anal canal are innervated by:

anus

the rectum is continuous with the:

pain, touch, and temp

the sensory fibers (afferents) in the inferior pectinate line region, convey the sensitivity to ______, ______and ________ in this area

internal anal sphincter; efferent (motor) sympathetic nerves

the sphincters (specifically, the ______ ______ sphincter) in the GI tract are typically innervated via the _______ ________ nerves, which control the tonus

hindgut (endoderm); proctodeum(ectoderm)

the superior section of the anal canal is derived form the ______, whereas the inferior section is derived from the _________.

lumbar section; hypogastric plexus; inferior hypogastric plexus

the sympathetic nerves come from the _______ ________ of the trunk through the _______ ________ to the rectum, and through the _____ _________ _________ to the upper part of the anal canal

superior rectal artery; inferior rectal artery

the upper part of the anal canal is supplied by the ______ ______ artery and the lower part by the ________ ______ artery

internal rectal venous plexus

the veins under the mucosa of the anus are normally dilated and form the:

superior rectal vein into the inferior mesenteric vein, and then into the portal vein

what drains the rectum and the upper part of the anal canal

inferior rectal artery- a branch of the internal pudendal artery (which is coming from the internal iliac artery)-

what supplies the lower part of the rectum?

the middle rectal artery coming from the internal iliac artery

what supplies the middle section?

superior rectal artery- the terminal branch of the inferior mesenteric artery-

what supplies the superior part of the rectum?

anal canal

which is more than one inch (2.5-3.5 cm) long, is the terminal part of the large intestine that lies in the perineum and extends from the upper part of the pelvic diaphragm to the anus