Rectum and Anal Canal, Blood Supply of the Pelvis and Perineum

Gross Anatomy


Rectum and Anal Canal, Blood Supply of the Pelvis and Perineum


Anatomy Tables for Today's Topic

Muscles
Nerves
Arteries
Veins
Lymph
Viscera

Muscles

Muscle Origin Insertion Action Innervation Artery Notes
anal sphincter, external perineal body or central tendinous point of the perineum encircles the anal canal; superficial fibers attach to the coccyx constricts the anal canal inferior rectal nerves (from the pudendal nerve) inferior rectal a. skeletal (voluntary) muscle, as contrasted with sphincter ani internus, which is smooth (involuntary) muscle; the external anal sphincter is considered part of the pelvic diaphragm
anal sphincter, internal encircles the anal canal encircles the anal canal constricts the anal canal parasympathetic fibers from S4 middle rectal a. smooth muscle (involuntary), as contrasted with sphincter ani externus, which is skeletal muscle (voluntary)
puborectalis posterior aspect of the body of the pubis unites with the puborectalis m. of other side posterior to the rectum draws the distal rectum forward and superiorly; aids in voluntary retention of feces branches of the ventral primary rami of spinal nerves S3-S4 inferior gluteal a. the combination of puborectalis, pubococcygeus and iliococcygeus is called the levator ani m.

Nerves

Nerve Source Branches Motor Sensory Notes
rectal plexus inferior hypogastric (pelvic) plexus, posterior part no named branches sympathetic: vascular smooth muscle of the pelvic viscera, especially the rectum; parasympathetic: smooth muscle and glands of the pelvic viscera, especially the rectum pain and general sensation from the rectum rectal plexus is continuous with the vesical plexus in the male, uterovaginal plexus in the female
rectal, inferior pudendal n. no named branches external anal sphincter skin of the anus inferior rectal nerve is one of the first branches of the pudendal n.
splanchnic, pelvic ventral primary rami of spinal nerves S2-S4 (cell bodies are located in the lateral horn gray of the sacral spinal cord) unnamed branches contribute to the pelvic plexus (inferior hypogastric) plexus smooth muscle and glands of the gut distal to the left colic flexure; smooth muscle and glands of all pelvic viscera none parasympathetic nerves; these contain preganglionic parasympathetic axons
splanchnic, sacral sacral sympathetic ganglia unnamed branches contribute to the pelvic plexus (inferior hypogastric) plexus vascular smooth muscle of the pelvic viscera pain from the pelvic viscera sacral splanchnic nn. contain both preganglionic and postganglionic sympathetic nerve fibers with postganglionic fibers predominating in number

Arteries

Artery Source Branches Supply to Notes
ductus deferens, artery of umbilical a.; may be a branch of the superior or inferior vesical a. no named branches ductus deferens, seminal vesical; possibly supplies the ureter artery of the ductus deferens is also known as: deferential a.
epigastric, inferior external iliac a. cremasteric a. lower rectus abdominis m., pyramidalis m., lower abdominal wall inferior epigastric m. anastomoses with the superior epigastric m. within the rectus abdominis m.
gluteal, inferior internal iliac a., anterior division unnamed muscular branches gluteus maximus m., hip joint inferior gluteal a. participates in the formation of the cruciate anastomoses of the hip
gluteal, superior internal iliac, posterior division superficial br., deep br. gluteus maximus m., gluteus medius m., gluteus minimus m., hip joint superior gluteal a. participates in the formation of the cruciate anastomoses of the hip
iliac, common abdominal aorta external iliac a., internal iliac a. pelvis, lower limb abdominal aorta bifurcates at the level of the L4 vertebral body to form the right and left common iliac aa.; the common iliac artery bifurcates anterior to the sacroiliac articulation into its terminal brs. (external iliac a. and internal iliac a.)
iliac, external common iliac a. inferior epigastric a., deep circumflex iliac a., femoral a. lower limb external iliac a. is continuous with the femoral a., the name change occurs at the inguinal ligament; the common iliac artery bifurcates anterior to the sacroiliac articulation
iliac, internal common iliac a. anterior division gives rise to the : umbilical a., obturator a., uterine a., vaginal a., inferior vesical a., middle rectal a., internal pudendal a., inferior gluteal a.; posterior division gives rise to the: iliolumbar a., lateral sacral a., superior gluteal a. pelvic viscera, gluteal region, hip, medial thigh common iliac artery bifurcates anterior to the sacroiliac articulation to form the internal iliac a. and the external iliac a.
iliolumbar internal iliac a., posterior division iliac br., lumbar br. iliacus m., psoas major m., quadratus lumborum m. lumbar br. of the iliolumbar a. sends a small spinal br. into the vertebral canal
lateral sacral internal iliac a., posterior division spinal brs. sacrum, sacral nerve rootlets, meninges, adjacent muscles there are usually 2 lateral sacral aa. on each side, a superior one and an inferior one
obturator internal iliac a., anterior division pubic br., acetabular br., anterior br., posterior br. medial thigh and hip anterior and posterior brs. pass on the anterior and posterior sides of the adductor brevis m.; aberrant obturator a. arises from the inferior epigastric a. in 30% of cases
ovarian abdominal aorta tubal brs., uterine brs. ovary, uterine tube ovarian a. anastomoses with the uterine a.
pudendal, internal internal iliac a., anterior division inferior rectal a., perineal a., artery of the bulb of the clitoris/penis, urethral a., deep clitoral/penile a., dorsal clitoral/penile a. anus, muscles of the superficial and deep perineal spaces, clitoris/penis, posterior aspect of the scrotum/labium majus internal pudendal a. is the primary blood supply to the perineum
rectal, inferior internal pudendal a. no named branches anus, ischioanal fossa inferior rectal a. anastomoses with the middle rectal a. and the superior rectal a.
rectal, middle internal iliac, anterior division no named branches middle portion of the rectum middle rectal a. anastomoses with the inferior rectal a and the superior rectal a.
rectal, superior inferior mesenteric a. two unnamed branches superior part of the rectum superior rectal a. is the continuation of the inferior mesenteric a. after the sigmoid brs. are given off; it anastomoses with the middle rectal a. and the inferior rectal a.
sacral, median abdominal aorta 5th lumbar aa. sacrum median sacral a. appears to be the continuation of the abdominal aorta in the median plane, although it is much smaller in size
scrotal, posterior perineal a. no named branches posterior aspect of the scrotum posterior scrotal a. passes superficial to the superficial transverse perineus m.
testicular abdominal aorta ureteric brs. testis, epididymis, lower part of the ductus deferens, ureter near its midpoint testicular a. is one of the contents of the spermatic cord; the origin of the testicular a. from the aorta at the L2 vertebral level indicates the embryonic level of origin of the testis prior to its descent
umbilical internal iliac a., anterior division superior vesical aa., a. of the ductus deferens superior part of the bladder; ductus deferens distal to the branches described at left, the lumen of the umbilical a. becomes obliterated after birth and the remnant of the vessel becomes the medial umbilical ligament
uterine internal iliac a., anterior division tubal br., vaginal br. uterus, uterine tube uterine a. anastomoses with the ovarian a. and the vaginal a.; it passes superior to the ureter in the pelvis; remember the saying "water under the bridge"
vaginal internal iliac a., anterior division; occasionally it arises from uterine a. numerous unnamed branches vagina anastomoses with the uterine a.; participates in the formation of the azygos arteries along the lateral surface of the vagina
vesical, inferior internal iliac a., anterior division or it may arise from the middle rectal a. no named branches lower part of the urinary bladder, prostate/vagina inferior vesical a. anastomoses with the middle rectal a.
vesical, superior umbilical a. no named branches superior aspect of the bladder superior vesical aa.arise from the umbilical a. proximal to where its lumen becomes obliterated

Veins

Vein Tributaries Drains Into Regions Drained Notes
ovarian v. no named tributaries right: inferior vena cava; left: left renal v. ovary and the distal part of the uterine tube; ureter connects with the uterine v.; a pampiniform plexus occurs, but is not as well developed as that seen in the male
prostatic venous plexus deep dorsal v. of the penis internal iliac v. penis and the prostate gland prostatic venous plexus is connected with the vesical venous plexus
pudendal, deep external part of the drainage of the superficial dorsal v. of the penis/clitoris femoral skin and superficial fascia of the penis/clitoris; pubic region deep external pudendal v. shares its region of drainage with the superficial external pudendal v.
pudendal, internal deep dorsal v. of the penis/clitoris, v. of the bulb, posterior labial/scrotal v., inferior rectal v. internal iliac crus and bulb of the clitoris/penis; urogenital region, anal region internal pudendal v. passes through the pudendal canal
pudendal, superficial external part of the drainage of the superficial dorsal v. of the penis/clitoris great saphenous skin and superficial fascia of the penis/clitoris; pubic region superficial external pudendal v. shares its region of drainage with the deep external pudendal v.
rectal venous plexus no named tributaries superior, middle & inferior rectal vv. rectum and anal canal; anus rectal venous plexus is a site of portal-caval anastomosis
testicular v. pampiniform plexus left: left renal v.; right: inferior vena cava testis, ureter left testicular v. is longer than the right testicular v.
uterine venous plexus multiple tributaries from the uterus; deep dorsal v. of the clitoris uterine vv. to the internal iliac v. uterus & uterine tubes connects with the ovarian v. and the vaginal venous plexus
vaginal venous plexus multiple tributaries from the vagina vaginal v. to the internal iliac v. or uterine v. vagina connects with the uterine venous plexus, the vesical venous plexus and the rectal venous plexus
vesical venous plexus multiple tributaries from the bladder in both sexes superior and inferior vesical vv. to the internal iliac v. urinary bladder in the male - connects with the prostatic venous plexus and the rectal venous plexus; in the female - connects with the rectal venous plexus, uterine venous plexus and vaginal venous plexus

Lymphatics

Structure Location Afferents from Efferents to Regions drained Notes
iliac nodes, common along the common iliac vessels; over the sacral promontory external iliac nodes, internal iliac nodes lumbar (lateral aortic) chain of nodes lower limb; pelvic organs, perineum, lower part of the anterior abdominal wall common iliac nodes are approximately 6 in number
iliac nodes, external along the external iliac vessels superficial inguinal nodes; deep inguinal nodes; inferior epigastric nodes common iliac nodes lower limb; external genitalia; lower part of the anterior abdominal wall external iliac nodes are 8 to 10 in number
iliac nodes, internal along the internal iliac vessels lymphatic vessels from the pelvic viscera common iliac nodes, external iliac nodes pelvis, perineum and gluteal region internal iliac nodes are 4 to 8 in number
lateral aortic nodes along the inferior vena cava and abdominal aorta from the aortic bifurcation to the aortic hiatus of the diaphragm common iliac nodes; lymphatic vessels from the posterior abdominal wall and viscera efferents form one lumbar trunk on each side lower limb; pelvic organs; perineum; anterior and posterior abdominal wall; kidney; suprarenal gland; respiratory diaphragm also known as: lumbar nodes; the intestinal trunk drains into to the left lumbar trunk; the lumbar trunks unite to form the thoracic duct/cisterna chyli
lumbar nodes along the inferior vena cava and abdominal aorta from the aortic bifurcation to the aortic hiatus of the diaphragm common iliac nodes; lymphatic vessels from the posterior abdominal wall and viscera efferents form one lumbar trunk on each side lower limb; pelvic organs; perineum; anterior and posterior abdominal wall; kidney; suprarenal gland; respiratory diaphragm also known as: lateral aortic nodes; the intestinal trunk drains into to the left lumbar trunk; the lumbar trunks unite to form the thoracic duct/cisterna chyli
lumbar trunk between the lumbar vertebral bodies and inferior vena cava (right) or aorta (left) at the upper end of the lumbar chain of nodes lumbar (lateral aortic) nodes; the intestinal trunk joins the left lumbar trunk thoracic duct/cisterna chyli left lumbar trunk - left side of the body below the respiratory diaphragm, gut; right lumbar trunk - right side of body below the diaphragm lumbar trunks unite to form the lower end of the thoracic duct; an enlargement of the lower end of the thoracic duct (called the cisterna chyli) occurs in about 25% of individuals, and when it is present, the lumbar trunks drain into it

Viscera

Organ/Part of Organ Location/Description Notes
anal canal terminal end of the digestive tract anal canal is continuous with the rectum above and opens at the anus below; it is regulated by external and internal anal sphincters
anal columns longitudinal folds of mucosa on the inner wall of the anal canal anal columns are connected inferiorly by anal valves; rectal vessels lie beneath the submucosa of the anal columns
anal valves folds of mucosa joining adjacent anal columns at their inferior ends anal valves can be difficult to locate in the older individual
pectinate line an irregular line joining the undersides of the anal valves pectinate line is where the mucosal lining of the digestive tract becomes continuous with the skin of the anal aperture
rectum distal end of the colon rectum begins at about the S3 vertebral level; it is continuous distally with the anal canal

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Some of the material presented in these tables is contained in the book:
MedCharts Anatomy by Thomas R. Gest and Jaye Schlesinger
Published by ILOC, Inc., New York. Copyright 1995.

Content of these tables has been edited for use in this course by Patrick W. Tank, Ph.D.
Copyright 2005, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences.

Unauthorized use is prohibited.