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Rectum And Anal Canal Flashcards

(49 cards)

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1
Q

Rectum

A

. 5 inches long
. Continuous proximally w/ the sigmoid colon rectosigmoid junction at S3) and distally w/ anal canal (at puborectalis m.)
. Retroperitoneal: sup. 1/3 has peritoneum on ant. And lat. surface, middle 1/3 has it on ant. Surface, inf. 1/3 has no peritoneal covering
. 2 flexures laerally, 3 anteriorly

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2
Q

What is found posterior to rectum?

A

. Last 3 sacral vertebrae and coccyx
. Anococcygeal ligament and piriformis mm.
. Sacral vessels and nerves
. Sympathetic trunks

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3
Q

What structures are directly anterior to rectum?

A

. Males: bladder, ureters, prostate, ductus deferens, seminal vesicles, rectovesical pouch, rectovesical septum
. Females: vagina and uterus, rectouterine pouch, rectouterine (vaginal) septum

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4
Q

What structures are lateral to rectum

A

. Pelvic colon
. Ileum
. Coccygeus
. Levator ani m.

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5
Q

Lateral flexures of rectum

A

. Sacral flexure: rectum following curve of sacrum and coccyx
. Anorectal flexure: rectum ends anteroinferior to tip of coccyx by turning sharply posteroinferiorly as it goes through pelvic diaphragm (angle caused by encircling fibers of puborectalis)

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6
Q

Rectum curvatures

A

. Superior, middle, and inferior curvatures
. Due to 3 internal infoldings of mucous and submucous coats overlying part of circular muscle layer of rectal wall (transverse rectal folds)
. Olds help support rectal contents
. Sup. And inf. Curves are concave to the left
. Middle curve is concave to the right

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7
Q

Anal canal

A

. Inf. 1.5 inches of GI tract
. Continuous w/ rectum at anorectal junction (marked by anorectal flexure)
. Inf. Opening of anal canal: anal orifice/anus

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8
Q

Anatomical relations of the anal canal

A

. Post.: coccyx and anococcygeal ligament
. Ant.: perineal body (central tendon of perineum)
. Lat.: external anal sphincter, ischioanal fossa

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9
Q

Muscular layer of anal canal wall

A

. Internal anal sphincter: thickening of circular smooth muscle layer of rectum under ANS control
. External anal sphincter: voluntary skeletal muscle, subcutaneous portion (directly under skin forming complete ring), superficial portion (elliptical, tip of coccyx/anococcygeal ligament to perineal body)m and deep portion (completely encircles anus)
. Innervated by inf. Rectal n. From pudendal n.

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10
Q

Anal columns

A

. Series of 5-10 longitudinal ridges in anal canal
. Contain terminal branches of sup. Rectal a. And v.
. Anorectal junction indicated by superior ends of anal columns

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11
Q

Anal sinuses

A

. Depressions btw adjacent columns, sup. To anal valves

. When compressed by poo, anal sinuses exude mucus that aids in evacuation of feces

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12
Q

Anal valves

A

. Horizontal folds of tissue, joins inf. Ends of adjacent anal columns

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13
Q

Anal crypt

A

. Inf. Portion of anal sinus
. Deep to anal valve
. Fecal matter can become trapped here causing infection

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14
Q

Pectinate line

A

. Irregular comb-shaped line drawn around circumference of anal canal
. Connects all anal valves
. Sup. To line: from endoderm
. Inf. To line: from ectoderm
. Areas sup, and inf. To line have different blood supply, innervation, and lymph drainage

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15
Q

Sup. Rectal a.

A

. Unpaired
. Terminal branch of inf. Mesenteric a.
. Supplies rectum and sup. Part of anal canal to level of anal columns

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16
Q

Middle rectal a.

A

. Paired
. From internal iliac aa.
. Supplies inf. 1/3 of rectum and anal canal
. Supplies muscular layer of anal canal

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17
Q

Inferior rectal a.

A

. Paired
. From internal pudendal aa.
. Supplies inf. Part of anal canal
. Anastomoses w/ sup. Rectal a. At level of anal columns

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18
Q

Superior rectal v.

A

. Sup. Tp pectinate line
. Drains into portal system via inf. Mesenteric v.
. Inc. portal pressure (portal hypertension) can cause internal hemorrhoids

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19
Q

Middle rectal v.

A

. Drains muscular layer
. Forms anastomoses w/sup. And inf. Rectal vv.
. Drains into internal iliac v.

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20
Q

Inf. Rectal vv.

Study These Flashcards
A

. Inf. To pectinate line

. Drains into internal iliac vv. Via internal pudendal v.

21
Q

Sympathetic innervation of rectum and anal canal

Study These Flashcards
A

. From upper lumbar levels via inf. Mesenteric plexus

. Dec. peristalsis, maintains tone of internal anal sphincter

22
Q

Parasympathetic innervation of rectum and anal canal

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A

. From pelvic splanchnics (S2-4) via inf. Hypogastric plexus
. Inc. peristalsis, relaxes internal anal sphincter

23
Q

Sensory innervation sup. To pectinate line

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A

. Visceral afferents
. Primarily sensitive to stretching
. Pathology: silent, not painful

24
Q

Sensory innervation inf. To pectinate line

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A

. Somatic afferents

. Pathology: painful

25
Lymph drainage sup. To pectinate line compared with inf. To pectinate line
. Sup: internal iliac nodes | . Inf: inguinal nodes
26
Difference btw hemorrhoids above and below pectinate line
Above: internal hemorrhoids converged w/ mucosa | . Below: external hemorrhoids covered w/ skin
27
Sacral plexus roots
. Ventral rami L4-S4 . Comprised fo lumbosacral trunk (L4-55, S1-3, part of S4) . Ventral rami of S2-3 emerge btw digitations of piriformis m. . Ventral rami divide into ant. And post. Divisions
28
Sacral plexus muscular branches
``` . Sciatic n. . Pudendal n. . Sup. Gluteal n. . Inf. Gluteal n. . N. To piriformis (S1-2) . N. To quadratus femoris and inf. Gemellus (L4-5, S1) . N. To obturator internus and sup. Gemellus (L5, S1-2) . N. To levator ani and coccygeus (S3-4) ```
29
Sciatic n.
. L4-S3 . Largest branch of sacral plexus . To lower extremity . Tibia and common fibular (peroneal) divisions . Exits greater sciatic foramen to gluteal region inf. To piriformis
30
Pudendal n. (S2-4)
. Goes to perineum . Exits greater sciatic foramen inf. To piriformis . Courses around sacrospinous ligament, through lesser sciatic foramen, and enters pudendal canal
31
Sup. Gluteal n.
. L4-S1 . To gluteal region . Sup. To piriformis, exits greater sciatic foramen
32
Inferior gluteal n.
. To gluteal region | . Inf. To piriformis, exits greater sciatic foramen
33
Cutaneous branch of sacral plexus
. Posterior femoral cutaneous n. | . S2-3
34
Sacral sympathetic trunks
. Descend on pelvic surface of sacrum med. to ventral sacral foramina . Preganglionic sympathetic fibers synapse in sacral sympathetic chain ganglia and Postganglionic fibers travel via gray communicantes to sacral and coccygeal nn. That distribute to body wall . Preganglionic fibers come off of sympathetic trunk as sacral splanchnics that synapse in inf. Hypogastric plexus and go to viscera
35
Ganglion impar
. Midline structure formed by convergence of sacral sympathetic trunks . Lies in front of coccyx
36
Lumbar sympathetic trunks
. Preganglionic sympathetic fibers leave trunk as lumbar splanchnic n. . Splanchnic nn. Synapse in inf. Mesenteric ganglia and plexus . Postganglionic sympathetic fibers travel through sup. Hypogastric plexus, inf. Hypogastric plexus, and smaller visceral plexuses and then to viscera
37
Sacral plexus parasympathetic nn.
. S2-4 . Pelvic splanchnic nn. (Preganglionic) leave ventral rami . Joins inf. Hypogastric plexus
38
Superior hypogastric plexus
. Formed by inf. Prolongation of aortic plexus . Divides into R/L hypogastric nn. . Enter pelvis on either side of pelvis . Hypogastric nn. Join w. Pelvic splanchnics to form inf. Hypogastric plexus
39
Inferior hypogastric plexus
. Gives rise to smaller, specific visceral plexuses
40
Posterior division of iliac a.
. 3 parietal branches . Iliolumbar a.: upward btw obturator n. And lumbosacral trunk . Lat. sacral a.: descends along ventral sacral foramina, sends spinal branches through foramina to sacral canal, skin, and muscle over sacrum . Sup. Gluteal a.: btw lumbosacral trunk and S1, exits pelvic cavity through greater sciatic foramen (sup. to piriformis m.)tp gluteal region
41
Anterior division of iliac a.
``` . 6 branches, parietal and visceral . Umbilical a. . Inf. Vesical a. . Middle rectal a. . Obturator a. . Internal pudendal a. . Inf. Gluteal a. ```
42
Umbilical a.
. Along side wall of pelvis . Gives off sup. Vesical aa. To bladder . Becomes medial umbilical ligaments on internal surface of anterolateral abdominal wall after last sup. Vesical branch
43
Inf. Vesical a.
. To bladder, ureter (M: seminal vesicles and prostate) | . Gives off a. To vas deferens in male
44
Middle rectal a.
. To rectum | . Prostate and seminal vesicles in males too
45
Obturator a.
. To med. thigh . Rounds alongside pelvic wall w/ obturator n. . Exits pelvis through obturator foramen . Variation: arises from inf. Epigastric a. In 40% people
46
Inferior gluteal a.
. To gluteal region . Exits pelvis btw S2-3 . Inf. To piriformis m.
47
Male/female differences in branches of internal iliac a.
. Females: uterine a. Replaces inf. Vesical a. | . Females have separate vaginal a. That may give off inf. Vesical a.
48
Uterine a.
. Courses in base of broad ligament to uterus | . Has ascending and descending branches
49
Pelvic venous drainage
. Internal iliac vv and tributaries . Vv correspond to aa except that iliolumbar vv. Don’t drain into internal iliac vv., but into common iliac vv. . Anastomoses w/ portal venous system in area of rectum/anal canal

Anatomy (49 decks)

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