GI Anatomy 7 Flashcards
1
Q
What vertebral level does the aorta birfurcate?
A
L4
2
Q
What vertebral level does the common iliac divide into an internal and external branch?
A
Between L5 and S1
3
Q
When does the external iliac become the femoral?
A
When it passes deep to the inguinal ligament
4
Q
What branch does the external iliac give off before it passes deep to the inguinal ligament?
A
Inferior epigastric
5
Q
What is the course of the inferior epigastric?
A
Ascends on the anterior abdominal wall and anastamoses with the superior epigastric (continuation of internal thoracic artery)
6
Q
Other than the internal iliac artery what 2 other arteries supply structures in the pelvis?
A
1) Median sacral artery - comes off the bifurcation of the aorta and descends in the midline, crosses the pelvic inlet and gives rise to the last pair of lumbar arteries
2) Ovarian artery (in women) - come of AA, supply ovaries and anastamose with the terminal parts of the uterine arteries
7
Q
What does the internal artery commonly divide into?
A
Anterior trunk which supplies pelvic viscera, gluteal region and thigh
Posterior trunk which supplies the body wall and gluteal region
8
Q
What branches tend to come off the anterior branch of the internal iliac?
A
1) Umbilical artery
2) Superior vesical arteries
3) Inferior vesical/vaginal artery
4) Uterine artery (only in females)
5) Obtruator artery
6) Internal pudendal
7) Middle rectal
8) Inferior gluteal
9
Q
Which arteries pass out of the greater sciatic foramen?
A
Superior gluteal (above piriformis) Inferior gluteal and internal pudendal (below piriformis)
10
Q
Which artery passes out of the obtruator canal?
A
Obtruator artery
11
Q
What artery leaves the pelvis by neither the greater sciatic or obtruator foramen?
A
iliolumbar artery from posterior trunk to supply muscles of the posterior abdominal wall
12
Q
Why is the internal pudendal artery not just called the pudendal artery?
A
Because there is also an external, deep and superficial pudendal arteries
13
Q
Which branches of the internal pudendal artery supply the erectile tissues of the penis and clitoris and vestibule in females?
A
Dorsal artery of the clitoris/penis
Deep artery of the clitoris/penis
14
Q
What is the venous drainage of the majority of the pelvic viscera, what is the exception to this?
A
Pelvic viscera surrounded by a network of veins from which blood passes via vessels which mirror the arteries to reach the internal iliac veins
15
Q
Into which vessels do the gonads drain?
A
right gonadal vein - into IVC
Left gonadal vein - into left renal vein
16
Q
Most of the pelvic viscera drains into internal iliac nodes, where do these drain?
A
Internal iliac Nodes associated with common iliacs Lateral aortic/lumbar nodes Lumbar trunks Cisterna Chyli
17
Q
Into which nodes do the gonads drain?
A
Directly (via vessels that accompany the gonadal arteries) into lateral aortic/lumbar nodes and in some cases into pre aortic nodes
18
Q
What nerve is in close relation to the ovary and what is the clinical significance of this?
A
Obtruator nerve - ovarian cancer = pain in medial thigh
19
Q
What is the sacral plexus?
A
Somatic nerves
Formed by the ventral rami of S1-S4 and also receives contributions from L4 and L5
20
Q
What are the 3 main sets of nerves/nerves present in the pelvis?
A
Sacral plexus - somatic
Autonomic plexus (pelvic plexus/inferior hypogastric)
Obtruator nerve
21
Q
What are the 2 main branches of the sacral plexus, what do they supply and how do they leave the pelvis?
A
1) Sciatic nerve - lower limb - leaves via greater sciatic foramen
2) Pudendal nerve - perineum - leaves greater sciatic foramen with the internal pudendal artery
22
Q
What autonomic nerves does the sacral plexus give rise to?
A
Pelvis splanchnic nerves (S2,S3,S4)
23
Q
What vertebral level does the obtruator nerve come from?
A
L2,L3,L4
24
Q
Other than the sciatic nerve, pudendal nerve and pelvic splanchnic nerves what else does the sacral plexus give rise to?
A
Nerves to supply the muscles of the pelvic floor - coccygeas, levator an
25
What is the nervi erigentes?
Another name for the pelvic splanchnic nerves because they are responsible for genital erection
26
Where does the pelvic plexus/inferior hypogastric plexus lie?
In the fascia around the rectum
27
What role do the parasympathetic nerves of the pelvic plexus have in micturation?
Stimulate bladder contraction
28
Where do sympathetic fibres to the pelvic viscera come from?
Thoracic and lumbar splanchnic nerves which branch off the sympathetic chain and travel via midline plexuses to join the pelvic plexus
29
Where do the sympathetic chains unite?
Infront of the sacrum
30
From the substance of what muscle do the roots of the sacral plexus emerge?
Piriformis
31
What is the obtruator canal bordered by?
Obtruator membrane and obtruator internus and superior pubic ramus
32
What passes through the obtruator canal?
Obtruator nerve artery and vein
33
What forms the pelvic floor anteriorly and posteriorly?
```
Anteriorly = levator ani (puborectalis, pubococcygeus, iliococcygeus)
Posteriorly = coccygeus
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34
What is the perineal body and what is its function?
Connective tissue structure positioned in the midline on the posterior border of the perineal membrane to which is attaches
Muscles of the pelvic floor and perineum attach to it
35
What is the function of the puborectalis muscle?
Forms a sling around the diaphragm as it pierces the pelvic diaphragm pulling the anal canal at a 90 degree angle to the rectum to prevent faeces freely passing out - forms part of the mechanism which keeps the gut closed
36
What is an episiotomy, when and why is it carried out?
Surgical incision made in the perineum (between vagina and anus) to prevent tearing during the delivering of a baby
37
Which bones make up the bony pelvis?
1) Sacrum
2) Coccyx
3) Right and left pelvic bones (ischium, ilium and pubis)
38
What is the acetabulum?
Point where the ischium, ilium and pelvic bones meet
39
What is the pectineal line on the bony pelvis?
Sharp superior margin of the superior pubic ramus
40
What is the arcuate line on the bony pelvis?
Ridge separating the upper and lower parts of the ilium
41
Which bony features define the pelvic brim?
1) Sacral Promontary (anterior to sacrum)
2) Margin of Ala (lateral to promontary, anterior margin sacrum)
3) Arcuate line (ilium)
4) Pectinate line (sharp superior line of superior pubic ramus)
5) Pubic crest
The last 3 make up the linea terminalis
42
Where does the sacrospinous ligament run to and from?
From the sacrum to the ischial spine
43
Where does the sacrotuberous ligament run from and to?
From the sacrum to the ischial tuberosity
44
Which ligament contributes to the borders of the greater sciatic foramen?
Sacrospinous ligament
45
Which ligaments contribute to the borders of the lesser sciatic foramen?
Superiorly - sacrospinous ligament
| Inferiorly - sacrotuberous ligament
46
What are the 4 differences between a male and female bony pelvis?
1) Female has larger angle of pelvic arch (80-85, in men 50-60)
2) Female has circular pelvic inlet, male has heart shaped pelvic inlet
3) Female has less prominent medially projecting ischial spines
4) Female has less prominent projecting promontory
47
What is the perineum?
Space inferior to the pelvic floor, bounded by superiorly by the pelvic outlet and inferiorly by the skin
48
What line separates the perineum into the urogenital triangle and the anal triangle?
Line between the 2 ischial tuberosities
49
How does the anal triangle lie in anatomical position?
Slightly posterior
50
How does the urogenital triangle lie in the anatomical position?
Horizontally
51
What is the ischioanal fossa?
Wedge shaped spaces in the lateral parts of the anal triangle (part of the perineum)
52
What forms the walls of the ischioanal fossa?
Medially = levator ani
Laterally = obtruator internus
Inferiorly = subcutaneous tissue and skin
These converge superiorly where the levator ani joins the obtruator fascia (tendinous arch)
53
Where does the rectum become the anal canal?
At the anorectal junction where the rectal ampulla narrows just before penetrating the pelvic floor (anus is the bit after passing through perineum)
54
What is the epithelial lining of the upper 2/3 and lower 1/3 anal canal?
Upper 2/3 = simple columnar non ciliated
| lower 1/3 = non keratinised stratified squamous
55
What is the arterial blood supply to the upper 2/3 and lower 1/3 of the anal canal?
Upper 2/3 = superior rectal (from inferior mesenteric) and middle rectal artery
Lower 1/3 = inferior rectal artery from internal pudendal
56
What is the venous drainage of the upper 2/3 and lowe 1/3 anal canal?
Upper 2/3 = superior rectal vein - inferior mesenteric
| Lowe 1/3 = inferior rectal vein
57
What is the nerve supply to the upper 2/3 and lower 1//3 of the anal canal?
Upper 2/3 = Inferior hypogastric plexus
| Lower 1/3 = inferior rectal nerves
58
What are the anal columns?
The longitudinal folds into which the mucosa of the upper anal canal is arranged
59
What are the anal valves?
Ridges at the inferior ends of the anal columns
60
What forms the pectinate line and what does this mark?
Pectinate line = formed by anal valves
| Marks the approximate margin between the embryologically different regions of the anal canal
61
What 2 sphincters surround the anal canal?
The internal and external anal sphincters
62
What does the internal anal sphincter lie around and what is it formed from?
Lies around the upper 2/3 of the anal canal
| Formed from the thickened lower end of the circular smooth muscle of the rectum
63
What are the 3 parts of the external anal sphincter and what is it formed from?
Striated smooth muscle surrounding the lower 2/3 of the anal canal
Has a deep, subcutaneous and superficial part
64
What is the deep part of the external anal sphincter related to posteriorly?
The fibres of the puborectalis muscle
65
What is the ischioanal fossa normally filled with?
Fat
66
What is the nerve supply to the internal anal sphincter?
PS fibres from pelvic splanchnic nerves (S2-S4)
67
What is the nerve supply to the external anal sphincter?
Inferior rectal nerve from pudendal (and a perineal branch of the 4th sacral nerve)
68
What happens to the ischioanal fossae anteriorly and posteriorly?
Anteriorly they extend into the urogenital triangle
| Posteriorly they unite
69
What are haemorrhoids?
Engorgement of the venous plexus at or inside the anal sphincter
Symptoms = pain, irritation, swelling
Internal - have a tendency to bleed
External
Prolapsed - internal haemorrhoids which have passed outside the anal canal and form lumps
70
Where does the superficial perineal (Colle's) fascia lie?
Deep to the perineal skin
Extends from one inferior pubic ramus to the other anteriorly and forms the inferior boundary of the superficial perineal pouch
71
What is located in the superficial perineal pouch?
The attachments of the external genitalia (in the male also the testes and vas)
72
What is a fistula and why do they form in the ischioanal fossae?
Fistula = abnormal or surgically made passage between a hollow or tubular organs and the body surface or between 2 organs
Ischioanal fossae are common sights of infection which results in abcesses which may rupture to produce a fistula
73
what is the pudendal canal?
Fascial canal in the lateral wall of the ischioanal fossae in which the pudendal nerve and internal pudendal artery and vein travel
74
How does the pudendal nerve enter the anal triangle and thus ischioanal fossae?
Passes through the lesser sciatic foramen
75
What branches does the pudendal nerve give off as it travels through the pudendal canal?
Inferior rectal nerve
Perineal nerve
Continues as the dorsal nerve of penis/clitoris
76
How and why would you carry out a pudendal nerve block?
During second stage of labour or minor vaginal surgery
Injection of local anaesthetic into pudendal nerve proximal to its terminal branches
2 approaches are transvaginal and transcutaneous (or perineal)
77
What is the urogenital diaphragm, where does it extend between and what does it merge with posteriorly?
A triangular layer of muscle and dense fascia which extends between the inferior ischiopubic rami and merges with the perineal body posteriorly
78
What is the fascial component of the urogenital triangle termed?
The perineal membrane
79
What does the urogenital diaphragm do?
Seperates the urogenital triangle into a deep and superficial part
80
What structures pierce the urogenital diaphragm?
Urethra in both sexes
| Vagina in the female
81
What forms the external urethral sphincter?
Muscles within the urogenital diaphragm (external urethral sphincter is considered to be within the deep perineal pouch)
82
What is the nerve supply to the external urethral sphincter?
Branch to the deep perineal pouch from the perineal nerve (From the pudendal nerve)
83
Which vessel does the external pudendal artery branch off and what does it supply?
Branches off the femoral artery in the thigh
| Supplies the anterior scrotumj
84
What are the branches of the internal pudendal artery?
1) Inferior rectal artery
2) Perineal artery which gives rise to a vessel to the musculature of the superficial perineal pouch and continues as the posterior scrotal or labial artery
3) Artery to bulb which gives rise to an artery to the external urethral sphincter and other muscles of the deep perineal pouch)
4) Deep artery of penis or clitoris
5) Dorsal artery of penis or clitoris
85
Why would rupture of the urethra in the bulb of the penis lead to swelling of the scrotum penis and lower abdominal wall?
Urine escapes into superficial perineal pouch leading to swelling of the penis and scrotum
Urine escapes into the deep perineal pouch and travels up around prostate and bladder leading to swelling of lower abdominal wall
86
What is the bulb of the penis and the crura of the corpus cavernosa?
Bulb of the penis = attached part of corpus spongiosum
| Crura of the corpus cavernosa = attached part of corpus cavernosum
87
What is the attachments of the bulb of the penis?
Attached to the perineal membrane
88
What is the attachments of the crura of the corpus cavernosa?
Runs on the medial surface of the ischiopubic rami and is attached to the perineal membrane (fascial layer of the perineal diaphragm)
89
What is glans penis?
Expanded part of corpus spongiosum
90
What are the 4 parts of the male urethra?
1) Prostatic urethra - through prostate gland
2) Membranous urethra - from prostatic urethra through urogenital diaphragm to the buld of penis
3) Bulbous urethra - running through the bulb of the penis
4) Spongy urethra - through corpus spongiosus
91
What is the mucosal fold in the male urethra?
Fold at posterior part of penile urethra
92
How should a urethral catheter be passed in a male?
Directed to the base of the urethra until its passed the mucosal fold and then should pass easily
93
What are the actions of the bulbospongiosus and ischiocavernosus muscles?
Bulbospongiosus - move blood from the attached parts of the penis/clitoris into the glans (in men also removal or residual urine from urethra after urination and pulsatile emission of semen during ejaculation)
Ischiocavernosus - Move blood from the attached part of the penis into the erect penis or clitoris
94
What is the innervation of bulbospongiosus and ischiocavernosus?
Pudendal nerve (S2-S4) (Specifically the branch called the perineal nerve - superficial branch?)
95
What arteries supply the penis?
The deep artery of the penis
Dorsal artery of the penis
Both come off the internal pudendal artery
96
Through what does the urethra run in the penis?
Corpus spongiosum
97
What are the erectile tissues of the penis?
2 Corpus cavernosa lie dorsally in anatomical position
| 1 corpus spongiosum lies ventrally in anatomical position
98
Through what do the deep arteries of the penis run?
Through the corpus cavernosa
99
What is the mechanism of penile erection?
Vascular event generated by PS fibres
Stimulation of these nerves causes specific arteries in the erectile tissues to relax allowing blood to fill the tissues and the penis to become erect
100
What is the sensory nerve supply to skin of the scrotum?
Anteriorly the ilioinguinal nerve
| Posteriorly the posterior scrotal nerve which is the continuation of the perineal nerve, a branch of the pudendal nerve
101
From what is the tunica vaginalis derived?
The peritoneum - remnant of the processus vaginalis - pouch of peritoneum dragged down when the testes descended
102
What artery lies medial to the deep inguinal ring?
Inferior epigastric
103
What is an indirect hernia?
Passes through deep inguinal ring
104
What is the vulva?
Name for the female external genitalia
105
What is the vestibule in the female vagina?
Area between the labia minora
106
What is the mons pubis in the female vagina?
Rounded mass of fatty tissue over the pubic symphysis - forms the anterior part of vulva
107
What is the perineal raphe?
Line between the vaginal opening and anal aperture in females
108
Why are urinary tract infections more common in females than males?
Women have a shorter urethra - less distance for the bacteria to travel to the bladder
109
What is the bulb of the vestibule in women and what is it attached to?
Mass of erectile tissue in which lies under the skin and fat of the labia majora - split into a left and right side with the vaginal opening running between the 2 sides
Firmly attached to the perineal membrane
Partially overly the greater vestibular glands and are themselves covered with a thin sheet of muscle called the bulbus spongiosus
110
What forms glans clitoris?
The joining of the 2 bulbs of vestibule anterior to the external urethral opening
111
`Other than the bulbs of vestibule what other masses of erectile tissue contribute to the formation of the clitoris and which part do they form?
Corpora cavernosa
| Form the body of the clitoris
112
What is the crus of the clitoris?
Attached part of the corpus cavernosa which is attached to the perineal membrane running along the medial surface of the ischiopubic rami
113
What is the function of the Bartholin's or vestibular glands?
Pea shaped mucous glands on each side of the vaginal openings (female version of the bulbourethral glands) - like the bulbourethral glands they produce secretions during sexual arousal
114
To which nodes does lymph from the perineal structures drain?
Deep parts of perineum - internal iliac nodes
Superficial tissues of penis and vagina - superficial inguinal nodes
Clitoris and penis - deep inguinal nodes and external iliac nodes
Testes - aortic/lumber/pre aortic nodes between L1 and L2
115
What is formed in infections of the vestibular glands in a female?
Bartholin's cyst
116
In the male what part of the urethra do the bulbourethral glands empty into?
The membranous urethra
117
What nerve is responsible for the cremasteric reflex?
The genital branch of the genitofemoral nerve which innervates the cremasteric muscles within the coverings of the spermatic cord
118
What is the blood supply to the anterior and posterior scrotum?
Anterior - external pudendal from the femoral artery
| Posterior - posterior scrotal from the perineal artery from the internal pudendal
