Abdomen Flashcards
What is the anterior abdominal wall?
It is the muscle coating over the abdomen.
What is the function of the anterior abdominal wall?
To allow for lateral rotation, flexion, and extension
What is the gross anatomy / boundaries of the anterior abdominal wall?
Campers fascia / scarpers fascia
External oblique (free edge makes the inguinal ligament)
Internal oblique
Transversus abdominis (internal oblique and transversus abdominis make the conjoint tendon)
Rectus abdominis and the rectus sheath (fibres of external oblique, internal oblique and transversus abdominis change relative to the umbilicus to make the conjoint tendon)
Rests on transversalis fascia and peritoneum
Has umbilical folds on the surface - median, lateral and medial umbilical folds
What are the relations of the anterior abdominal wall?
Median umbilical ligament - obliterated urachus
Lateral umbilical ligament - inferior epigastric artery and vein
Medial umbilical ligament - obliterated umbilical artery
What is the arterial supply of the abdominal wall?
Superior epigastric artery (comes off the internal thoracic artery) + musculophrenic artery
Inferior epigastric artery (comes off the external iliac artery) + deep circumflex iliac artery
Thoracoabdominal artery (continuation of intercostals / lumbar artery)
What is the venous drainage of the anterior abdominal wall?
Superior epigastric vein
Inferior epigastric vein
Thoracoabdominal vein
What is the lymphatic drainage of the abdominal wall?
Superiorly - to the axilla
Inferiorly - to the inguinal nodes
What is the nerve supply of the anterior abdominal wall?
T7 - T12 does the entire anterior abdominal wall (and L1)
**Note - the conjoint tendon is L1, therefore anything which forms the conjoint tendon i.e. transversus abdominis and internal oblique will also be L1
What is the muscles / ligaments and fascia involved with the anterior abdominal wall?
transversalis fascia
peritoneum posteriorly
Median, medial and lateral umbilical ligaments
Conjoint tendon (made by fibres of TA + IO)
inguinal ligament (made of free edge of external oblique)
What are the anatomical variations of the anterior abdominal wall?
Pyramidalis (muscle that may or may not be present)
Persistent vitello intestine duct
Urachus (partial or completely patent)
Congenital herniation - exomphalos, oomphocele
Persistent vitellointestinal duct
How do the fibres of external oblique, internal oblique, transversus abdominis vary with respect to the rectus sheath?
Above arcuate line - EO, IO completely wrap around rectus abdominis, TA and TF only posterior
Below arcuate line - EO, IO, TA all anterior, TF posterior
Just above pubis - EO, IO, TA infront of rectus abdominis, TF posterior
What is the rectus abdominis?
It is one of the main anterior abdominal wall muscles.
It is covered by an aponeuroses which is formed by the anterolateral abdominal wall muscles called the rectus sheath.
It contains tendinous intersections.
What is the function of the rectus abdominis?
It is involved in the flexion of trunk.
What is the anatomy of the rectus sheath?
It is formed by the aponeuroses of the anterior abdominal wall muscles, which cover the rectus abdominis above the arcuate line (not the umbilicus).
Below the arcuate line, the three anterolateral muscles will pass anterior to rectus abdominis.
What is the origin and insertion of the rectus abdominis muscle?
Origin: pubic symphysis and pubic crest
Insertion: Xiphoid process, medial costal cartilage
Contains tendinous intersections
What is the contents of the rectus sheath?
External oblique aponeurosis
Internal oblique aponeurosis
Transversus abdominis aponeurosis
Transversalis fascia
Rectus abdominis muscle
What is the course of the rectus sheath relative to the arcuate line?
The rectus sheath:
Above the arcuate line:
EO aponeuroses is anterior
IO aponeuroses is anterior and posterior
Transversus aponeuroses is posterior
Then transversalis fascia
Below the arcuate line:
EO, IO, TA is anterior
Whereas transversalis fascia is posterior
What are the relations to the rectus abdominis muscle?
Midline - linea alba
Laterally - semilunaris
Posteriorly - transversalis fascia
Superior and inferior epigastric arteries run in the rectus sheath- posterior to rectus abdominis
What is the arterial supply of the rectus abdominis muscle?
Superior epigastric artery
Inferior epigastric artery
They anastomose in the rectus sheath to form the external iliac - subclavian anastomosis.
What is the venous drainage of the rectus abdominis muscle?
The superior epigastric vein and inferior epigastric vein
What is the lymphatic drainage of the rectus sheath?
Superiorly drains to the axilla
Inferiorly drains to the inguinal nodes
What is the nerve supply of the rectus abdominis?
Nerve supply is T7-T12
And then additionally L1 due to the conjoint tendon
What are the muscles / ligaments involved with the rectus abdominis?
Linea alba
Arcuate line
Linea semilunaris
What are the anatomical variations associated with the rectus abdominis muscle?
Pyramidalis
What is the inguinal ligament?
It is a fibrous band made of the free edge of the fibres of external oblique.
What is the function of the inguinal ligament?
Function of the inguinal ligament is to form the floor of the inguinal canal.
Also gives origin to:
- internal oblique; lateral 2/3
- transversus abdominis; lateral 1/3
What is the gross anatomy of the inguinal ligament?
Origin: ASIS
Insertion: onto the pubic tubercle
- additionally gives origin to; pectineal ligament, lacunar ligament, reflected inguinal ligament (which crosses the midline)
Its inrolled edges form the floor of the inguinal canal
It is continuous with the fascia lata
What is the course of the inguinal ligament?
superiorly, sits the spermatic cord
What are the relations of the inguinal ligament?
Superiorly: deep inguinal ring (1-2cm above midpoint)
Inferiorly: femoral artery, femoral vein, femoral nerve
Medially: pubic symphysis, lacunar ligament, rectus abdominis
Laterally: ASIS, lateral cutaneous nerve of thigh, deep circumflex iliac artery
Posteriorly: inferior epigastric artery and vein
It is continous with the fascia lata
What is the arterial supply of the inguinal ligament?
External iliac artery
- the obturator - pubic anastomosis (which is important for a femoral hernia repair)
What is the venous drainage of the inguinal ligament?
Femoral vein
What is the lymphatic drainage of the inguinal ligament?
The inguinal lymph nodes
What is the nerve supply of the inguinal ligament?
ilioinguinal nerve (L1)
What is the function of the inguinal canal?
It is the passage between the anterior abdominal wall and the perineum
Transmits spermatic cord + ilioinguinal nerve in men.
Transmits round ligament of uterus+ ilioinguinal nerve in women.
Where does the inguinal canal sit?
In between the deep and superficial inguinal rings.
What is the gross anatomy of the inguinal canal?
2 rings -
Deep inguinal ring - crura of external oblique
Superficial inguinal ring - hole in transversalis fascia
Roof -
Arching fibres of internal oblique
Arching fibres of transversus abdominis
Internal oblique and transversus abdominis insert as the conjoint tendon
Anterior wall -
External oblique aponeurosis
Internal oblique aponeurosis (lateral 2/3)
Floor -
Inguinal ligament
Medially reinforced by lacunar ligament
Posterior wall -
Transversalis fascia
Conjoint tendon (medially)
What is the contents of the inguinal canal?
Spermatic cord
Round ligament
Ilioinguinal nerve L1
What are the relations of the inguinal canal?
Transmits the ilioinguinal nerve and the spermatic cord / round ligament
Superiorly: inferior epigastric artery and vein
Inferiorly: Femoral N/A/V
Medially: pubic tubercle/symphysis, rectus abdominis
Laterally: ASIS
What is the arterial supply to the inguinal canal?
obturator - pudendal anastomosis
What is the nerve supply of the inguinal canal?
L1, ilioinguinal nerve
What is the lymphatic drainage of the inguinal canal?
inguinal lymph nodes
What is the action of psoas major?
It is responsible for hip flexion
Where does the psoas muscle sit?
In the iliopsoas compartment
What is the origin and insertion of the psoas major?
ORIGIN: Vertebral bodies / intervertebral discs / transverse processes of T12 - L5
INSERTION: lesser trochanter of the femur
What is the course of the psoas muscle?
Goes lateral to the vertebral bodies
Then fuses with iliacus to form iliopsoas
Goes under the inguinal ligament, attaches to the lesser trochanter
What is the nerve supply for the psoas muscle?
L1-L2
What are the relations of the psoas muscle?
Anterior:
- genitofemoral N (L1-L2)
Lateral:
- iliohypogastric (L1)
- ilioinguinal
- lateral femoral cutaneous nerve (L2-L3)
- femoral nerve (L2 - L4)
Medially:
- obturator N (L2-L4)
- lumbosacral trunk
What is the arterial supply of the psoas?
The lumbar branches of the iliolumbar artery
What is the nerve supply of the psoas?
L1 - L2 via lumbar plexus
What is the muscles / ligaments / fascia involved with the psoas?
enclosed by psoas fascia
Hence why groin pain L1 - L2 is a sign of psoas abscess
The psoas fascia can retain pus
What is the anatomical variation of psoas major?
Presence of psoas minor
Where does the abdominal aorta sit?
In the retroperitoneum
What is the origin and course of the abdominal aorta?
Origin: comes through the diagphramatic hiatus at T12 with the azygos vein and thoracic duct.
Courses through the retroperitoneum, anterior and to left of the vertebrae
Terminates at L4-L5 and becomes the right and left common iliac.
What are the branches of the abdominal aorta?
Unpaired visceral branches
- Coeliac trunk T12
- Superior mesenteric artery L1
- Inferior mesenteric artery L2
Paired visceral
- adrenal arteries
- gonadal arteries
- renal arteries
Parietal
- inferior phrenic artery
- lumbar arteries
- median sacral artery
What are the relations to the abdominal aorta?
Anterior:
- Splenic vein and uncinate process of the pancreas
- Left renal vein
- Median arcuate ligament
- third part of duodenum
Posterior:
- T12 - L4 vertebrae
Superior:
- aortic hiatus
Lateral:
- sympathetic chain (ON LEFT)
- IVC, cisterna chili (ON RIGHT)
What are the relations of the veins involved with the abdominal aorta?
IVC will sit to the right and slightly anterior
The left renal vein crosses the abdominal aorta
What are the lymphatics related to the abdominal aorta?
para aortic nodes in the retroperitoneum
immediately medial/ posterior is the cisterna chili L2
What is the peritoneum?
It is a single serous membrane that lines the abdominal cavity
The parietal peritoneum and visceral peritoneum and it is connected by the supply structures in the mesentery
What is the function of the peritoneum?
The mesothelial cells secrete fluid, allow bowel to flow over one another
Double folds of mesentery will contain supply structures to structures in the visceral peritoneum
What is the gross anatomy of the peritoneum?
Greater sac - contains most of the abdominal contents
Lesser sac - posterior to the stomach and its mesenteries
What are the recesses involved in the peritoneum?
4 - duodenal
paraduodenal (contains IMV)
superior duodenal
inferior duodenal
retroduodenal
3 - caecal
superior ileocaecal
inferior ileocaecal
retrocaecal
2 - colon
Right paracolic gutter
Left paracolic gutter
What does the peritoneum contain?
Contains structures which are supplied by mesentery - e.g. small bowel
Primary and secondary retroperitoneal structures
What are the main compartments with respect to the peritoneum?
Supramesocolic
On right - includes morrisons pouch
Inframesocolic
Divided into 2 spaces by small bowel mesentry; Right infracolic [points at caecum] and left infracolic [can drain to pelvis]
2x gutters related to bowel which collect free fluid - left and right paracolic gutter
Right paracolic - communicates with lesser sac
Left paracolic - limited superiorly by phreniocolic ligament
What is the nerve supply of the peritoneum?
Parietal peritoneum has somatic sensation
Visceral peritoneum will use referred sensation to the dermatomal segment
What is the retroperitoneum?
The retroperitoneum is everything posterior to the peritoneum
Retroperitoneal space is everything between the peritoneum and transversalis fascia
What are the spaces in the retroperitoneum?
Divided by peri renal fascia
- Anterior perirenal space
Pancreas, ascending/descending colon, duodenum - Perirenal space
kidneys and adrenals - Posterior perirenal space
properitoneal fat
What is the difference between primary retroperitoneal and secondary retroperitoneal structures?
Primary retroperitoneal - never had a mesentery (aorta, kidneys)
Secondary retroperitoneal - had a mesentery, but it has regressed during development (ascending / descending colon)
What are the contents of the retroperitoneal space?
Arteries:
- Aorta and its parietal branches (median sacral, inferior phrenic, lumbar)
- Renal arteries
Veins:
- inferior vena cava
- azygos and hemi-azygos
Nerves:
- sympathetic chain
- iliohypogastric, ilioinguinal, lateral femoral cutaneous nerve of thigh, femoral nerve
Lymphatics:
- cisterna chili at L2
- thoracic duct
Viscera:
- Pancreas, retroperitoneal duodenum, ascending + descending colon
- kidneys, adrenal glands, and their vessels
What is the purpose of the stomach?
It is a J shaped pouch that holds a food bolus
Involved in digestion via acid secretion and emulsion of a food bolus
What is the gross anatomy of the stomach?
Cardia (continuous with GOJ)
Fundus (most superior part)
Body
Antrum
Pylorus (is marked by the pre pyloric vein)
What are the relations of the stomach?
Anterior:
left lobe of liver
left hemidiagphram
Posterior:
pancreas
splenic artery
left kidney + spleen
aortic / coeliac trunk
lesser sac
Inferior:
transverse mesocolon
What is the arterial supply of the stomach?
Lesser curvature
- Left gastric (coeliac trunk)
- Right gastric (proper hepatic + common hepatic)
Greater curvature
- left gastroepiploic (from splenic A)
- right gastroepiploic (gastroduodenal A, from common hepatic A)
- short gastric arteries
What is the venous drainage of stomach?
Lesser curvature
- left gastric vein + right gastric vein to portal
Greater curvature
- left / right gastroepiploic to splenic V
- prepyloric V to sphincter
What is the lymphatic drainage of the stomach?
nodes in greater + lesser omentum
drain to coeliac nodes
What is the nerve supply of the stomach?
vagal trunk
T7- T9 (pain referred to epigastric)
What is the muscles/ligaments/fascia of the stomach?
Lesser omentum - ventral mesentry
Greater omentum - dorsal mesentry
What is the anatomical variation of stomach?
Right gastric A from common hepatic A, gastroduodenal A, left hepatic A
hypertonic/orthotonic/atonic/hypotonic
What are the coeliac trunk variants?
Any of its branches can come from the abdominal aorta.
- left gastric
- common hepatic
- splenic
any of its branches can come from the superior mesenteric artery
superior mesenteric artery can come off the coeliac trunk
can provide origin too:
- right hepatic artery
- left hepatic artery
- dorsal pancreatic artery
- gastroduodenal artery
- inferior phrenic artery
What is the lesser sac and what is its function?
It is the space behind the lesser omentum.
Its purpose is to allow the stomach to expand superiorly.
How is the lesser sac formed?
It is formed by the reflections of the lesser omentum and greater omentum
What is the gross anatomy of the lesser sac?
Anterior:
- lesser omentum
- stomach
- greater omentum
Posterior:
- Greater omentum (this overlies the transverse mesocolon)
- Transverse mesocolon
- Pancreas
- Kidneys
- Upper kidney/adrenal/aorta/coeliac plexus
Superior:
- caudate lobe of liver
Inferior:
-transverse mesocolon
Left:
- splenorenal ligament
- gastrosplenic ligament
Right:
- foramen of winslow
- * superior is the caudate lobe
* inferior is the duodenum
* anterior is the portal vein with hepatoduodenal ligament
*posterior is IVC
What are the relations to the lesser sac?
Laterally - spleen
Anterior - stomach
Posterior - pancreas
What is the function of the coeliac trunk?
To supply the foregut.
What is the origin of the coeliac trunk? And what are its branches?
Arises from the abdominal aorta ventrally at T12.
Left gastric A, Common hepatic A, Splenic A
What does the coeliac trunk supply?
Supplies the foregut structures:
- gastrointestinal tract from the GOJ to the second part of the duodenum
- pancreas
- gall bladder
- liver
- spleen
What are the relations of the coeliac trunk?
Superior: Aortic hiatus (with azygos and thoracic duct)
Inferior: Pancreas, SMA
Anterior: Lesser omentum
Posterior: abdominal aorta
Left: stomach
Right: IVC
What is the lymphatic supply of the coeliac trunk?
coeliac lymph nodes
what is the nerve supply of the coeliac lymph nodes?
coeliac plexus
What are the anatomical variations of the coeliac trunk?
Any of its branches can come off the abdominal aorta.
There can be a common origin of the coeliac trunk + SMA.
Any of its branches can come from the superior mesenteric artery.
Can provide origin too; dorsal pancreatic A, right hepatic A, left hepatic A, gastroduodenal A, inferior phrenic A
What is the arc of buhler?
Communication between coeliac trunk and SMA
What are the collateral systems between the coeliac trunk + superior mesenteric artery?
- GASTRODUODENAL A: common hepatic A + inferior pancreaticoduodenal A (coming off SMA).
- Arc of buhler: persistent embryonic collection between superior mesenteric artery + coeliac axis.
- DORSAL PANCREATIC A: splenic A and anterior and posterior pancreaticoduodenal A (kirks arcade)
- Link between right gastroepiploic (GDA) and left gastroepiploic (splenic)
What is the function of the superior mesenteric artery?
It supplies the midgut.
What is the origin and course of the superior mesenteric artery?
Origin is L1, courses inferiorly and laterally. and through the mesentery of the small bowel
Terminates at the ileum ileocolic A.
What are the branches of the superior mesenteric artery?
On the left:
- Jejunal arteries
- ileal arteries
On the right:
- ileocolic A
- appendiceal A comes off ileocolic A
- Right colic A
- Middle colic A
- Caecal A: anterior caecal A, posterior caecal A
Pancreatic:
- inferior pancreaticoduodenal - anterior and posterior branches
What are the relations to the superior mesenteric artery?
The superior mesenteric vein will always lie to the right- otherwise can be suggestive of malrotation
Anastomoses with the IMA with the margin artery of drummond
Anterior is the neck of pancreas, and posterior is the uncinated process
What is the lymphatic drainage of the superior mesenteric artery?
Superior mesenteric nodes (around SMA origin)
What is the nerve supply of the superior mesenteric artery?
Superior mesenteric plexus
What are the anatomical variations of the superior mesenteric artery?
Can replace:
Common hepatic A
Right hepatic A
Splenic A
Left gastric A
Arc of buhler
arc of riolan (this is a connection between IMA + SMA)
Accessory middle / right colic A
Absent right / middle colic A
Common origin of R/M colic A
What is the function of the inferior mesenteric A?
To supply the hindgut
What is the origin and course and branches of the inferior mesenteric A?
L3 from the abdominal aorta (unpaired)
Travels inferiorly and to the left, terminates as the superior rectal A
What are the branches of the inferior mesenteric A?
Left colic A
Sigmoid A
Superior rectal A
What are the relations of the inferior mesenteric A?
Superior: 3rd part of duodenum
Anastomoses with SMA via marginal artery of drummond (via arc of riolan as well if present)
How is the liver anatomically divided?
Divided into 8 segments (couinad classification) and will be with a portal vein, bile duct and hepatic artery supplying it
The hepatic veins will divide the liver sagitally, whereas the portal vein will divide the liver axially.
Left hepatic will divide segments 2+3 / segment 4
Right hepatic will divide segment 5 / 8 and 6 and 7.
Middle hepatic will divide segment 4 from 5/8
What are the relations of the liver?
Caudate lobe is posterior and 1
Lobes 2 + 3 are to the left of the falciform ligament
What is an anatomical variant of the liver?
Riedels lobe - extension of segment 6
Where does the blood supply of the liver sit and how does it occur?
Sits in the free edge of the lesser omentum. Portal vein is posterior. And CBD is lateral
Coeliac Trunk -> Common hepatic -> proper hepatic -> R+L hepatic A
What is the branches of the common hepatic A?
proper hepatic A
gastroduodenal A (gives off superior pancreaticoduodenal A and gastroepiploic A)
Enters the porta hepatis and becomes the right and left hepatic (from proper hepatic A) which it terminates
What is significant about the anatomical relations of the Right hepatic artery?
It should pass anterior to the common hepatic duct.
It should also pass anterior to the portal vein
So right hepatic artery should be most anterior
What are the possible anatomical variations in the hepatic artery?
Can be accessory or replaced.
Common hepatic A -
* can come off directly from the aorta
* can come off the SMA directly
* can not exist at all, right and left hepatic artery can come off directly from the coeliac trunk
Right hepatic A -
* can be replaced by SMA
* can come off the coeliac trunk
* can be duplicated, accessory R hepatic A
Left hepatic A -
* can be duplicated as an accessory left hepatic A
* can be replaced as the Left gastric A
What is the purpose of the portal vein?
To provide the venous drainage of the spleen, liver, pancreas, gall bladder, gastrointestinal tract
What is the normal pressure of the portal vein?
Normal pressure 10mmhg. > 40mmhg portal hypertension
What is the function of the portal vein?
Provides 85 percent of the blood supply to the liver.
This is why during arterial enhancement of the liver it tends to be poor on imaging, and is much better during venous phase.
What is the origin of the portal vein?
Union of splenic vein and superior mesenteric vein.
Meets behind the neck of pancreas. At level L1/L2.
What is the course of the portal vein?
Runs in the free edge of the lesser omentum.
It is the most posterior structure.
The CBD is lateral and the hepatic artery is anteromedial.
What is the termination of the portal vein?
Terminates into the porta hepatis.
Becomes the R) + L) portal veins.
What are the tributaries of the portal vein?
Tributaries/branches include:
- Splenic Vein
- Inferior mesenteric Vein
- Superior mesenteric Vein
- Right gastric vein
- Left gastric vein
- Cystic vein
What are the relations of the portal vein?
Anterior - neck of pancreas
Posterior - foramen of winslow / lesser sac / IVC
(as it enters the porta, the caudate lobe seperates the portal vein and IVC)
In the portal triad - remember the portal vein is posterior to the hepatic artery and bile duct.
CBD lateral, portal vein is posterior, hepatic artery (anteromedial)
Where are the portosystemic anastomosis?
Umbilical - re opened paraumbilical vein
Lower end of oesophagus - via left gastric vein
Wall of anal canal - via superior rectal vein
Bare area of liver - phrenic vein, intercostal vein, hepatic vein
+/- ascending and descending colon
What are the muscles and ligaments attached to the portal vein?
Ligamentum teres (attached to the left portal vein) + ligamentum venosum
What are the variations in the portal vein?
Trifurcation
Sits anterior to hepatic A
Sits anterior to head of pancreas / first part of duo
Anterior to CBD
Enters IVC
Pulmonary vein may enter it
Right portal vein passes anterior to Right hepatic A
Where does the superior mesenteric vein run?
Runs with SMA in the small bowel mesentery
SMV runs to the right.
What are the relations to the splenic vein?
RUns inferior to the splenic artery
Posterior to pancreas
Anterior to left kidney
What vessels are involved with the portosystemic anastomosis?
Umbilical vein - via the paraumbilical vein
Lower oesophageal sphincter - via left gastric vein
Rectal - superior rectal vein
Bare area of liver - phrenic V, costal V, hepatic V
What is the lymphatic drainage of the portosystemic anastomoses?
Porta hepatis nodes
What are the anatomical variants associated with the portal vein?
trifurcation
duplicated (from non union of SMV / splenic)
anterior to neck of pancreas / duodenum
portal vein anterior to hepatic artery
portal vein anterior to the common bile duct
portal vein may enter ivc
pulmonary vein may enter portal vein
congenital portal vein stricture
Right portal vein is anterior to hepatic artery
What are the anatomical variants associated with the SMV?
may lie to the left of the SMA ?malrotation
Left gastric vein to SMV
Inferior mesenteric vein drains to the SMV (instead of splenic V)
What are the anatomical variants associated with the inferior mesenteric vein?
drains into the splenic V + superior mesenteric V confluence instead of the splenic V.
What is the purpose of the superior mesenteric vein?
Purpose is to drain the midgut to the portal vein
runs to the right of the superior mesenteric artery
What is the origin of the superior mesenteric vein?
Ileocolic vein (think reverse of the SMA!)
runs in the mesentery and lies to the right of the SMA.
Where does the superior mesenteric vein terminate?
Terminates with the splenic vein as the portal vein.
What are the tributaries or branches of the superior mesenteric vein?
Right colic vein
Middle colic vein
Ileocolic vein
Jejenal / ileal vein
R gastroepiploic vein
inferior pancreaticoduodenal vein
What are the relations to the superior mesenteric vein?
Will always lie to the right of the superior mesenteric artery
Anterior - neck of pancreas
Posterior - uncinated process of pancreas
What is the lymphatic drainage of the superior mesenteric vein?
Related to the SMA lymph nodes.
What are the anatomical variations of the superior mesenteric vein?
Left gastric vein into SMV
Left gastric vein into the splenic V
Inferior mesenteric vein drains into the SMV vein as opposed to the splenic
Inferior mesenteric vein drains into SMV / splenic confluence
What is the purpose of the inferior vena cava?
It is the common drainage pathway for the lower trunk, abdomen and pelvis
Where does the inferior vena cava sit?
Sits in the retroperitoneum, to the right of the aorta.
What is the gross anatomy of the inferior vena cava?
It is formed by the union of the common iliac veins (L5)
goes through the retroperitoneum and then through the R diagphramatic hiatus at T8 WITH THE PHRENIC N
Terminates in R atrium of heart
What are the branches of the IVC?
Common iliac veins
Renal vein (L1)!
R Gonadal vein
R adrenal vein (left adrenal and left gonadal drain into the left renal V)
Inferior phrenics
Right / Middle / Left hepatic V
azygos / hemi azygos V
What are the relations of the IVC?
Anterior:
- lesser sac/foramen of winslow/ portal vein
Posterior:
- vertebral body
Superior:
- diaphragmatic hiatus at T8
Inferior:
- common iliac vein (unites at L5)
On left - aorta.
through diagphragmatic hiatus, goes at T8, related to phrenic N
What is the lymphatic drainage of the IVC?
retroperitoneal nodes
What are the anatomical variants of the IVC?
IVC duplication
High union
Left sided IVC
Circumcaval ureter
Eustachian valve
Left renal vein can pass posterior to aorta
What are the kidneys?
They are paired retroperitoneal organs.
Sit between L2 - L3
Their function is to connect to the ureter
What is the function of the kidney?
To filter the blood and produce urine. Endocrine function
Where do the kidneys sit?
Oblique lie. Retroperitoneal. T12 - L3
In the perirenal space in the retroperitoneum
Left is higher than right
What is the gross anatomy of the kidney?
Superior pole
Middle - hilum, vein artery ureter (ANT TO POS)
Inferior - has a fibrous capsule
Surrounding perirenal fascia - open at the bottom so that pus/urine can extravasate out of kidney
Renal pelvis connects to the ureter
What is the contents of the kidney?
Cortex - pyramids, nephrons
Medulla - pelvis, major caylx, infundibula, minor caylx
What are the relations of the left kidney?
Anterior: pancreas, splenic A, stomach
Inferior: splenic flexure
Lateral: spleen, 12th rib
Superior: adrenal gland
Sits on quadratus lumborum
Medial will be a great vessel - aorta to the left kidney
What are the relations of the right kidney?
Anterior: 2nd part of duodenum
Inferior: hepatic flexure
Lateral: 12th rib
Superior: adrenal gland
Sits on quadratus lumborum
Medial will be a great vessel - IVC to the right kidney
What is the venous drainage of the kidneys?
Right renal vein drains directly into the IVC
Left renal vein is longer, goes anterior to the aorta to plug into IVC
What is the lymphatic drainage of the kidneys?
HILAR -> The para aortic lymph nodes
What is the nerve supply of the kidney?
T11-T12
What are the muscles/ligaments/fascia around the kidney?
Perirenal fascia: which divides the retroperitoneum
Anterior perirenal fascia
Posterior perirenal fascia
What are the anatomical variants of the kidney when considering structure of kidney?
- Horseshoe kidney
- Duplex kidney (2 ureters, 2 orifices)
- Pelvic kidney (doesn’t ascend)
- Renal agenesis
- Renal malrotation
- Pancake kidney (kidneys fused together in the pelvis)
- Thoracic kidney
-Dromedary hump - Persistent fetal lobulation
What are the arterial variants that can occur with the kidney?
accessory renal artery - occurs in 30 percent of people!
aberrant renal artery - from SMA, from coeliac trunk or IMA.
Rearrangement of V - A - T, can be anterior or posterior
What are the venous variants that can occur with the kidney?
Accessory renal vein
retroaortic renal vein
circumaortic renal vein
left renal vein drains to iliac vein
What are the ureteric variants that can occur with the kidney?
Bifid ureter
retrocaval ureter (behind IVC)
Fenestrated ureter
circumcaval ureter (around IVC)
What is the gall bladder?
It is a pear shaped sac which is responsible for the storage and transmits it to the 2nd part of the duodenum.
Where does the gall bladder sit?
Sits under the right lobe of the liver, under 9th costal cartilage
What is the gross anatomy of the gall bladder?
It is made of the fundus, body and neck.
Neck has the cystic duct, which joins the common hepatic duct and becomes the bile duct. It has a spiral valve
What is the bile duct?
It is formed by the union of the common hepatic duct and the cystic duct.
What is the course of the bile duct?
It is supraduodenal
Retroduodenal
Paraduodenal
And joins the pancreatic duct
Terminates in the ampulla of vater (D2)
What are the relations of the gall bladder?
Superior - liver
Inferior - hepatic flexure, transverse colon, D2
Anterior - transverse colon, liver, 9th costal cartilage
What are the relations of the bile duct?
It will run in the free edge of the lesser omentum.
Will be intimately related to the hepatic artery and portal vein. Is lateral to the hepatic artery and portal vein
What is the relations of the cystic artery?
In 2/3 of people it is posterior to the right hepatic duct
What is the arterial supply of the gall bladder?
It is usually the cystic artery which comes off the right hepatic A.
In some people it can come off proper hepatic A, common hepatic A, or GDA.
What is the venous drainage of the gall bladder?
The cystic vein. Which drains into the portal vein.
What is the lymphatic drainage of the gall bladder?
To the portal nodes.
What is the nerve supply of the gall bladder?
T7 - T9
Also has sympathetic supply from the coeliac ganglia and right phrenic N (C3, C4, C5)
What are the anatomical variants associated with the gall bladder?
Phyrgian cap (fundus folds over onto body)
accessory gall bladder
gall bladder agenesis
left sided gall bladder
ducts can go straight from liver to gall bladder, circumventing cystic duct/CHD
What is the anatomical variant associated with the arteries of the gall bladder?
Cystic A can be replaced by right hepatic A, proper hepatic A, common hepatic A, gastroduodenal A
What are the cystic duct variants associated with the gall bladder?
cystic duct duplicate
cystic duct absence
low insertion, medial insertion, parallel insertion of cystic duct
Cystic artery can run anterior or posterior to RHD
What are the anatomical variants associated with the common hepatic duct?
cystic artery can run anterior to the right hepatic duct (usually runs posterior).
Absent common hepatic duct (non union of left and right hepatic ducts)
accessory hepatic duct - to cystic duct or common bile duct
Abberant hepatic duct
What are the anatomical variants associated with the common bile duct?
Supraduodenal CBD, in the free edge of the lesser omentum (i.e. it is not the most lateral structure)
Goes through pancreas
Partially covered posteriorly
Uncovered and be seperate from the pancreas
May pass lateral to pancreatic head
Can exit into D1, D2, D3
CBD may not unite with pancreatic duct
What are the common cystic artery variants?
Arteries can travel directly from the gall bladder to the liver. Important for lap chole
Cystic artery duplication
Cystic artery can arise from, coeliac trunk, left hepatic A, proper hepatic A, gastroduodenal A, superior mesenteric A
IN 2/3 OF INDIVIDUALS THE CHD IS ANTERIOR TO THE RIGHT HEPATIC ARTERY
What is the biliary tree anatomy?
Bile is produced by hepatocytes which will travel through bile canaliculi to the biliary ductules of portal triads to the bile ducts, and then the common hepatic duct, cystic duct to then be stored in the gall bladder.
Cystic duct and the common hepatic duct will unite to create the common bile duct.
CBD has the supraduodenal part (which runs in the free edge of the lesser omentum, lateral to the portal vein + hepatic artery), retroduodenal part and paraduodenal part. Joins pancreatic duct
Drains via the ampulla of vater to D2.
What are the relations to the biliary tree?
Gall bladder - will sit in the gall bladder fossa under the 9th costal cartilage
Common hepatic duct, the right hepatic duct should be anterior to the cystic artery
Cystic duct will plug into a variable position to form the CBD
How does the CBD relate to the duodenum?
Supraduodenal - runs in the free edge of the lesser omentum
Retroduodenal - behind D1
Paraduodenal - runs in the posterior surface of the pancreatic head, GDA is anterior
What is the arterial supply of the biliary tree?
Cystic artery branches
right hepatic artery branches
posterior superior pancreaticoduodenal A branches
What is the venous drainage of the biliary tree?
To the portal vein
What is the lymphatic drainage of the biliary tree?
porta hepatis
What is the nerve supply of the biliary tree?
Parasympathetic - Vagal trunk
Sympathetic - coeliac ganglia and R phrenic
What are the ureters?
Paired tubes that transport urine made by the kidneys to the bladder. They are retroperitoneal
What is the gross anatomy of the ureter?
Starts at the renal pelvis
Travels down on psoas major
On the tips of the transverse processes (sagitally)
Goes into pelvis, crosses anterior to bifurcation of iliac arteries (therefore is anterior to the SI joint)
Terminates via entering the bladder
What are the anatomical narrowings associated with the ureter?
PUJ
Pelvic brim
VUJ
What are the relations of the ureter?
Courses in the saggital plane of the transverse processes
Runs over psoas
On right -
anterior is D2, gonadal A +V, right colic vessels, ileocolic vessels
on left -
anterior gonadal A +V, left colic A, sigmoid mesentery, colon
in pelvis, the ureter is the most anterior structure, only exception is the vas deferens or uterine artery
What is the arterial supply of the ureter?
Renal A
Gonadal A (aortic branches)
Vesical A
What is the venous drainage of the ureter?
drain to renal V or gonadal V
What is the nerve supply of the ureter?
T10 - L1
What is the lymphatic drainage of the ureter?
Upper 1/3 - renal LN
Middle 1/3 - para aortic LN
lower 1/3 - int/ext iliac LN
What is the anatomical variation of the ureter?
Bifid ureter
Circumcaval ureter
Retrocaval ureter
Duplicate ureter
Ectopic ureter
Duplex collecting system
Uterocoele
What are the relations of the ureter in the pelvis?
Posterior:
SACROILIAC JOINTS
BIFURCATION OF THE ILIAC A
Anterior:
DUCTUS DEFERENS
UTERINE A
Inferior:
Male - seminal vesicle
Female - lateral fornix of vagina
What is the duodenum?
It is a C shaped loop of bowel that encircles the pancreatic head.
It is the link between the foregut (coeliac) and the midgut (superior mesenteric).
What is the function of the duodenum?
Function is to house the ampulla in D2. This is the outflow of the tract of the biliary system.
Where does the duodenum sit?
D2 sits in the transpyloric plane.
Runs from the pylorus to duodenal - jejunal flexure. L2-L3
Predominantly retroperitoneal apart from the first 2.5cm.
What is the gross anatomy of the duodenum?
C shaped organ which encircles the pancreatic head.
D1 - gastroduodenal artery is posterior. Pre pyloric vein marks the pylorus anteriorly.
D2 - runs in the transpyloric plane.
D3 - superior mesenteric artery and vein run anterior.
D4 - marked at the end by the ligament of treitz
What are the relations of the duodenum?
D2 sits in the transpyloric plane
What is the arterial supply of the duodenum?
Superior -
from coeliac - superopancreaticoduodenal A
Gastroduodenal A
Inferiorly -
from SMA
inferopancreaticoduodenal A
What is the venous drainage of the duodenum?
The duodenal cap will drain to the pre pyloric vein.
Proximal / superior duodenum will drain to the superiorpancreaticoduodenal vein which drains to portal vein.
Distal / inferior duodenum will drain to the inferior pancreaticoduodenal vein which drains to the SMV.
What is the lymphatic drainage of the duodenum?
Proximal / superior will drain to the coeliac nodes.
Distal / inferior will drain to the superior mesenteric nodes.
What is the nerve supply of the duodenum?
T7 - T10
Sympathetics - coeliac and superior mesenteric trunk
Parasympathetics - anterior and posterior vagal trunk
What are the muscles or ligaments invovled with the duodenum?
Ligament of treitz
What are the anatomical variants involved with the duodenum?
Duodenal diverticulum
Duodenal atresia
Duodenal duplication
Accessory duodenal ampulla
What are the relations of the first part of the duodenum?
D1 -
Anterior: gall bladder, liver, pre pyloric vein
Posterior: gastroduodenal A, pancreas, common bile duct, portal vein
Superior: lesser sac, foramen of winslow
Inferior: pancreas
What are the relations of the second part of the duodenum?
D2 -
Anterior: transverse mesocolon
Posterior: Right kidney, right ureter
Medial: ampulla, pancreatic head
Lateral: ascending colon, hepatic flexure
What are the relations of the third part of the duodenum?
D3 -
Anterior: superior mesenteric vein, superior mesenteric artery
Posterior: right psoas, right ureter, gonadal vessels
Superior: pancreatic head
Inferior: small bowel
What are the relations of the fourth part of the duodenum?
D4 -
Anterior: continuation as hilum
Posterior: left psoas
Medial: SMA/SMV
Superior: stomach
What is the pancreas?
It is a retroperitoneal organ which is nestled in the C shape of the duodenum.
It has both endocrine (insulin/glucagon/somatostatin) and exocrine function (secreting pancreatic juice)
What is the gross anatomy of the pancreatic head?
GDA will run anteriorly over the pancreatic head.
CBD will run posteriorly, lateral to the pancreatic head.
What is the gross anatomy of the neck of the pancreas?
Posterior to pancreatic head + neck, is the portal vein or portal confluence
What is the gross anatomy of the body and tail of the pancreas?
The splenic vein and splenic artery run along the body and tail
What is the gross anatomy of the uncinate process?
crossed anteriorly by SMV and SMA
What is involved with pancreatic ductal drainage?
There is the main pancreatic duct - which drains to ampulla in D2
accessory pancreatic duct which drains to minor papilla
both empty into D2 segment of duodenum
What is the arterial supply of the pancreas?
Given it is at foregut / midgut junction
splenic A (from coeliac)
superior pancreaticoduodenal A (GDA from coeliac.)
dorsal pancreatic A
inferior pancreaticoduodenal A (from SMA)
What is the venous drainage of the pancreas?
Pancreaticoduodenal veins
Splenic vein
What is the lymphatic drainage of the pancreas?
coeliac nodes / SMA nodes
What is the nerve supply of the pancreas?
T7 - T9 (from foregut)
T10 - midgut
What are the anatomical variants of the pancreas?
Pancreas divisum
Annular pancreas
Pancreatic rests/ ectopic pancreas
pancreatic duct anomalies
What is the function of the pancreatic duct?
To empty pancreatic juice via the major and minor papilla into the duodenum
What is a meckel’s diverticulum?
It is an outpouching, 2ft from the caecum, 2 inches long, can contain gastric mucosa, liver or pancreatic tissue.
What are the differences between the jejunum and the ileum - Jejunum only.
Makes up 40 percent of the length of the small intestine.
Thick walled. - wider. 3.5cm.
Has both straight arteries and arcade.
Numerous valvulae conviennentes
Is positioned in the left upper abdomen.
If an occlusion occurs in a straight artery - then leads to infarction.
If it occurs in an arterial arcade, doesn’t always lead to infarction due to collateral supply.
What are the differences between the jejunum and ileium - ileum only?
60 percent of the length of small intestine.
Narrower? 2.5cm
Contains peyers patches.
Larger series of arcades. (3-5). Shorter straight arteries
What is the nerve supply of the jejunum and ileum?
The PNS will augment peristalsis.
The SNS vasoconstrictor will inhibit peristalsis - from lateral horn of the spinal segments T9+T10.
What is the blood supply of the jejunum and ileum?
Left side of the superior mesenteric artery, travels through the root of the mesentry.
The arterial arcades - Anastomoses loops of the jejunal branches
The straight arteries - travel directly from arcades to the mesenteric border of the gut.
SMA will anastomose with the ileocolic branch to the terminal ileum
What is the caecum?
It is a blind pouch, past the ileocaecal valve.
What is posterior to the caecum?
Posterior to the caecum is the peritoneal floor of the right iliac fossa.
Iliacus
Psoas fascia
Lateral femoral cutaneous nerve
Femoral nerve
What are the taeniae coli?
3x bands of longitudinal muscle which will run and converge on the caecum 2cm below the ileocaecal valve. Converge on the appendix.
What is the retrocaecal recess?
Two folds of peritoneum posterior to the caecum.
What is the blood supply of the caecum?
Anterior and posterior caecal arteries which are a branch of the ileocolic A.
What is the gross anatomy of the pancreatic duct?
the main pancreatic duct drains into Major papilla drains into D2
ACCESSORY pancreatic duct drains into the minor papilla
What are the anatomical variants involved in the pancreatic duct?
Pancreatic divisum - failure or fusion of dorsal and ventral pancreatic buds, so no communication or fusion between accessory or main duct
Ansa pancreatica - fusion of the main and accessory pancreatic ducts
meandering main pancreatic ducts
Double accessory duct
Double main duct
tortuosity of ducts
What is the spleen?
Spleen is the unilateral organ of the reticuloendothelial system.
What is the function of the spleen?
Immune response.
erythropoesis, erythrocyte removal, blood storage
Where does the spleen sit?
Lies under the 9-11 ribs. in the left upper quadrant
Under left diagphram
Intra peritoneal
What is the gross anatomy of the spleen?
Notched anteriorly
Protected by ribs 9 to 11
Superior pole
Inferior pole - covered by a thin capsule
Hilum, has a splenic artery + vein
It is attached to the stomach via the gastrosplenic ligament (transmits short gastric A + gastroepiploic vessels)
attached to the kidney via the lineorenal ligament (transmits splenic A + vein)
What are the relations of the spleen?
Anterior; stomach (and gastrosplenic ligament)
Inferior; splenic flexure
Medial; left kidney, pancreatic tail
Lateral; Ribs 9, 10, 11
What is the arterial supply of the spleen?
Splenic A.
From coeliac!
What is the venous drainage of the spleen?
Splenic V.
drains to superior mesenteric vein.
What is the lymphatic drainage of the spleen?
Coeliac nodes.
What is the nerve supply of the spleen?
Coeliac plexus
What are the muscles/ligaments/fascia involved with the spleen?
gastrosplenic ligament
- carry splenic A +V, pancreatic tail
lineorenal ligament
- carry short gastric and LEFT gastroepiploic
What are the variations of the spleen?
Accessory spleen / splenunculus
Wandering spleen
Polysplenia
Asplenia
Retrorenal spleen
Spenogonadal fusion
What is the liver?
Single largest organ in the body
Function is to create bile and also drain the blood from the gastrointestinal tract
Sits in RUQ
What is the gross anatomy of the liver?
Wedge shaped organ
Divided into 9 segments, 1 caudate lobe.
Divided medially by the falciform ligament
Mostly covered by visceral peritoneum, bare area
What are the relations of the liver?
portal triad in the free edge of the lesser omentum
Posterior - IVC and hepatic veins
Inferior - gall bladder in gall bladder fossa
What is the blood supply of the liver?
Hepatic artery + portal vein
The venous drainage is the hepatic veins
What is the lymphatic drainage of the liver?
Drains to the nodes in the porta hepatis
EXCEPT the bare area - which will communicate with the lymph nodes outside the porta hepatis, the extraperitoneal lymph nodes -> drain to the posterior mediastinal lymph nodes
What is the nerve supply of the liver?
Sympathetic nerve supply is from coeliac plexus
Parasympathetic nerve supply of the liver is from the anterior and posterior vagal trunks
There will also be a contribution from the phrenics to the bare area
What are the muscles/ligaments/fascia involved with the liver?
liver capsule
falciform ligament
triangular ligament
coronary ligaments
What are the anatomical variations of the liver?
riedel lobe
saddle like liver
left lobe atrophy
left/right lobe agenesis
What is the caecum?
The caecum is the first part of the large bowel. After the ileocaecal valve.
It has retrocaecal recesses.
superiorileo caecal recesses.
inferior ileocaecal recesses
What is the ileocaecal valve?
It is made of smooth muscle, and protrudes into the lumen.
What is the appendix?
It is a finger like appendage which grows out of the inferior caecum.
Appendiceal artery comes off ileocolic.
Has a mesentery
What are the relations to the caecum?
Anterior: anterior abdominal wall, small bowel
Posterior: ilacus, psoas, femoral N, lateral femoral cutaneous N of thigh, retrocaecal recess
Medial: ileocaecal valve and terminal ileum
**appendix can be anterior, posterior, medial. - variable
Superior: ascending colon
Inferior: lateral 1/3 of inguinal ligament
What is the arterial supply of the caecum?
The anterior and posterior caecal arteries which come off the ileocolic A.
(SMA)
What is the venous drainage of the caecum?
The anterior and posterior caecal veins which drain to the SMV.
What is the lymphatic drainage of the caecum?
paracolic lymph nodes, to the SMA lymph nodes.
What is the nerve supply of the caecum?
Pelvic sphlancic nerves (S2-S4)
Superior mesenteric plexus - SYMPATHETIC
What is the muscles/ligaments/ Fascia of the caecum?
appendix is attached inferiorly
retroperitoneal. if volvulus occurs if the CAECUM HAS A MESENTRY
What are the anatomical variations of the caecum?
Cone shaped caecum
If caecum has a mesentry
Subhepatic caecum
Mobile caecum
What are the general principles behind the arterial supply of the colon?
Arterial supply to the colon uses derivatives of the SMA, IMA and the rectal arteries (which come off the internal iliac and IMA)
rectum - uses the superior rectal artery, middle rectal artery (internal iliac A), and the inferior rectal artery PLUS median sacral artery
SMA does the caecum, and the proximal 2/3 large bowel
IMA goes from White Line of Toldt of transverse colon to rectum,
What is the arterial supply of the colon?
Right colic, middle colic, left colic arteries
These 3 colic arteries are joined by the marginal artery of drummond.
Right colic + middle colic - from SMA (has ascending + descending branch)
Middle colic - has a left and right branch from SMA
Left colic - from the IMA. has ascending and descending branch.
Sigmoid artery - comes from the IMA!
What is the arterial supply of the rectum?
Superior rectal A - CONTINUATION of the inferior mesenteric A
Middle rectal A - comes off the internal iliac A
Inferior rectal A - comes off the internal pudendal A (which comes off internal iliac A)
Median sacral A - comes off the aorta and descends directly down
What are the variations associated with the rectal arterial / colonic arterial supply?
SMA can be replaced by common hepatic, right hepatic, left gastric, splenic A
accessory right / middle colic A
Arc of buhler - coeliac - SMA connection
Arc of riolan - SMA - IMA connection
What is the rectum and what is its function?
The rectum is the termination of the large intestine.
links the large bowel to the anus
Where does the rectum sit?
from S3 (rectosigmoid junction) to the coccyx
Termination is the anorectal junction which is determined by a sling of puborectalis
What is the gross anatomy of the rectum?
No tanaeia
No mesentry
No appendices epiploicae
3x internal rectal valves.
What are the relations of the rectum?
Posterior:
Relations:
Anterior:
=================
rectouterine/vesicouterine pouch
uterus / vagina in women. Prostate/seminal vesicle in men
bladder and ureters
S3, S4, S5 mesorectal fascia
lymph nodes
median sacral nodes
Ischial spine/levator ani
piriformis / obturator internus
What is the arterial supply of the rectum?
upper 1/3 - superior rectal A
middle 1/3 - middle rectal A
lower 1/3 - inferior rectal A
What is the venous drainage of the rectum?
upper 1/3 - superior rectal vein [drains to IMV and portal V]
middle 1/3 - middle rectal vein [internal iliac V]
lower 1/3. - internal pudendal vein [internal iliac V]
What is the lymphatic drainage of the rectum?
Follows the veins - upper 1/3 - IMA and portal nodes
Middle + lower 1/3 - internal iliac nodes
What is the nerve supply of the rectum?
Upper 1/3 - inferior mesenteric plexus
Middle 1/3 - superior hypogastric plexus
Lower 1/3 - inferior hypogastric plexus
What are the muscles / ligaments associated with the rectum?
mesorectal fascia
peritoneum -
upper 1/3: will be at the front and sides
middle 1/3: front only
lower 1/3: no peritoneum
What are the anatomical variations associated with the rectum?
fistula between rectum and pelvic viscera
imperforate rectum: high imperforate anus
What is the anal canal?
It is the termination of the gastrointestinal tract. Its function is to eliminate faeces.
Where does the anus sit?
Anus sits between puborectalis at S3 - and continues to the outside world
(puborectalis S3 is where the rectum stops)
What is the gross anatomy of the anus?
A tube within a funnel - 2 sphincters
Anal columns
Anal valves
Internal sphincter: made from continuation of smooth muscle of rectum (is involuntary and autonomic T11-L1)
External sphincter: deep, superficial and subcutaneous parts
richly and somatically innervated S2-S4. skeletal muscle
What is the pectinate line?
THe pectinate line will divide the anus up into its embryological origin:
superior; endoderm therefore it will be visceral / autonomic
inferior; ectoderm, therefore somatic
What are the relations of the anus?
Laterally - ischioanal fossa
inferior rectal nerve
anterior - bulbospongiosus
What is the arterial supply and venous drainage of the anus?
above pectinate line - superior rectal artery / superior rectal vein (IMV, splenic, portal vein)
below pectinate line - inferior rectal artery (internal iliac vein after inguinal, then IVC)
therefore venous drainage of anus is site of portosystemic anastomosis
What is the lymphatic supply of the anus?
Above pectinate line - inferior mesenteric lymph nodes
below pectinate lines - inguinal nodes
What is the nerve supply of the anus?
Above pectinate line - T11-L1, autonomic hypogastric plexus
below pectinate line - somatic S2-S4 (inferior rectal N from pudendal N)
What are the anatomical variations associated with the anus
imperforate anus
What are clinical applications associated with the anus?
Internal haemorrhoid (from internal mesenteric plexus = ectoderm = autonomic = painless). External haemorrhoid containing inferior rectal vein = ectoderm = somatic (inf. Rectal n.) = VERY PAINFUL
o DO NOT FORGET that below the pectinate line, the anus drains to inguinal LN. So, fissure in ano or an anal cancer will cause INGUINAL LYMPHADENOPATHY.
What is the transpyloric plane?
The transpyloric plane sits between L1 and L2.
It is mid way between the xiphisternum and umbilicus.
or between the angle of louis and pubic symphysis.
What are the structures in the transpyloric plane?
Gall bladder fundus
Neck of pancreas
Ampulla
L1 to L2 intervertebral disc
End of the spinal cord
Superior mesenteric artery
Hilum of the kidneys
Cisterna chili
Origin of portal vein
2nd part of duodenum!
Pylorus
What are the adrenal glands?
They are paired organs sitting on top of the kidneys
What is the function of the adrenal glands?
to make androgens, steroids, catelcholamines (adrenaline)
Where do the adrenal glands sit?
Sit in the retroperitoneum. In the perirenal space.
Sit superomedially to the kidneys. In a seperate capsule
What is the gross anatomy of the adrenal gland?
Cortex - is mesodermal, which creates steroids + androgens
Medulla - is ectodermal, which creates catelcholamines
What are the relations to the right adrenal gland?
anterior: liver
posterior: right crus of diagphram, quadratus lumborum
superior: RIGHT inferior phrenic A
medially: IVC
What are the relations to the left adrenal gland?
anterior: lesser sac, stomach, lesser omentum, splenic A, pancreas
posterior: left diagphramatic crus, quadratus lumborum
superior: LEFT inferior phrenic A
medial: aorta, coeliac axis
laterally: spleen
What is the arterial supply of the adrenal glands?
Superior adrenal A - comes off the inferior phrenic A
Middle adrenal A - comes off the aorta
Inferior adrenal A - comes off renal A
What is the venous drainage of the adrenals?
Right drains to the IVC
Left adrenal drains to the left renal vein
What is the lymphatic drainage of the adrenal glands?
The paraaortic lymph nodes
What is the nerve supply of the adrenal glands?
Sympathetic supply comes from the sphalncic plexus.
What are the muscles / ligaments / fascia involved with the adrenals?
They are covered in perirenal fascia but this is seperate from the kidneys.
What are the anatomical variations associated with the adrenal glands?
ectopic adrenal tissue. This is usually around the coeliac axis. However can get displaced by the gonads so can also be found; in broad ligament, spermatic cord, testis, epididimyis
Horseshoe adrenal gland
Pancake adrenal gland
What is the spermatic cord? And what is its function?
Cord which contains the epididymis and testis. To provide neurovascular supply to the testis.
Where does the spermatic cord sit?
Sits initially in the inguinal canal and descends to the scrotum
What is the gross anatomy of the spermatic cord? What is it made of?
Transversalis fascia - internal spermatic fascia
External oblique fascia - cremasteric fascia
internal oblique fascia - external spermatic fascia
What are the contents of the spermatic cord? Rule of 3’s
3 arteries
- testicular A
- artery to the vas
- cremasteric A
3 nerves
- genital branch of genitofemoral N
- cremasteric N
- autonomics
3 other things
- ductus deferens / vas deferens
- pampniform plexus
- lymphatics
What is the course of the spermatic cord?
origin: through the deep inguinal ring, through inguinal canal, destination: scrotum via superficial inguinal ring
What is the relations associated with the spermatic cord?
Anterior: ilioinguinal N
What are the anatomic variations associated with the spermatic cord?
patent processus vaginalis
paradidimyis
What are the testis and epididymis?
Essential organs of the male reproductive system, involved in sperm production and testosterone production
Where does the testis sit?
Sits in the scrotum, surrounded by the epididimis and spermatic cord
What is the general structure of the testicle?
Structure
Has an inferior and superior pole
2x coats
- tunica vaginalis - covers gubernaculum
- tunica albuginea - covers testis
Seminiferous tubule
Rete testis
Efferent ductules
Epidimyis (head)
Where is the epididimyis located?
Posterior to testis
Continuous with ductus deferens
- head and tail
What is the course of the sperm?
seminiferous tubules -> rete testis -> efferent ductules -> epidiymis -> vas deferens
What is the arterial supply of the testicles?
Testicular artery (which comes off the aorta)
What is the arterial supply of the epididimyis?
The arterial supply to the vas deferens, and cremasteric artery anastomoses.
What is the venous drainage of the testicles?
The pampniform plexus. -> to testicular vein and then IVC
What is the lymphatic drainage of the testicles?
To the para aortic lymph nodes.
What is the nerve supply of the testis?
It is the genital branch of the genitofemoral N.
Which sits in the spermatic cord.
What are the anatomical variants of the testis?
Undescended testis
Bilobed testis
Testicular appendages - testicular appendix, epidiymal appendix, vas abberans
What is the vas deferens?
It connects the epidiymis to the ejaculator duct.
It will start at the tail of the epidiymis, ascends in scrotum as part of spermatic cord, through the inguinal canal.
Hooks around inferior epigastric artery, goes anterior to the ureter, then joins the duct of the seminal vesicles to become the ejaculatory duct
What is the arterial supply of the vas deferens?
It is the artery to the vas. This runs in the spermatic cord.
Comes off the superior vesical or inferior vesical artery which comes off the internal iliac.
What is the venous drainage of the vas deferens?
internal iliac veins
What is the lymphatic drainage of the vas deferens?
Internal iliac nodes
What is the nerve supply of the vas deferens?
Sympathetics - inferior hypogastric plexus
What is significant about the vas deferns?
It is the most superficial structure in the pelvis
What is the anatomical variation associated with the vas deferns?
congential abscence of the vas deferens
What is the function of the prostate?
To provide 30 percent of the seminal vesicle fluid.
Where does the prostate sit?
Underneath the bladder, superior to the perineal membrane, above the deep perineal pouch
What is the gross anatomy of the prostate?
The prostate is an inverted pyramid.
It has 2x tubes that pass through it - ejaculatory duct
prostatic urethra
What is the zonal anatomy of the prostate?
Central Zone
- surrounds the ejaculatory duct (remember ejaculatory duct is formed by the union of the vas deferens and the seminal vesicle)
Transition Zone
- surrounds the prostatic urethra (BPH happens here!)
Peripheral Zone
- surrounds the central and transition zone (70 percent of prostatic ca happens here!)
What are the relations to the prostate gland?
Anterior: pubic symphysis
Posterior: rectovesical fascia, rectum
Superior: bladder, internal urethral sphincter, seminal vesicle
Inferior: levator ani, deep perineal pouch
Lateral: prostatic vessels, levator ani, obturator internus
What is the arterial supply of the prostate?
Inferior vesical artery
internal pudendal A
middle rectal A
What is the venous drainage of the prostate?
Prostatic plexus, drains to internal iliac vein
What is the lymphatic drainage of the prostate?
Internal iliac nodes
What is the nerve supply to the prostate?
Inferior hypogastric plexus
What are the muscles/ligaments / fascia associated with the prostate?
Puboprostatic capsule
Prostatic fascia
What is the function of the external iliac artery?
It is one of the larger terminal branches of the common iliac A.
Supplies blood to the lower limb, and anterolateral chest wall.
What is the origin, course and termination of the external iliac artery?
It is the larger, anterior branch of the common iliac artery.
runs anterior to the sacroiliac joint.
runs medially along iliopsoas and medially along inguinal ligament
Under the inguinal ligament, it becomes the femoral A
What are the branches of the external iliac A?
Deep circumflex iliac A
Inferior epigastric A
What are the relations of the external iliac A?
Will be anterior to the sacroiliac joint,
related to iliopsoas and the external iliac vein,
runs down the inguinal ligament,
Has the ureter run anterior to it at its origin
What is the lymphatic drainage of the external iliac artery?
The external iliac nodes- which drain to the paraaortic nodes
What are the anatomical variations associated with the external iliac artery?
The inferior epigastric artery can anastomose with the obturator A
The inferior epigastric artery can be replaced by the obturator A
What is the iliac - subclavian anastomosis?
inferior epigastric artery (from the external iliac A)
and the superior epigastric A (from the internal thoracic A which comes off subclavian A)
What is the internal iliac artery?
Smaller branch of the common iliac A.
What is the function of the internal iliac artery?
supplies the pelvis, perineum, pelvic viscera, medial thigh
What is the origin and course of the internal iliac artery?
Comes off the common iliac artery, anteriorly to the sacroiliac joint. Then travels posteromedially to the greater sciatic foramen.
This is due to the largest branch, superior gluteal A, travelling through the greater sciatic foramen.
What is the termination of the internal iliac artery?
Into the anterior and posterior divisions
What are the branches of the internal iliac artery?
Anterior and Posterior divisions
Anterior - 3x bladder, 3x visceral, 3x parietal
Bladder: superior vesical, inferior vesical, obliterated umbilical
Visceral: middle rectal, uterine, vaginal
Parietal: obturator, internal pudendal, inferior gluteal
Posterior branches:
Superior gluteal A
Iliolumbar A
Lateral Sacral A
What are the relations of the internal iliac artery?
sacroiliac joint will be posterior
Runs with the external iliac vein
What are the anatomical variations of the internal iliac artery?
Persistent sciatic artery, continuation of the internal iliac artery- occurs through greater sciatic notch.
obturator A comes from the inferior epigastric (instead of the anterior division of internal iliac)
What is the bladder?
It is the most anterior pelvic viscera. Stores urine
What is the gross anatomy of the bladder?
It has a base - which is where the two ureters enter at the vesicoureteric junction - TRIGONE.
It has a neck - where the urethra exits. Surrounded by the internal urethral sphincter.
It has a apex which points towards the pubic symphysis. This is fused by remnants of the urachus - median umbilical ligament.
What are the relations of the bladder?
Anterior: pubic symphysis
Posterior: rectum, seminal vesicle, rectovesical pouch
in women: uterovesical pouch, uterus, rectum
Superior: peritoneum, uterus
Inferior: prostate + pelvic floor
Lateral: levator ani, obturator internus
What is the arterial supply of the bladder
Superior vesical A
Inferior vesical A
Both are branches of the internal iliac A
What is the venous drainage of the bladder?
venous plexus which drains to the internal iliac vein
What is the lymphatic drainage of the bladder?
internal iliac nodes, go to retroperitoneal aortic nodes
What is the nerve supply of the bladder?
Motor nerves - sympathetic
Above trigone - T12 / L1
Below trigone - S2
What are the muscles / ligaments and fascia surrounding the bladder?
detrusor muscle
urachus
What is the pelvic floor?
It is a gutter shaped diagphram which is hung around the midline viscera - urethra, vagina, anal canal
It is made up of the superior diagphram - levator ani and coccygeus
inferior diagphram - perineum
What is the function of the pelvic floor?
supports the pelvic organs
aids in continence
What is the gross anatomy of the pelvic floor?
Made up of the levator ani:
pubococcygeus- origin is the body of pubis. insertion is the coccygeus, anal raphe (most medial fibres of pubococcygeus/iliococcygeus are puborectalis or pubourethralis)
iliococcygeus - tendinous arch of obturator internus. inserts onto coccygeus or anal raphe
coccygeus - origin: ischial spine / sacrospinous ligament. inserts onto the coccygeus
What does the pelvic floor contain?
Urethra
Vagina
Anus
What are the relations of the pelvic floor?
Inferior to the pelvic floor is the perineum
What is the arterial supply of the pelvic floor?
Internal pudendal artery
Inferior gluteal artery
What is the venous drainage of the pelvic floor?
internal pudendal vein
What is the lymphatic drainage of the pelvic floor?
internal iliac lymph nodes
What is the nerve supply to the pelvic floor?
pelvic surface - S4
perineal surface - pudendal
what is the anatomical variation associated with the pelvic floor?
thinning or aplasia of one side
What is the muscles / ligaments / fascia invovled with the pelvic floor?
tendinous arch of the obturator internus fascia - gives rise to iliococcygeus
sacrospinous ligament - gives rise to ischiococcygeus
What is the perineum?
It is the diamond shaped space between the ischial spine + pubis + coccyx.
What is the function of the perineum?
Transmits the urethra and anus and vagina in females.
What is the gross anatomy of the perineum?
Anterior: pubic symphysis
Posterior: coccyx, sacrotuberous ligament
Lateral: ischiopubic rami
Superior: pelvic floor (levator ani, coccygeus)
Describe the anterior urogenital triangle
Anterior urogenital triangle -
contains perineal membrane.
perineal membrane will give rise to the bulb of the penis + clitoris.
contains the deep and superficial perineal pouch
What does the deep perineal pouch contain?
above perineal membrane.
in men, contains the external uretheral sphincter and membranous urethra.
In women contains the urethrovaginal sphincter, compressor urethrae, and deep perineal muscles
What does the superficial perineal pouch contain?
Below perineal membrane,
corpus cavernosum, spongiosum, bulbous urethra in men
in women, contains corpus cavernosum and crus of clitoris, and the bulb of vestibule
What does the posterior anal triangle contain?
contains the anus and its sphincters.
ischiorectal fossa
anococcygeal body
What is the arterial supply of the perineum?
internal iliac A
internal pudendal A
-> gives the inferior rectal A, perineal A, dorsal A of penis
What is the venous drainage of the perineum?
The venous drianage is the internal iliac vein and the internal pudendal vein
gives the inferior rectal vein, perineal vein, dorsal vein of penis
What is the lymphatic drainage of the perineum?
internal iliac lymph nodes
What is the nerve supply of the perineum?
S2-S4 Pudendal N
gives off inferior rectal N
perineal N
dorsal N of penis/clitoris
What is the female urethra gross anatomy?
neck of bladder to ext urethral sphincter
goes through deep peroneal pouch, compressor urethrae, urethrovaginal sphincter
and opens into the vestibule of the vagina
2.5cm below the clitoris
What are the relations to the female urethra?
anterior; pubic symphysis
posterior; vagina
lateral; rectalis, puborectalis
inferior; vaginal vestibule
What is the arterial supply to the female urethra?
internal pudendal A./ vaginal A
What is the venous drainage of the female urethra?
internal pudendal V/ vaginal V
What is the lymphatic drainage of the female urethra?
To the internal iliac nodes
What is the nerve supply for the female urethra?
pudendal N
What is the anatomical variation associated with the female urethra?
urethral agenesis
What is the obturator artery?
branch of the internal iliac artery
supplies the medial thigh
What is the origin and course of the obturator artery?
from internal iliac, runs along pelvis and is crossed by vas deferens, runs into the obturator foramen, with the obturator N and obturator V, leaves pelvic cavity and medial adductor thigh.
Gives anterior / posterior branches around obturator foramen
What are the branches of the obturator A?
In pelvis -
branches to ilium, psoas, iliacus
and anastomoses with iliolumbar A
In medial thigh - anterior + posterior divisions
What are the relations associated with the obturator A?
Runs in the obturator foramen, so with obturator N + Vein
adjacent to pubis
What are anatomical variants associated with the obturator A?
Replaced by inferior epigastric A
or replaces the inferior epigastric A
What is the ischiorectal fossa?
It is the paired fat pads which surround the anus.
What is the function of the ischiorectal fossa?
Allow for movement of the anus with defecation, and a degree of movement through the pelvic floor leveator ani
Have the pudendal (alcocks) canal on the lateral wall where the inferior rectal artery + nerve, perineal artery and nerve will travel and enter through.
What is the gross anatomy of the ischiorectal fossa?
Roof: levator ani
Floor: perineal membrane/fascia, deep perineal pouch
Medial: external anal sphincter, anal canal
Lateral: obturator internus, ischial tuberosity, pudendal canal
What are the contents of the ischioanal fossa?
fat
pudendal N
superior + deep perineal N
internal pudendal A
inferior rectal A
perineal A
Dorsal N of penis / clitoris and ARTERY
What runs through the pudendal canal?
internal pudendal A + pudendal N, then branch into the inferior rectal N + A, perineal N + A
What is the arterial supply of the ischiorectal fossa?
inferior rectal A
perineal A
What is the venous drainage of the ischiorectal fossa?
internal iliac V
What is the lymphatic drainage of the ischiorectal fossa?
internal iliac chain + inguinal region
What is the nerve supply of the ischioanal fossa?
inferior rectal N
perineal N
What bones are involved with the sacroiliac joint and what sort of a joint is it?
Sacrum
Ilium
Synovial and fibrous
Given it is a synovial joint it will have a joint capsule
What are the ligaments involved with the sacroiliac joint?
sacrospinous
sacrotuberous
anterior sacroiliac ligament
posterior sacroiliac ligament
interosseous sacroiliac ligament
iliolumbar ligament
What is the artery around the sacroiliac joint?
The artery for the common iliac artery bifurcation is infront of the sacroiliac joint
What is the nerve supply of the sacroiliac joint?
superior gluteal + obturator N
from lumbosacral plexus
What are the surrounding muscles around the sacroiliac joint?
Piriformis
gluteus maximus
What are the relations to the sacroiliac joint?
Sacrotuberous ligament
biceps femoris (inferiorly)
gluteus maximus from gluteal surface
Sacrospinous ligament
gives origin to ischiococcygeus
What is the gross anatomy of the uterus?
Fundus - below fundus, fallopian tubes enter at cornu
Body - laterally becomes the broad ligament. covered in peritoneum
External os - entrance into the uterus
Internal os - entrance into the vagina
What are the key peritoneal reflections of importance in the uterus?
rectouterine pouch of douglas
uterovesical pouch
What are the relations of the uterus?
Anterior:
Vesicouterine pouch, superior surface of bladder
Posterior:
Posterior fornix, rectouterine pouch of douglas
Superior: peritoneum
Inferior: bladder, vagina
Lateral: broad ligament, uterine vessels, ureter, ovary
What is the arterial supply of the uterus?
Uterine artery
(plus anastomosis with ovarian A)
Uterine artery will pass anterior to ureter - with the gonadal vessels N/A/V
Runs in lateral cervical ligament
What is the venous drainage of the uterus?
Uterine vein - which drains to internal iliac V
What is the lymphatic drainage of the uterus?
fundus - to para aortic zone
Body and cervix - to internal and external nodes, and inguinal and sacral
What is the nerve supply of the uterus?
The inferior hypogastric plexus + pelvic splanchic nerves
What are the muscles/ ligaments / fascia involved with the uterus?
Rectouterine pouch of douglas
vesicouterine pouch
BROAD LIGAMENT (which contains uterine and ovarian + vessels)
Cardinal/lateral cervical ligament
Uterosacral ligament
Ovarian ligament
Round ligament
What are the anatomical variants associated with the uterus?
vaginal / uterine agenesis
unicornuate uterus
uterine didelphys
bicornuate uterus
steptate uterus / arcuate uterus
What is the unicorunate uterus?
Class 2 mullerian duct anomaly
1 mullerian duct completely elongates, the other does not, leading to a unicornuate uterus with 1x fallopian tube
What is uterine didelphys?
Class 3 mullerian duct anomaly, mullerian ducts don’t fuse in the midline, completely or incompletely. Hence, total duplication of uterus with divergent horns and 2x cervices.
What is the bicornuate uterus?
2x horns
and heart shaped.
What is a septate uterus?
get persistence of a midline septum, with or without duplicated vagina (includes arcuate uterus)
What is the broad ligament?
It is the double fold of peritoneum that covers the uterus laterally.
Not a supporting ligament
Transmits the nerves + arterial supply of the ovary and uterus
Transmits the mesosalpinx (fallopian tubes), mesovarium (ovary), uterine vessels, and 2x ligaments, round + broad
What are the contents of the broad ligament?
Ovary
Fallopian Tube
Ovarian A (from Aorta)
Uterine A (from internal iliac A)
Ovarian V (IVC)
Uterine V (internal iliac V)
Round ligament
Ovarian ligament
Ureter
Vestigal remains of mesonephric tubes
What are the relations of the broad ligament?
Anterior: bladder
Posterior: pouch of douglas, rectum
Lateral: obturator internus fascia (crosses obturator N/A/V, superior vesical A)
Medial: uterus
Superior: continuous with suspensory ligament of ovary
How is the peritneoum of broad ligament related to the ovary?
Posterior fold of the broad ligament will cover the ovary partially, called the mesovarium.
Surface of ovary is devoid to allow exit of ova.
Upper edge of peritoneum contains the fallopian tube which is the mesosalpinx
What is the ovary?
Essential for the female reproductive system
Produce eggs and estrogen
Sits in the broad ligament in the mesovarium
Nestled in the bifurcation of the internal and external iliac A.
What is the arterial supply of the ovary?
The ovarian A
From aorta as the gonadal A
What is the venous drainage of the ovary?
The ovarian V (from IVC)
Descends in the suspensory ligament of the ovary
What are the relations of the ovaries?
Nestled in the bifurcation of the internal and external iliac A
Therefore it lies over the external iliac Vein and obturator N
iliac bifurcation is immediately anterior to sacroiliac joint
What are the relations of the ovaries?
Anteriorly: broad ligament and ovarian vessels
Posterior: ureter
Inferior: levator ani
Medially: ovarian ligament
What is the lymphatic drainage of the ovary?
para aortic nodes
What is the nerve supply of the ovary?
aortic / renal / inferior hypogastric plexus
What are the muscles / ligaments / fascia of the ovary?
Broad ligament - in mesovarium
Ovarian ligament - continuation of the round ligament, attached to lower pole
Suspensory ligament of the ovary - contains ovarian A + vein from IVC
OVARIES ARE NOT COVERED BY PERITONEUM ANTERIORLY, SO OVARIAN MALIGNANCY CAN SPREAD TO THE PERITONEUM
What is the fallopian tube?
Catches eggs from the fimbriae and transports it to uterus
What is the gross anatomy of the fallopian tube?
fimbriae
infundibulum
ampulla
isthmus
What are the relations of the fallopian tube?
fimbriae are pointed to the upper pole of the ovary
isthmus empties to the cornu of the uterus
What is the arterial supply and venous drainage of the fallopian tube?
ovarian artery / uterine artery
ovarian vein / uterine vein
What is the lymphatic drainage of the fallopian tube?
to para aortic lymph nodes like the ovary
What is the nerve supply of the fallopian tubes?
The inferior hypogastric plexusW
What are the muscles, ligaments and fascia related to the fallopian tube?
lies in the broad ligament (mesosalpinx)
What is the path of the eggs from the fallopian tube?
fimbriae -> infundibulum -> ampulla -> isthmus -> ostium of uterus
What is the lumbar plexus?
Nerve supply to pelvis, perenium, and lower limb
Where does the lumbar plexus sit?
posterior lateral wall of pelvic cavity
relation to psoas
What is the origin of the lumbar plexus?
L1-L4 anterior rami
Core relation is psoas muscle
What are the branches of the lumbar plexus?
Lateral to psoas
iliohypogastric L1
ilioinguinal L1
lateral fem cut N of thigh L2, L3
Femoral N L2, L3, L4
lumbosacral trunk L4, L5
obturator N L2-L5
Anterior to psoas
========== ========
genitofemoral N L1-2
What are the key relations around the lumbar plexus?
relate to psoas
Lateral femoral cutaneous N of thigh will go through ASIS
obturator N and femoral N are reflections of each other, obturator is anterior division, femoral is posterior division
What is the sacral plexus?
The nerve supply to the pelvis, pernieum and lower limb
Where does the sacral plexus sit?
On piriformis
What are the branches of the sacral plexus?
There are 6 branches of the sacral roots, prior to dividing into the anterior and posterior branches
- pudendal N (S2, S3, S4)
- pelvic sphlancic N
- N to piriformis
- posterior femoral cutaneous N
- perforating cutaneous N
- perineal branch to S4
Anterior division;
sciatic N (tibial part)
- N to obturator internus / superior gemelli
- N to quadratus femoris / inferior gemelli
Posterior division;
sciatic N (common peroneal, fibular part)
- superior gluteal N
- inferior gluteal N
What are the relations to the sacral plexus?
anteriorly - common iliac A and vein and ureter
What are the anatomical variants for the sacral plexus?
sciatic - comes above or through piriformis
Common peroneal / fibular parts do not unite and have seperate outcomes
What is the pudendal N?
It is the N to the perineum
What is the gross anatomy of the pudendal N?
Origin is the sacral plexus S2-S4
Course runs through the greater sciatic foramen. Goes to gluteal region. Then does a U turn and enters through the lesser sciatic foramen
Runs along the wall of obturator internus and alcocks (pudendal canal) and is in the lateral wall of the ischioanal fossa
Terminates by dividing into the skin / skeletal muscle branches
What are the terminal branches of the pudendal N?
The inferior rectal N
Dorsal N of the penis / clitoris
Perineal N
What does the pudendal N innervate?
External anal sphincter
External urethral sphincter
skin of perineum
Lower anus
What are the relations of the pudendal N?
internal pudendal A
goes inferior to piriformis
goes through both greater and lesser sciatic foramen
