Abdomen Flashcards
How many regions is the abdomen divided into
9
Why do we have Camper’s and Scarpa’s fascia in the abdomen but not the limbs
The enveloping structures of the upper limb do not allow stretch but those of the abdomen do
What are the requirements for abdominal incisions
Provide direct access
Adequate exposure
Extension must be possible while minimising disruption of neurovascular supply
Muscle cutting vs splitting
Transaction causes irreversible damage/ necrosis
Splitting in direction of the fibres minimises injury
Compare longitudinal and transverse incisions
Longitudinal are preferred for exploratory laparotomy as they provide good exposure but scarring may be pronounced
Transverse give better cosmetic results and less post operative pain
Compare midline and para median incisions
Midline: through linea alba is relatively bloodless and avoid major nerves but increases risk of dehiscence and incisional hernia
Para median: made parallel to midline through rectus Sheath and gives better wound scrutiny
Give the initial steps of key hole surgery
Creation of pneumoperitoneum
Insertion of laparoscope
Placement of additional parts
What is herniating tissue
The tissue that fills the hernia eg fat, gut and/ or omentum
Where do hernias appear
Any site or weakness in the musclo-aponeurotic abdominal wall
What is te hernial sac
A protrusion or peritoneum which emerges from the hernial orifice
What are complications associated with hernias
Pain
Irreducibility
Strangulation
How common are epigastric hernias of the linea alba
Occurs in 3-5% of population
Discuss the congenital and acquired hernias of the umbilicus
Congenital: seen in newborns as anterior abdomen wall is weak at umbilical ring. Often small and close spontaneously
Acquired: develop in the obese with extra peritoneal fat, peritoneum and/or bowel protruding into hernia sac
What is a direct inguinal hernia
Always acquired
Protrudes through a weakened conjoint tendon, medial to inferior epigastric artery
Describe indirect inguinal hernia
Enters deep inguinal ring lateral to inferior epigastric artery
May be congenital due to patent processus vaginalis
Femoral hernia
Emerges through femoral canal below inguinal ligament
Irreducibility and strangulation occur more commonly due to narrow neck of canal, necessitating emergency surgery
What is the lumbar triangle
An area of weakness in posterolateral abdominal wall
Bounded by lat dorsi, external oblique and iliac crest
Which structures form the greater omentum
A fatty peritoneal fold hanging from the stomach and transverse colon
What is the purpose of the sphincter at the gastro-oesophageal junction
Prevent acid reflux
Which sex has a longer urethra
Males
Where do testicular and ovarian lymphatics drain
Para-aortic lymph nodes
What forms the pelvic floor
Levator ani
What is the largest cavity in the body
Abdominal cavity
What are the boundaries of the abdominal cavity
Bounded by the abdominal wall on all sides
Separated from the thoracic cavity by the diaphragm superiorly
Continuous with the pelvic cavity inferiorly (there is a physical separation further down at the pelvic diaphragm)
In reality what is in the peritoneal cavity
How does it differ by sex
50-100ml of fluid
Males: completely closed
Females: communication with the exterior exists via the uterine tubes, uterus and vagina (providing a possible route for infection)
What connects the greater and lesser sac
The epiploic foramen
What are the intraperitoneal spaces
Subphrenic
Subhepatic
Paracolic gutters
Rectovesical/ uterine pouch
Where are the subphrenic and subhepatic spaces
Right and left between diaphragm and liver
Hepatorenal pouch on the right of the lesser sac on the left
What is the clinical importance of intraperitoneal spaces
Potential spaces for the collection of fluid and sites of abscess formation
What does the term intraperitoneal refer to
The viscera enclosed by layers of peritoneum rather than in the peritoneal cavity itself
What features do the intraperitoneal viscera have
Suspended by mesenteries with varying levels of mobility
Which organs are intraperitoneal
Stomach Liver Gall bladder Proximal and distal parts of the duodenum Jejunum, ileum Transverse and sigmoid colon Spleen
Which organs are retroperitoneal
What features do they have
Kidneys and adrenal glands
Developed outside the peritoneal cavity
Covered only anteriorly
Which viscera are secondarily retroperitoneal
Most of duodenum
Pancreas (not tail)
Ascending and descending colon
What disadvantage can there be for the intestine being mobile
Abnormal twisting can occur (volvulus) around the axis of the mesentery leading to ischaemia
Give the 6 functions of the peritoneum
Support Lubrications Protection Absorption Healing Storage
Scared Lions Paw At Heat Sores
How does the peritoneum provide support
Physical and nutritional via vessels running in mesentery
How does the peritoneum provide lubrication
Secreting peritoneal fluid to facilitate viscera movement
How does the peritoneum provide protection
Phagocytosis and sealing infected areas to limit spread
How does the peritoneum provide absorption
Fluids and small molecules can pass through mesothelium
How does the peritoneum provide healing
Transforming mesothelial cells into fibroblasts to promote wound healing
How does the peritoneum provide storage
Greater omentum stores fat
What did Morison call the peritoneum
When
“The abdominal policeman”
1906
What is ascites
Excess fluid due to increased production of malignancy or decreased serum albumin in cirrhosis
Appears dark on CT, usually surrounding an organ/ compartment but fluid is limited only to that physical compartment
What haemoperitoneum
Blood in the peritoneal cavity due to trauma/ rupture
What is peritonitis
Inflammation (local or general)
Adhesions May develop between visceral and parietal layers
What is pneumoperitoneum
Gas in the peritoneal cavity due to perforated viscus or after surgery
Why is the peritoneum important for renal patients
Cancer patients?
Used in peritoneal dialysis to remove metabolites
Chemotherapy for ovarian carcinoma is administered here
What innervates the parietal peritoneum
Somatic spinal nerves that supply the overlying abdominal wall and therefore is sensitive to pain
What innervates the visceral peritoneum
Same autonomic nerve supply as viscera
Only stretch sensitive, NOT to pain
Describe the arterial supply to the abdomen
Supplied by abdominal aorta
2 paired lateral branches supply retroperitoneal organs
3 unpaired Anterior branches run in mesenteries
The marginal artery forms a continuous arcade along the entire Colon
Anastomoses provide collateral flow if there is an obstruction but also allow spread of infection
What drains the gut
Portal circulation which convey blood to the liver sinusoids for metabolism and detoxification
Where do hepatic veins move blood to
Inferior vena cava
What is the communication between the Portal and systemic circulations
Portosystemic anastomoses
What is a common cause of portal hypertension?
Obstruction to portal venous flow usually due to cirrhosis caused by alcoholism or viral hepatitis
What kind of valves does the portal vein have and what does this mean
NO VALVES
Increased pressure readily leads to back flow into systemic circulation
Why is portal/ hepatic circulation important when considering drug consumption
Medication that is affected by the liver must not be taken orally in order to bypass portal circulation
Name a drug that must NOT be taken orally
GTN sublingual tablets for angina
They will be affected by the liver so must Avoid portal circulation
What is referred pain
Pain that originates in one part of the body but is perceived in another part
Why does referred pain occur
General visceral afferent which respond to stimuli accompany sympathetic fibres to the same spinal cord segment. As the dermatomes are supplied by the same sensory ganglia and spinal segments, the pain is perceived as originating from the skin
Why may a gall bladder infection be felt in your shoulder?
Inflamed gall bladder will irritate the diaphragm which is detected by the phrenic nerve and pain is referred to the C4 dermatome
What are the spinal roots of the phrenic nerve
C3-5
Describe the immediate pain felt in appendicitis
It is visceral and so diffuse and poorly localised
What happens to the pain as appendicitis progresses
The inflamed viscus will come into contact with the parietal peritoneum which is supplied by somatic spinal nerves, and the pain will then become localised
Describe the direction of pain progression in appendicitis
Starts around the umbilical region (T10) and moves to right Iliac fossa
What is the mesentery like in the embryo
A dorsal mesentery runs the entire length of the GI tract connecting it to the dorsal body wall
Ventral mesentery is only present at the level of septum transversum where the stomach and liver develop
What is the mesogastrium
Mesentery that attaches to the stomach
What does “the mesentery” refer to
Refers to small bowel mesentery
Extends from duodenojejunal flexure to right iliac fossa
What is the mesoappendix
Connects appendix to small bowel mesentery
Transverse mesocolon
Connects transverse colon to posterior abdominal wall and forms floor of lesser sac
Sigmoid/ pelvic mesocolon
Connects sigmoid colon to posterior abdominal wall and contains pre-ganglionic parasympathetic fibres ascending from the pelvis to supply descending colon
What is derived from the dorsal mesogastrium
Greater omentum
Lienorenal ligament
How many layers does the greater omentum have
4 (it is 2 layers of 2 layers)
What is the greater omentum divided into
Gastrocolic and gastrosplenic ligaments
What is the lienorenal ligament
Peritoneum between spleen and posterior abdominal wall in region of left kidney
What are the derivatives of the central mesogastrium
Falciform ligament - connects ventral liver to anterior abdominal wall
Lesser omentum - connects lesser curve of stomach to liver
What is the lesser omentum divided into
Hepatogastric and hepatoduodenal ligaments
What are the 3 functions associated with the GI tract
Peristalsis
Absorption
Excretion
Where does the oesophagus go from and to
From the pharynx to the stomach
What is the oesophagus guarded by
The upper oesophageal sphincter whose relaxation is triggered by the swallowing reflex
What is dysphagia
Difficulty swallowing due to obstruction of the passage of food
What is odynophagia
Painful swallowing
What is heart burn
A burning sensation in the chest posterior to the sternum or in the epigastrium usually as a result of GORD
What is GORD
Gastro-oesophageal reflux disease
What is the LOS
Lower oesophageal sphincter
What is the diaphragmatic crura
Where the right crus forms a sling around the lower oesophagus
What is a hiatus hernia
When part of the stomach passes through the oesophageal hiatus of the diaphragm into the posterior mediastinum
What does the pylorus do
What happens if the sphincter is too lax or tight
Regulates flow of chime into the first part of the duodenum
Lax- Bile reflux may occur leading to antral gastritis and pain
Tight- gastric outlet obstruction (GOO) occurs
What can cause the pylorus to be too tight
Tumours
Peptic ulcer disease
Congenital hypertrophic pyloric stenosis
Ingestion Of foreign bodies
What comprises the small intestine
Duodenum, jejunum and ileum
Which parts of the small intestine are retroperitoneal or mesenteric
Jejunum and ileum are suspended on a mesentery
Most of the duodenum is secondarily retroperitoneal
Give the presentation of a patient with functional disease of the small intestine
Pain due to spasm Bloating Excessive flatus Diarrhoea Constipation
What are the causes of organic disease due to obstruction
Extra mural (adhesions, malignant invasion etc) Or Mural ( plain abdominal radiographs will show dilated loops of small bowls with multiple fluid levels seen on erect films)
Where does the large intestine span from and what is it comprised of
From ileocaecal valve to anus
Comprising the caecum, appendix, ascending, transverse, descending and sigmoid colon, rectum, and anal canal
What are the outer longitudinal muscles of the large intestine? Where is this different?
It exists as 3 bands: the Taeniae coli. These produce the characteristic sacculations or haustrations
Not in the appendix, rectum and anal canal
What are the appendices epiplociae
Peritoneal tags filled with fat
Name 3 benign diseases of the large intestine
Inflammatory bowel disease (eg Crohn’s disease which affects other parts of the GI tract and ulcerative colitis which only affects the colon)
Diverticular disease (in descending and sigmoid colon)
Polyps (fleshy protrusions arising from colonic mucosa)
What does colonic diverticula consist of
Mucosal herniation through thickened muscle
Discuss colorectal adenocarcinoma
3rd most commonly diagnosed carcinoma after lung and breast
Largely preventable by early detection by colonoscopy
Surgical resection remains the definitive treatment modality and may require stoma formation for discharge of colonic contents
Differences between ileum and jejunum
Jejunum: Upper 2/5 Umbilical region Fewer vascular arcades Less fat in mesentery Thick vascular mucosa Few lymphoid follicles Tall villi
Ileum: Lower 3/5 Suprapubic region and pelvis Thin pink walls and narrower lumen Complex vascular arcades More fat in mesentery Short villi Peyer’s patches
What supplies the muscles of the abdominal wall
Where do they drain
T7-12 and L1 (ilioinguinal)
The neurovascular bundle runs between the internal oblique and trans versus abdominis
Above the umbilicus they drain to the pectoral axillary nerves
Below the lymph drains to the superficial inguinal nodes
What are the boundaries of the inguinal canal
Posterior: transversalis fascia laterally and conjoint tendon medially
Anterior: external oblique aponeurosis
Roof: fibres of internal oblique and trans versus abdominis forming conjoint tendon
Floor: inverted edge of inguinal ligament and lacunar ligament
Where is the entrance and exit of the inguinal canal
What is important about this oblique passage
What does the canal transmit in women
Entrance: deep ring
Exit: superficial ring
Prevents abdominal contents from pro lapsing through canal when intra abdominal pressure is raised
The round ligament
What passes through the inguinal canal in men
Vas deferens with its artery and testicular vessels
Spermatic cord
Where is the abdomen
The area between the diaphragm and pelvis, bound by the anterior and posterior abdominal walls
What forms the semi rigid frame of the posterior abdomen
The vertebral column
What is the main flexor of the spine
Name 3 other muscles that also move the trunk
Rectus abdominis
External oblique
Internal oblique
Tans versus abdominis
What lines the abdominal cavity
Parietal peritoneum
What are the parts of the abdominal viscera are suspended on the mesentery
Stomach Jejunum Ileum Transverse colon Sigmoid colon
How does the mesentery form
As intestinal loops invaginate into the wall of the embryonic peritoneal sac with their attached nerves and vessels, a peritoneal fold is formed
Where does the right side of the stomach lie due to embryonic rotation of the gut
Where does the caecum lie
Posteriorly
In the right iliac fossa
How does the blood supply of the abdominal viscera arise
How are the mid, hind, and fore guts supplied
From the abdominal aorta via unpaired branches
The coeliac trunk supplies the foregut
The superior mesenteric artery supplies the midgut
The inferior mesenteric artery supplies the hindgut
What does the foregut include
Stomach Part of duodenum Liver Gall bladder Pancreas Spleen
What is the midgut
From part of duodenum to 2/3 along transverse colon
Veins draining the blood from the gut form the what
Portal venous system which conveys nutrient rich blood to the liver for processing
What does the hepatic vein do
Returns detoxified blood to the systematic system via the IVC
Where is the IVC in relation to the liver
Posterior to liver
Name 2 notable sites of portosystemic anastomoses
Gastro-oesophageal junction
Distal rectum
What can cause portal venous hypertension
What can it lead to
Cirrhosis of the liver
Formation of oesophageal varices which may result in life threatening haemorrhage
What is the foramen of Winslow
AKA epiploric foramen
The entry from the greater sac to the lesser sac
How is the lesser peritoneal sac created
Where does it lie
What is it closely related to
Embryological rotation
Lies posteriorly
Pancreas and splenic vessels
What lies within the loop of the duodenum
Pancreas
How do bile and pancreatic secretions enter the duodenum
At the ampulla of Vater
Where does the duodenum become the jejunum
The duodenojejunal flexure
Where is the ileocaecal junction
Right iliac fossa
What is the arterial supply of the kidneys
What about venous drainage
Via paired renal arteries directly from aorta
Via renal veins into IVC
Describe the path of the urethra in males
From bladder it passes through the prostate then through the perineal next brand surrounded by the sphincter urethrae
Urethra then enters the bulb of the corpus spongiosum, becoming first the spongy Urethra and then the penile urethra to end at the external urethral meatus
It is joined by ducts from seminal vesicles and prostate gland
What is the urethra a conduit for
Urine and semen
How does the female urethra compare to Male
Where is it in relation to the vagina
Female is much shorter
Anterior to the vagina
Where does the uterus lie in relation to the bladder and rectum
Posterior to bladder and and anterior to rectum
What is the pouch of Douglas
The rectouterine pouch
What supplies the pelvis mostly
Internal iliac artery
Briefly describe the descent of the testes
From the posterior abdominal wall through the inguinal canal in the anterior abdominal wall
Where do the lymphatics from the testes and ovaries drain to
Para-aortic lymph nodes
Where does the peritoneum lie
Inferior and superior to the pelvic floor
What forms the pelvic floor
Levator ani muscle which arises from the lateral abdominal wall to join its opposite number in a midline raphé
What lies between levator ani and ischial tuberosity
What is it filled with
Give a fact about it
Ischioanal fossa
Fat
It is liable to infections and access formation from the anal canal
What is the penis comprised of
2 copora cavernosa
The urethra is covered by the corpus spongiosum which continues as the glans penis distally
What happens to the corpora cavernosa posteriorly
They divide to attach to the ischiopubic rami where they are covered by the ischiocavernosus muscle
Describe the scrotum
A thin pouch of skin containing the testes, each suspended by a spermatic cord containing structures that accompanied the testes during its descent in development
What are the labia
Where does the urethra open
Outer folds to the entrance to the vagina
Anteriorly
What is anterior the the urethral opening
What is it comprised of
The clitoris
A glans and two corpora cavernosa which are smaller but homologous to those in the penis
Describe the path of the pudendal nerve
What does it supply
Which artery supplies the same structures
From the sacral plexus and leaves the pelvis via the greater sciatic foramen
It crosses the sacrospinous ligament and enters the peritoneum through the lesser sciatic foramen
Muscles of the area and is sensory to the skin of the anus, perineum, and external genitalia
Internal pudendal artery
Where does the internal pudendal artery come from
Internal iliac artery
What lies half way between the suprasternal notch and the pubic symphysis
The transpyloric plane
Which neurovascular bundles run between the internal oblique and transversus abdominis
T7-L1
Can the obliques help expiration
They push the diaphragm up in deep expiration and coughing
How are the obliques and transversus abdominis related anteriorly (briefly)
They aponeuorse anteriorly forming the linea alba
What does rectus abdominis lie within
Anterior and posterior layers of the rectus sheath formed by other muscles
What does the arcuate line mark
The free lower edge of the posterior layer of the rectum sheath
What forms the inguinal ligament
What does this ligament attach to
The lower aponeurotic edge of the external oblique
The anterior superior iliac spine and pubic tubercle
What is the superficial inguinal ring
A triangular opening on the external oblique aponeurosis above the public crest
Describe the conjoint tendon
Formed from internal oblique and transversus abdominis
It is attached to the pubic crest and pectineal line
It supports the superficial ring
What is the inguinal canal
An oblique canal lying above the medial half of the inguinal ligament
It transmits the spermatic cord in the Male and the round ligament in females
Where does the deep inguinal ring lie
Lateral to the inferior epigastric artery
Why does much of the abdominal cavity lie under the ribs
The domes of the diaphragm arch high above the costal margin
What is the posterior abdominal wall formed of
Ribs 9,10,11 and 12 posterior to the diaphragm and all five lumbar vertebrae
Iliac bones
How are the lumbar vertebrae curved
Combed forward so push into the abdomen
Which abdominal organs are housed in the pelvic cavity
Sigmoid colon and ileum
On a slim person where does the umbilicus lie
Opposite L3
Other than the pylorus, what lies in the transpyloric plane
From posterior to anterior:
L1 vertebra End of spinal cord Origins of portal vein and superior mesenteric artery Renal hila Neck of pancreas Second part of duodenum Duodenojejunal flexure Tips of 9th costal cartilages Fundus of gall bladder
How to remember transpyloric plane
3 Neuroskeletal: L1 vertebra, end of spinal cord, 9th costal cartilages
3 ‘tubes’: portal vein and superior mesenteric artery origins, duodenojejunal flexure, 2nd part of duodenum
3 ‘organ bits’: fundus of gall bladder, neck of pancreas, renal hila
And obviously pylorus
From where does external oblique arise
Direction of fibres?
Lower eight ribs, interdigitating with serratus anterior and latissimus dorsi
Down and forwards
Where does the external oblique insert
Posterior fibres descend to anterior half of the iliac crest
Anterior fibres become aponeurotic at the anterior superior iliac spine eventually joining the linea alba or becoming the inguinal ligament. This attaches to the pubic tubercle.
From where does the internal oblique arise
Lumbar fascia
Anterior 2/3 of iliac crest and lateral 2/3 of inguinal ligament
What happens to the fibres of the internal oblique as the my leave the inguinal ligament
Arch over inguinal canal to join lower fibres of transversus abdominis to form the conjoint tendon
Origin of of transversus abdominis
Inner surfaces of lower 6 costal cartilages (interdigitating with diaphragm),
lumbar fascia,
anterior 2/3 of iliac crest
and
lateral Half of inguinal ligament
How do the 2 bellies of rectus abdominis arise
Where do they insert
As two heads from the pubic symphysis and pubic crest
Anterior aspects of 5-7th costal cartilages
What forms the rectus sheath
The aponeuroses of the other abdominal muscles
Where does the linea alba end
Pubic symphysis
What happens to the internal oblique aponeurosis
Divides into 2 layers to enclose the rectus muscle before rejoining and fusing with the other aponeuroses in the midline
The transversus abdominis fuses with the posterior layer and the external oblique with the anterior layer
How is the anterior rectus sheath attached to the rectus muscle
By transverse tendinous intersections
Where are the tendinous intersections on the rectus abdominis
What forms the six pack
One at xiphisternum
One at umbilicus
One in between
Intervening muscle fibres
What happens to the rectus sheath below the umbilicus
3-4cm below all three aponeuroses pass anterior to the rectus abdominis muscle leaving the sheath deficient posteriorly
What is the free lower edge of the posterior rectus sheath
Arcuate line
What happens to the rectum abdominis below the arcuate line
It lies on the transversalis fascia
What supplies the rectus abdominis muscle
Where does it com from
Superior epigastric artery
Internal thoracic artery
What does the superior epigastric artery anastomose with
What is that a branch of
Inferior epigastric artery
External iliac artery
How does the superior epigastric artery run to supply rectus abdominis?
What about the inferior epigastric?
Between the posterior shealth and muscle
Runs up behind the rectum where the posterior sheath is deficient and then between sheath and muscle
Which additional nerve supplies the lower fibres of the internal oblique and transversus abdominis
L1 (ilioinguinal nerve)
Give 4 functions of the muscles of the abdominal wall
Move trunk
Depress ribs (not transversus abdominis)
Compress abdomen when coughing, sneezing and during expulsive efforts
Support abdominal viscera
What is the lymphatic drainage of the abdominal wall
Above umbilicus: pectoral group of axillary nodes
Below umbilicus: lymph drains to superficial inguinal nodes
