GI S3 (Done) Flashcards
Describe the basic features of the abdominal wall
Continuous
Subdivided into:
Anterior
Lateral walls (left and right)
Posterior wall
Lateral and anterior wall boundary is indefinite therefore the term ‘anterolateral abdominal wall’ is used to describe them together
Describe the boundaries of the anterolateral abdominal wall
Superiorly:
Xiphoid process
Cartilages of the 7th - 10th ribs
Inferiorly:
Inguinal ligament
Superior margin of the pelvic girdle (iliac crests, pubic crests and pubic symphisis)
What are the layers of the abdominal gut wall?
Skin
Subcutaneous tissue (superficial fascia and fat)
Muscles and their apneurosis
Deep fascia
Extraperitoneal fat
Parietal peritoneum
Label the black boxes
Top to bottom, right column first:
Skin
Superficial fatty layer of subcutaneous tissue
Deep membranous layer of subcutaneous tissue
Investing (Deep) fascia - superficial, intermediate and deep
2nd Column:
External oblique
Internal oblique
Transversus abdominus
Extraperitoneal fat
Endoabdominal fascia
Parietal peritoneum
What is the umbilicus?
Center of anterolateral abdominal wall
L3
What is the Epigastric Fossa?
Slight depression in epigastrum
Just inferior to xiphoid process
Heartburn commonly felt at this site
What is the linea alba?
What is a common abnormality?
Apneuroses of abdominal muscles
Separates the left and right rectus abdominis
Visible in lean individual
Apneuroses of right and left, Intermediate and deep layers of the gut wall interweave here
If lax then rectus abdominis spread apart on contraction (Divercation of recti)
What is the inguinal groove?
Skin crease parallel and just inferior to inguinal ligament
Marks the division between abdominal wall and thigh
What are the Semilunar lines?
Slightly curved, tendinous lines on either side of the rectus abdominis
What are the tendinous intersections of the rectus abdominis?
Clearly visible (in lean individuals) horizontal lines through the rectus abdominis
What are the Arcuate lines?
Where the inferior limit of the posterior rectus sheath ends
1/3 of the way between the umbilicus and the pubic crest
Label the Boxes
Top to bottom:
1st column:
Xiphoid process
Right costal margin
Umbilicus
Iliac crest
ASIS
Inguinal ligament
Pubic tubercle
2nd Column:
Epigastric fossa
Linea alba
Semilunar lines
Pubic symphysis
3rd Column
Serratus anterior
Ext. Oblique
Rectus abdominis
Linea alba
Umbilicus
Inguinal ligament
There are two types of muscle in the abdominal wall, what are they and what are the muscles in each category?
Flat:
External oblique
Internal oblique
Transversus abdominis
Vertical:
Rectus abdominis
Pyrimidalis
What directions do the fibres of the flat muscles of the abdominal wall run?
What is the order of the flat muscles in the abdominal wall?
External oblique:
Posterior to anterior
Superficial
Internal oblique:
Anterior to posterior
Middle
Transversus abdominis:
Transverse
Deep
What is the rectus sheath?
3 flat muscles are continued antero-medially as the the rectus sheath (apneuroses) that enclose the rectus abdominis and Pyrimidalis
Label the boxes
1st Column:
Rectus sheath
Rectus abdominis
Linea alba
Rectus sheath
2nd Column:
Apneuroses of TA
Parietal peritoneum
Transversalis fascia
TA muscle
Int. Oblique
Ext. Oblique
Subcutaneous tissue
Apneuroses of Ext. Oblique
Lamina of apneuroses of Int. Oblique
Skin
Parietal peritoneum
Extraperitoneal fat
Transversalis fascia
Membranous and Fatty layers of Subcutaneous tissue
What are the major considerations when designing a surgical abdominal insicion
Capable of closing
Strong and long lasting
Minimise incidence of insicional herniae
Not directly through muscle (Sutures will ‘cut out’)
List the major abdominal incisions
Midline
Transverse
Appendicectomy
Gridiron
Breifly describe a midline surgical incision
Insicion through linea alba
Briefly describe a transverse surgical incision
Cut through the external oblique apneuroses
Describe an appendicectomy incison
Incision at McBurney’s point
2/3 the distance between umbilicus and ASIS
Through a Gidiron muscle splitting incision
What is a Gidiron incision?
Separation of the muscle fibres of the flat muscles with scissors to get through to the peritoneum
What is a ‘patent urachus’ and what is a common consequence?
What are the common causes?
Urachus connects the bladder and umbilicus, when patent allows urine to leak from the umbilicus
Causes:
Congenital
Benign prostatic hypertrophy in older men
What is the vitelline duct?
What are the abnormalities that can be caused by it’s persistence?
A duct that connects the midgut to the yolk sac in the embryo
Abnormalities:
Meckel’s Diverticulum
Vitelline Cyst
Vitelline Fistula
Omphalocoele
Gastoschisis
Describe a Meckel’s Diverticulum?
Most common GI abnormality
Cul-de-sac in the ileum
Rule of 2’s:
- 2% of pop. affected
- 2ft from ileocecal valve
- 2 inches long
- Usually detected in <2’s
- 2:1 Male:Female
Can be asymptomatic
OR
Can contain ectopic gastric/pancreatic tissue that secretes enzymes and acid causing ulceration
What is a vitelline cyst?
The vitelline duct forms a cyst connected to the lieum and abdominal wall via thin fibrous strands
What is a vitelline fistula?
Direct communication between umbilicus and intestinal tract
This can result in faecal matter coming out of the umbilicus
What is an Omphalocoele?
Persistence of physiological herniation
Part of the gut tube fails to return to the abdominal cavity following its normal herniation into the umbilical cord
Epithelial layer around the umbilical cord (Amnion) covers the defect
What is Gastroschisis?
Failure of closure of the abdominal wall during embryo folding
Leaves the gut tube and its derivatives outside the body
There is no covering of the gut tube as they herniate directly through the abdominal wall into the amniotic cavity
Label these 3 abnormal structures
Meckel’s Diverticulum
Vitelline cyst
Vitelline fistulla
How does somatic pain become referred?
Noxious stimlus to proximal part of a somatic nerve is percieved in the distal dermatome
E.g. Shingles affects nerves, but is felt distally along nerve course to the infection
How does visceral referred pain come about?
In the abdomen and thorax visceral afferent pain fibres follow sympathetic fibres
Course back to the same spinal cord segments that ive rise to the pre-ganglionic sympathetic fibres
CNS therefore percieves pain as coming from the somatic portion of the body supplied by the relevant spinal cord segments
What can cause visceral pain?
Ischaemia
Abnormally strong muscle contraction
Stretch
ONLY
Where in the abdomen might visceral referred pain be felt and what regions of the gut are actually producing pain in each case?
Epigastric region:
Foregut pain
Umbilicus region:
Midgut pain
Suprapubic region:
Hindgut pain
Identify the source of the pain shown in the diagram
Gallbladder
Identify the source of the pain shown in this diagram
Hepatic Pain (Liver)
Identify the source of pain shown in this diagram
Splenic Pain
Identify the possible sources of the pain shown in the diagram
Gastric (Stomach)
Duodenal
Identify the source of the pain shown in this diagram
Oesophageal Pain
Identify the possible sources of the pain in this diagram
Explain the distribution
Pancreatic
Abdominal aorta
Distribution:
Retroperitoneal structures can cause central back pain
Identify the source of the pain shown in the diagram
Explain the change
Acute appendicitis
Early:
Pain begins in umbilicus because innervation of appendix enters spine at that level
Late:
Localises to lower right quadrant due to irritation of somatic nerves in the parietal peritoneum
What is the cause of the pain shown in the diagram?
Small bowel colic
What is the cause of the pain shown in the diagram?
Large bowel colic
What is the cause of the pain shown in the diagram?
Renal/ureteric colic
What is the cause of the pain shown in the diagram?
Uterine/Ovarian pain
What is the cause of the pain shown in the diagram?
Bladder pain
From what structure is the pain shown in the diagram?
Explain this and give three causes
Referred diaphragmatic pain
Explain:
Blood pooling in pelvis makes patient faint, liable to lie down
Blood runs up the abdomen to the diaphragm (C3/4/5 innervation) which corresponds to shoulder pain
Left shoulder only, liver prevents irritation of right hemidiaphragm
3 Causes:
Ruptured spleen
Ectopic pregnancy
Perforated Ulcer
What is the major difference in the peritoneal cavities of men and women?
In men:
Completely closed to the exterior
In women:
Communication pathway to the exterior via the uterine tubes, cavity and vagina (potential pathway for infection)
What structures secrete and absorb peritoneal fluid?
Secreted by the peritoneal epithelium (Simple squamous)
Absorbed by peritoneal lymphatic vessels (particularly on interior surface of diaphragm
Describe the 2 reflections of the peritoneum
Parietal:
Lines the surrounding abdominal wall and structures
Served by same blood, lymph and (somatic) nerve supply as surrounding abd. wall (except central part of diaphragm)
Visceral:
Invests the viscera of the abdomen (Stomach, intestines etc)
Same blood, lymph and (visceral) nerve supply as underlying viscera
What tissue directly underlies the parietal peritoneum and what is it’s significance?
Structure:
Extraperitoneal connective tissue
Significance:
Parietal peritoneum only attaches loosely to the adbominal wall via this tissue, allows for considerable expansion of bladder/rectum
Frequently contains a large amount of fat (Particulalry in obese males)
What is mesentery?
A double layer of peritoneum that occurs as a result of invagination of the peritoneum
A continuity of the visceral and parietal pleura
Connects intraperitoneal structures to the body wall
What are the Omenta?
(in general and specifics of each)
Omenta:
Double layered extension or fold of peritoneum that passes from the stomach and proximal duodenum to the adjacent organs in the abd. cavity
Greater:
Four layers
Hangs like an apron from the greater curve of the stomach
Attaches to the anterior surface of the transverse colon and its mesentery
Lesser:
Smaller double layered
Connects lesser curvature of stomach and the proximal part of the duodenum to the liver and stomach to portal triad
What is a peritoneal ligament?
A double layer of peritoneum that connects an organ to another organ or the body wall
What are the peritoneal ligaments that attach to the liver?
Where does each one also attach?
Falciform ligament
Anterior abd. wall
Hepatogastric ligament
Membranous portion of the lesser omentum
Stomach
Hepatoduodenal ligament
Thickened edge of the lesser omenta which conducts the portal triad
Duodenum
What are the peritoneal ligaments that attach to the stomach?
Hepatogastric ligament
Gastrophrenic ligament
Gastrophrenic ligament
Gastrocolic ligament (Greater omentum)
What are the functions of ‘Bare areas’ on organs?
Allow entry and exit of neurovascular structures
How do we broadly classify structures associated with the peritoneum classified?
Infraperitoneal
Completely covered with peritoneum but not enclosed (Due to mesentery)
Retroperitoneal
Only partially covered by the parietal peritoneum
What are the retroperitoneal structures?
Aorta and IVC
Oesophagus
Duodenum (Except for proximal part)
Most of the Pancreas
Ascending and descending colon + rectum
Label the regions (in columns)
1st column:
Right Hypochondriac region
Right lumbar region
Right Iliac region
ASIS
2nd column:
Epigastric region
Umbilical region
Hypogastric/suprapubic region
3rd column:
Left hypochondriac region
Left Lumbar region
Left Iliac region
What lines divide the 9 sections of the surface abdomen?
Divided Vertically by:
Midclavicular lines
Divided Horizontally by:
Subcostal line
Transtubecular line
What is the transverse mesocolon and its significance?
Mesentery of the transverse colon
Significance:
Divides the peritoneal cavity into the supracolic and infracolic compartments
Supracolic:
Stomach, Liver, Spleen
Infracolic:
Small intestine and ascending + descending colon
Further divided into left and right by the small intestine mesentery
What allows free communcation between supra and infracolic compartments of the peritoneal cavity?
Paracolic gutters lateral to ascending and descending colon
What makes up the Greater sac?
Infra and supracolic compartments
Describe the lesser sac
Hint: Sections, borders and function
Found behind the liver and stomach
Superior recess:
Posterior to liver
Bounded superiorly by the diaphragm and posterior layers of the liver’s coronary ligament
Inferior recess:
Behind the stomach
Bounded anteriorly by stomach and greater omentum
Bounded posteriorly by the pancreas, transverse mesocolon and the transverse colon
Function:
Allows free movement of the stomach on the structures posterior and inferior because its anterior and posterior walls slide smoothly over each other
Describe the communication of the greater and lesser sacs
Epiploic foramen
Location:
Opening located posterior to the free edge of the lesser omentum (hepatoduodenal ligament)
Can be located by running a finger along the gall bladder to free the edge of the lesser omentum
Label the boxes
What spaces are represented in red, blue and green?
Boxes, top to bottom:
Superior recess of the lesser sac
Lung
Lesser omentum
Falciform ligament
Subhepatic space
Pancreas
Duodenum
Transverse mesocolon
Transverse colon
Inferior recess of lesser sac
Mesentery of S. intestine
Greater omentum
Rectovesical pouch
Urinary bladder
Red:
Infracolic compartment
Blue:
Lesser sac (supracolic)
Green:
Greater sac (Supracolic)
Label the black boxes clockwise from top left
Label the red box
Black:
Transverse colon
Supracolic compartment
Transverse mesocolon
Phrenicocolic lagament
Left colic flexure
Tenia coli
Root of S. Intestine mesentery
Descending colon
Left paracolic gutter
Left infracolic space
Right infracolic space
Right paracolic gutter
Ascending colon
Right colic flexure
Red:
Infracolic compartment
What are the key features of the subphrenic spaces?
Right:
Lies between diaphragm superiorly and superior, anterior and lateral surfaces of the the right lob of the liver inferiorly
To the right of the falciform ligament
Common site for fluid collection post right sided abd. inflammation
Left:
Lies between the diaphragm superiorly and the left lob of the diaphragm inferiorly
To the left of the falciform ligament
Common site for fluid collection, particularly after a splenectomy
Substantially larger than the right space (Liver is on right)
What is the recto-uterine pouch?
Small peritoneal reflection in females between the rectum and the posterior cervix and uterine fundus forming a small pouch
What is the vesico-uterine pouch?
Shallow pouch in females between the anterior surface of the uterine fundus and the upper surface of the bladder
What is the rectovesical pouch?
Shallow pouch found in males.
Formed where the peritoneum leaves the rectum at the junction of the middle and lower 1/3s then passes over the seminal vesicles and the superior aspect of the bladder
Describe the mesentery of the small instestine
Broad, fan shaped fold
Connects ileum and jejunum to posterior abd. wall
Carries blood, lymph and nerves
Allows free movement of S.intestine
Root:
15cm from the duodenojejunal flexure on the left side at L2 to the ileocecal junction
What is the sigmoid mesocolon?
Peritoneal fold attaching the sigmoid colon to the pelvic wall
What are the chief sites of hernias?
Why these sites?
Inguinal Canal
Femoral Ring
Umbilicus
All sites of potential weakness
Describe the inguinal canal, it’s contents and associations
Canal and associations:
Oblique passage extending downward and medial
From deep to superficial inguinal ring (~4cm)
Between muscles of anterior abdominal wall:
- Transversalis apneurosis posterior
- External oblique and Internal oblique (lateral 1/3 only) anteriorly*
Parallel and superior to inguinal ligament (**Floor)
Inferior to the medial crus of the external oblique apneurosis (**Roof)
Contents:
Spermatic cord in men
Round ligament in women
Ilioinguinal nerve in both sexes
Label the black boxes from top center clockwise
Apneurosis of ext. oblique
Deep inguinal ring
Femoral vein
Superficial inguinal ring
Lacunar ligament
Pectineal ligament
Pectineus
Femoral canal
Femoral sheath
AIIS (anterior inferior iliac spine)
Femoral artery
Femoral nerve
Inguinal ligament
Iliopsoas
Label the boxes top to bottom
Superfcal inguinal ring
Spermatic cord and ilioinguinal nerve
What is an inguinal hernia?
A protrusion of the abdominal cavity contents throught the inguinal canal
Very common (Men 27%, Women 3% lifetime risk)
Describe the two types of Inguinal hernia
Direct:
Protrudes into the inguinal canal through a weakened area in the transversalis fascia near the medial inguinal fossa within Hesselbach’s triangle
Indirect:
Protrudes through the deep inguinal ring within the diverging arms of the transversalis fascial sling
Result of failure of embryonic closure of the deep inguinal ring after the testicle has passed through it
What are the borders of Hesselbach’s Triangle?
Inferior:
Medial half of the inguinal ligament
Medially:
Lower lateral border of the rectus abdominus
Laterally:
Inferior epigastric artery
What is an epigastric hernia?
What are the primary risk factors?
Occur in the epigastric region
Between xiphoid process and Linea alba
Risk factors:
Obesity
Pregnancy
What is an umbilical hernia?
Describe the two types
Occur throught the umbilical ring
Usually small
Congenital:
Result from increased intraabdominal pressure + Weakeness/incomplete closure of abd. wall post umbilical cord ligation at birth
Acquired:
Common in women and obese people
Where do femoral hernias occur?
How do they present clinically?
A protrusion of abd. viscera into the femoral canal through the femoral ring
Present as a small tender mass in the femoral triangle
What is the effect of a femoral hernia on the surrounding tissues?
What structures are found laterally and medially of femoral hernias?
Compress contents of the femoral canal:
- Loose connective tissue
- Fat
- Lymphatics
Lateral:
Femoral vein
Medial:
Lacunar ligament
Describe briefly the differences in size of a femoral hernia that may occur
Initially:
Small, contained within canal
Later:
Canenlarge by passing through the saphenous opening into the subcutaneous tissue of the thigh
In who are femoral hernias more common?
What is the major clinical complication? Why is this of particular concern in femoral hernias?
More common in women (Still less common than Inguinal hernias)
Strangulation:
Sharp, rigid boundaries of the femoral ring increase risk
What are the two major complications of hernias?
Strangulation:
Constriction of blood vessels preventing flow of blood to hernia (Ischaemia/necrosis)
Incarceration:
Hernia cannot be reduced (pushed back into place) without very much external effort
Label the boxes
Top left anticlockwise:
Inguinal ligament
Adductor longus
Sartorius
Femoral hernia
Saphenous opening
Great saphenous vein
Femoral hernia
Femoral sheath
Femoral ring
Intestine
Label the boxes
Top right anticlockwise:
Epigastric hernia
Incisional hernia
Umbilical hernia
Indirect inguinal hernia
Direct inguinal hernia
Femoral hernia
