Surgical Anatomy And Hernias Flashcards
What is the most superficial muscle of the abdomen?
Rectus abdominus
What is the origin of the external obliques?
Ribs
What is the origin of the internal obliques?
Iliac crests
What is the origin on transveralis abdominus?
Transverse processes of spine
How can the greater omentum help during infections?
Fat can move across to wall off the infection
Limits it to an abscess rather than all over
How is the rectus abdominus muscle divided?
Down the midline by the linea alba
At the edges by linea semilunaris
Transversely by tendinous intersections
What is the arcuate line?
The point where (below it) the rectus abdominus has no posterior fascial sheath
1/3 of way from umbilicus to pubic symphysis
Below this, surgery is less traumatic
What do we call the incision used for a C section?
Pfannenstiel
What is a divarication of recti?
Fat bulge
Due to laxity of linea alba
Very common in ladies who have had lots of children
Why do we try not to sew through muscles?
Because tightening the knot shreds the muscles
Which incision would be used for an appendicectomy?
McBurney’s point
Gridiron muscle splitting incision
Describe a patent urachus
Failure of allantois to fuse/close
Tube between the apex of the bladder and the umbilicus
Can present at birth or later in life (esp in men with BPH)
What is exampholos? (Omphalocoele)
Gut sitting on the abdomen
Viscera covered by peritoneum and amnion
Quite common
Easy to deal with surgically
What is gastroschisis?
Split in the abdomen
Contents spill out
Usually a vertical defect (usually to the right hand side)
Viscera not covered by peritoneum and amnion
Serious - some of the gut dies
Higher mortality
Describe somatic referred pain
Pain caused by a stimulus to the proximal part of a somatic nerve
Perceived in the distal dermatome of that nerve
Often the brain thinks the source of the pain is the end of the nerve
Describe visceral referred pain
Visceral afferent pain fibres follow sympathetic fibres back to the same spinal cord segments they came from
CNS perceives pain as coming from the somatic portion
Give some causes of visceral pain
Ischaemia
Abnormally strong muscle contraction
Inflammation
Stretch
Where does the pain of the gut derivatives refer to?
Foregut - epigastric
Midgut - periumbilical
Hindgut - suprapubic
What are the causes of shoulder pain due to referred diaphragmatic irritation?
Ectopic pregnancy
Ruptured spleen
Perforated ulcer
Define a hernia
A protrusion of viscera beyond the normal confines of its containing cavity
What are the 3 general parts of any hernia?
Sac
Contents of sac
Covering of sac
Give some examples of weaknesses in the abdominal wall
Inguinal canal
Femoral canal
Umbilicus
Previous incisions
What is the most common type of abdominal hernia?
Inguinal hernia
What is the inguinal canal?
An oblique passage through the lower abdominal wall from the peritoneal cavity to the scrotum or labia
Are men or women more likely to get inguinal hernias and why?
Men
The testes descend through the inguinal leaving a wider canal than in females
Are testes intra- or retroperitoneal?
Retroperitoneal
What is the processus vaginalis?
Precedes the descending teste into the scrotal pouch
Should normally obliterate/recede leaving a pouch of peritoneum (tunica vaginalis) which attaches to a portion of the testes
What is more likely to occur if the processus vaginalis doesn’t close?
Inguinal hernias
Scrotal hernias
In men, what lies in the inguinal canal?
Spermatic cord
What forms the inguinal ligament and where does the ligament run?
Formed by the free, rolled edge of external oblique
ASIS to pubic tubercle
What is the anterior border of the inguinal canal?
Aponeurosis of external oblique
What is the floor of the inguinal canal?
Inguinal ligament
Reinforced medially by the lacuna ligament
What forms the lacuna ligament?
Aponeurosis of external oblique
What is the roof of the inguinal canal?
Arching fibres of internal oblique and transversus abdominus
What is the posterior border of the inguinal canal?
Medially = Conjoint tendon - merged fibres of internal oblique and transversus abdominus
Whole length = transversalis fascia
In which structures do the deep and superficial inguinal rings sit?
Deep = posterior wall of inguinal canal in transversalis fascia Superficial = anterior wall of inguinal canal in aponeurosis of external oblique
Name the 2 different types of inguinal hernia and state which is the more common
Indirect (commonest)
Direct
Which side of the body are indirect inguinal hernias more likely to occur on?
Right hand side
What structures do we use are the markers for the origin of inguinal hernias?
Inferior epigastric vessels
Indirect = lateral to
Direct = medial to
Which artery continues under the inguinal ligament as the femoral artery?
External iliac
Under which point is the deep inguinal ring?
Mid point of the inguinal ligament
Under which point is the femoral artery?
Mid inguinal point
What forms the borders of Hesselbach’s triangle?
Edge of rectus abdominus muscle
Inferior epigastric vessels
Inguinal ligament
When are direct hernias more likely to occur?
If there is a weak or absent conjoin tendon
Are femoral hernias more likely to occur in males or females and why?
Females
The angle of the pelvis is wider so the femoral ring is slightly broader
Describe the common course of a femoral hernia
Bulges into the femoral canal
Bulges out of the saphenous opening in the thigh
Describe an acquired infantile umbilical hernia
Very common
Often occur when infant is straining or crying
Usually self resolving by the age of 2 years
Contents herniate through weakness in scar of umbilicus
Describe an acquired adult umbilical hernia
More common in females
Through the linea alba
Can be caused by anything that raises intraabdominal pressure
Describe an epigastric hernia
Relatively common
Occurs through the linea alba
Between the xiphoid process and the umbilicus
Usually due to chronic straining forces
Describe an incarcerated hernia
‘Stuck’
Irreducible ie. cannot push back inside
What does strangulated mean?
Blood supply is cut off
Somatic abdominal pain can arise from which structures of the abdomen?
Skin
Fascia
Muscles
Parietal peritoneum
What is the innervation to the peripheral part of the diaphragm?
Intercostal nerves (T7-T11)
What is the innervation of the anterior abdominal wall?
Thoracic nerves (T7-T12) And L1
What is the innervation to the pelvic wall?
Obturator nerve (L2, 3, 4)
What structures does visceral abdominal pain arise from?
Abdominal organs
Visceral peritoneum
Mesenteries
What is the difference between somatic and visceral pain?
Somatic = severe, precisely localised Visceral = dull, poorly localised
Where is visceral abdominal pain usually referred to?
The midline
Why might sweating, salivation, nausea etc. accompany visceral pain?
Many visceral afferent fibres that enter the spinal cord also participate in reflex activity
Describe referred somatic pain
Nerve fibres from the diseased structure and the area where the pain is felt ascend in the CNS along a common pathway so the pain is unable to distinguish
Describe referred visceral pain
Afferent pain fibres ascend in company with the sympathetic nerves
They enter the spinal cord at a particular level and will cause referred pain in that dermatome
