GI Session 3- Abdomen And Hernias

Question 1

What are the main functions of the abdominal wall?

Answer 1

Forms a firm, flexible wall which keeps the abdominal viscera in the abdominal cavity
Protects abdominal viscera from injury
Maintains anatomical position of abdominal viscera against gravity
Assists in forceful expiration by pushing the abdominal viscera upwards
Involved an action that increases intra abdominal pressure

Question 2

What are the layers of the abdominal wall? (Ex to in)

Answer 2

Skin
Superficial fascia
Muscles and associated fascia
Parietal peritoneum

Question 3

How does the composition of the superficial fascia differ depending on its location?

Answer 3

Above umbilicus- single sheet of connective tissue
Below umbilicus- divided into 2 layers, fatty superficial layer (camper’s fascia) and membranous deep layer (scarpa’s fascia). Superficial vessels and nerves run between the 2 layers of fascia.

Question 4

How many muscles are there in the abdominal wall and what groups can they be divided into?

Answer 4

2 vertical muscles

3 flat muscles

Question 5

Name the 3 flat muscles and where they are located

Answer 5

External oblique, internal oblique and transversus abdominis

Located laterally in the abdominal wall stacked upon one another

Question 6

What movement are the flat muscles responsible for?

Answer 6

Flex, laterally flex and rotate the trunk

Question 7

Describe the external oblique muscle

Answer 7

Larges and most superficial

Fibres run inferomedially, as fibres approach the midline they for a an aponeurosis

Question 8

What is the linea alba?

Answer 8

Fibrous structures that extends from the xiphoid process of the sternum to the pubic symphysis
Where all the aponeuroses of the flat muscles become entwined

Question 9

Describe the internal oblique muscle

Answer 9

Lies deep to the external oblique
Smaller and thinner in structure
Fibres run superomedially

Question 10

Describe the transversus abdominis muscle

Answer 10

Deepest of the flat muscles
Transversely running fibres
Deep to this muscle is the transversalis fascia

Question 11

Name the 2 vertical muscles

Answer 11

Rectus abdominis

Pyramidalis

Question 12

Describe the rectus abdominis muscle

Answer 12

Long paired muscle found either side of the midline in the abdominal wall
It is split in 2 by the linea alba
Lateral border creates the linea semilunaris
Tendinous intersections connect to linea alba and create 6 pack

Question 13

What is the function of the rectus abdominis?

Answer 13

Compressing abdominal viscera
Stabilises pelvis during walking
Depresses the ribs

Question 14

Describe the pyramidalis and its function

Answer 14

Small triangle shaped muscle
Superficial to the rectus abdominus
Located inferiority- base on pubis bone and apex of the triangle attached to the linea alba
Acts to tense linea alba

Question 15

What is the rectus sheath?

Answer 15

Formed by the aponeuroses of 3 flat muscles and encloses rectus abdominis and pyramidalis muscles

Question 16

What forms the anterior and posterior walls of the rectus sheath?

Answer 16

Anterior wall- aponeuroses of external oblique and half internal oblique
Posterior- aponeuroses of half internal oblique and transversus abdominis
Halfway between umbilicus and pubic symphysis all aponeuroses move to anterior wall so no posterior wall

Question 17

What is the area of transition between posterior wall and no posterior wall called?

Answer 17

Arcuate line

Question 18

What must be considered by a surgeon when deciding on an incision?

Answer 18

Direction of muscle fibres
Location of nerves
Ease of access to desired viscera

Question 19

Describe the 2 vertical incision that can be made

Answer 19

Median- through linea alba, can be extended the whole length of the abdomen curving round umbilicus
Paramedian- lateral to linea alba

Question 20

What are the advantages of a median incision?

Answer 20

Minimal blood loss
Major nerves avoided
Used for any procedure requiring access to the abdominal cavity

Question 21

What are the advantages/disadvantages of paramedian incision?

Answer 21

Provides access to more lateral structures

Ligates blood and nerve supply to muscles medial to the incision, resulting in their atrophy

Question 22

Describe the different transverse incisions that can be used

Answer 22

Transverse- inferior and lateral to umbilicus
Suprapubic- 5cm superior to pubic symphysis
Subcostal- inferior to xiphoid process, and extents inferior parallel to costal margin
McBurney- grid iron incision, 2 perpendicular lines at McBurneys point

Question 23

Where is McBurneys point?

Answer 23

1/3 of the distance between ASIS and umbilicus

Question 24

What are the different transverse incisions used for?

Answer 24

Transverse- colon, duodenum and pancreas
Suprapubic- pelvic organs
Subcostal- gall bladder (R), spleen (L)
McBurney- appendicectomies

Question 25

What advantages/disadvantages do the different transverse incisions have?

Answer 25

Transverse- least damage to nerve supply, heals well Suprapubic- can perforate bladder as fascia thins around bladder area McBurney- excellent healing as muscle fibres not cut

Question 26

Name the 9 regions the abdomen can be split into

Answer 26

``` R and L hyperchondrium Epigastric R and L flank Umbilical R and L groin Pubic ```

Question 27

How is the abdomen split into 9?

Answer 27

2 horizontal and 2 vertical planes

Question 28

What are the 2 horizontal planes?

Answer 28

Transpyloric plane- horizontal line halfway between xiphoid process and umbilicus, passing through pyloris of the stomach Intertubecular plane- horizontal line joining iliac crests

Question 29

Where do the 2 vertical planes lie?

Answer 29

Run vertically from the mid clavicle to mid inguinal point | Called mid clavicular lines

Question 30

Name some developmental defects of the abdominal wall

Answer 30

Ectopic cordis- heart develops outside chest Patent urachus Urachal cyst Patent vitellointestinal duct Exampholos- viscera covered by peritoneum and amnion Gastroschisis- vertical defect to right of umbilicus, viscera not covered by peritoneum and amnion

Question 31

What is somatic referred pain?

Answer 31

Pain caused by a noxious stimulus to the proximal part of a somatic nerve that is perceived in the distal dermatome of the nerve

Question 32

What is visceral referred pain?

Answer 32

In the thorax and abdomen, visceral afferent pain fibres follow sympathetic fibres back to the same spinal cord segments that gave rise to the preganglionic sympathetic fibres. CNS perceives visceral pain as coming from the somatic portion of the body supplied by the relevant spinal cord segments

Question 33

What can cause visceral pain?

Answer 33

Ischaemia Abnormally strong muscle contraction Inflammation Stretch

Question 34

What are the 2 potential sites of weakness in the abdominal wall?

Answer 34

Inguinal canal Femoral canal Umbilicus Previous incisions

Question 35

Describe the inguinal canal

Answer 35

Oblique passage that extends in a downward and medial direction Begins at deep inguinal ring a and continues for 4cm ending at superficial inguinal ring

Question 36

What are the boundaries of the inguinal canal?

Answer 36

Anterior wall- aponeurosis of external oblique, and reinforced by internal oblique muscle laterally Posterior wall- transversalis fascia Roof- transversalis fascia, internal oblique and transversus abdominis Floor- inguinal ligament, and thickened medially by lacunar ligament

Question 37

What are the contents of the inguinal canal?

Answer 37

In men- spermatic cord passes through | In women- round ligament of uterus traverses through the canal

Question 38

Define hernia

Answer 38

The protrusion of an organ or fascia through the wall of cavity that normally contain it

Question 39

What is a direct/indirect hernia?

Answer 39

Indirect- where the peritoneal sac enters the inguinal canal through the deep inguinal ring Direct- where the peritoneal sac enters the inguinal canal through the posterior wall of the inguinal canal. Bulges through Hesselbach's triangle

Question 40

How is an indirect inguinal hernia formed?

Answer 40

Congenital origin- failure of processes vaginalis to regress Degree of herniation depends on the amount of processes vaginalis still present. As sac moves through canal it acquires same 5 coverings as contents of canal

Question 41

How is a direct inguinal hernia formed?

Answer 41

Acquired in origin due to weakening in abdominal musculature Peritoneal sac originates from an area medial to epigastric vessels and bulges into the inguinal canal via posterior wall

Question 42

What is the anatomical difference between direct and indirect inguinal hernias?

Answer 42

Indirect inguinal hernia- lateral to the inferior epigastric vessels Direct inguinal hernia- medial to inferior epigastric vessels

Question 43

Describe a femoral hernia

Answer 43

More common in females as they have wider hips | Can easily become incarcerated or strangulated

Question 44

Describe an umbilical hernia

Answer 44

1. Congenital omphalocele Contents herniated into umbilical cord Has peritoneal covering Different to gastrochisis 2. Acquired infantile- contents herniated through weakness in scar of umbilicus 3. Acquired adult- goes through linea alba in region of umbilicus, more likely in females

Question 45

Describe an epigastric hernia

Answer 45

Occurs through linea alba between xiphoid process and umbilicus Usually starts with small hernia Chronic straining forces more fat out which can eventually pull peritoneum through

Question 46

What are the symptoms of an epigastric hernia?

Answer 46

Based around what happens if loops of bowel get trapped | -pain, vomiting, sepsis

Question 47

Define incarcerated

Answer 47

'Stuck', irreducable

Question 48

Define strangulated

Answer 48

Blood supply is disrupted- can lead to tissue necrosis