1.1.1 Anatomy of the Abdominal Wall, Inguinal Region and Hernias

Question 1

The anterior abdominal wall is divided into 9 regions, allowing for easy location of the underlying organs precisely in relation to the surface of the body .

2 horizontal lines: subcostal planes and intertubercular planes.

• subcostal plane: just below the ________
• intertubercular plane: between the iliac tubercles, traverses ___ vertebrae

2 vertical lines drawn: paramedian mid-clavicular planes on both sides
- A vertical line is drawn from the middle of the clavicle to the _______ (midpoint of ASIS and pubic symphysis)

Answer 1

subcostal margin; L5; midinguinal point

Question 2

Clinically, the abdomen is divided into 4 quadrants instead of 9 regions
o A horizontal and vertical line is drawn to cut through the umbilicus to divide the abdomen into 4 quadrants
o The gallbladder and liver sits in the right upper quadrant while the stomach and spleen sits in the ________
o The ____________ contains the cecum and appendix

Answer 2

left upper quadrant; right lower quadrant

Question 3

There are several surface features that can be palpated, including the xiphoid process, costal margin, iliac crest, ASIS and pubic symphysis
o Umbilicus – distinct landmark representing the _____ region
o _______ muscle can be seen in a muscular person
o __________ – lateral borders of the rectus abdominis muscle
o Linea alba – fibrous midline of the abdomen from ______ to pubic symphysis

Answer 3

L3; Rectus abdominis ; Linea semilunaris; xiphoid process

Question 4

Abdominal wall muscles
- Anterior wall consists of 2 bands of muscles – a paired vertical rectus abdominis muscles within the rectus sheath
- Lateral wall has 3 flat sheet muscles – external oblique, internal oblique and transversus abdominis (innermost layer)
- Posterior wall – post vertebral muscles (_______ group – for the stability and movement of the vertebral column)
o Lateral to the vertebral bodies are the _____________________muscles (muscles of the lower limb)

Answer 4

erector spinae; psoas, quadratus lumborum and iliacus

Question 5

Lateral wall muscles – the 3 muscles in the lateral wall are separate in flanks
- Continue anteriorly as ________ and contribute to the rectus sheath containing the rectus muscles
- These 3 muscles compress the abdomen and increase the ____________ to aid expiration, evacuation of urine, faeces, parturition (childbirth) and heavy lifting
o Support the viscera (mainly protecting the intestines)
o Involved in the flexion and rotation of the trunk

Answer 5

aponeurotic sheets; intra-abdominal pressure

Question 6

External oblique – attached to the ___________, with a free posterior border
o Muscle fibres fan out to attach to the xiphoid process, linea alba, pubic crest & tubercle, and anterior half of the iliac crest
o Directed downward and forward
o When fibres come towards the anterior side, they become aponeurotic to form the rectus sheath

• Inguinal ligament – the lower aponeurotic edge of external oblique rolls _____ and forms the inguinal ligament – runs from the ASIS to the _________
  o Towards the midline, the superficial inguinal ring is an opening above the inguinal ligament into the inguinal canal

Answer 6

external surface of the lower 8 ribs; inwards; pubic tubercle

Question 7

Internal oblique – takes origin laterally from the thoracolumbar fascia (attached to the vertebral spines), anterior ⅔ of the ______ and the lateral ½ of the ________
o Medially, the muscle is attached to the lower 3 ribs and costal cartilages, xiphoid process, rectus sheath and _________ (at the inferior point of the rectus sheath)
o Runs in the opposite direction from the external oblique muscle – runs _____________
- The crisscross fashion of the external and internal oblique provides more strength to the abdominal wall rather than running in the same direction

Answer 7

iliac crest; inguinal ligament; conjoint tendon; downwards and backwards

Question 8

Transversus abdominis – lateral origin from __________, thoracolumbar fascia, anterior ⅔ of the iliac crest and lateral ⅓ of the inguinal ligament
o Attached medially to the xiphoid process, ______ (rectus sheath), pubic symphysis and the conjoint tendon
o The neurovascular plane lie between the ______________ muscle layers

Answer 8

lower 6 costal cartilages; linea alba; internal oblique and transversus abdominis

Question 9

Rectus abdominis – long strap muscle of enclosed in the rectus sheath (aponeuroses of the 3 lateral flank muscles), with 2 heads
- Superiorly, the muscle is attached to the 5 to 7 costal cartilages and the xiphoid process
- Inferiorly, the muscle is attached to the pubic
symphysis and the ______ (upper border of the pubic bone)
- The muscle is divided into segments by_________ (3 on each side) which are attached to the anterior wall of the rectus sheath
-Tendinous intersections are attached to the anterior wall of the rectus sheath – muscle has some stability and does not move around in the rectus sheath

Answer 9

pubic crest; tendinous intersections

Question 10

Rectus sheath – formed by the aponeuroses of the 3 muscles (external oblique, internal oblique and transversus abdominis)

o Above umbilicus – internal oblique aponeurosis splits and encloses the rectus abdominis, with the aponeuroses of the external oblique in front and the transversus abdominis behind the rectus muscle

o Below umbilicus – all 3 aponeurotic layers are anterior to the rectus muscle
§ The rectus muscle lies against the ______ – weak support int his region as the peritoneum of the abdominal cavity is posterior to the fascia

There is a change in aponeurotic arrangement at the ________ at the umbilicus
o The posterior wall of the aponeurotic sheath becomes incomplete and stops short below the umbilicus at the arcuate line
o Below the arcuate line, the rectus abdominis
muscle is in contact with the transversalis fascia
o The rectus abdominis is the most powerful ___ of the vertebral column (lower thoracic and lumbar) and the external and internal oblique of both sides are also important in this action
o As it is attached to the lower thoracic cage (costal cartilage) to the pubic symphysis, when the muscle contracts, it brings the 2 bones together, resulting in flexion

Answer 10

fascia of the transveralis muscle; arcuate line; flexor

Question 11

Posterior wall muscles
- Psoas major – attached to the bodies and discs of all 5 lumbar vertebrae to the _________
o A flexor of the hip and trunk

• Quadratus lumborum: _____to the psoas major
  o Takes origin from the lower border of the 12th rib and ______ of the 5th lumbar vertebrae, attaching to the adjacent iliac crest
  o Stabilises the 12th rib for respiratory purposes and also serves as a lateral flexor of the trunk

Answer 11

lesser trochanter of the femur; lateral; transverse process

Question 12

Blood supply of the rectus muscle comes from the superior and inferior epigastric arteries

o Superior epigastric artery – terminal branch of the (branch _________ of the subclavian artery) running on the internal aspect of the sternum, entering the rectus sheath from the posterior aspect
o Inferior epigastric artery – branch of the ___________ (which is a branch of the common iliac artery from the abdominal aorta)
- These 2 vessels enter the ______ and anastomose, forming a potential by-pass to the abdominal aorta – if there is a block in the abdominal aorta, the anastomosis can bring about collateral circulation

Answer 12

internal thoracic artery; external iliac artery; rectus sheath

Question 13

Blood supply of the flank muscles is segmentally supplied
o The _____ intercostal arteries, subcostal artery, lumbar arteries and ________ arteries (a branch of the external iliac artery) all supply the 3 flank muscles.
- Venous drainage of the anterior abdominal wall follows the arteries (deep veins bear the same names accompanying the arteries)

Answer 13

7th to 11th; deep circumflex iliac

Question 14

Nerve supply of abdominal wall

• Motor nerves are segmentally supplied from T7 – T12 and L1 spinal nerves
  o External oblique muscle is supplied by ______
  o Internal oblique and transversus abdominis are supplied by _________
  o Rectus abdominis is supplied by ______
• For the dermatomes (sensory to the skin), T7 represents the ______, T10 represents the umbilicus and L1 represents the _______
  o T4 represents the nipple line and T5 is the _________
  o Inner wall of the abdomen is lined by parietal peritoneum – innervated by segmental nerves that supply the corresponding body wall areas
  § Sensitive to pain as it is supplied by somatic sensory nerves
  o The visceral peritoneum has no somatic sensory innervation

Answer 14

T7 – T11; T7 – T12 and L1; T7 – T12

epigastrium; inguinal ligament; xiphoid process

Question 15

Posterior abdominal wall nerves – lies posterior to
the kidneys
o Subcostal nerve – lies just below the ______, supplies the anterior abdominal wall
o Illiohypogastric and ilioinguinal nerve – both arises from the ____ segment, supplying parts of the inguinal region
o Lumbar plexus L1 to L4 – mainly for the lower limb but it also provides sensory branches to the parietal peritoneum
- Nerve supply of posterior wall muscles –
o Quadratus lumborum – ________
o Psoas major – L2 – L4
o Iliacus – femoral nerve from L2 – L4

Answer 15

12th rib; L1 ; T12 and L1 – L4

Question 16

Lymphatic drainage – divided into superficial tissues and deeper tissues
- Superficial lymphatics accompany the subcutaneous veins
o Above the transumbilical plane, superficial lymphatics drain into the pectoral group of the __________
o Below the transumbilical plane, superficial lymphatics drain into the ________________
- Deep lymphatics accompany the deep veins in the
extraperitoneal tissues
o Above the transumbilical plane, the deep lymphatics drain into the ______________
o Below the transumbilical plane, the deep lymphatics drain into the external iliac and para aortic lymph nodes
- There are no lymph nodes in the tissues of the abdominal wall except on the posterior abdominal region along the aorta

Answer 16

axillary lymph nodes; superficial inguinal lymph nodes; mediastinal lymph nodes

Question 17

Inguinal region – also known as the groin
- Inguinal ligament – runs between the ASIS and the pubic tubercle
o Many structures exit and enter the abdominal cavity into the lower limb – a weak area which is clinically important as hernias occur in this area in both sexes (more for males than females)
- Inguinal canal – oblique passageway in the lower part of the anterior abdominal wall, present in both males and females and about 4cm long in adults
o Lies above the medial half of the inguinal ligament and extends from the deep inguinal ring (a hole in the ________) to the superficial inguinal ring (a hole in the external oblique aponeurosis)
§ Deep ring – 1.5cm above the midpoint of the inguinal ligament
§ Superficial ring – immediately superomedial to the pubic tubercle
- In males, the inguinal canal contains the _____________
- In females, it contains the _________ (connects uterus to labia majora) and ilioinguinal nerve

Answer 17

transveralis fascia; spermatic cord and ilioinguinal nerve; round ligament

Question 18

• Boundaries of the inguinal canal – there are 4 walls of the inguinal canal, anterior wall, floor, roof and posterior wall
  o Anterior wall – external oblique aponeurosis (for the whole length) and internal oblique muscle fibres reinforcing the ________
  o Floor – rolled inferior edge (gutter-like) of the external oblique aponeurosis (inguinal ligament)
  o Roof – arching fibres of the ___________ (for the whole length) that fuses at the medial end with the aponeurosis of the transverse abdominis to form the medially conjoint tendon
  o Posterior wall – ___________ and the medially conjoint tendon (on the medial aspect)
• Medially conjoint tendon – formed by the lowest fibres of the internal oblique and similar fibres of the transversus abdominis aponeuroses tendon
  o The tendon is attached medially to the ______

Answer 18

lateral 1/3; internal oblique aponeurosis; transversalis fascia; linea alba

Question 19

Hernia – abnormal protrusion of an organ through the structure that usually contains the organ e.g. intestines pushing through the abdominal wall

• There are 3 different structures in a hernia.
  1. Sac (e.g. peritoneum) – neck, body and _____
  2. Defect – the hole through which the hernia has occurred
  3. Contents of the sac (e.g. bowel, bladder)
• Hernias can be reducible, irreducible, obstructed or strangulated
  o Reducible hernia – sac can be returned to the containing cavity by reducing the ______________
  o Irreducible hernia – sac cannot be returned to the containing cavity
  o Obstructed hernia – sac contains a blocked bowel (by a twisting motion of the bowel leading to the constriction of the neck)
  o __________ hernia – sac has contents with a compromised blood supply, leading to injury to the tissue
• Typical clinical features of hernia include lump in the groin, hernia may come and go (or there all the time), painful, vomiting, constipation and other associated conditions
• Common hernias in the inguinal region are inguinal hernias and femoral hernias

Answer 19

fundus; intra-abdominal pressure; Strangulated

Question 20

Inguinal hernias – further classified as indirect or direct

• Indirect inguinal hernia defect – always in the internal ring (midway of inguinal ligament) which is always lateral to the inferior epigastric vessels
• Direct hernia defect – goes through the __________ (behind the external ring of the inguinal canal) which is always medial to the inferior epigastric vessel

Answer 20

Hasselbach Triangle (boundaries are inferior epigastric vessels, rectus abdominis, and inguinal ligament)

Question 21

Femoral hernias – through the femoral canal, not as common as inguinal hernias
- Femoral hernias are more common in elderly and females than males – pelvic region in the females are wider than males, increasing the chance for a femoral hernia to occur
o Femoral hernias have a high incidence of obstruction and strangulation

• The superior border of the femoral canal is the inguinal ligament, inferior border is the _____, medial border is the ________and lateral border is the _________.
• If there is a swelling below the inguinal ligament (from ASIS to pubic tubercle), it is most probably a femoral hernia
• On examination, femoral hernias tend to be ________ and hot and painful if they are strangulated
  o They can be distinguished from inguinal hernias because they appear below and lateral to the pubic tubercle whereas inguinal hernias are above and medial to the pubic tubercle

Answer 21

pectineus fascia; lacunar ligament; femoral vein; irreducible