Abdominal wall - ANATOMY Flashcards
How is the abdominal wall separated?
Into 9 regions, divided by the mid-clavicular, subcostal and intertubular planes
Name the 9 regions of the abdomen
Epigastric
Left hypochondriac
Right hypochondriac
Umbilical
Left and right lumbar
Suprapubic
Left and right iliac
How else can the abdomen be separated?
Into 4 quadrants
What are the 4 quadrants of the abdomen?
Left and right upper and lower quadrants
What separates these quadrants?
Line down the centre and one horizontal at the belly button
On the antero-lateral abdominal wall, what are some surface landmarks?
Linea alba - midline
Umbilicus - belly button
Costal margin - ribcage as it slopes
Xiphoid process
Iliac crest - lateral protrusion of hip bone
ASIS - Anterior protusion of hip bone
Pubic symphysis - pubic bone middle
Pubic tubercle - on both sides of the pubic symphysis
How many layers of muscle are there on the lateral abdominal wall?
Three Oblique - external - internal - transversus abdominal
What are the muscles on the anterior wall?
Paired vertical rectus abdominis - abs
What are the muscles on the posterior wall?
Post-vertebral
- erector spinae
Psoas
Quadratus lumborum
Iliacus
Where and what are the flank sheet muscles?
Muscles covering the lateral abdominal wall - which are?
What is the function of the flank sheet muscles?
Compress the abdomen and increase intra-abdominal pressure -
Supports viscera - guard intestines
Flexes and rotates trunk
What is the external oblique muscle attached to?
External surface of lower 8 ribs
- ORIGIN
HAS A FREE POSTERIOR BORDER
Attaches to - INSERTION
- xiphoid process
- linea alba
- pubic crest + tubercle
- anterior half of iliac crest
Muscle fibres are directed down and forward
What is aponeurosis?
A sheet of white fibrous tissue that take the place of tendon in flat muscle, with a wide point of attachment.
The aponeuroses form the rectus sheath
What is the internal oblique attached to?
Lateral
Thoracolumbar fascia
Iliac crest
Inguinal ligament
Medial
Lower 3 ribs
Xiphoid process
Rectus sheath
Fibres are downward and backward
What is the transversus abdominis attached to?
Lateral
- Lower 6 costal cartilages
- Thoracolumbar fascia
- Iliac crest - anterior 3rd
- Inguinal ligament - lateral 3rd
Medial
- Xiphoid process
- Linea alba
- Symphysis pubis
- Conjoint tendon
Fibres are horizontal
What is the rectus abdominis attached to?
Superior
- 5-7 costal cartilages
- Xiphoid process
Inferior
- Symphysis pubis
- Pubic crest
Fibres run longitudinally
What forms the rectus sheath? What does it do?
Aponeurosis of 3 muscles. Covers rectus abdominis
How is the rectus sheath divided?
Above umbilicus
- Internal oblique aponeuorsis ENCLOSES rectus abdominis
- External oblique is anterior to abdominis
- Internal is POSTERIOR
Below umbilicus
- All three aponeurotic layers sit anterior to the rectus muscle
Posterior rectus sheath ends at ARCUATE Line before umbilicus, after this it joins the transversalis fascia, anterior to the rectus abdominis
What are the posterior abdominal wall muscles?
Psoas major
- hip and trunk flexor
- joins to the 5 lumbar vertebra
Quadratus lumborum
- stabilises 12th rib and lateral trunk flexor
Iliacus muscle
- hip joint flexor
Nerve supply of the posterior abdominal wall
Subcostal
Iliohypogastric
Ilio-linguinal
What is the nerve supply of the abdominal wall?
Segmental
- External oblique
- T7-11
- Internal oblique and
transverse
- T7-12 and L1
- Rectus
- T7-12
Dermatomes at
- T7 - epigastrium
- T10 - umbilicus
- L1 - inguinal ligament
What is the inguinal region?
Junction between abdominal wall and thigh
Lymphatic drainage of the abdominal wall
None on the abdominal wall
Superficial
- go to the axiliiary lymph node
Deep
- mediastinal and external
WHy is this area weak?
Muscles not directly attached to any structure
What are the landmarks of inguinal region?
ASIS (anterior superior iliac spine) and pubic tubercle
Why is this area weak?
Muscles not directly attached to any structure - ligament fills - thus weak
What is the clinical and anatomical importance of this region?
C: Site of potential herniation
- femoral or inguinal
A: Site of structure entry and exit
What is the inguinal canal used for?
The inguinal canal has an inherent weakness, allowing hernia formation
M
- testis and spermatic cord descend from abdomen into the scrotum via the canal
- ilioingual nerve
- genito-femoral nerve
F
- uterine ligament descends
- ilion ingual nerve
- genito-femoral nerve
What is a hernia?
Where part of, or a whole organ/ tissue abnormally protudes through the wall of the structure containing the organ.
Occurs if the deep inguinal ring is large enough for part of organ to ‘pop’ through
Describe a hernia
Protrusion of peritoneum through defective abdominal wall, forming hernial sac
Some organ is contained in the peritoneum
Covered by skin - lump-like
Requires
- wall weaknesss
- hernial sac
- contents
What is the structure of the inguinal canal?
Oblique passageway in the lwoer anterior abdominal wall
4cm long
What are some facts about herniae in the groin
Inguinal > femoral
In femoral, female > male
- larger pelvis and hence space for herniation
Most inguinal herniae are congenital
What is the structure of the inguinal canal?
Oblique passageway in the lower anterior abdominal wall
4cm long, above medial half of inguinal ligament
Deep ring 1.5cm above midpoint
Superficial ring right above and medial to tubercle
How many walls are there of the inguinal canal and what are they made of?
Anterior
- external oblique aponeurosis
- internal oblique for reinforcement - lateral 3rd
Floor
- rolled inferior edge of ext oblique - inguinal ligament
Roof
- arching fibres of both internal and external oblique muscles
Posterior
- transversalis fascia
- medially conjoint tendon
Made from the various muscles and ligament
What is an inguinal hernia?
Compare the types
Direct - ACQUIRED
- goes through Hesselbach’s triangle - inguinal - posterior to superficial ring
- always medial to inferior epigastric vessels
- just goes through superficial ring
- associated with chronic straining
- doesn’t go into scrotum
Indirect - CONGENITAL
- internal ring is LATERAL to inferior epigastric vessels
- goes through deep ring THEN superficial
- through to scrotum as it takes path that testes would
- defective DEEP ring - dilation
What are the layers of fat along the abdominal wall, superficial to deep?
Camper’s fascia
Scarpa’s fascia
Preparietal fat
What happens if the abdominal aorta is blocked?
The superior and inferior epigastric arteries can anastomose, forming a bypass.
How are the parietal and visceral peritoneum innervated?
Parietal - same as anterior abdominal wall
Visceral - no innervation
What is the femoral canal?
Canal beneath inguinal ligament containing lymph vessel, the femoral vein and artery pass lateral to it
Vessels + canal = femoral sheath
What is a conjoint tendon?
Lowest fibres of the internal oblique aponeurosis and transversus abdominis aponeurosis join, forming this tendon.
Attaches medially to linea alba
What is a femoral hernia?
Hernia via femoral canal
Not as common as inguinal
More common in women and elderly
High incidence of obstruction and strangulation
Where is the femoral canal located?
In relation to it:
Superior - inguinal ligament
Inferior - pectineus fascia
Medial - lacunar (Gimbernat) ligament
Lateral - femoral vein
How are femoral herniae characterised?
Irreducible
Hot and painful if strangulated
Distinguishable from inguinal as below and lateral to pubic tubercle
Where are inguinal hernias positioned?
Above and medial to pubic tubercle
