Abdominal wall anatomy Flashcards by Kelvin Sunn Yap

At what vertebral Lebel is the transpyloric plane of the abdomen?

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Name the main structures that the transpyloric plane passes through.

Fundus of GB
Hila of kidneys
First part of duodenum
Neck of the pancreas
Origin of SMA
Origin of portal vein
Pylorus of stomach
Hilum of spleen

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At which vertebral level does the trans tubercular plane cross through?

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Where do the vertical lines of the abdominal regions pass between?

A point halfway between the pubic tubercle and the associated ASIS.

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What marks the lower margin of the thorax and start of abdomen?

Costal margin

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What structures form the costal margin?

Costal cartilages anteriorly
Ribs 7-10 laterally
Ribs 11-12 posteriorly

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What is the linea alba?

A fibrous structure that runs down the midline of the abdomen in the median plane.

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Where does the linea alba run between?

Xiphoid process and pubic symphysis.

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What is the linea alba formed by?

The fusion of the aponeurosis of the muscles of the anterior abdominal wall.

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What is the pubic symphysis?

The midline cartilaginous structure that unites the superior rami of the left and right pubic bones.

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What are the layers of the anterior abdominal wall from external to internal?

Skin
Superficial fascia
Muscles and associated fascia
Parietal peritoneum

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What are the 3 ‘flat’ muscles of the anterior abdominal wall?

External obliques
Internal obliques
Transverse abdominis

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What are the 2 ‘vertical’ muscles of the anterior abdominal wall?

Rectus abdominis
Pyramidalis

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Where are the flat muscles of the abdominal wall located?

Laterally.

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How do the flat muscles strengthen the anterior abdominal wall and reduce the risk of hernias?

By running in different directions and the fibres ‘crossing’ each other.

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In the anteromedial aspect of the abdominal wall, each flat muscle forms what?

An aponeurosis.

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What is an aponeurosis?

A broad, flat tendon

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What do the aponeuroses of the anterior abdominal Wal, cover?

The rectus abdomens muscle.

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The aponeurosis of the flat muscles of the anterior abdominal wall become entwined in the midline and form what?

The linea alba.

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What is the order of the flat muscles of the abdomen from external to internal?

External obliques
Internal obliques
Transversus abdominis

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In which direction do the fibres of the external obliques run?

Inferomedially

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What is the innervation of the external obliques?

Thoracoabdominal nerves (T7-T10)
Subcostal nerve (T12)

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What are the actions of the external obliques?

Contralateral rotation of the torso

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What is the origin of the external obliques?

Ribs 5 - 12

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What is the attachment of the external obliques?

Iliac crest + pubic tubercle

In what direction do the fibres of the internal obliques run?

Superomedially

What is the innervation of the internal obliques?

Thoracoabdominal nerves (T7-T11) Subcostal nerve (T12) Branches of lumbar plexus

What are the functions of the internal obliques?

Bilateral contraction compresses abdomen Unilateral contraction ipsilaterally rotates torso

What is the origin of the internal obqliues?

Inguinal ligament Iliac crest Lumbodorsal fascia

What is the attachment of the internal obliques?

Ribs 10-12

In what direction do the fibres of the transversus abdominis run?

Transversely

What is found deep to the transverse abdominis?

Transversals fascia

What is the innervation of the transverse abdominis?

Thoracoabdominal nerves (T7-T11) Subcostal nerve (T12) Branches of lumbar plexus

What is the function of the transverse abdominis?

Compression of abdominal contents

What is the origin of the transverse abdominis?

Inguinal ligament Costal cartilages 7-12 Iliac crest Thoracolumbar fascia

What is the attachment of the transverse abdominis?

Conjoint tendon Xiphoid process Linea alba Pubic crest

Where is the rectus abdominis found?

Either side of the midline in the abdominal wall.

What splits the rectus abdominis into 2?

Linea alba

What do the lateral borders of the rectus abdominis create?

Linea semilunari (surface marking)

What structures transversely intersect the rectus abdominis?

Tendinous intersections (fibrous strips)

What is the innervation of the rectus abdominis?

Thoracoabdominal nerves (T7-T11)

What are the functions of the rectus abdominis?

Depresses the ribs Stabilises the pelvis during walking Assists flat muscles in compressing abdominal viscera

What is the origin of the rectus abdominis?

Crest of pubic bone

What are the attachments of the rectus abdominis?

Xiphoid process Costal cartilage of ribs 5-7

What is the rectus sheath formed by?

The aponeuroses of the 3 flat muscles.

What does the rectus sheath enclose?

The rectus abdominis and pyramidalis muscles Posterior intercostal nerves Superior epigastric artery Inferior epigastric artery

What is the arcuate line?

The demarcation point where the posterior layer of the rectus sheath ends. Below the arcuate line, the rectus abdominis comes into direct contact with the transversals fascia.

The vertical planes of the abdomen line up with which other hypothetical line?

Mid-clavicular lines.

The fibres of the rectus abdominis have what orientation?

Run vertically.

At what level does the thoracic aorta become the abdominal aorta?

T12

In which space does the abdominal aorta descend in?

Retroperitoneal space, anterior and to the left of the lumbar vertebrae and IVC.

Where does the abdominal aorta end?

At the L4 level, slightly to the left of the midline.

What does the abdominal aorta bifurcate into?

Right and left common iliac arteries.

What are the 3 main groups of branches of the abdominal aorta?

Single ventral gut arteries Paired visceral arteries Pairs wall arteries

Which 3 vessels are single ventral gut arteries?

Coeliac artery SMA IMA

At what level does the coeliac artery arise from?

T12

At what level does the superior mesenteric artery arise from?

At what level does the inferior mesenteric artery arise from?

Which 3 vessels are classed as paired visceral vessels?

Middle adrenal arteries Renal arteries Gonadal arteries

Which level do the middle adrenal arteries arise from?

Which level do the renal arteries arise from?

When the abdominal aorta is healthy, in what direction should it move when palpated?

Upwards in a pulsatile motion.

What direction will the abdominal aorta move in upon palpation if there is an abdominal aortic aneurysm?

Outwards

Define abdominal aortic aneurysm.

An enlargement of the aorta at least 1.5 times its normal diameter or >3cm in total.

At what size can AAAs become prone to rupture?

>6cm

Where does the IVC arise from?

At what vertebral level does the IVC arise?

At what location does the IVC ascend?

At what vertebral level does the IVC pierce the diaphragm?

Name the veins which drain into the IVC.

Common iliac Lumbar Right gonadal Renal Hepatic There are more but RCEM doesn't require knowledge of them.

Which areas are drained by the common iliac veins?

Lower limbs and gluteal regions

Which areas are drained by the lumber veins?

Posterior abdominal wall

Which areas are drained by the right gonadal vein?

Right testis/ ovary

Which areas are drained by the renal veins?

Kidneys Left adrenal Left testis/ovary

Which areas are drained by the left, right and middle hepatic veins?

Liver

What are the 2 groups of abdominal lymph nodes?

Pre-aortic Para-aortic

Where do the pre-aortic lynph nodes lie?

Anterior to the aorta, around origins of visceral arteries.

Which areas do the pre-aortic lymph nodes drain?

GI tract Liver Spleen Pancreas

The pre-aortic lymph nodes can be divided into which 3 further groups?

Coeliac lymph nodes Superior mesenteric lymph nodes Inferior mesenteric lymph nodes

Where do the efferent lymphatics of the pre-aortic nodes drain into?

Intestinal trunk.

Where do the para-aortic lymph nodes lie?

Laterally on either side of the aorta

Which areas are drained by the para-aortic lymph nodes?

Kidneys Upper parts of ureters Gonads Fallopian tubes Uterus

Where do the efferent lymphatics from the para-aortic lymph nodes drain into?

Lumbar trunk.

What are the 5 muscles which form the posterior abdominal wall?

Iliacus Psoas major Psoas minor Quadratus lumborum Diaphragm

Where is the quadrtus lumborum in relation to the posts major?

Superficial to it

What is the innervation of the quadratus lumborum?

Anterior rami or T12 - L4

What are the functions of the quadratus lumborum?

Extension and lateral flexion of the vertebral column **Also fixes 12th rib during inspiration so that contraction of diaphragm is more efficient.

What is the innervation of posts major?

Anterior rami of L1-L3

What is the function of posts major?

Flexion of the thigh at the hip Lateral flexion of the vertebral column.

What is the innervation of iliacus?

Femoral nerve (L2-L4)

What is the function of iliacus?

Flexion and lateral rotation of the thigh at the hip

What is the posts sign?

Performed by flexing the thigh at the hip. Positive if this causes lower abdominal pain.

What does the posts sign suggest?

Appendicitis.

Where is the lumbar plexus located?

Within the psoas major, anterior to the transverse processes of the lumbar vertebrae.

What is the lumbar plexus formed by?

The anterior rami (divisions) of the lumbar spinal nerves L1-L4.

What are the 6 branches of the lumbar plexus?

Iliohypogastric nerve Ilioinguinal nerve Genitofemoral nerve Lateral cutaneous nerve Femoral nerve Obturator nerve

Which roots form the iliohypogastric nerve?

L1 (+ some T12)

Which roots form the ilioinguinal nerve?

Which roots form the genitofemoral nerve?

L1 + L2.

Which nerve roots form the lateral cutaneous nerve?

L2, L3

Which nerve roots form the femoral nerve?

L2 - L4

Which nerve roots form the obturator nerve?

L2 - L4

Which muscles are supplied by the iliohypogastric nerve?

Internal obliques Transversus abdominis

Which cutaneous areas are supplied by the iliohypogastric nerve?

Posterolateral gluteal skin.

Which muscles are innervated by the ilioinguinal nerve?

Internal obliques and transverse abdominis

Which cutaneous areas are supplied by the ilioinguinal nerve?

Superior antero-medial thigh Skin over root of penis and anterior scrotum OR Skin over mons pubis + labia majora

Which muscles are supplied by the genitofemoral nerve?

Cremasteric muscle (genital branch)

Which cutaneous areas are supplied by the genitofemoral nerve?

Genital = anterior scrotum/ mons pubis + labora majora. Femoral = skin on upper anterior thigh

What is the motor function of the lateral cutaneous nerve?

None.

What cutaneous areas are supplied by the lateral cutaneous nerve?

Anterior and lateral thigh down to the knee.

Which muscles are supplied by the obturator nerve?

Medial thigh muscles: Obturator externes Adductor longus Adductor brevis Adductor magnus Gracilis

What cutaneous areas are supplied by the obturator nerve?

Skin over medial thigh

Which muscles are supplied by the femoral nerve?

Anterior thigh muscles: Iliacus Pectineus Sartorius Quadriceps femoris

Which cutaneous areas are supplied by the femoral nerve?

Skin on anterior thigh and medial leg