2 - Anterior Abdominal Wall and Peritoneum Flashcards
What are the boundaries of the abdomen? (broadly)
Superior = Diaphragm and inferior thoracic aperture
Inferior = Iliac crest, Inguinal Ligament and the Pelvic Inlet (continuous) (superior lower limb)
Posterior = The lumbar vertebrae, Psoas Major, Iliacus and Quadratus Lumborum
Lateral and Anterior = the abdominal wall muscles
What is peritoneum?
A single layer of epithelial like cells (mesothelium) with a supportive CT layer that lines the abdominal cavity
The viscera of the abdomen are …
suspended in the peritoneal cavity by mesentery or are between the cavity and the body/muscular body wall
Parietal and visceral peritoneum?
P = Lines abdominal wall
V = Lines/covers suspended viscera
Are continuous
Intra/Retroperitoneal?
Intraperitoneal = Suspended by mesenteries from the abdominal wall Retroperitoneal = Organ lies between the parietal peritoneum and abdominal wall
How do neurovascular structures reach the intraperitoneal structures?
Travel in mesenteries
Abdominal and pelvic cavities are continuous and structures pass between the 2… give an example of a process
Birth
Identify the layers of the abdominal wall from the skin to peritoneum
Skin l Camper’s Fascia l Scarper’s Fascia l External Oblique l Internal Oblique l Transversus Abdominis l Transversalis Fascia l Extraperitoneal Fascia l Parietal Peritoneum
What nerves, broadly, supply the abdominal wall and parietal peritoneum?
The anterior rami of spinal nerves T7 > T12 as well as L1 (iliohypogastric). These then split into anterior and lateral cutaneous branches
What nerves are intercostal and which are subcostal?
T7 > T11 are intercostal. T12 and L1 are SUBcostal
Where do the nerves run?
In between the abdominal muscles internal oblique and transversus abdominis
The peritoneal cavity is split into the … and …
Greater sac and lesser sac (omental bursa)
The lesser omentum can be divided into the …
Hepatoduodenal and hepatogastric ligaments
What is the greater omentum?
Is a large apron-like fold of VISCERAL peritoneum that hangs down form the stomach and anterior transverse colon. It is a double fold that connects the stomach to the posterior abdominal wall. It is derived from dorsal mesogastrium
What is omentum?
Double layer of peritoneum that attaches the stomach to another organ. Greater = greater curvature of stomach. Lesser = lesser curvature of the stomach
What is the lesser omentum?
A double fold of peritoneum that extends from the liver to the lesser curvature of the stomach and the duodenum
What do the lesser and greater omentum arse from?
Greater = dorsal mesogastrium Lesser = Ventral mesogastrium
Peritoneal folds from…
Mesentery, ligaments and omentum. They contain vessels and maintain the position of the viscera
What are the 2 divisions of extra peritoneal fascia?
Retro and preperitoneal fascia
What are the 4 divisons of the abdomen?
Right upper … quadrant
What are the 9 divisions of the abdomen?
Right and left hypochondrium (below the cartilage of the ribs) Epigastric Right and left flank Umbilical Right and left groin Pubic/Suprapubic
What are the planes that form the 9 divisions of the abdomen?
2x Midclavicular Plane
1x Subcostal Plance
1x Intertubercular Plane
What side is the stomach and liver on?
Stomach = left upper quadrant Liver = right upper quadrant
Where does the superficial fascia divide into Camper’s and Scarper’s?
Below the umbilicus. Camper’s fascia is superficial and fatty. Scarper’s is deep and membranous
Why are there muscles protecting the abdomen rather than bones like in the thoracic region?
Because we want flexibility and movement as the viscera are always moving when we eat and breathe etc. The only bones in this region are the lumbar vertebra and the lower thoracic aperture/ribs (outlet)
Describe Rectus Abdominis
O= Pubic symphisis, crest and tubercle
I = Costal cartilages of ribs 5-7 AND xiphoid process
> flex trunk, support and compresses abdominal wall, can force air out
> anterior rami of thoracic spinal nerves
> most superficial (linea alba is underneath)
External Oblique?
O = Lower ribs (5-12)
I = Iliac crest and linea alba via aponeurosis
Aponeurosis runs from xiphoid process to pubic symphysis where its lower border forms the inguinal ligament
> flex trunk, turn to OPPOSITE side and bend trunk to same side
> O and I can swap to pull lges up and to side
> anterior rami of thoracic spinal nerves
> fibres infero-medial
Internal Oblique?
O = Fascia of the back (thoracolumbar) inguinal ligament and iliac crest
I = Ribs 9-12, linea alba and pubis symphysis
> flex trunk, bend and turn trunk to SAME side (works with ext oblique of opposite side)
> Anterior Rami of thoracic spinal nerves AND some L1
> Supero-medial fibres
As well as the anterior rami of the thoracic spinal nerves, which muscle also receives innervation from L1?
The internal obliques and transversus abdominis
Transversus Abdominis?
O: Thoracolumbar fascia, iliac crest, inguinal ligament, costal CARTILAGES of ribs 7-12
I: Linea alba, pubic crest via conjoint tendon, pectineal line
> Supports abdominal wall
> Anterior rami of thoracic nerves and some L1
> transverse fibres
At the upper 3/4 of the abdomen the aponeurosis from which muscle splits?
The internal oblique. External oblique runs anterior and transversus abdominis posterior
What happens at the inferior 1/4 of the abdomen?
All 3 muscles course round the anterior of rectus to form the rectus sheath.
What is behind rectus abd. at the lower 1/4?
Only transversalis fascia, extraperitoneal fascia and pariteal peritoneum
What is the arcuate line and where is it found?
Line where the posterior rectus sheath ends. Half way umbilicus > pubis. From here only see transversalis fascia. Continues whole way anteriorly/infront of rectus
What arteries supply the abdominal wall, where do they come from and where do they run?
Sup Epigastric (from internal thoracic) Inferior Epigastric (ext iliac) > run under rectus, on top of transversalis fascia and within the rectus sheath on the TOP of the posterior rectus sheath. They anastomose but the inferior is larger and more important
What is the significance and purpose of the arcuate line?
If the posterior rectus sheath continued then the inferior epigastric artery would have to penetrate through the aponeurotic sheath as it comes from deep/inferior to more superficial/superior. This is unyielding and would clamp off the artery if you sat in a particular position for too long. This way the artery only has to go through the softer transversalis fascia and then lie under the rectus abdominis muscle on top of the transversalis fascia and within the rectus sheath
Thoracoepigastric veins (superior) drain to …
Axillary Vein
Superficial Epigastric Veins (inferior) drain to …
Femoral Vein
Nervous supply?
Anterior Rami of spinal nerves 7-12 and L1 (iliohypogastric and ilioinguinal). These branch into the lateral and anterior cutaneous branches. Lateral has L1 anterior doesn’t.
Where do the nerves travel?
In a fascial/neurovascular plain between the internal oblique and transversus abdominis
Dermatomes?
> The skin, muscle AND PARIETAL peritoneum are supplied by anterior rami of spinal nerves T7-T12 (intercostal) and L1 (iliohypogastric/ilioinguinal)
run in the neurovascular plane before piercing the muscular wall to reach the skin
Describe the lymphatic drainage
Follows the superficial layers drainage pattern so follows the veins.
Superior from umbilicus > anterior axillary
Inferior > superficial inguinal
Posterior > Posterior Axillary
Purpose of peritoneum?
Peritoneal cavity contains a small amount of serous fluid to reduce the friction of movement and avoid inflammation
Sensation in the parietal peritoneum?
Is ALSO innervated by the somatic nerves to the body wall T7-T12 and L1, as well as the phrenic nerve (diaphragm) and obturator nerve (down in the pelvis)
> this means it is sensitive to pain, touch, temperature, and pain
Sensation in visceral peritoneum and mesenteries?
Not innervated by T7-T12. Is instead innervated by ANS afferent fibres which are sensitive to stretch/distention i.e. when you eat too much
Mesenteries formed by..
The visceral peritoneum comes back around itself to form a mesentery anchoring the viscera to the posterior body wall
GI tract is suspended by…
mesenteries
Midgut and Hindgut are suspended by…
Only DORSAL mesentery
Foregut is suspended by…
BOTH ventral and dorsal mesenteries. Means the foregut is attached to the body wall both anteriorly and posteriorly by peritoneal folds.
Where is infraperitoneal?
Pelvic.
What organs are intra-peritoneal?
Completely contained in peritoneum and suspended by a mesentery > stomach > liver > gall bladder > spleen > proximal duodenum > SI > appendix > transverse colon > sigmoid colon
What organs are retro-peritoneal?
Covered one 1 side/between peritoneum and body wall. > kidneys > pancreas > distal duodenum > ascending and descending colon > upper 2/3 of rectum
Greater Sac?
Peritoneal Cavity Proper
Lesser Sac?
Also called the omental bursa. Behind the lesser omentum and stomach. Is more clinically relevant as is a blind ended pouch
How is the lesser omentum formed?
Created due to the rotation of the foregut structures which drags the lesser omentum round to create a ‘pocket’
What is in the lesser and greater sacs?
Serous flui/peritoneal space
What is the free edge of the omental bursa called?
omental foramen (of Winslow)
What does the lesser omentum attach to and what does it consist of?
Attaches from the liver to the stomach and proximal duodenum
Consists of the hepatoduodenal ligament and hepatogastric ligament
The anterior of the omental foramen is bounded by the … which contains the …
Lesser omentum which contains the portal triad
The posterior of the omental foramen is bounded by the …
Inferior Vena Cava
The inferior 1/3 of the rectum is…
infra-peritoneal
Peritoneal fold containing the jejunum to terminal ileum
mesentery
peritoneal fold containing transverse colon?
Transverse mesocolon
Sigmoid colon mesentery?
Sigmoid Mesocolon
What and where are the paracolic gutters?
They are peritoneal sulci/reflections lateral to the ascending and descending colon
What do they paracolic gutters do?
They create a pathway for peritoneal fluid OR pus/bile/blood to migrate around the abdomen
Which paracolic gutter is more clinically relevant and why?
It is larger in size and the left side is usually limited by the phrenico-colic ligament. The right side peritoneum is continuous with the peritoneum of the of the hepatic recess and lesser sac
What is the clinical significance of paracolic gutters?
The migration of fluid can cause pain to present in sites DISTANT from the affected organ/pathology. I.e. if sitting fluid will migrate down and present as appendicitis, if supine will migrate to the lesser sac which is a blind ended pouch, collect and form an abscess
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