Anatomy - Week 7 - Abdomen And Anterior Abdominal Wall/ lower GIT, posterior abdominal wall and arteries supplying the GIT Flashcards
What 3 pieces ?
Ilium, pubis, ischium
In order to carry out a thorough examination of a patients abdomen, what do you needa know?
9 regions and 4 quadrants of the abdomen
What are the 4 abdominopelvic quadrants?
Right upper quadrant (RUQ)
Left upper quadrant (LUQ)
Left lower quadrant (LLQ)
Right lower quadrant (RLQ)
What are the nine regions of the abdomen?
Right hypochondrium (right lobe of liver) Left hypochondrium (left lobe of liver & spleen) Epigastric region (liver and stomach) Right flank (lateral - ascending colon) Left flank (lateral - descending colon) Umbilical region (small intestine) Right groin (caecum, appendix) Left groin (sigmoid colon) Pubic region (lower part of small intestine, bladder, uterus)
What are the main planes of the 9 regions?
Midclavicular planes Subcostal plane (10th costal margin) Intertubercular plane (iliac tubercles)
What is the innervation of the anterior abdominal wall?
Intercostal nerves T7 - T11 and subcostal nerve T12 supply the skin and muscle of the anterior abdominal wall
What supplies the skin over the xiphoid process?
T6
What supplies the skin around the umbilicis?
T10
What does L1 supply?
Skin and muscle in the inguinal and suprapubic regions of the abdominal wall are supplied by L1
What are the anterolateral muscles of the abdominal wall?
5 muscles in this group (3 flat, 2 vertical) External oblique (most superficial, fibres pass toward the midline) Internal oblique (deep to external oblique, fibres passes away from midline) Transversus abdominis (deep to internal oblique, fibres transverse) 2 vertical muscles - rectus abdominis (long flat, extends along the anterior abdominal wall)
What is the direction of the external oblique muscle fibres?
Downward, forwards, medially
What is the aponeurosis of the external oblique?
It is a flattened tendon that arises from a muscle
What is the action of the abdominal muscleS?
Supports and protects abdominal contents, assist in forced expiration, micturition, defection, delivery by increasing intra-abdominal pressure
Describe the position rectus sheath
Between the costal margin and the level of the anterosuperior iliac spine, the aponeuroisis for the internal oblique splits to enclose the rectus muscle
The external oblique aponeurosis is directed in front of the muscle
Transversus aponeurosis is directed behind the muscle
What is the rectus sheath formed From?
Formed from the aponeurosis of the muscles of the anterior abdominal wall, the external and internal obliques and the transversus abdominis.
The anterior aspect of the sheath is formed from the aponeurosis of the external oblique muscle and anterior half of the internal oblique aponeurosis
The posterior aspect of the sheath is formed from posterior half of the internal oblique aponeurosis and the aponeurosis from transverse abdominis.
What forms the anterior wall?
Between the level of the anterosuperior iliac spine and the pubis , the aponeurosis of all three muscles form the anterior wall.
What forms the posterior wall?
Only the fascia transversalis ( the rectus muscle lies in contact with the fascia transversalis)
What is not attached to the posterior wall of the rectus sheath?
The rectus abdominis muscle
What is the anterior wall firmly attached by to the rectus sheath?
Muscles tendinous intersections
What the contents of the rectus sheath?
1- encloses the rectus abdominis and pyramidalis muscle (if present)
2- contains the anterior rami of lower six thoracic nerves and the superior and inferior epigastric vessels
What is the arterial supply of the antero-lateral abdominal wall?
Branches of the internal thoracic artery - the superior epigastric and musculophrenic arteries
Branches of the external iliac artery - inferior epigastric and deep circumflex arteries
Inferior phrenic artery - branch of the abdominal aorta
Lower posterior intercostal and subcostal arteries - from thoracic aorta
Lumbar arteries from the abdominal aorta
What is the nerve supply to the antero-lateral abdominal wall?
The oblique and transversus abdominis muscles are supplied by the lower six thoracic nerves and the iliohypogastric and ilioinguinal nerves (L1)
The rectus abdominis muscle is supplied by the lower six thoracic nerves
Where does the descending thoracic aorta pass through the diaphragm?
At the aortic hiatus at the level of the 12th thoracic vertebra
The descending thoracic aorta descends on the posterior abdominal wall, where does it end?
It ends at the vertebral level L4 by dividing into the right and left common Iliac arteries.
What do the left and right common iliac arteries turn into?
They divide into the external iliac artery (which will pass below the inguinal ligament and become the femora artery) and internal iliac artery (which supply the pelvis and its structures)
What is the celiac Trunk?
Is the most superior of the unpaired visceral branches.
Where does the celiac trunk arise?
It arises just below the diaphragm at the diaphragm at vertebral level T12 -L1 on the anterior surface of the abdominal aorta and immediately divides to give rise to 3 branches.
What are the 3 branches that the abdominal aorta give rise to when it divides?
The common hepatic artery
Splenic artery
Left gastric artery
What are the structures of the foregut supplied by?
Abdominal oesophagus - left gastric artery
Stomach - left and right gastric arteries, left and right gastro-epipolic arteries and the short gastric artery
Part of the duodenum proximal to the entry of the bile duct- gastroduodenal and superior pancreaticoduodenal arteries
Liver - hepatic artery
Gall bladder - cystic artery
Part of the pancreas - is superior pancreaticoduodenal artery
Spleen - splenic artery
What is the jejunum?
The 4th part of the duodenum becomes the jejunum and here the small intestine resumes an intra peritoneal course ]
The jejunum forms the proximal 2/5 of the small intestine after the duodenum. The ilium is the remaining 3/5 & it ends at the ileocecal junction where the terminal ilium opens into the caecum.
Jejunum and ilium are attached to the posterior abdominal wall by a mesentry in which the blood vessels and nerve to the small intestine travel
Which has more fat inside the mesentry, the ilium or the jejunum?
The ileum
Which has a thinner wall the ilium or jejunum?
Ilium
What is absent from the ilium?
The mucosal folds of the small intestine
What is the ilium abundant in?
Peyers patches
Where does the superior mesenteric artery arise?
It’s arises from the abdominal aorta immediately below the celiac trunk art the lower part of L1
What are the branches of the superior mesenteric artery?
Inferior pancreaticoduodenal artery
The middle, right colic arteries
Ileocolic arteries
What supplies blood to the jejunum and ilium?
Jejunal and ideal branches of the superior mesenteric artery
What supplies blood to the distal half of the duodenum?
Inferior pancreaticoduodenal artery
What supplies blood to the lower portion of the pancreas?
Inferior pancreatic-duodenal artery
What supplies the blood to the caecum?
The ileocolic artery
What supplies the blood to the appendix?
Appendicular artery (from the ileocolic artery)
What supplies the blood to the ascending and transverse colon?
Right and middle colic arteries respectively
What does the large intestine (colon) consist of?
(Extends from the ileo-colic junction to anus) It consists of the - Cecum Appendix Ascending, transverse and descending colon Sigmoid colon Rectum Anal canal
What is the features ascending colon?
Ascends from the cecum to the right colic flexure (hepatic flexure) this section is retroperitoneal like the descending colon
What is the features transverse colon?
Has a mesentery (transverse mesocolon) as it approaches the left side its ascends to the level of the spleen and deflects downwards at a flexure known as the left colic flexure (splenic flexure)
What are differences between large intestine and small intestine?
The longitudinal smooth muscle coat of the large intestine is called teniae coli which originate at the base of the appendix and continue along the large intestine
The large intestine also exhibit sacculations known as haustra
There are small bags of fat filled peritoneum called appendices epiploicae
Haustrations, teniae coli and appendices epiploicae are absent in the small intestine
At the ileocecal junction there is ileocecal valve which prevents the back flow to the ileum
What is the inferior mesenteric artery?
It is the most inferior of the unpaired visceral branch of the abdominal aorta and arises at vertebral level level L3
What are the branches of the inferior mesenteric artery?
It’s branches include the left colic artery, sigmoid arteries and the superior rectal artery
What does the inferior mesenteric artery and its branches provide blood to?
Descending colon - left colic artery
Sigmoid colon - sigmoid arteries
Rectum - superior rectal artery
What is the position of the inferior vena cava?
It leaves the abdomen and passes through diaphragm and enters the thorax at the T8 vertebral level, it is to the right side of the abdominal aorta.
What are the branches of the IVC corresponding to the paired parietal branches of the abdominal aorta?
Inferior phrenic veins and lumbar veins
What are the branches of the IVC corresponding to the paired parietal branches of the abdominal aorta?
Right suprarenal vein Right and left renal veins Right gonadal vein Left suprarenal The left gonadal veins which drain indirectly into IVC via left renal vein.
What is the portal system?
Venous drainage for the spleen, pancreas, gall bladder and GIT (except the inferior part of the rectum), which takes blood from the above mentioned viscera and delivers it to liver then via hepatic veins to inferior vena cava
What are the muscles of the posterior abdominal wall?
Psoas major, Psoas minor, quadratus lumborum and iliacus
What are the key details of the psoas major muscle?
Origin - from bodies of the vertebrae t12 and all five of the lumbar vertebrae
Insertion - lesser trochanter of the femur
Action - flexes thigh at the hip joint when the trunk is stabilised and flexes the trunk when the body is in the supine position
Nerve supply - anterior rami of L1 - L3
What are the key details of the Psoas minor?
(Absent in 50% of the population)
Origin- vertebrae T12 and L1 and intervening intervertebral disc
Insertion - pectineal line of the pelvic brim
Action - weak flexor of the trunk
Nerve supply - anterior rami of L1
What are the key details of the iliacus?
Origin - iliac fossa
Insertion - into lesser trochanter of femu
Action - with the psoas major , they form the iliopsoas (the chief flexor of the thigh)
Nerve supply - femoral nerve (L2 - L4)
What are the key details quadratus lumborum?
Origin - transverse process of L5 vertebra and adjoining part of iliac crest and into transverse processes of first 4 lumbar vertebrae
Insertion - inferior border of rib 12
Action - fixes the twelfth rib and aid lateral bending of the trunk
Nerve supply - anterior rami of T12 and L1 - L4
