4.3 Flashcards
Abdomen surface anatomy
Regions of the abdomen
Midclavicular lines (vertical, green)
- midpoint of clavicles and inguinal ligament
Sucostal line (blue)
- pass across inferior border of 10th costal cartilage
Intertubercular line (purple)
- join iliac tubercles and crosses L5
- Left and right hypochondriac
- Epigastric
- Left and right lumbar (lateral)
- Umbilical
- eft and right inguinal (iliac)
- Hypogastric (pubic)
The abdominal wall is divided into what two regions?
Anterolateral: muscles and aponeurosis
Posterior: musculoaponeurotic and lumbar spine
Anterolateral abdominal wall: boundaries
Superior: costal margin (ribs 7-10) and xiphoid
Inferior: inguinal ligament and pelvic girdle
Posterior: blends with posterior wall
Anterolateral abdominal wall: components
Skin, subcutaneous
Muscles, aponeurosis
Deep fascia, extraperitoneal fat, parietal peritoneum
Anterolateral abdominal wall: 4 quadrants
RUQ: liver, gallbladder, intestines, head of pancreas, R adrenal gland, superior R kidney, distal stomach
LUQ: left lobe of liver, stomach, spleen, body of pancreas, L adrenal gland, L kidney, intestines
RLQ: interior R kidney, cecum, intestines, appendix, R ovary, R ureter, R spermatic cord
LLQ: inferior L kidney, intestines, L ovary, L ureter, L spermatic cord
Anterolateral abdominal wall: muscles
External and internal abdominal oblique
Transversus abdominis
Rectus abdominis
Anterolateral abdominal wall: rectus sheath
Aponeurosis of abdominal muscles
- External and internal oblique and transversus abdominis
* all anterior below arcuate line
* below arcuate line:
> EO - anterior
> IO - splits at the linea semilunaris and goes anterior and posterior
> TA - posterior
- The arcuate line is between the umbilicus and pubic crest. It marks the inferior termination of posterior rectus sheath.
- For the entire length of the rectus abdominis muscles, the anterior and posterior sheath interlock at the midline to form the linea alba.
Neurovascular plane: Anterior Wall
Neurovasculature is located in the deep fascial plane between internal oblique and transversus abdominis.
Lateral cutaneous branches pierce through the obliques to reach skin near anterior axillary line.
Anterior cutaneous branches pierce the rectus sheath and become cutaneous near midline.
Superior and inferior epigastric vessels are located in rectus sheath
Arterial supply for anterior wall
Internal thoracic
- superior epigastric
- musculophrenic
External iliac
- inferior epigastric
The superior and inferior epigastric arteries run vertically within the rectus abdominis and anastomosis in umbilical region. They provide a collatearl channel to lower limbs in the event that there is blockage of common external iliac arteries which would otherwise lead to ischemia to affected limb.
The remaining arteries run in an oblique direction that parallels the direction of the abdominal oblique muscles and nerves.
Cutaneous innervation for anterior wall
Thoracoabdominal nerves (T7-T11): anterior continuation of intercostal nerves
Subcostal nerve (T12): inferior to rib 12
Iliohypogastric and ilioinguinal (L1): anterior ramus of L1 from lumbar plexus
Contents of posterior abdominal wall
5 lumbar vertebral and IV discs
6 muscles
- diaphragm
- quadratus lumborum
- psoas major
- psoas minor
- iliacus
- transverse abdominal
Fascia
- endoabdominal fascia: surface of muscles; continuous with transversalis fascia
- parietal peritoneum: covers abdominal cavity
Diaphragmatic hernias
Hiatal hernia: at esophageal sphincter
- functionally the external lower esophageal sphincter (LES)
- defective function can lead to GERD and hiatal hernias
Lumbocostal triangle
- weak area of diaphragm through which abdominal contents may herniate into thorax
Neurovasculature of posterior abdominal wall
Abdominal aorta
Somatic nerves
- subcostal
- lumbar spinal
* quadratus lumborum
> subcostal and lumbar
* psoas and iliacus
> lumbar
Abdominal fascia
Pleura: lines thoracic cavity and lungs
Peritoneum: lines abdominal cavity and its organs
Peritoneal cavity
Parietal peritoneum lines cavity wall
Visceral peritoneum lines organs
Mesentery: folds of peritoneum create attachments to wall and covering
- double layered
Ligaments and omentum: attach organs to one another
Retroperitoneal: covered on one surface covered by parietal peritoneum
Intraperitoneal: nearly fully covered with visceral peritoneum
Omentum
Folds of peritoneum
Barrier and immune functions
Greater omentum: over small intestine and transverse colon
Lesser omentum: attaches stomach to liver
Stomach
Lesser curvature - lesser omentum
Greater curvature - greater omentum
Function: chemical and physical digestion
Duodenum
C shaped
All parts are retroperitoneal except superior part
Receives bile
Function: chemical digestion
Duodenal flexure
- marked by ligament of Treitz
* double fold of peritoneum suspending DJ flexure from retroperitoneum
- point at which small bowel becomes intraperitoneal
- clinical distinction between upper and lower GI tract
Jejunum and ileum
Intraperitoneal
Jejunum
- upper region
- absorbs carbohydrates and proteins
Ileum
- lower region
- absorbs bile and fat
Cecum
1st part of the large intestine
Ileum enters obliquely
Large intestine
Teniae coli: 3 longitudinal bands along length of colon that converge on appendix
Haustra: sacculations in wall
Epiploic (omental) appendices: small, fatty projections
Function - absorb fluid and electrolytes
Appendicitis
Causes tenderness at McBurney’s point between umbilicus and ASIS
Blockage of appendix lumen, usually by fecal stone
Swelling and inflammation
Progression of pain
- preumbilical: referred pain from midgut
- RLQ pain: irritation of parietal peritoneum
Psoas sign
- clinical test
- passive extension of R hip wile sidelying on left side
- positive it there’s pain
- useful for retrocecal appendix
Obturator sign
- clinical test
- works when appendix is in pelvis
- passive internal rotation of flexed thigh
- positive if there’s pain
Diverticulosis
Diverticula: outpockets of mucosal lining of intestine
Usually occurs in elderly people and in sigmoid colon
Occurs at weak point in mucosal wall where arteries pierce the wall
Can become infected and rupture
Pancreas
Retroperitoneal
Releases digestive enzymes into duodenum
Spleen
Intraperitoneal
Immune function and removes damaged RBCs
Liver
Stores nutrients, synthesizes proteins, and detoxifies blood
Biliary system
Liver forms bile –> hepatic ducts –> gallbladder (storage)
Assists with absorption and digestion of fats
