Ch18 - Posterior Abdominal Wall (PAW) and Kidneys Flashcards
Diagram
Three muscular Parts of the Diaphgram
Central Tendon (moveable part)
Three Openings in Diaphragm
Caval opening (Hiatus)
“: IVC traverses at T8, in the central tendon. Diaphragm contraction opens IVC allowing more blood flow during inspiration.
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Esophageal hiatus
“ vagal trunks traverse as well at T10”
Aortic Hiatus
“aorta and thoracic duct traverse at T12”
Innervation of the Diaphragm
Kehr’s sign
An enlarged spleen may refer pain to diaphragm.
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“Development of the diaphragm”
The diaphragm is derived from which four embryonic tissues.
- Septum Transversum.
- Somatic Mesoderm.
- Dorsal mesentery of the esophagus.
- Pleuroperitoneal membranes.
Septum Transversum
- the septum transversum gives rise to a major part of the diaphragm.
- the craial-most part of the head mesoderm, is moved caudal to the future heart and pericardium, between these structures and the neck of the yolk sac. (Vol 1, 59 of 182)
Somatic mesoderm
“Somatic mesoderm from the embryo’s body wall grows inward toward the central tendon, forming the muscular peripheral parts of the diaphragm, where it attaches to the ribs, costal cartilages, and sternum.”
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Esophagus mesentery
(Dorsal mesentery of the esophagus)
“acquires muscle forming cells and gives rise to the crura of the diaphragm. ”
Pleuroperitoneal Membranes
- Two sheets of mesenchyme grow in the center of the “domes” of the diaphragm, to the left and right of the central tendon.
- These pleuroperitoneal membranes partition the intra-embryonic coelom (remember the IEC?).
- Above the membranes is the cranial “bicycle handlebars” part of the IEC.
- Below the membranes are the left and right caudal limbs of the IEC = the coelomic ducts.
- Formation of the pleuroperitoneal membranes is a crucial step in separating the thoracic cavity from the abdominal cavity.
Congenital Diaphragmatic Hernia
- Faulty formation of the diaphragm that allows communication between thoracic and abdominal cavities is called congenital diaphragmatic hernia.
- The culprit is usually malformation of a pleuroperitoneal membrane.
- These are much more likely to occur on the left side than on the right, because the left pleuroperitoneal membrane is larger and closes later than does the right.
- If the hernia is large enough, abdominal organs can bulge into the thoracic cavity, stunting the growth of the lungs (pulmonary hypoplasia).
- This can be a life-threatening condition.
List Arteries and Veins of Posterior Abdominal Wall
Arteries of Posterior Abdominal Wall
“The abdominal aorta spans from T12 to L4, where it bifurcates into the right and left common iliac arteries. It has three types of arterial branches that supply “the gut, glands, and the wall.”
Veins of Posterior Abdominal Wall
Nutcracker syndrome
- The relationship between the superior mesenteric artery (SMA) passing over the left renal vein can have rare consequences.
- “Nutcracker syndrome” is a vascular compression pathology where the left renal vein is compressed within a “vise” between the SMA and abdominal aorta.
- This uncommon disorder produces hematuria and left flank pain.”
Lumbar Plexus
- Iliohypogastric n. (L1)
- Ilioinguinal n. (L1)
- “Genitofemoral n. (L1, L2)
- Lateral cutaneous nerve of the thigh (L2, L3)
- “Femoral n. (L2, L3, L4)”
- Obturator n. (L2, L3, L4)
- Lumbosacral trunk (L4,5)
Lumbar Plexus & Its Dermatomes
Lumbar Plexus - Identify
Iliohypogastric nerve. (L1)
- Innervates: muscles in the inferior part of the anterior abdominal wall; sensory from the skin above the pubis and lateral buttocks.
- Best place to find it: anterior to quadratus lumborum, superior to the ilioinguinal nerve.
Ilioinguinal n. (L1)
- Innervates: muscles in the inferior part of the anterior abdominal wall; sensory from skin of scrotum or labium majora.
- Best place to find it: anterior to quadratus lumborum, inferior to iliohypogastric; runs along the iliac crest”
Genitofemoral n. (L1, L2)
- Genital branch: through the deep inguinal ring, to innervate cremaster muscle in males.
- Femoral branch: descends deep to the inguinal ligament; sensory from skin of anterior upper thigh
- Best place to find it: pierces psoas major and descends on its anterior surface.”
Lateral cutaneous nerve of the thigh (L2, L3)
- Sensory from the lateral skin of the entire thigh…“skinny jeans” nerve.
- Best place to find it: passes under the inguinal ligament just medial to the anterior superior iliac spine (ASIS) ”
Femoral n. (L2, L3, L4)
- Innervates: muscles of the anterior thigh (“quads”); sensory from skin of anterior thigh and on the medial leg.
- Best place to find it: sandwiched between psoas major and iliacus muscles. A big nerve!”
Obturator n. (L2, L3, L4)
- Innervates: adductor muscles (medial thigh)
- Best place to find it: medial to psoas major in the lateral wall of the pelvic cavity.
Lumbosacral trunk (L4,5)
- Contributes the L4,5 segments to the sciatic nerve in the pelvis.
- Best place to find it: medial to psoas major, on the ala of the sacrum.