TBL20 - Posterior Abdominal Wall

Question 1

What part of the spinal column occupies the central part of the posterior abdominal wall? What do these vertebral bodies provide attachments for and what does this muscle join? What is the chief flexor of the thigh?

Answer 1

1) The five lumbar vertebrae and associated IV discs occupy the central part of the posterior abdominal wall
2) The vertebral bodies provide proximal attachments for the psoas major muscle (ignore the psoas minor) that joins the iliacus to form the iliopsoas muscle
3) The iliopsoas is the chief flexor of the thigh

Question 2

What forms the superior part of the muscular posterior abdominal wall? What are the central and inferior parts of the muscular abdominal wall formed by?

Answer 2

1) The diaphragm forms the superior part of the muscular posterior abdominal wall
2) The central and inferior parts of the wall are formed by the transverse abdominis and quadratus lumborum muscles

Question 3

Which abdominal organs when inflamed would elicit a positive psoas test and how is the test administered?

Answer 3

1) The iliopsoas muscle has extensive, clinically important relations to the kidneys, ureters, cecum, appendix, sigmoid colon, pancreas, lumbar lymph nodes, and nerves of the posterior abdominal wall. When any of these structures is diseased, movement of the iliopsoas usually causes pain
2) The person is asked to lie on the unaffected side and extend the thigh on the affected side against the resistance of the examiner’s hand. The elicitation of pain with this maneuver is a positive psoas sign

Question 4

What are hiccups, and how is their characteristic sound produced?

Answer 4

Hiccups (hiccoughs) are involuntary, spasmodic contractions of the diaphragm, causing sudden inhalations that are rapidly interrupted by spasmodic closure of the glottis (aperture of the larynx) that checks the inflow of air and produces the characteristic sound

Question 5

What covers the internal surface of the posterior abdominal wall and how is it named?

Answer 5

Like the anterolateral abdominal wall, the internal surface of the posterior abdominal wall is lined by endoabdominal fascia named by the muscles it covers e.g., transversalis, psoas, and diaphragmatic fasciae

Question 6

Where do the subcostal (T12), iliohypogastric (L1), and ilioinguinal (L1) course on the posterior abdominal wall? What do these nerves supply?

Answer 6

1) The subcostal (T12) and iliohypogastric and ilioinguinal (L1) nerves course inferolaterally on the anterior surface of the muscular portion of the posterior abdominal wall
2) The nerves supply skeletal muscles and skin of the inguinal and hypogastric regions

Question 7

What muscle does the genitofemoral nerve pierce? What muscle does it supply? Where does the genitofemoral nerve supply sensory innervation to? What does the ilioinguinal nerve provide to the superomedial thigh?

Answer 7

1) The genitofemoral nerve pierces the psoas muscle
2) The genitofemoral nerve supplies the cremaster muscle
3) The genitofemoral nerve is sensory to the proximal thigh
4) The ilioinguinal nerve provides somatic sensory fibers to the superomedial thigh

Question 8

What nerves supply somatic innervation to the anterior and medial thigh, respectively?

Answer 8

The femoral and obturator nerves supply somatic innervation to the anterior and medial thigh, respectively

Question 9

Why can pain from ureteric calculi extend from the hypogastric region into the proximal anterior thigh?

Answer 9

1) A renal calculus (kidney stone) may pass from the kidney into the renal pelvis and then into the ureter
2) If the stone is sharp or larger than the normal lumen of the ureter (approximately 3 mm), it causes excessive distension of this muscular tube, the ureteric calculus will cause severe intermittent pain (ureteric colic) as it is gradually forced down the ureter by waves of contraction
3) Depending on the level of obstruction, which changes, the pain may be referred to the lumbar or inguinal regions, or to the external genitalia and/or testis
4) The pain is referred to the cutaneous areas innervated by spinal cord segments and sensory ganglia, which also receive visceral afferents from the ureter, mainly T11–L2. The pain passes inferoanteriorly “from the loin to the groin” as the stone progresses through the ureter. (The loin is the lumbar
region, and the groin is the inguinal region)
5) The pain may extend into the proximal anterior aspect of the thigh by projection through the genitofemoral nerve (L1, L2), the scrotum in males and the labia majora in females

Question 10

Why does rupture of an aortic aneurysm cause severe abdominal or back pain?

Answer 10

1) Acute rupture of an abdominal aortic aneurysm is associated with severe pain in the abdomen or back
2) Ask