Abdominal Dissection 2: Posterior Wall & Inguinal Region

Study Notes

Begin with the cadaver in a supine position; retract the gastrointestinal tract to the side opposite the area of study.
Remove portions of the peritoneum and retroperitoneal fat to enhance mobility of associated structures.

Examine the external and internal abdominal obliques and the transversus abdominus muscles.
Identify the kidney and its vascular structures, the renal artery and vein, which are typically surrounded by considerable perirenal fat.

Trace the ureter as it exits the kidney and descends into the pelvis, noting its proximity to the gonadal artery and vein.
In males, follow the path of the testicular artery and vein to the deep inguinal ring.
In females, track the ovarian artery and vein towards the ovary.

Reflect the kidney medially to locate the quadratus lumborum, situated deep, inferior, and medial to the kidney.
Review the muscle's attachments, actions, and innervation for comprehensive understanding.

Identify the psoas major originating from the lumbar vertebral bodies, along with the psoas minor, which is a thin musculotendinous strip on its surface.
The iliacus muscle lies lateral to the psoas major as it crosses the iliac crest into the pelvis.
Study the respective attachments, actions, and innervation of both psoas major and iliacus muscles.

Palpate the 12th rib and probe through the transversalis fascia to locate the subcostal nerve beneath it.
Scrape the transversalis fascia further to find the iliohypogastric nerve, starting from an estimated height of the L1 vertebral body.
The ilioinguinal nerve usually arises from a common trunk with the iliohypogastric nerve.
Identify the lateral cutaneous nerve of the thigh crossing the iliacus muscle diagonally.
Locate the femoral nerve nestled between the iliacus and psoas major.
Follow the genitofemoral nerve on the anterior surface of the psoas major and its subsequent branches.
The obturator nerve can be found deep on the medial side of the psoas major, often requiring removal of the peritoneal layer for visibility.
The lumbosacral trunk lies medial to the psoas major, positioned between the posterior major and the L5 vertebra.
Review the spinal segments associated with each nerve identified.

In the midline of the abdomen, identify the inferior vena cava and abdominal aorta, tracing their bifurcation into common iliac arteries and their internal and external branches.
On the external iliac artery, locate the inferior epigastric artery and follow it to the deep surface of the rectus abdominus, assessing its relationship to the deep inguinal ring and inguinal ligament.