Week 8 Anatomy 1-5

Posterior abdominal wall borders

Superior: diaphragm · Inferior: pelvic brim · Medial: five lumbar vertebrae · Lateral: anterior abdominal wall muscles · Posterior: thoracolumbar fascia · Anterior: peritoneum

Psoas major — origin

Transverse processes of lumbar vertebrae + bodies/discs of T12–S1

Psoas major — insertion / action / nerve

Lesser trochanter (iliopsoas) / flexes thigh + trunk + vertebral column (with iliacus) / lumbar plexus L1–L3

Iliacus — origin

Iliac fossa, anterior sacro-iliac ligaments, ala of sacrum

Iliacus — insertion / action / nerve

Lesser trochanter (iliopsoas) / flexes thigh + trunk (with psoas) / femoral nerve L2–L4

Quadratus lumborum — origin / insertion

Medial half of inferior 12th rib + tips of lumbar TPs → iliolumbar ligament + internal lip of iliac crest

Quadratus lumborum — action / nerve

Extends + laterally flexes vertebral column; fixes 12th rib in inhalation / T12, L1–L4

Diaphragm — origins (3)

Sternal (xiphoid), costal (inner surface of inferior 6 costal cartilages/ribs), lumbar (arcuate ligaments, ALL, IV discs)

Diaphragm — insertion / action / nerve

Central tendon, no bony attachment / contracts in inspiration, dome descends / phrenic nerve C3–C5

Nerves MEDIAL to psoas

Obturator (L2–4, adductors); lumbosacral trunk (L4–5); autonomics (celiac/mesenteric ganglia, splanchnic nerves)

Nerve THROUGH psoas

Genitofemoral (L1–L2)

Genitofemoral — genital branch

Through the deep inguinal ring; sensory to scrotum (or round ligament → mons pubis + labia majora in females)

Genitofemoral — femoral branch

Under the inguinal ligament; sensory to upper anterior thigh

Subcostal nerve (T12)

Anterior to QL; supplies external oblique + anterolateral abdominal skin

Iliohypogastric (L1)

Passes over QL; sensory to lateral gluteal, motor to internal oblique + transversus abdominis

Ilioinguinal (L1)

Below iliohypogastric; through the superficial inguinal ring; anterior labial/scrotal nerve

Lateral femoral cutaneous (L2–3)

Under the inguinal ligament, just medial to ASIS; skin of anterolateral thigh

Femoral nerve (L2–4)

Supplies iliacus, hip flexors, quads

What is 31?

Psoas major

What is number 16?

Femoral nerve

What is 28?

Left genitofemoral nerve

What is 14?

Lateral femoral cutaneous

Abdominal aorta — start & end

Begins at the T12 diaphragmatic hiatus, terminates at L4

Aorta — unpaired branches

Celiac trunk, superior mesenteric, inferior mesenteric

Aorta — paired branches

Suprarenal, renal, gonadal

Aorta — terminal branches

Common iliac (at the iliac crest level) → internal + external iliac

IVC — diaphragm exit

T8

IVC — tributaries

Common iliac, hepatic, suprarenal, renal (+ left gonad via left renal), right gonad

Kidney level & position

Posterior abdominal wall, T12–L3; right lower than left; retroperitoneal

Kidney coverings (out → in)

Renal fascia (binds to wall) → perirenal fat capsule → fibrous capsule

Renal hilum contents (anterior → posterior)

Renal Vein, Renal Artery, Ureter (VAU)

Renal sinus

Fat-filled space embedding the renal pelvis, artery, and vein

Parenchyma divisions

Outer cortex + inner medulla

Renal columns & pyramids

Cortical columns project inward, dividing the medulla into 6–10 renal pyramids

Urine collection path

Renal papilla → minor calyx → major calyx → renal pelvis → ureter

What structure is 3?

Renal pelvis

What sutrcture is 9 vs 10?

Cortex, medulla

What is structure 11?

Renal papilla

What are structures 5 and 12?

Major renal calyx, minor renal calyx

Renal arteries — origin & level

Branch directly from the abdominal aorta at L1–L2

Right renal artery — special feature

Longer; passes posterior to the IVC

Renal veins — drainage

Drain into the IVC

Left renal vein — course

Crosses anterior to the aorta and posterior to the SMA

Left renal vein — what it receives

Left gonadal vein + left suprarenal vein