Posterior abdominal wall Flashcards
What are the muscles of the posterior abdominal wall?
- Psoas major
- Psoas minor
- Quadratus lumborum
- Ileacus
What are the origins and insertions of psoas major?
Origins: Intervening discs, bodies and transverse processes of vertebrae L1-L5.
Insertions: Lesser trochanter (femur) – via iliopsoas tendon.
What is the innervation and function of psoas major?
Innervation: L1-L3 (segmental).
Functions: Flexes hip joint and trunk.
What are the origins and insertions of psoas minor?
Origins: Bodies of vertebrae T12-L1.
Insertions: Fascia over psoas muscle.
What is the innervation and function of psoas minor?
Innervation: L1.
Functions: Flexes spine.
What are the origins and insertions of quadratus lumborum?
Origins:
- Transverse process of L5
- Iliolumbar ligament
- Iliac crest (posterior 1/3)
Insertions:
- 12th rib
- Transverse processes of L1-L4
What is the innervation and function of quadratus lumborum?
Innervation: T12-L4.
Functions:
- Stabilises vertebral column
- Flexes 12th rib
What are the origins and insertions of iliacus?
Origins: Iliac crest.
Insertions: Lesser trochanter (via iliopsoas tendon).
What is the innervation and function of iliacus?
Innervation: L2-L4 (femoral nerve).
Functions: Flexes hip joint.
How does the lumbar plexus form?
- From anterior rami of upper 4 lumbar spinal nerves
- In Psoas major
What are the branches of the lumbar plexus?
- Iliohypogastric nerve (L1, main)
- Ilioinguinal nerve (L1, collateral)
- Genitofemoral nerve (L1,2)
- Lateral cutaneous nerve of the thigh (L2,3)
- Femoral nerve (L2-4, posterior divisions)
- Obturator nerve (L2-4, anterior divisions)
What does the ilioinguinal (L1) nerve supply?
Conjoint tendon (sensory)
What does the iliohypogastric nerve (L1) supply?
Conjoint tendon
Where does the ilioinguinal nerve originate?
As a collateral branch of the iliohypogastric nerve.
What does the femoral branch (L1) of the genitofemoral nerve supply?
Skin over upper anterior thigh.
What does the genital branch (L2) of the genitofemoral nerve supply?
- Cremasteric muscles
- Skin of anterior scrotum (males)
- Skin of mans pubis & labia majora
What does the lateral femoral cutaneous nerve (L2,3) supply?
Skin of the lateral thigh.
What does the femoral nerve (L2-4) supply?
- Quadriceps muscles
- Sartorius
- Pectineus
- Skin over thigh
What does the obturator (L2-4) supply?
- Adductor muscles
- Skin over medial thigh
At what level does the abdominal aorta bifurcate?
L4
At what level does the IVC form?
L5
What are the main tributaries of the IVC?
- Inferior phrenic veins
- Hepatic vein
- Adrenal veins
- Renal veins
- Gonadal veins
- Lumbar veins
What structure pass through the diaphragm and at what vertebral levels?
- Caval (T8): IVC, right phrenic nerve.
- Anterior hiatus (T9): Superior epigastric artery.
- Oesophageal hiatus (T10): Oesophagus, vagal trunks, lymphatics, oesophageal branches of left gastric vein.
- Aortic hiatus (T12, posterior to crura): Aorta, azygos/hemi-azygos veins, thoracic duct.
- Sympathetic chain passes through diaphragm posterior to medial arcuate ligament.
- Subcostal neurovascular bundle passes though diaphragm posterior to lateral arcuate ligaments.
What are the attachments of the diaphragm?
Anterior: Xephisternum
Lateral: Lower 6 ribs
Posterior: Various ligaments
What are the attachments of the various posterior ligaments of the diaphragm?
- Left crus: Body of L1-2 vertebrae
- Right crus: Body of L1-3 vertebrae
- Medial arcuate ligaments: Body of L2, transverse processes of L1
- Lateral arcuate ligaments: Transverse processes of L1, 12th rib
What are the relations of the genitofemoral nerve?
- Exits psoas major on anterior surface
- Femoral branch enters anterior compartment of the thigh in femoral sheath
- Genital branch travels through the inguinal canal
What are the relations of the ilioinguinal nerve?
- Exits psoas major via lateral surface
- Travels through the inguinal canal
What are the relations of the iliohypogastric nerve?
- Exits psoas major on lateral surface
What are the relations of the lateral cutaneous nerve of the thigh?
- Enters the anterior compartment of the thigh medial to ASIS and posterior to inguinal ligament
What are the relations of the femoral nerve?
- Enters the anterior compartment of the thigh posterior to inguinal ligament
- It lies outside the femoral sheath lateral to the femoral artery
What are the relations of the obturator nerve?
- Enters medial compartment of the thigh through the obturator foraman
What are the branches of the abdominal aorta?
Unpaired visceral:
- Coeliac trunk
- SMA
- IMA
Paired visceral:
- Renal arteries
- Middle adrenal adrenal arteries
- Gonadal arteries
Parietal:
- Inferior phrenic arteries
- Lumbar arteries
- Median sacral artery
What are the asymmetries of the renal arteries and veins?
- Right renal artery longer than the left
- Right renal vein shorter than the left
What are the lymph nodes associated with the abdominal aorta?
- Pre-aortic lymph nodes: Anterior
- Para-aortic lymph nodes: Lateral
What do the pre-aortic lymph nodes drain?
- GI tract
- Spleen
- Pancreas
- Gallbladder
- Liver
What do the para-aortic lymph nodes drain?
- Kidneys
- Gonads
- Adrenal glands
- Lower limbs
- Body wall
What are the relations of vessels at the renal hila?
- Renal veins are the most anterior structures
- Renal arteries are behind the veins
- Ureters are posterior
What are the relative positions of the kidneys and adrenal glands?
- The right kidney is slightly lower than the left kidney
- The right adrenal gland is associated with the upper pole of the right kidney
- The left adrenal gland is associated with the medial border of the left kidney
What are the muscular relations of the kidneys?
- Superior: Diaphragm
- Inferomedial: Psoas major
- Inferior: Quadratus lumborum
- Inferolateral: Transversus abdominis
What are the surrounding structures of the kidneys?
The kidneys and adrenal glands are surrounded by perirenal fat, followed by a layer of renal fascia, followed by a layer of pararenal fat.
How long are the ureters?
~25 cm
What are the sites of constriction of the ureters?
- Pelviureteric junction
- Pelvic brim
- Junction with bladder
What is the internal structure of a kidney?
- Each kidney consists of an outer capsule, a cortex, medulla and a pelvis.
- The renal medulla consists of renal pyramids.
- The apex of each pyramid drains into a minor calyx (of which there are 2 rows of 7 per kidney).
- The minor calyces join to form major calyces (of which there are 2-3).
- The major calyces join to form the renal pelvis which drains into the ureter.
What is the relation of the ureters to the iliac vessels?
At pelvic brim, the urters are anterior to the bifurcation of the common iliac artery.
What are the bony relations of the ureters?
- Transverse processes of L1-5.
- Pelvic brim
- Ischial spine
What is the parasympathetic supply to the abdominal viscera?
- Vagus: Foregut and midgut
- Pelvic splanchnic (S2-4): Hindgut
What are the major plexuses in the abdomen?
- Coeliac plexus: Gives rise to the hepatic, splenic and renal plexuses. Supplies foregut
- Superior mesenteric plexus: Supplies midgut
- Inferior mesenteric plexus: Supplies hindgut
- Superior hyopgastric plexus: Gives rise to the inferior hypogastric plexuses supplying pelvic structures
