Week 20 Anatomy

Liver.

Connections

Anterior abdo wall	Falciform ligament- splits liver into R and L lobes
Stomach	Hepatogastric ligament(lesser omentum), free edge carries the portal triad
Duodenum	Hepatoduodenal ligamnet(THE free edge)

• IVC and gall bladder and hepatic artery going across make a H that splits the R lobe further into caudate lobe above and quadrate lobe below. These are anatomical lobes.
• Liver is functionally independent in R and L.
• It has 4 divisions and 8 hepatic segments.
• 80% supply by portal vein(contains 40% more oxygen than systemic veins) and 20% by hepatic artery.
• Portal vein, hepatic artery, bile duct and lymph travel together –> sinusoidal cells to central vein which drains into hepatic vein.

 

Spleen.

• Left  9, 10, 11 ribs
• Anteriorly stomach, posteriorly diaphragm and pleura/lungs, laterally chest wall, medially L kidney, inferiorly Splenic flexure. 12cmx7cm

 

Posterior abdominal wall

• Aorta, IVC, kidneys, ureters, psoas major, iliacus, quadratus lumborum, pancreas, asc and desc colon, lumbar vertebrae, thoracolumbar fascia, lumbar plexus
• Lumbar plexus
  • Forms on lumbar transverse processes within the proximal attachment of psoas major.
  • Anterior Rami of L1-4
  • Femoral nerve, obturator nerve, lubosacral trunk(goes to join sacral plexus), ilioinguinal, iliohypogastric, genitofemoral, lateral cutaneous nerve of thigh, accesory obturator nerve.

 

Inferior Vena Cava

• The IVC is formed by the joining of the left and right common iliac veins and brings blood into the right atrium of the heart. It also anastomoses with the azygos vein system (which runs on the right side of the vertebral column) and venous plexuses next to the spinal cord.
• The caval opening is at T8.

 

Stomach

• Cardia, Fundus, Body, Pylorus
• Cardia opening T11
• Pyloric opening L1

 

Kidneys.

• T12-L3 R slightly inferior to L
• 10cmx5cmx2.5cm
• Sit on quadratus lumborum, superiorly diaphragm
• Renal pelvis –> major calises, minor calices and renal papilla

 

Ureters

(course / course on Xrays / structures crossed).

• Start at renal pelvis –> descend on psoas major along tips of transverse processes–> crossed pelvis brim at site of bifurcation of common iliac artery–> comes across pelvic side wall to insert in posterior aspect of bladder.
• Narrowest at pelvic brim, vesicoureteric junction, pelvoureteric junction.
• Supplied by renal artery, ‘
• Lymph to Lumbar nodes, common iliac nodes and pelvic part drains to internal iliac nodes.
• The ureters are crossed over by:  vas deferens/gonadal vessels
• The ureters cross over: genitofemoral nerve – the sacroiliac joint at the bifurcation of the iliac vessels
• The ureters pass on top of the psoas muscle.

 

Duodenum

• The first part of the duodenum runs to the right, upwards and backwards from the pylorus. The second part is covered in front by peritoneum and crossed by the attachment of the transverse mesocolon.
• The second part curves downwards over the hilum of the right kidney.
• The third part curves forward from the right paravertebral gutter over the slope of the right psoas muscle and passes over the forwardly projecting inferior vena cava and aorta to reach the left posas muscle.
• The fourth part ascends to the left of the aorta to lie on the left psoas muscle and left sympathetic trunk, to reach the lower border of the pancreas
• Only the first 2cm of the first part is mobile

 

 

Abdominal aorta and its branches.

• Inferior phrenic T12
• Coeliac trunk L1
• Suprarenal L1
• Superior mesenteric L1
• Renal L1/L2
• Gonodal L2
• Inferior mesenteric L3
• Common iliac L4
• Lumbar L1-4

 

Layers of the Abdominal wall.

• Anterolaterally – Skin, subcut fat(Camper fascia), Scarpa Fascia, external oblique, internal oblique and transverse abdominal muscle covered in investing fascia, transversalis fascia, extraperitoneal fat, parietal peritoneum.
• Rectus abdominus in midline
• Quadratus lumborum at back.

 

Abdominal Nerves

• Thoracoabdominal nerves T7-11
• Iliohypogastric(L1)
• Ilioinguinal – ASIS and down along inguinal ligament (L1)

 

Inguinal canal

• From ASIS to pubic tubercle
• Deep ring 2 fingers breadth above half way point, lateral to inferior epigastric artery. Evagination of transversalis fascia
• Superficial ring  is medial to pubic tubercle. Gap in fibres of external oblique – between the crura.

• Borders.
  • Floor – inguinal ligament laterally, lacunar ligament medially.
  • Anteriorly – internal oblique + aponeurosis external oblique laterally, aponeurosis of EO medially
  • Posteriorly – transversalis fascia laterally and conjoint tendon medially
  • Roof – transverse abdominus laterally and internal oblique and medial crus of EO aponeurosis medially.

Spermatic cord contents

• Female – round ligament
• Male – vas deferens, testicular artery, panpiniform plexus,  artery of vas, cremaseteric artery.
• Scarpas becomes cremasteric muscle (genital branch of genitofemoral (L1,2))
• Tunica vaginalis is from parietal peritoneum
• External oblique –> external spermatic fascia
• transversalis fascia–> forms internal fascia in spermatic cord.
• Dartos fascia inserts into scrotal skin and acts with cremastor.
• Sympathetic nerve fibres
• Genital branch of genitofemoral nerve.

 

Testis.

• Epididymis and testis covered by tunica vaginalis
• Seminiferous tubule –> straight tubule–>rete testes–> efferent ductules–>lobules of epididymis–> head, body, tail –> vas.

 

Transpyloric plane

• Half way between pubic symphysis and jugular notch
• Cuts through pylorus, 9th CC and lower border of L1 vertebra.
• Fundus of gall bladder
• End of spinal cord
• Pancreas body
• Origin of SMA
• Termination of SMV at portal vein
• L and R colic flexures
• Hilum of kidneys
• Duodenojejunal flexure
• 1st part duodenum
• Spleen
• Cisterna chyli

 

Blood supply / venous drainage of gut.

• Coeliac – forgut ie till 2nd part of duodenum
• SMA – til somewhere in transverse colon
• IMA – till rectum

Venous drainage

• Superior mesenteric vein – biggest
• Inferior mesenteric vein joins splenic vein then together they join superior mesenteric vein to form portal vein.