Unit 21

Posterior Abdominal WallDiaphragm

Lymphatics and Nerves

Dr. Paul Severso

n

The diaphragm is a dome-shaped

musculotendinous partition that separates

the thorax from the abdomen. It is the chief muscle of inspiration, its central part descending during inspiration. The

periphery of the diaphragm is fixed at its points of origin from the ribs, sternum and lumbar

vertebra in the form of crura. The muscular

fibers converge on the aponeurotic central

tendon.

Double-domed

Clean and Identify:

Inferior Phrenic Arteries

Plate 332

Inferior Phrenic Arteries

AIVCThe Pericardiacophrenic,

Superior Phrenic, and Musculophrenic arteries also supply

the diaphragm

Clean and

identify the

Phrenic nerves

Plate 195

C345…….

Left Phrenic Nerve

Rt. Phrenic Nerve

Motor innervation = Phrenic NerveSensory

= Two sources1. T5-T122. Phrenic

Nerve

Plate 193B

T5-T12 lower intercostal nerves

-sensory to peripheral part of

diaphragm

Phrenic nerve containing

somatic efferent

motor fibers (only motor nerve) and

somatic afferent fibers to

most of the diaphragm

Plate 195

L4

Identify the origin of the diaphragm:

1. Sternocostal Origin

2. Lumbar portion: Crura

3. Arcuate Ligaments

Sternal Origin

Costal Origin

Origin

Identify the origin of the diaphragm:1. Sternocostal Origin2. Lumbar portion:

Crura 3. Arcuate Ligaments

Plate 195

Right Crus

Left Crus

Look for the splanchnic nerves as they pass through the crura

Note the right crus passing to the left of

the esophageal

hiatus: it forms a

physiological sphincter for

the esophagus

L2

L3

L4

Origin

Site for

hiatal hernia

s

Plate 195

Identify the origin of the diaphragm:

1. Sternocostal Origin2. Lumbar portion:

Crura3. Arcuate Ligaments

Median Arcuate Ligament

Medial Arcuate Ligament

Lateral Arcuate Ligament

PsoasQL

QL = Quadratus Lumborum

L2

L3

L4 L1 Transverse Process

12th rib

Origin

All of these fibers insert

into the central tendon of the

diaphragm

Plate 195

This is the central

aponeurotic part that is shaped

like a cloverleaf

Central Tendon of

the Diaphragm

Insertion

Identify the Lumbocostal

Triangle

Site of a Congenital

Diaphragmatic Hernia

Plate 195

5X more common on left

Lumbocostal Triangle

Lumbocostal Triangle

Defect in the diaphragm occurs once in 2200 births and is associated with

herniation of abdominal contents into the thorax

Gas in

bowel

Significant cause of pulmonary hypoplasia/hypertension in infants – 50% do not survive - related to whether the liver has

herniated

Moore page 330

The heart and lungs

are compressed and shifted

to the right!

If diagnosed

before birth, fetal intervention may be possible

Clean/Identify the following openings in

the diaphragm:

T8T10T12

Plate 195

Caval Opening T8 Esophageal

Hiatus T10

Aortic Hiatus T12

The Aortic Hiatus is formed by the

Crura and the Median Arcuate

Ligament

Hiatuses

Follow the course of the ureter

retroperitoneally It is narrowed

in 3 places where

“stones” or calculi

can become lodged

Painful! “loin to groin”

Plate 341

Ureter25-30 cm

1

2

3 narrowest

Ureter

Stones larger than 3 mm (the diameter of the lumen) are

especially painful – distention of the ureter as the muscular coat

contracts causes the colicky pain-renal colic

Also here over the pelvic brim

Treatment: Lithotripsy

(sound waves), surgery or

“passing” of the stone

Intravenous Urography

(Pyelogram)

IVP – left kidney is excreting white contrast material but the right kidney is all backed up with no

contrast material in the collecting system. A stone is visible at the origin of the right ureter (arrow)

producing acute obstruction. The patient presented with typical

renal colic.

Kidney stone – calcium oxalate & calcium

phosphate = 75-85% of stones;

Struvite - second most common (Ammonium

magnesium phosphate)

contrast

IVP

There is a stone at the very end of

the right ureter

where it enters the bladder – note the enlarged

right collecting

system and ureter

(Hydronephrosis and

hydroureter).

Locate the Gonadal

artery and vein on

both sides

Plate 341

Left Gonadal Vein and Artery

Rt. Gonadal Vein and Artery

L2

L3

Gonadal Vessels

Plate 318

Prevertebral Ganglia:

Celiac Ganglion and Plexus

Superior Mesenteric Ganglion and

Plexus

Intermesenteric Plexus

Inferior Mesenteric Plexus and Ganglia

Superior Hypogastri

c Plexus

Try to identify the autonomic

nerve plexuses

and associated

ganglia near the major

branches of aorta

Locate the superior

hypogastric plexus:

Contains lower lumbar splanchnics and pelvic

splanchnics

Locate the sympathetic trunk and the Paravertebral

ganglia

Plate 318

Paravertebral Gangliaof Sympathetic

Trunk

Plate 318

Most lumbar splanchnic nerves

join the Intermesenteric and Inferior Mesenteric plexus as well as

the Superior Hypogastric plexus

3rd lumbar ganglion

1st, 2nd and 3rd lumbar splanchnic

nerves

4th lumbar splanchnic

nerve

1

2

Locate and identify some

Lumbar Splanchnic

nerves

Plate 264

Locate the 4 pair of Lumbar

Arteries – braches of the aorta

Lumbar Arteries

Lumbar Arteries

The abdominal aorta may have an aneurysm (AAA)

If recognized, these can be repaired with a Dacron prosthetic graft. If unrecognized, 90% mortality rate because of heavy blood loss.

Severe pain in abdomen or back.

Congenital or acquired weakness

Identify the muscles of

the posterior abdominal

wallQ = Quadratus

LumborumP = Psoas Major

I = Iliacus

Q

P

I

Remember the transversalis fascia

Plate 263

Psoas Minor

Iliopsoas

Transverse Abdominis

Find the Cisterna

Chyli and the beginning of the Thoracic

Duct, the largest

lymphatic duct in the

body

Plate 316

Thoracic Duct

Cisterna Chyli

Chyle (lymph) enters blood

It is found between the right crus of the

diaphragm and the aorta at L1-2

Rt. Lumbar Lymph

Trunk/NodesLeft Lumbar

Lymph Trunk/Nodes

Intestinal Lymph

Trunk(s): from Celiac, SM and IM

nodes

Cisterna Chyli

Plate 266

It receives three tributaries;

Intestinal Lymph TrunkRt. and Left Lumbar Lymph Trunks

Common Iliac Nodes

Cisterna Chyli

Plate 498A

Femoral NerveL2-4

ObturatorNerve L2-4

T12

L1

L2

L3

L4

Anterior DivisionPosterior Division

This is the Lumbar

Plexus formed by ventral

rami of L1 – L3 and 1/2 of

L4

L5

Subcostal Nerve

Iliohypogastric

Ilioinguinal GenitofemoralL1-2

Lat. Femoral Cutaneous L2-

3

Accessory Obturator

Nerve

Transect the Psoas Major and identify the rest of

the branches

Plate 498B

Genitofemoral L1,2

Femoral L2-4

Obturator L2-4

Subcostal T12

Iliohypogastric &

IlioinguinalL1

Lat. Femoral Cutaneous

L2,3

Identify the following

branches of the lumbar

plexus

Lumbosacral trunks

(1/2 L4-L5)

L1L2

L3L4

L5

These are SOMATIC NERVES!

T7-T12 intercostal nerves and

L1

Motor to muscles and

sensory to skin and

peritoneum

Plate 257

Nerves course between the

IO and TA

T10

T7

Abdomen

Ilioinguinal Nerve (L1)

IliohypogastricNerve (L1)

T12 L1

Laboratory/Quiz