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posterior abdominal wall

formed by the lumbar vertebrae and their intervertebral discs, the diaphragm, the psoas, iliacus and quadratus lumborum muscles and the thoracolumbar fascia


lumbar vertebra

huge kidney shaped body. Triangular foramen. short blunt spinous process. Large blunt transverse process. superior articular facets face medially, inferior face laterally. Thickest intervertebral discs.


movements of the vertebral column-flexion

Bending of the vertebral column in an anterior direction


extension of the VC

Bending of the vertebral column in a posterior direction


lateral flexion of the VC

Bending of the vertebral column to one side


lateral extension of VC

Returning of the vertebral column to an upright position following lateral flexion


rotation of the VC

Twisting of the vertebral column



A combination of all movements


which movement is least extensive in the lumbar region



right crus of diaphragm

Arises from the first three or four lumbar vertebrae-higher due to liver


left crus of diaphragm

Arises from the first two or three lumbar vertebrae


median arcuate ligament

Fibrous structure that unites the right and left crura


medial arcuate ligament

Thickening of the fascia that covers the psoas major muscle, extends from the body to the tip of the transverse process of L1.


lateral arcuate ligament

Thickening of the fascia that covers the quadratus lumborum muscle, extends from the transverse process of T12 to the 12th rib.


aortic hiatus

opens at T12
the right and left crura and the median arcuate ligament form the aortic hiatus.


At which vertebral level is the caval opening located?



which level does the oesophagus open



what passes through the caval opening

IVC, right phrenic nerve


What passes through the Oesophageal hiatus

oesophagus, lymphatics from oesophagus, oesophageal branches of the left gastric artery, right and left vagi


what passes through the aortic hiatus

aorta, thoracic duct, azygous vein


muscles of the posterior abdominal wall

psoas major, iliacus and quadratus lumborum. The psoas major muscle arises from the bodies and transverse processes of T12-L5 vertebra and the intervening discs. The psoas major and iliacus combine to form the iliopsoas muscle which is the main flexor of the hip joint. The quadratus lumborum fixes the twelfth rib during inspiration-originates iliac crest and ilio lumbar ligament, inserts ino last rib and transverse processes of LV. T12 to L4. Iliacus originates from the iliac fossa. they insert into the lesser trochanter. femoral nerve. (l2 l4)


internal aspect of the abominal wall

covered with fascia which lies between the parietal peritoneum and the muscle. The psoas and iliacus are covered by the endoabdominal fascia which is continuous superiorly with the diaphragmatic fascia and laterally with the transversalis fascia. The quadratus lumborum is covered by thoracolumbar fascia. The fascia is named according to the muscle that it covers.


Which ligament is formed by a thickening of the superior part of the quadratus lumborum fascia?

lateral arcuate ligament. inferiorly the ilio lumbar ligament


vessels of the post abdominal wall

The main vessels of the posterior abdominal wall lie anterior to the bodies of the lumbar vertebrae


abdominal aorta

The abdominal aorta begins at the aortic hiatus at the level of T12 and ends by bifurcating into the right and left common iliac arteries-L4
The surface markings of the bifurcation lie 2cm below and to the left of the umbilicus.


Posterior relations of the abdominal aoa

The abdominal aorta lies in front the bodies of theT12 -L4, the lumbar veins cross behind the aorta on route to the vena cava


lateral relations of the aorta

right-azygous vein, right crus of diaphragm, IVC, Cysterna chyli, thoracic duct, right coeliac ganglion
left-left crus of diaphragm, left sympathetic chain, left coeliac ganglion


anterior relations of the abdominal aorta in oder that they cross the aorta

coeliac plexus and ganglion
body of pancreas and splenic vein
left renal vein
horizontal part of duodenum


upaired visceral branch of the aorta

coeliac trunk, superior and inferior mesenteric


paired visceral branch of the aorta

gonadal, suprarenal artery, renal


paired parietal branch of the aorta

lumbar artery, subcostal artery, inferior phrenic


order of branches of the aorta

inferior phrenic, coeliac trunk, sup and middle supra renal, subcostal, superior mesenteric, enal, lumbar, gonadal, inf mesenteric, median sacral


inferior vena cava

21 veins drain into it. formed by the joining of the R and L common iliac at L5. the median sacral is another vein of origin, pierces the diaphragm at T8. 3 anterior visceral tributaries (three hepatic), 3 lateral visceral tributaries (suprarenal, renal, gonadal), 5 lateral abdominal wall tributaries (inferior phrenic and four lumbar) and 3 veins of origin (two common iliac and the median sacral)


nerves of the posterior abdominal wall

Both somatic and autonomic nerves are associated with the posterior abdominal wall.
Somatic nerves

The dorsal rami of L1-5 supply the muscles and skin of the back. The ventral rami form the lumbar plexus and supply the muscles and skin of the inferior aspect of the trunk and the lower limb. The ventral rami receive grey rami communicantes from the sympathetic chain and L1 and L2 give off white rami communicantes to the sympathetic chain.


intervertebral discs

The intervertebral discs make up a quarter of the length of the vertebral column. Each disc consists of a peripheral annulus fibrosus and a central nucleus pulposus.
The annulus fibrosus
consists of several layers of fibrocartilage, and the
nucleus pulposus contains
loose fibers suspended in a mucoprotein gel with the consistency of jelly.
The nucleus acts as a shock absorber and the annulus allows pressure to be evenly distributed across the disc.


aging on intervertebral discs

As a person ages, the nucleus pulposus begins to dehydrate and the concentration of proteoglycans in the matrix decreases, thus limiting the ability of the disc to absorb shock. The annulus also
becomes weaker with age so is more likely to tear.
Prolapsed discs can occur, which is when the nucleus pulposus is forced out of the disc, which may put pressure on the nerve located near the disc.


ligaments of the vertebral column

The anterior and posterior longitudinal ligaments provide support for these joints. The anterior is the thicker & stronger of the two and covers the front & sides of the vertebral bodies. It runs the
whole length of the vertebral column, and limits extension of the spine. The posterior runs along the back of the vertebral bodies and helps in a small way to limit flexion of the vertebral column. It is
narrow where it overlies each body, and widens out to cover the back of each disc



The diaphragm is a double-domed, musculotendinous p
artition, separating the thoracic and abdominal cavities. It curves superiorly into right
and left domes, normally the right dome is higher
than the left owing to the presence of the liver. T
he muscular part of the diaphragm is situated
peripherally with fibers that converge radially on
the trifoliate central aponeurotic part, the central tendon, which actually lies slightly closer to the
anterior thorax. The surrounding muscular part of
the diaphragm forms a continuous sheet, however, for descriptive reasons it is divided into 3 parts, based on the peripheral attachments


sternal part

Consisting of 2 muscular slips that attach to the posterior aspect of the xiphoid process. This part is not always present.


costal part

Consisting of wide muscular slips that attach to the internal surfaces of the inferior 6 costal cartilages and their adjoining ribs on each side; the costal parts form the right and left domes.


lumbar part

Arising from two aponeurotic arches, the medial & lateral arcuate ligaments, and the three superior lumbar vertebrae. The lumbar part forms right and left muscular crura that ascend to the central tendon.
The crura of the diaphragm
are musculotendinous bands that arise from the anterior surfaces of the bodies of the superior three lumbar
vertebrae, the anterior longitudinal ligament, and the IV discs. The right crus (larger and longer than the left crus) arises from the first three or four lumbar vertebrae. The left crus arises from the first two or three.


ligaments and the diaphragm

The diaphragm is also attached on each side to the
medial and lateral arcuate ligaments. The medial
arcuate ligament is a thickening of the fascia cove
ring the psoas major, spanning between the lumbar vertebral bodies and the tip of the transverse process of L1. The lateral arcuate ligament covers the quadratus lumborum muscles, continuing from the L12 transverse process to the tip of the 12th rib.



Supperior attachment: Transverse processes of lumbar vertebrae; sides of bodies of T12-L5 vertebrae &
intervening IV discs.
Inferior attachment:By a strong tendon to lesser trochanter of femur.
Action:Acting inferiorly with
iliacus, it flexes thigh. Acting superiorly, it flexes vertebral
column laterally to balance the trunk. When sitting, it acts inferiorly with iliacus to flex trunk.
Innervation: ant rami of L1-3



superior attachment: Superior 2/3 of iliac fossa, ala of sacrum,
and anterior sacroiliac ligaments.
Posterior attachment: Lesser trochanter of femur and shift
inferior to it, and to psoas major tendon.
Action:Flexes thigh and
stabilises hip joint; acts with psoas major
Innervation: Femoral nerve L2 4


quadratus lumborum

Superior attachment:Medial ½ of inferior border of 12th ribs and tips of lumbar transverse processes.
Inf attachment: Iliolumbar ligament and internal lip of iliac crest
Action: Extends and laterally
flexes vertebral column, flexes 12th rib during inspiration.
Innervation:Anterior branches of T12 and L1-L4 nerves


thoracolumbar fascia

The thoracolumbar fascia extends between the 12th rib and the iliac crest. It is attached medially to the lumbar vertebrae and laterally to the transversus abdominis, internal oblique, and latissimus
dorsi muscles.


from superior to inferior branches of the abdominal aorta

Prostitutes: Phrenic (Inferior).
Cause: Celiac.
Sagging: Superior Mesenteric.
Swollen: Suprarenal (Middle).
Red: Renal.
Testicles [In Men]: Testicular (or ovarian in women).
Living: Lumbar.
In: Inferior Mesenteric.
Sin: Sacral.



The veins of the posterior abdominal wall are tribu
taries of the IVC, except for the
left testicular or ovarian vein, which enters the left renal vein instead of entering the IVC. The IVC, the largest vein
in the body, has no valves except for a variable, non-functional one at its orifice in the right atrium of the heart.
The IVC begins at the level of the L5 vertebra as the common iliac veins unite. This occurs ~2.5cm to the right of the median plane, inferior to the aortic bifurcation. It exits the abdominal cavity by
passing through the caval opening in the diaphragm at the level of T8.


relations of the IVC

Anterior: At beginning of IVC: Proximal part of right common
iliac artery.
Posterior: Right psoas major.
To the left: L3-L5 vertebrae,
To the right: Right sympathetic trunk, right ureter.


branches of the IVC

The veins that correspond to the unpaired visceral
branches of the aorta are instead tributaries of
the hepatic portal vein. The blood they carry does
ultimately enter the IVC via the hepatic veins, after traversing the liver. The branches corresponding to the paired visceral branches of the abdominal aorta include the right suprarenal vein, the right and left renal veins, and the right gonadal (testicular or ovarian) vein. The
left suprarenal and gonadal veins drain indirectly
into the IVC because they are tributaries of the left
renal vein. Paired parietal branches of the IVC include the inferior phrenic veins, the 3rd (L3) and 4th (L4) lumbar veins, and the common iliac veins. The ascending lumbar and azygos veins connect the I
VC and SVC, either directly or indirectly
providing collateral pathways.


From inf to superior branches of the IVC

I: Iliacs.
Like: Lumbar.
To: Testicular (Or ovarian).
Rise: Renal.
So: Suprarenal.
High: Hepatic.


common iliac lymph nodes

drain: Hypogastric & external iliac nodes. Efferent veseel-lateral aortic nodes.


lateral aortic lymph nodes

drain: Common iliac nodes, lymphatics of testis, ovaries, uterine tubes, the body of the
uterus, kidneys, suprarenal glands, and lateral abdominal muscles.
Efferent vessels:Most join the cisterna chyli. Others drain straight into the thoracic duct


Inferior mesenteric lymph nodes

drain:Descending colon, sigmoid colon, and upper part of rectum.
Efferent vessel: preaortic then cisterna chyli.


superior mesenteric lymph nodes

drain: Jejunum, ileum, cecum, appendix, ascending colon, and transverse colon.
Efferent vessel: preaortic then cisterna chyli


celiac lymp nodes

Drain: Stomach, liver, spleen, duodenum, gallbladder and pancreas
Efferent vesses: preaortic then cisterna chyli.


lymphatic system.

The left & right lumbar and the intestinal trunks drain into the inferior end of the thoracic duct. In some individuals, this part of the thoracic duct is
enlarged to form the cisterna chyli. The thoracic duct usually extends from the level of
L2 to the root of the neck. It traverse the diaphragm at the aortic aperture and ascends the superior & posterior mediastinum between the
descending thoracic aorta to its left and the azygos vein to its right. At the level of C7, the duct curves posteriorly to the left carotid artery and left internal jugular vein to empty into the junction of
the left subclavian vein and left jugular vein, below the clavicle.


somatic nerves

subcostal, lumbar L1-5, femoral, obturatior, lumbosacral L4-5, ilioinguinal and iliohypogastric: L1.


subcostal nerve

This is the anterior division of the T12 spinal
nerve. It enters the abdomen
posterior to the lateral arcuate ligament, crosses
the quadratus lumborum muscle, pierces the
transversus abdominis and the internal oblique musc
les. It supplies the skin of the lower abdomen,
the lateral side of the gluteal region, parts of th
e abdominal transverse, oblique, and rectus muscles, as well as usually the pyramidal muscle, and the ad
jacent peritoneum.


lumbar spinal nerves L1 5

The dorsal rami of L1-5 supply the muscles and skin of the back. The ventral rami form
the lumbar plexus and supply the muscles and skin of the inferior aspect of the
trunk and the lower limb. The ventral rami receive grey rami communicantes from the sympathetic chain and L1 and L2 give off white rami communicantes to the sympathetic chain.
The main nerves of the lumbar plexus are:
Femoral nerve (L2-4):
Supplies skin of thigh and legs, anterior muscles of thigh, and hip & knee joints.
Obturator nerve (L2-4):
Supplies posterior superior gemellus muscle, and obturator internus muscle.
Lumbosacral trunk (L4-5):
Contributes along with sacral branches to form the
sciatic nerve, which supplies muscles of the posterior thigh, and the entire leg & foot.
Ilioinguinal & iliohypogastric nerves (L1): Supplies skin of scrotum or labia majora, adjacent part of thigh, the skin above the pubis and over the lateral side of the gluteal region, and occasionally the pyramidal muscle


autonomic nerves

Networks of sympathetic and parasympathetic nerve fibres surround the aorta and continue into the pelvis below its bifurcation. These plexuses contain pre & postganglionic sympathetic fibres, prevertebral sympathetic ganglia, preganglionic parasympathetic fibres (of vagus and pelvic splanchnic nerves) and visceral afferent fibres. The autonomic plexuses include the celiac, superior
mesenteric, inferior mesenteric, intermesenteric, and the superior & inferior hypogastric plexuses. The parasympathetic ganglia are located in the walls of the organs that they supply.


sympathetic splanchnic nerves

Lumbar splanchnic nerves arise from the medial aspect of the lumbar sympathetic trunks and convey presynaptic sympathetic fibres for the innervation of pelvic
viscera. The abdominal component of the sympathetic trunk consists of 4 lumbar paravertebral ganglia and their interconnecting nerves. It is continuous above with the thoracic part of the trunk
and below with the sacral part of the trunk. It crosses into the thorax deep to the medial arcuate ligaments of the diaphragm, and into the pelvis at the sacral promontory. Within the abdomen, it
lies on the anterolateral aspects of the bodies of
the lumbar vertebrae in a groove formed by the
adjacent psoas major.


greater lesser and least splanchnic nerves

hese arise in the thorax and pass through the diaphragm to enter the abdomen.
Greater: T5-9, preganglionic sympathetic and visceral afferent. -celiac gang. supplies Oesophagus, stomach, spleen,
pancreas, liver, biliary system, duodenum, greater omentum.
Lesser: T10-11, goes to SM ganglia, supplies Jejunum, ileum, cecum, ascending colon, transverse colon, descending colon.
Least: T12, - renal ganglia, supplies kidneys suprarenal and ureters.


lumbar splanchnic nerves

arise abdominal portion symp trunk, L1-2, - inf mesenteric, supply DC, SC, proximal rectum.


Sacral splanchnic nerves

S1-5, Mainly postganglionic
sympathetic, some
preganglionic sympathetic, and visceral afferent. goes to inf hypogastric ganglia, supplies pelvic organs and vessels.


parasympathetic splanchnic nerves

Pelvic splanchnic nerves arise from spinal cord segments S2-S4. They carry preganglionic parasympathetic fibres. They innervate the distal 1/3 of the transverse colon, descending colon, sigmoid colon, and rectum


Visceral fibres

Visceral pain afferent information is transmitted
to the central nervous system
alongside sympathetic and parasympathetic fibres and then synapses in dorsal root ganglia. Visceral reflex afferent information is transmitted to the central nervous system alongside sympathetic and parasympathetic fibres, as well as in somatic nerves. Some aspects of reflex control
is at a non-conscious level so forms a reflex arc.


the umbillical ligaments

the mendian is a remenant of the urachus, the medial a remenant of the umbilical artery. the lateral umbilical ligament is the hypogastric vessels.



• Micturition is the process by which the urinary bladder empties when it becomes filled.
• This involves two main steps:
1. The bladder fills until the tension in its walls rises above a threshold level.
2. This elicits a nervous reflex called the micturition reflex that empties the bladder or, if this fails, at least causes a conscious desire to urinate.
• Although the micturition reflex is an autonomic spinal cord reflex, it can also be inhibited or facilitated by centres in the cerebral cortex or brain stem.


transport of urine from the kidneys to ureter to bladder

• Urine that is expelled from the bladder has the same composition as fluid flowing out of the collecting ducts of the kidneys.
• Urine flows from the collecting ducts into the renal calyces, thus stretching them.
• This increases their pacemaker activity, which in turn initiates peristaltic contractions that spread to the renal pelvis and then downward along the length of the ureter, thereby forcing urine from the renal pelvis to the bladder.• The walls of the ureters contain smooth muscle.
 These are innervated by both sympathetic and parasympathetic nerves and by an intramural plexus (nerve plexus within the wall) that extends along the entire length of the ureters.
 Peristaltic contractions in the ureter are enhanced by parasympathetic stimulation and inhibited by sympathetic stimulation.

• The ureters enter the bladder through the detrusor muscle in the trigone region.
 The normal tone of the detrusor muscle in the bladder wall tends to compress the ureter, thereby preventing back flow of urine from the bladder when pressure builds up in the bladder during micturition or bladder compression


back flow of urine

• Sometimes, the contraction of the bladder during micturition does not always lead to complete occlusion of the ureter (valve).
• As a result, some of the urine in the bladder is propelled backward into the ureter - vesicoureteral reflux.
• Such reflux can lead to enlargement (dilatation) of the ureters.
• If severe it increases the pressure in the renal calyces and the renal medulla, causing renal dysfunction.


pain sensation in the ureters-ureterorenal reflex

• The ureters are well supplied with pain nerve fibres.
• When a ureter becomes blocked (e.g. by a ureteral stone), intense reflex constriction occurs, associated with severe pain.
• Also, the pain impulses cause a sympathetic reflex back to the kidney to constrict the renal arterioles, thereby decreasing urine output from the kidney.
• This effect is called the ureterorenal reflex and is important for preventing excessive flow of fluid into the pelvis of a kidney with a blocked ureter.