Posterior Abdominal Wall and Diaphragm Flashcards
What are the bones associated with the posterior adbomen?
5 lumbar vertebrae + associated intervertebral discs, XI and XII ribs, sacrum, ala (wing) of sacrum
How do the lumbar vertebrae differ from the cervical and thoracic vertebrae?
lumbar vertebrae are much larger, their pedicles are short and stocky, their transverse processes are long and slender, and the spinous processes are large;
no costal facet like thoracic vertebrae; no transverse foramen like cervical vertebrae
Which are the free/floating ribs? why?
XI and XII, because they do not fuse with the sternum or with eachother (costal cartilage like other false ribs)
What is located inferior to the 5th lumbar vertebrae?
the upper margin of the sacrum (formed by the fusion of the five sacral vertebrae into a single wedge shaped structure)
Describe the anterior and posterior surface of the sacrum
anterior = concave posterior = convex
What forms the sacroiliac join (be specific!)
upper part of illium articulates with the ala transeverse process of S1 (sacral vertebrae 1)
what is the promontory of the sacrum?
the anterior edge of S1 that projects forward
Where is Rib XI located with respect to the kidney? (which kidney?)
located posterior to the superior part of the LEFT kidney
where is rib XII located with respect the kidney? which kidney?
located posterior to the superior part of the LEFT and RIGHT kidneys
What muscles make up the posterior abdominal wall? Where are they located with respect to each other?
Psoas Major + minor = medial
Quadratus lumborum = lateral
iliacus = inferior
diaphragm = superior
Where is the psoas major muscle located with respect to the lumbar vertebrae?
lateral
Where does the psoas major muscle tendon run with respect to the inguinal ligament? hip joint?
runs POSTERIOR to inguinal ligament;
ANTERIOR to hip joint
what does the psoas major muscle insert on?
the lesser trochanter of the femur
What is the origin of the psoas major muscle?
- bodies of all 5 lumbar vertebrae and + T12
2. transverse process + intervertebrael discs of lumbar vertebrae
what is the psoas major muscle innervated by?
lumbar plexus (Ventral rami of L1 L2 L3)
what is the action of the psoas major?
acting superior with iliacus: flexion of the thigh
acting inferior alone: flexion of the vertebral column laterally
acting with other psoas major + iliacus: flexion of the trunk
what is the psoas minor attached to superiorly?
the sides of T12 and L1 + intervening intervertebral disc
what is the psoas minor attached to inferiorly?
iliopubic eminence on the pelvic rim
what is the psoas minor innervated by?
ventral ramus of L1
where is the psoas minor located with respect to psoas major?
psoas minor is anterior to the psoas major
what is the function of the psoas minor?
helps the psoas major to flex the pelvis and lumbar region of the vertebral column
what is the chief flexor of the thigh?
iliopsoas (iliacus + Psoas major)
where is the iliacus located with respect to the psoas major muscle?
lateral and inferior to the psoas major
What is the origin of the iliacus?
superior 2/3 of the iliac fossa
what is the insertion of the iliacus?
join the fibers of the tenos od psoas major and attach to the lesser trochanter of the femur
what is the iliacus innervated by?
femoral nerve (L2, L3, L4)
what muscle extends across the sacroiliac joint?
iliacus
what is the function of the iliacus muscle?
flexes the thigh and stabilizes the hip joint with the psoas major
what is the iliopsoas? what is its action?
iliacus + psoas major
action = chief flexor of the thigh + help to maintain erect posture at the joint
How is an abscess resulting from tuberculosis in the lumbar region related to the psoas muscle?
the abscess tends to spread from the vertebrae in the fascia enclosing the pasoas major muscle and could produce a psoraes abscess; pus from the abscess could pass inferiorly along the the psoas over the pelvic brim, deep to the inguinal ligament and into the femoral triangle
what overlaps the quadratus lumborum medially?
psoas major
what is the origin of the quadratus lumborum
tips of the transverse processes of all 5 lumbar vertebrae and the medial half of the inferior border of rib XII
what is the insertion of quadratus lumborum
iliolumbar ligament and internal lip of the iliac crest
what does the iliolumbar ligmanet connect?
the tips of L5 to the iliac crest
what is the innervation of quadratus lumborum
ventral branches of T12, L1, L2, L3, L4
what is the action of the quadratus lumborum
extends and laterally flexes the vertebral column; fixes rib XII during inspiration
what is the principal muscle of respiration?
diaphragm
what forms the floor of the thoracic cavity and roof of the abdominal cavity?
diaphragm
How does the diaphragm move during inspriation
descends; only the dome moves, the peripheral parts are unable to move because they are attached to the inferior margin of the osteocartilagenous thoracic cage and the superior lumbar vertebrae
why does only the dome of the diaphragm move during inspiration?
because the peripheral parts are unable to move because they are attached to the inferior margin of the osteocartilagenous thoracic cage and the superior lumbar vertebrae
what does the muscular portion of the diaphragm insert onto?
the central tendon (central aponeurotic part of the diaphragm)
what are the divisions of the diaphragm?
sternal, coastal, lumbar
what are the attachments of the sternal portion of the muscular diaphragm?
- posterior aspect of the xiphoid process of the sternum
2. converge onto central tendon and form a sternocostal hiatus
what is the sternocostal hiatus? where is located? what forms it? what goes through it?
a small anterolateral gap formed by the sternal diaphragm muscle inserting on the central tendon of the diaphragm;
superior epigastric artery runs through it
what is the origin of the costal muscle fibers of the diaphragm?
the internal surface of the inferior six ribs on their costal cartilages on each side
what does the costal muscle fibers of the diaphragm form? what is their function?
form the right and left hemidiaphragm/domes;
move during inspiration
what is the vertebrocostal triangle/trigone? what is it formed by? what is its contents in the living person?
an interval that separate costal part of the diaphragm that arises from the Xi and XII ribs from the lumbar part;
filled with loose CT in the adult
what is the origin of the lumbar muscle fibers of the diaphragm?
the lumbar vertebrae by two musculotendinous crura (L-Leg),
what are the left crus of the diaphragm attached to?
attached on each side of the aorta to the anterolateral surfaces of the superior two (left) or three (right) lumbar vertebrae and their intervertebral discs
how does the right crus differ from the left crus?
right = broader and longer than the left crus
Where are the crura of the diaphragm united? by what?
united opposite the disc between T12 and L1;
by median arcute ligmanet = a tendinous band arch
what is the diaphragm attached to?
the medial and lateral arcuate ligaments
what are the medial arcuate ligaments formed by?
thickening of the psoas fascia over the superior part of the psoas major muscule
where do the medial arcuate ligaments radiate towrards?
the central tendon
what are the lateral arcuate ligaments formed by?
thickenings of the anterior layer of the thoracolumbar fascia over the superior part of the quadratus lumborum muscle;
what muscle does the medial arcuate ligament travel over? the lateral arcuate ligament?
medial = psoas major lateral = quadratus lumborum
where do the lateral and medial arcuate ligaments unite?
the mediaN arcuate ligament
What is the central tendon? what does it fuse to? What are its divisions?
a strong aponeurosis that the muscle fibers of the diaphragm converge radially to;
It is fused with the inferior surface of the fibrous pericardium;
Divided into 3 areas which resembly a clover leaf
Where is diaphragmatic herniation most prone? what is caused by?
Herniation prone at areas where the diaphragm muscle fuses to the aponeurosis;
Herniation results from sudden increase in intrathoracic or intra-abdominal pressure (ie: car accident);
where do most diaphragmatic ruptures occur?
On the left side, through the weak vertebrocostal triangle (an area where muscle fibers of the costal and lumbar parts of the diaphragm fuse)
What is a congenital hernia?
an esophageal or sternocostal opening when the diaphragm ruptures and the stomach (most common), intestines, or spleen herniates into the thorax
At what thoracic level is the vena caval foramen located?
T8
what is the vena caval foramen? How does it function in inspiration?
a foramen that allows the inferior vena cava to descend through the diaphragm to the abdomen;
When the diaphragm contracts during inspiration, it widens the foramen and stretches and dilates the inferior vena cava
where is the esophageal hiatus located with respect to the (vena) caval opening?
posterolateral to the caval opening
what is the esophageal hiatus formed by?
the right crus
At what vertebral level is the esophageal hiatus located?
T10
What runs though the esophageal hiatus?
esophagus, anterior and posterior vagal trunks
what forms the esophageal sphincter?
muscle fibers of the right crus
what is the function of the esophageal sphincter?
it constricts the distal end of the esophagus during inspiration to prevent reflex of gastric contents into the esophagus;
the sphincter closes the esophagus when not eating to prevent stomach juices from getting back into the esophagus
Does the aorta pierce through the diaphragm?
NO
Is the aorta affected by contractions of the diaphragm during inspiration?
NO!! the aorta does NOT pierce the diaphragm (aorta hiatus is posterior to the mediaN arcuate ligament)
where is the aortic hiatus located?
posterior to the mediaN arcuate ligament
At what vertebral level is the aortic hiatus located?
T12
what runs through the aortic hiatus?
aorta, thoracic duct, azygous vein
where is the sternocostal hiatus located? what runs through it?
located between the sternal and costal parts of the diaphragm; the superior epigastric vessels usually pass through it
where do the subcostal nerves and vessels pass through the diaphragm?
posterior to the lateral arcuate ligaments
where does the sympathetic trunk pass through the diaphragm?
posterior to the medial arcuate ligament
where do the greater and lesser splanchnic nerves pass through the diaphragm?
they pierce the crura
where does the hemiazygous vein pass through diaphragm?
through the left crus of the diaphragm r medial arcuate ligament
what happens to the central tendon during inspiration?
the diaphragm contracts which brings the central tendon down, allowing the volume of the thorax to increase
where is diaphragm pain referred?
to shoulder because phrenic nerve = C3,4,5 (and C5 = part of brachial plexus)
+ costal margin of abdomen (due to sensory impulses traveling with the intercostal nerves)
what arteries supply the diaphragm superiorly?
superior phrenic branch of the thoracic aorta + musculophrenic (internal thoracic) + pericardiacophrenic (internal thoracic)
what arteries supply the diaphragm inferiorly?
inferior phrenic artery (from abdominal aorta)
what nerves innervate the diaphragm (motor + sensory)
- phrenic nerve = sensory (pain/propriorecption) + motor
- Intercostal nerve 6 + 7 (ventral spinal T6 + 7) = peripheral sensory
- subcostal nerve (ventral spinal T12) = peripheral sensory
Describe the lymphatic drainage of the thoracic surface of the diaphragm
lymph nodes drain into the phrenic nodes and then parasternal and posterior mediastinal lymph nodes
Describe the lymphatic drainage of the abdominal surface of the diaphragm
drains into superior lumbar lymph nodes
What is the action of the diaphragm? what happens to the domes during contraction?
diaphragm = chief muscle of inspiration;
when it contracts, the right and left domes inferiorly which increases the volume of the thorax which allows air to be taken into the lungs
How is diaphragmatic contraction related to venous return?
when the diaphragm contract, the inferior vena cava dilates (due to the caval foramen) with allows the return of venous blood into the heart
How is the diaphragm related to abdominal straining?
it assists the anterior abdominal muscles in raising intra abdominal pressure during micturition, defecation, and parturition (child birth)
Where is endoabdominal fascia located?
between the parietal peritoneum and the muscles of the posterior abdominal wall
What does the iliac fascia cover?
encloses the psoas and iliacus muscles
what forms the medial arcuate ligament of the diaphragm?
the iliac fascia thickening (superiorly)
What does the iliac fascia fuse with/continuous with?
superiorly the iliac fascia fuses with the anterior layer of the thoracolumbar fascia;
iliac fascia is continuous with the transversalis fascia laterally
what does the thoracolumbar fascia enclose?
deep muscle of the back
where does the lumbar part of the thoracolumbar fascia extend?
between the 12th rib and the iliac crest
what does the thoracolumbar fascia attach to laterally?
the internal oblique an transversus abdominis
what lies between the anterior and middle layer of the thoracolumbar fascia (medially)
the quadratus lumborum
what lies between the middle and posterior layers of the thoracolumbar fascia (medially)
deep back muscles
what do the lumbar nerves exit the spinal cord through?
the intervertebral foramina, inferior to the corresponding vertebrae (then they divide into dorsal and ventral primary rami)
what do the lumbar posterior rami supply?
the muscles of the skin of the back
what do the lumbar ventral primary rami supply?
the psoas major muscle (connect with the sympathetic trunk)
Do the lumbar ventral rami receive rami communicantes? which communicantes?
all five receive gray rami from sympathetic trunk;
L1 + L2 also send white rami communicates to the sympathetic trunk
what is the lumbar plexus formed by? where?
formed by the ventral rami of L1 - L4 within the psoas major muscle
What nerves are located lateral to the psoas major muscle? (superior to inferior)
- Iliohypogastric (L1)
- Ilioinguinal (L2)
- Lateral Femoral Cutaneous (L2 + L3)
- Femoral (L2 L3 L4)
From what lumbar nerve is the iliohypogastric nerve derived from
L1
where does the iliohypogastric nerve travel (course)
anterior to the fascia of the quadratus lumborum and near the anterior superior iliac spine, it pierces the transversus abdominis and divides into lateral/anterior branches
What does the lateral branch of the iliohypogastric nerve supply? course?
pierces through the internal and external oblique muscles and supplies the skin of the lateral side of the gluteal region
What does the medial branch of the iliohypogastric nerve supply? course?
runs BETWEEN the internal and external obliques and pierces the aponeurosis of the external oblique to supply the skin of the abdomen superior to the pubis (skin on top of the pubis)
From what lumbar nerve is the ilioinguinal nerve derived from
L2
where is the ilioinguinal located with respect to the iliohypogastric nerve?
located inferior to the iliohypogastric nerve
what is the course of the ilioinguinal nerve?
pierces the transversus abdominis, runs medially in the inguinal canal and exits through the superficial inguinal ring
what does the ilioinguinal nerve supply?
anterior side of the thigh and skin over the anterior scrotum and labia majora
From what lumbar nerve is the lateral femoral cutaneous nerve derived from?
L2 + L3
what is the course of the lateral femoral cutaneous nerve
runs obliquely on the iliacus muscle towards the anterior superior iliac spine and enters the thigh BELOW the inguinal ligament; then it is generally located between the sartorius and tensor fascia lata muscles;
divides into anterior and posterior branches
what does the lateral femoral cutaneous nerve supply?
anterior and lateral skin of the thigh
From what lumbar nerve is the femoral nerve derived from?
L2, L3 , L4
what is the course of the femoral nerve?
emerges from the psoas major muscle and descends inferiorly between psoas and iliacus and reaches the thigh POSTERIOR to the inguinal ligament
what is the function of the femoral nerve?
primary motor innervation to the iliacus and extensor muscles of the thigh;
sensory to the anterior and medial side of the thigh
what is the saphenous nerve?
terminal branch of the femoral nerve
what is the course of the saphenous nerve?
passes deep to the sartorius muscle while accompanying the femroal artery; runs with the great saphenous vein in the leg; in the distal part of the leg it divides into two terminal branches
what does the saphenous nerve supply?
sensory to skin of the anterior and medial side of the foot
what nerves located anterior to the psoas major?
Genitofemoral (L1, L2)
From what lumbar nerves is the genitofemoral nerve derived from?
ventral rami L1 + L2
what is the course of the genitofemoral nerve?
runs anterior to psoas major muscle and divides into the genital and femoral branches
what is the course of the genital nerve?
enters the inguinal canal through the deep ring
what is the function of the genital nerve?
motor to the cremasteric muscle (in males)
sensory to anterior scrotum and anterior labia majora and adjacent parts of the thigh
what does the femoral branch of the genitofemoral nerve supply? course?
enters the femoral sheath and supplies the skin of the femoral triangle
what nerves are located medial to the psoas major?
- obturator (L2 L3 L4)
2. Lumbosacral (L4,L5)
From what lumbar nerve is the obturator derived from?
L2, L3, L4 ventral rami
what is the course of the obturator nerve?
emerges from the medial side of the psoas at the inlet of the pelvis; runs inferiorly on the lateral wall of the pelvis (obturator internus) and enters the medial thigh through the obturator forament
what does the obturator nerve supply?
motor to all three adductor muscles (magnus, longus, brevis) and to gracilis
sensory to the skin of the medial side of the thigh and to the hip joint
from what lumbar nerves is the lumbosacral trunk derived?
inferior part of the ventral ramus of L4 + L5
what is the course of the lumbosacral trunk?
descends into the pelvis to help from the SACRAL plexus
does the lumbosacral trunk contribute to the lumbar plexus?
no
Where does the abdominal aorta start/end?
begins at the aortic hiatus at the intervertebral disc between T12/L2 and ends around L4 by dividing into two common iliacs
what does the abdominal aorta run adjacent to?
lies against the vertebral bodies
Where does the celiac trunk branch from the abdominal aorta?
At vertebral level T12; immediately inferior to the aortic hiatus
what does the celiac trunk supply?
abdominal foregut
where does the superior mesenteric artery branch from the abdominal aorta?
at the level of LV1; immediately inferior to the celiac trunk
what does the superior mesenteric artery supply?
the small intestine (jejunum + Ileum), and ascending and transverse parts of the colon
where does the inferior mesenteric artery branch off of the abdominal aorta?
at the level of L3; inferior to the renal arteries and from the left side of the aorta
what does the inferior mesenteric artery supply?
the descending colon, sigmoid colon and its terminal branch to the upper rectum
what is the terminal branch of the inferior mesenteric artery? what does it supply?
superior rectal artery, supplies the upper rectum
where do the middle suprarenal arteries arise? run? supply?
arise close to the origin of the superior mesenteric artery; run laterally to the suprarenal glands; supply supra renal glands
where are the renal arteries located? supply?
located inferior to the superior mesenteric artery; supply the kidneys
what is the course of the gonadal arteries? supply?
branches arise inferior to the renal arteries and run inferior on the psoas major muscle; the right artery passes over the IVC gives rise to testicular and ovarian arteries
what is the course of the testicular artery?
passes through the deep ring and enters the inguinal canal to become part of the spermatic cord
(Off of gonadal artery)
what is the course of the ovarian artery? supply?
from Gonadal artery; crosses the ends of the external iliac vessels to enter the pelvis where it supplies the ovary and uterine tube
**does not exit the abdominal cavity!
what vessels arise from the posteriolateral surface of the aorta?
inferior phrenic arteries and lumbar arteries
what is the course of the inferior phrenic arteries?
arise from the abdominal aorta just inferior to the diaphragm (lateral to the celiac trunk) ; pass superolaterally over the crura of the diaphragm
what do the inferior phrenic arteries supply?
the inferior surface of the diaphragm
How many lumbar arteries are there?
4
what is the course of the lumbar arteries? what do they supply?
Each pair passes around the sides of the four superior lumbar vertebrae and divides into anterior and posterior branches to supply the body wall
where does the median sacral artery arise? course?
arises from the posterior side of the aorta just proximal to its bifurcation and descends in the midline anterior to L4 and L5
Does the IVC have any valves?
Has a non-functional valve near its orifice
What is the IVC formed by? where?
union of the two common iliac veins anterior to L5 vertebrae, 2.5 cm to the RIGHT of the median plane and INFERIOR to the bifurcation of the aorta
what is the course of the IVC?
ascends on the right psoas major muscle, to the right of the aorta, and passes through the caval opening at the level of T8
where do lumbar veins drain into?
either IVC or ascending lumbar vein (vertical connecting vein)
where is the ascending lumbar vein located in the abdomen?
posterior to the psoas major muscle
where does the ascending lumbar vein enter the thorax?
enters the thorax posterior to the medial arcuate ligament
what does the left ascending lumbar vein join? right?
left ascending lumbar joins the LEFT SUBCOSTAL VEIN to form the HEMIAZYGOUS
right ascending lumbar joins the RIGHT SUBCOSTAL VEIN to form the AZYGOUS VEIN
how would the abdomen drain if the IVC were occluded?
blood can be channeled through the lumbar veins to the ascending lumbar veins to the azygous (or hemi then azygous) to the RA
what is the cisterna chyli?
a sac-like expansion at the inferior end of the thoracic duct (frequently absent); that receives lymph from lumbar lymph nodes and passes it to the thorax via the thoracic duct
where is the cisterna chyli located?
on the right side of the bodies of L1 and L2 vertebrae posterior to the right crus of the diaphragm
