Ch18 - Posterior Abdominal Wall (PAW) and Kidneys

Question 1

Diagram

Answer 1

Question 2

Three muscular Parts of the Diaphgram

Answer 2

Question 3

Central Tendon (moveable part)

Answer 3

Question 4

Three Openings in Diaphragm

Answer 4

Question 5

Caval opening (Hiatus)

Answer 5

“: IVC traverses at T8, in the central tendon. Diaphragm contraction opens IVC allowing more blood flow during inspiration.
”

Question 6

Esophageal hiatus

Answer 6

“ vagal trunks traverse as well at T10”

Question 7

Aortic Hiatus

Answer 7

“aorta and thoracic duct traverse at T12”

Question 8

Innervation of the Diaphragm

Answer 8

Question 9

Kehr’s sign

Answer 9

An enlarged spleen may refer pain to diaphragm.

88 of 199

Question 10

“Development of the diaphragm”

Answer 10

Question 11

The diaphragm is derived from which four embryonic tissues.

Answer 11

1. Septum Transversum.
2. Somatic Mesoderm.
3. Dorsal mesentery of the esophagus.
4. Pleuroperitoneal membranes.

Question 12

Septum Transversum

Answer 12

• the septum transversum gives rise to a major part of the diaphragm.
• the craial-most part of the head mesoderm, is moved caudal to the future heart and pericardium, between these structures and the neck of the yolk sac. (Vol 1, 59 of 182)

Question 13

Somatic mesoderm

Answer 13

“Somatic mesoderm from the embryo’s body wall grows inward toward the central tendon, forming the muscular peripheral parts of the diaphragm, where it attaches to the ribs, costal cartilages, and sternum.”

160 of 199

Question 14

Esophagus mesentery

(Dorsal mesentery of the esophagus)

Answer 14

“acquires muscle forming cells and gives rise to the crura of the diaphragm. ”

Question 15

Pleuroperitoneal Membranes

Answer 15

• Two sheets of mesenchyme grow in the center of the “domes” of the diaphragm, to the left and right of the central tendon.
• These pleuroperitoneal membranes partition the intra-embryonic coelom (remember the IEC?).
• Above the membranes is the cranial “bicycle handlebars” part of the IEC.
• Below the membranes are the left and right caudal limbs of the IEC = the coelomic ducts.
• Formation of the pleuroperitoneal membranes is a crucial step in separating the thoracic cavity from the abdominal cavity.

Question 16

Congenital Diaphragmatic Hernia

Answer 16

• Faulty formation of the diaphragm that allows communication between thoracic and abdominal cavities is called congenital diaphragmatic hernia.
• The culprit is usually malformation of a pleuroperitoneal membrane.
• These are much more likely to occur on the left side than on the right, because the left pleuroperitoneal membrane is larger and closes later than does the right.
• If the hernia is large enough, abdominal organs can bulge into the thoracic cavity, stunting the growth of the lungs (pulmonary hypoplasia).
• This can be a life-threatening condition.

Question 17

List Arteries and Veins of Posterior Abdominal Wall

Answer 17

Question 18

Arteries of Posterior Abdominal Wall

Answer 18

“The abdominal aorta spans from T12 to L4, where it bifurcates into the right and left common iliac arteries. It has three types of arterial branches that supply “the gut, glands, and the wall.”

Question 19

Veins of Posterior Abdominal Wall

Answer 19

Question 20

Nutcracker syndrome

Answer 20

• The relationship between the superior mesenteric artery (SMA) passing over the left renal vein can have rare consequences.
• “Nutcracker syndrome” is a vascular compression pathology where the left renal vein is compressed within a “vise” between the SMA and abdominal aorta.
• This uncommon disorder produces hematuria and left flank pain.”

Question 21

Lumbar Plexus

Answer 21

1. Iliohypogastric n. (L1)
2. Ilioinguinal n. (L1)
3. “Genitofemoral n. (L1, L2)
4. Lateral cutaneous nerve of the thigh (L2, L3)
5. “Femoral n. (L2, L3, L4)”
6. Obturator n. (L2, L3, L4)
7. Lumbosacral trunk (L4,5)

Question 22

Lumbar Plexus & Its Dermatomes

Answer 22

Question 23

Lumbar Plexus - Identify

Answer 23

Question 24

Iliohypogastric nerve. (L1)

Answer 24

• Innervates: muscles in the inferior part of the anterior abdominal wall; sensory from the skin above the pubis and lateral buttocks.
• Best place to find it: anterior to quadratus lumborum, superior to the ilioinguinal nerve.

Question 25

Ilioinguinal n. (L1)

Answer 25

* Innervates: muscles in the **inferior** part of the **anterior abdominal wall**; _sensory_ from skin of _scrotum_ or _labium majora_. * Best place to find it: anterior to quadratus lumborum, inferior to iliohypogastric; runs along the iliac crest”

Question 26

Genitofemoral n. (L1, L2)

Answer 26

* **Genital branch**: through the **deep inguinal ring**, to innervate **cremaster muscl**e in males. * **Femoral branch**: descends deep to the **inguinal** **ligament**; sensory from skin of anterior upper thigh * Best place to find it: pierces **psoas major** and descends on its anterior surface.”

Question 27

Lateral cutaneous nerve of the thigh (L2, L3)

Answer 27

* Sensory from the lateral skin of the entire thigh…“skinny jeans” nerve. * Best place to find it: passes under the inguinal ligament just medial to the anterior superior iliac spine (ASIS) ”

Question 28

Femoral n. (L2, L3, L4)

Answer 28

* Innervates: muscles of the **anterior thigh** (“quads”); **sensory** from skin of anterior thigh and on the medial leg. * Best place to find it: sandwiched between psoas major and iliacus muscles. ​
A big nerve!”

Question 29

Obturator n. (L2, L3, L4)

Answer 29

* Innervates: **adductor muscles** (medial thigh) * Best place to find it: medial to psoas major in the lateral wall of the pelvic cavity.

Question 30

Lumbosacral trunk (L4,5)

Answer 30

* Contributes the L4,5 segments to the sciatic nerve in the pelvis. * Best place to find it: medial to psoas major, on the ala of the sacrum.

Question 31

Psoas major muscle

Answer 31

* Long and thick; the “tenderloin” * Origin: lateral bodies, transverse processes of T12–L5; inserts: lesser trochanter of femur (with the iiacus muscle, now called iliopsoas) by a strong tendon * Action: main thigh flexor, laterally flexes vertebral column”

Question 32

Psoas minor

Answer 32

thin strip anterior to psoas major; absent in 40% of individuals

Question 33

Iliacus muscle

Answer 33

* Originates in iliac fossa, fuses with the psoas major inferiorly, inserts on lesser trochanter * Action: flexes the thigh ”

Question 34

Quadratus lumborum muscle

Answer 34

* **Thick** muscular sheet in the **PAW**; iliac crest up to rib 12 and transverse processes of lumbar vertebrae. * Enclosed between **two** layers of **lumbar fascia**, which join to form a thick sheet of lumbar fascia lateral to **quadratus lumborum**. * Action: laterally flexes the vertebral column, as when bending sideways. Stabilizes 12th rib during inspiration.

Question 35

Psoas major muscle

Answer 35

* Long and thick; the “tenderloin” * Origin: lateral bodies, transverse processes of T12–L5; inserts: lesser trochanter of femur (with the iiacus muscle, now called **iliopsoas**) by a strong tendon. * Action: main thigh flexor, laterally flexes vertebral column.

Question 36

Muscles of PAW

Answer 36

Question 37

PAW Lymph Vessels

Answer 37

Question 38

Cisterna chyli

Answer 38

lies near T12, and is the beginning of the thoracic duct, and ascends along the abdominal-vertebral between the right crus of the diaphragm and the aorta, leaving through the aortic hiatus.

Question 39

Kidney - Identify Organs

Answer 39

Question 40

Kidneys - Gross external anatomy

Answer 40

* Fist sized and bean-shaped **retroperitoneal** organs. * Lie T12–L3; _right_ kidney is slightly _lower_ than the left (due to the liver). * **Fibrous renal capsule**. * **Renal Hilum** and **Renal sinus** (cavity within kidney, accessed via the hilum): located at IV disc between L1 and L2 * **Renal vein** is anterior to **renal artery**, which is anterior to **renal pelvis** (expanded upper part of ureter).

Question 41

Kidney - Anatomical Relationship

Answer 41

* Anterior: **_right_**: right suprarenal gland, liver, descending duodenum, right colic flexure, small intestine; left: left suprarenal gland, stomach, pancreas, small intestine, spleen, left colic flexure, descending colon. * Posterior: both: diaphragm, psoas major, quadratus lumborum, thoracolumbar fascia, rib 12, T12 and L1 spinal nerves

Question 42

Kidney - Gross "internal" anatomy

Answer 42

* **Renal cortex**: receives 90% of blood flow to kidney (receives ~20% of cardiac output!) * Lighter outer part just deep to capsule; where urine is made * **Renal columns**: extensions of cortex between renal pyramids * **Renal medulla** (composed of the dark colored renal pyramids) * Where urine is concentrated, or diluted * **Renal papilla**: apex of a **renal pyramid**; where the urine is excreted. * **Minor calices** (singular: calyx): where papilla excretes urine; 2–3 per major calyx”

Question 43

Renal Cortex

Answer 43

* receives 90% of blood flow to kidney (receives ~20% of cardiac output!) * Lighter outer part just deep to capsule; where urine is made * Renal columns: extensions of cortex between renal pyramids

Question 44

Renal medulla

Answer 44

* composed of the dark colored renal pyramids * Where urine is concentrated, or diluted * Renal papilla: apex of a renal pyramid; where the urine is excreted.

Question 45

Minor calices (singular: calyx)

Answer 45

where papilla excretes urine; 2–3 per major calyx”

Question 46

Major calices

Answer 46

where papilla excretes urine; 2–3 per major calyx”

Question 47

Renal vessels

Answer 47

**Renal artery** --\> 5 segmental (arise in the sinus, dividing kidney into distinct vascular segments) -\> lobar -\> interlobar (in renal columns) -\> **arcuate** (arch over base of pyramid) -\> interlobular (in cortex) ”

Question 48

Kidney - Anatomy

Answer 48

Question 49

**_Accessory Renal Artery_**

Answer 49

About 30% of individuals have an accessory renal artery (usually a “polar” artery from development). This is important for surgery!

Question 50

Layers around the kidney

Answer 50

* **Renal capsule** (outer layer of kidney) * **Perirenal fat** (aka Perinephric fat): surrounds the kidney and extends into the renal sinus * **Renal fascia** (Gerota’s fascia): encloses the kidneys, suprarenal glands and the perirenal fat * **Pararenal fat** (aka Paranephric fat): thickest posteriorly and an extension of the lumbar extraperitoneal fat; usually lots of it ” * **_Clinical Application_**: * All these layers must be traversed to reach the kidney during surgery. Also, the front and back layers of the renal fascia are not fused very tightly below the kidney, so a kidney can move inferiorly and this can kink the ureter and prevent urine from draining.

Question 51

Ureter

Answer 51

* Muscular ducts that carry urine from the kidneys to the urinary bladder. * In the same sagittal plane as the tips of the transverse processes of the lumbar vertebrae (which helps identify ureters on x-rays). * Blood supply: from renal artery, abdominal aorta, and vessels in the pelvis; is segmental so surgeons must be careful of manipulation or accidental injury causing ischemia.

Question 52

Ureter - Anatomy

Answer 52

Question 53

kidney stones

Answer 53

* Three narrowings along the course of the ureter, which are important as kidney stones frequently are lodged in these locations: 1. The ureteropelvic junction (as pelvis of ureter narrows to become ureter proper) 2. As it crosses over the pelvic brim and common iliac vessels. 3. The passageway through the wall of the bladder”

Question 54

SUPRARENAL GLANDS ​
 (AKA ADRENAL GLANDS)

Answer 54

* Located between the kidney and the diaphragm . * The right one is pyramid-shaped, the left one crescent-shaped. * Two glands in one: “stress” hormones 1. Cortex: from mesoderm and secretes corticosteroids and androgens 2. Medulla: from neural crest cells and secretes catecholamines * Rich blood supply/many arteries (R/L superior, middle, inferior suprarenal aa); just one vein (the **R/L suprarenal vein**) * The suprarenal glands are also enclosed by the renal fascia”

Question 55

Identify Vessels

Answer 55

Question 56

Kidneys

Answer 56

Question 57

Fibrous (renal) capsule

Answer 57

Adherent to kidney

Question 58

Perirenal fat

Answer 58

Covers fibrous capsule

Question 59

Pararenal fat

Answer 59

Lies external to the renal fascia, and forms part of the retroperitoneal fat

Question 60

Renal (Gerota’s) fascia

Answer 60

* Surrounds perirenal fat. * Covers kidneys, suprarenal glands, ureters, and renal vessels. * Continuouslaterally with **transversalis fascia.**

Question 61

Kidneys and Suprarenal Glands

Answer 61

Question 62

Kidneys & Ureters - 1

Answer 62

Question 63

Kidneys & Ureters - 2

Answer 63

Question 64

Ureters - 1

Answer 64

​ * Muscular tubes that covey urine from the renal pelvis to the bladder through peristaltic (wavelike) contractions. * Three main points of constriction where kidney stones may become stuck

Question 65

Ureters - 2

Answer 65

Question 66

Internal Anatomy of the Kidney

Answer 66

**Renal Hilum**: entrance to kidney * site where renal artery, renal vein, and * enal pelvis pass to/from kidney **Renal Sinus**: fat-filled cavity inside the kidney * Contains urine collecting system = calyces and renal pelvis **Renal medulla** is the inner part of the kidney. * The renal medulla is split up into a number of sections, known as the renal pyramids **Renal cortex** is the outer portion of the kidney between the renal capsule and the renal medulla * Cortical columns are projections of the renal cortex between the renal pyramids

Question 67

Internal Anatomy of the Kidney - Identify

Answer 67

Question 68

The renal papilla, the minor calyx, the major calyces, and the large renal pelvis.

Answer 68

Question 69

Internal Anatomy of the Kidney - Renal Papilla, Minor Calyces, and Major Calyces.

Answer 69

* The **renal papilla** is the location where the renal pyramids empty urine into the minor calyx. * The **minor calyces** funnel urine into the major calyces. * The **major calyces** funnel into the large renal pelvis.

Question 70

Muscles of Posterior Abdominal Wall - 1

Answer 70

Quadratus lumborum * Attachments: iliac crest; 12th rib & transverse processes of lumbar vertebrae. * Extends and laterally flexes lumbar spine Psoas major (and minor if present) * Origin = bodies & transverse processes of vertebrae T12-L5 * Lateral and superior portion laterally flexes spine Iliacus • Origin = iliac fossa Iliospsoas * Psoas major and iliacus muscles unite and insert as iliopsoas on lesser trochanter of femur. * Primary flexor of thigh

Question 71

Muscles of Posterior Abdominal Wall - 2

Answer 71

Question 72

Diaphragm - 1

Answer 72

Question 73

Diaphragm - 2

Answer 73

Question 74

Openings of the Diaphragm

Answer 74

Question 75

Openings of the Diaphragm - 2