Posterior Abdominal Region

Question 1

Lymphatic vessels

Answer 1

• begin as ‘porous’ blind-ended lymphatic capillaries in tissues
• collect fluid lost from capillary beds, delievered back to venous side of vascular syst.
• include pathogens, lymphotic system, cell products(hormones), and cell debris
• major route of transport for fat absorbed by gut
• movement of lymph generated by contraction of skeletal muscles, pulses in arteries, while unidirectional flow is maintained by the presence of valves.

Question 2

• chylomicrons
• lacteals (in small intestine)
• lymph
• chyle

Answer 2

• protein-coated lipid droplets where fats are packaged by intestinal epithelium
• lymphatic capillaries, where chylomicrons drain
• clear, colorless fluid
• in small intestine, opaque, milky becoz of presence of chylomicrons

Question 3

Lymph nodes

Answer 3

• small, encapsulated structures contain defense like lymphocytes and macrophages
• act as filters that trap and phagocytose particulate matter in the lymph that goes through.
• detect and defend against foreign antigens
• drain body surface, digestive sys, respiratory sys
• palpate at axilla, groin, femoral region, and neck

Question 4

Lymphatic trunks and ducts

-

Answer 4

• coalesce to form larger trunks or ducts, which drain into venous system where internal jugular veins -> subclavian -> brachiocephalic veins
• lymph from right side ->veins right side of neck
• lymph from left side ->veins left side of neck

Question 5

• pre-aortic nodes

- right/left lateral aortic (lumbar) nodes

Answer 5

• anterior to abdominal aorta. divide into celiac, superior mesenteric, inferior mesenteric
• on either side of aorta, receiving from the body wall, kidneys, suprarenal glands, testes/ovaries. form a saccular dilation(cisterna chyli), post to right side of ab aorta and marks beginning of thoracic duct.

Question 6

• sympathetic trunks and ganglia

- lumbar splanchnic nerves

Answer 6

• pass through the posterior abdominal region anterolateral to the lumbar vertebral bodies, before continuing into the pelvic cavity
• carry preganglionic sympathetic fibers and visceral afferent fibers

Question 7

-Abdominal prevertebral plexus and ganglia

Answer 7

• a network of nerve fibers surrounding the abdominal aorta, from aortic hiatus to bifurcation into right and left common iliac arteries.
• subdivided into:
  
  • celiac plexus: from diaphragm -> celiac trunk and superior mesenteric artery
  • abdominal aortic plexus: below superior mesenteric artery
  • superior hypogastric plexus: bifurcation of abdominal aorta

Question 8

Lumbar plexus

Answer 8

• Iliohypogastric nerve - T12/L1
• Ilioinguinal nerve - L1
• genitofemoral nerve - L2
• lateral cutaneous nerve of thigh - L3
• To iliacus muscle - L4
• Femoral nerve
• Obturator nerve
• to lumbosacral trunk

*forms in psoas major muscle anterior to its attachment to the transverse processes of the lumbar vertebrae

Question 9

• left kidney
• right kidney
• spleen

Answer 9

• higher than right. at rib XI
• at rib XII
• left side back in the area of ribs IX to XI, follows contour of rib X.

Question 10

Kidneys

• found where
• relation to right
• relation to left
• posteriorly inferior structures
• anterior to what ribs
• renal fat/fascia

Answer 10

• retroperitoneal, TXII to LIII. Left kidney higher than right kidney
• right suprarenal gland, liver, descending duodenum, small intestine
• left suprarenal gland, stomach, spleen, pancreas, left colic flexure, descending colon, jejunum
• psoas major, quadratus lumborum, transversus abdominis muscles
• right: rib XII, left: ribs XI, XII
• perinephric (perirenal fat):surrounds kidney
• renal fascia: membranous condensation surrounds perinephric
• paranephric fat (pararenal fat)

Question 11

Hiatus hernia

Answer 11

• at level of esophageal hiatus, diaphragm is lax, allowing fundus of stomach to herniate into posterior mediastinum.
• causes acid reflux and ulcer

Question 12

Kidney structure

Answer 12

• hilum of kidney
• renal cortex
• renal medulla
• renal pyramids
• renal sinus
• renal papilla
• minor calyx
• major calyx
• renal pelvis

Question 13

Renal vasculature and lymphatics

• ureter junctions and constrictions
• ureter arteries

Answer 13

• right/left renal artery: supplies each kidney
• extrahilar arteries
• right/left renal veins
• lumbar nodes
• ureteropelvic junction-ureters descend retroperitoneally on the medial aspect of the psoas major muscle
  1. inferior to kidney
  2. pelvic brim
  3. enters wall of bladder

*abdominal aorta, R/L renal artery, testicular arteries, common iliac artery, external iliac artery, internal iliac artery

Question 14

• Urinary tract stones

- urinary tract cancer

Answer 14

• freq in men, 20-60 years sedentary. urine becomes saturated w/ salts and pH variations causes salts to precipate. may have hematuria.
• develop from proximal tubular epithelium or urothelium. they grow outwards from kidney invading the fat and fascia, and may spread to renal vein.

Question 15

Suprarenal vasculature

Answer 15

• inferior phrenic arteries -> superior suprarenal arteries, middle suprarenal artery, inferior suprarenal arteries
• R/L suprarenal vein

Question 16

Branches of Abdominal aorta (vert TXII, LIV)
1. Visceral

2. Posterior
   * Inferior Phrenic arteries

Answer 16

1. (Unpaired) celiac trunk: ab foregut -> superior mesenteric artery: ab midgut -> inferior mesenteric: hindgut
   - (Paired) middle suprarenal arteries: suprarenal gland -> renal arteries: kidneys -> testicular/ovarian arteries
2. inferior phrenic arteries, lumbar arteries (4 pairs), median sacral artery
   * to suprarenal gland, to inferior surface of diaphragm

Question 17

Veins associated with IVC

Answer 17

• common iliac vein
• lumbar vein
• right testicular/ovarian vein
• renal veins
• right suprarenal vein
• inferior phrenic veins
• hepatic veins

*lumbar veins, ascending lumbar veins, iliolumbar vein

Question 18

Explain the dev’t of the inguinal canal

Answer 18

-Before the descent of the testis and the ovary fr their site of origin high on the posterior abdomial wall(L1), a peritoneal diverticulum called the processus vaginalis is formed. The processus vaginalis passes through the layers of the lower part of the ant ab wall & as it does so, acquires a tubular covering from each layer. It transverses the transversalis fascia at the deep inguinal ring and acquires a tubular covering, the internal spermatic fascia. As it passes thru the lower part of the internal oblique muscles, it takes w/ it some of its lowest fibers, which form the cremaster muscle. The muscle fibers are embedded in fascia and thus the 2nd tubular sheath is known as the cremasteric fascia. The processus vaginalis passes under the archine fibers of the transversus abdominis muscle and does not acquire a covering from this abdominal layer. On reaching the aponeurosis of the external oblique, it evaginates this to form the superficial inguinal ring and acquires a 3rd tubular fascia coat, the external spermatic fascia. It is in this manner that the inguinal canal is formed in both sexes. (In the girl, the terms spermatic fascia should be replaced by the covering of the round ligament of the uterus) Meanwhile a band of mesenchyme extending from the lower pole of the developing gonad through the inguinal canal to the labioscrotal swelling, has condensed to form the gubernaculum. in the boy, the testes descend through the pelvis, in the inguinal canal during the 7th and 8th mo of fetal life. The normal stimulus for the descent of testes is testorone which is secreted by the fetal testes. The testes follows the gubernaculm and descends behind the peritoneum on the post ab wall. The testes passes behind the processus vaginalis and pulls down its ducts bv nerves and lymph vessels. The testes takes up its final position in the developing scrotum by the end of the 8th mo. Bvc the testes and its accompanying vessels, ducts , and so on follow the course prevly taken by the processus vaginalis. They acquire the same 3 coverings as they pass down the inguinal canal. Thus, the spermatic cord is covered by 3 concentric layers of the fascia, the external spermatic fascia, the cremasteric fascia, and the internal spermatic fascia. in the girls, the ovaries descends into the pelvis following the gubernaculm. The gubernaculm becomes attached to the side of the developing uterus and the gonad descends no farther. The part of the gubernaculm extending from the uterus into the developing labio majora persists as the round ligament of uterus. Thus in the girl, the only structures that pass through the inguinal canal from the abdominal cavity are the round ligament of the uterus and a few lymph vessels. The lymph vessels convey a small amount of lymph from the body of the uterus to the superficial inguinal nodes.

Question 19

Describe the layers of the walls of the scrotum

Answer 19

• Skin: Thin, wrinkled & pigmented & forms a single pouch. A slightly raised ridge in the middle indicates the line of fusion of the 2 lateral labioscrotal swellings (in the female, the swellings remain separate and form the labia majora)
• Superficial fascia: continuous w/ the fatty and membranous layers of the anterior ab wall. The fat is however replaced by smooth muscle called the dartos muscle. This is innervated by sympathetic nerve fibers and is responsible for the wrinkling of the overlying skin. The membranous layer of the superficial fascia (often referred to as Colle’s fascia) is continuous in front w/ the membranous layer of the anterior ab wall (Scarpa’s fascia) and behind it is attached to the perineal body and the post edge of the perineal mb at the sides, it is attached to the ischiopubic rami. Both layer of superficial fascia contribute to a median partition that crosses the scrotum and separates the testes from each other.
• Spermatic fasciae: these 3 layers lie beneath the superficial fascia and are derived from the 3 layers of the anterior abdominal wall on each side, as prevly explained. The external spermatic fascia is derived from the aponeurosis of the external oblique muscle, the cremasteric fascia is derived from the internal oblique muscle, and finally, the internal spermatic fascia is derived from the fascia transversalis. The cremasteric muscle is supplied by the genital branch of the genitofemoral nerve. The cremaster muscle can be made to contract by stroking the skin on the medial aspect of the thigh. This is called the cremasteric reflex. The afferent fibers of this reflex are travel in the femoral branch of the genitofemoral nerve (L1&L2), & the efferent motor nerve fibers travel in the genital branch of the genitofemoral nerve. The func.of the cremasteric muscle is to raise the testis and the scrotum upward for warmth and for protection against injury
• Tunica vaginalis: This lies within the spermatic fasciae and covers the ant, medial, and lateral surfaces of each testis. It is the lower expanded part of the processus vaginalis: normally just b4 birth, it becomes shut of from the upper part of the processus and the peritoneal cavity. The tunica vaginalis is thus a crossed sac, invaginated from behind by the testis.

Question 20

What are the clinical condition that involve the scrotum, testis, and describe each?

Answer 20

• Variocele: the veins of the pampiniform plexus are eloneated and dialated. It is a common disorder in adolescents and young adults w/ most occuring on the left side. This is thought to be b/c the right testicular vein joins the low-pressure IVC, whereas the left vein joins the left renal vein. In which the venous pressure is higher. Rarely, malignant dz. Of the left kidney extends along the renal vein and blocks the exit of the testicular vein. A rapidly developing left-sided variocele should always lead to examine the left kidney.
• Malignant tumor of the testis: spreads upwards via the lymph vessels to the lumbar (para-aortic) lymph nodes at the level of the 1st lumbar vertebra. It is only later, when the tumor spreads locally to invl the tissues and skin of the scrotum that the superficial inguinal lymph nodes are involved.
• Torsion of the testis: A rotation of the testis around the spermatic cord w/in the scrotum. It is often asso’d w/ an excessively tunica vaginalis. Torsion commonly occurs in active young men and children andis accompanied by severe pain. If not treated quickly the testicular artery may be occluded followed by necrosis of the testis.
• Processus vaginalis: the formation of the processus vaginalis and its passage thru the lower part of the ant ab wall w/ the formation of the inguinal canal in both sexes. Normally, the upper part becomes obliterated just b4 birth and the lower part remains as the tunica vaginalis. The processus is subject to the following common congenital anomalies:
  1. it may persist partially in its entirety as a preformed hernial sac for an indirect inguinal hernia
  2. it may become very much narrowed, but its lumen remains in communication w/ the abdominal cavity. Peritoneal fluid accumulates in it, forming a congenital hydrocele.
  3. The upper and lower ends of the processus may become obliterated, leaving small immediate cystic area referred to as an encysted hydrocele of the cord. The tunica vaginalis is closely related to the front and sides of the testis. It is not surprising to find that inflammation of the testis can cause an accumulation of fluid w/in the tunica vaginalis. This is referred to simply as a hydrocele. Most hydroceles are idiopathic. To remove excess fluid from the tunica vaginalis, a procedure termed tapping a hydrocele. A fine trocar and cannula are inserted through the scrotal skin. The following anatomic stuctures are traversed by the cannula, skin, dartos muscle and membranous layer of fascia (Colle’s fascia), external spermatic fascia, cremasteric fascia, internal spermatic fascia, and parietal layer of the tunica vaginalis

Question 21

• Psoas muscle abscess

- diaphragmatic hernias

Answer 21

• infection of intervertebral disc, spreads anterolaterally, passing into the psoas muscle sheath, spreads within, and may appear below the inguinal ligament.
• failure to fuse components of diaphragm:
  
  • (Morgagni’s hernia) bet xiphoid process and costal margins on right
  • (Bochdalek’s hernia) left post pleuroperitoneal canal.
• allows ab bowel to enter thoracic cavity and reduce respiratory function
  
  • central tendon