Anterior Abdominal Wall, Inguinal Region, & Peritoneum

Question 1

4 Regions

Answer 1

line drawn through midsternal plane and transumbilical plane at L4; varied location in obese people

Question 2

9 Regions

Answer 2

– 2 lines drawn at right/left mid-clavicular; horizontal lines drawn inferior to costal margin (subcostal) and at transtubercle points of the iliac crest (belly button is in middle of middle square)
 Right hypochondrium, epigastric, left hypochondrium
 Right flank, umbilical, left flank
 Right groin, pubic, left groin

Question 3

Superficial Fascias

Answer 3

 Camper’s fascia – outer layer composed predominantly of fat
• Thin in athletes or emaciated/skinny people; thick in obese patients
• Superficial veins, arteries, nerves reside in it
 Scarpa’s fascia – deep to Camper’s fascia
• Continues inferiorly into perineal region as superficial perineal (Colle’s) fascia
• Attaches to the fascia lata of the thigh and prevents fluid deep to Scarpa’s fascia from entering into thigh
• May be robust in individuals and keeps extravesated urine between it and the deeper external oblique aponeurosis

Question 4

CC: Urethra Rupture Outcome

Answer 4

if the urethra ruptures in the male, urine can accumulate between Scarpa’s fascia and the muscles posterior to it; this urine can then leak into the scrotum causing the scrotum to swell

Question 5

Nerves of Anterior Abdominal Wall

Answer 5

 Provide motor & sensory innervations to skin, parietal paeritoneum, and muscles of anterior abdominal wall
 T7, T8, T9 serve region from xiphoid to umbilicus
 T10 - region of umbilicus
 T11, T12, L1 serve region from umbilicus to pubic symphysis

Question 6

Blood Supply of Anterior Abdominal Wall (superior, lateral, inferior)

Answer 6

 Superiorly – musculophrenic and superior epigastric arteries (terminal branches of internal thoracic artery)
 Laterally – 10th through 12th intercostals arteries
 Inferiorly – inferior epigastric and deep circumflex iliac arteries (branches of external iliac arteries
• Inferior epigastric is important landmark in helping to define inguinal hernias
• Enters the posterior rectus sheath at the arcuate line
 Inferior and superior epigastric anastomose with each other providing alternate pathways

Question 7

Lymphatics of Anterior Abdominal Wall

Answer 7

 Superior to umbilicus – drain into axillary lymph nodes
 Inferior to umbilicus – drain to superficial inguinal lymph nodes
 Superficial nodes enter the external iliac nodes and proceed to the lumbar (aortic) nodes
EXCEPTION: testes drain directly into abdoment to para-aortic lymph nodes

Question 8

Muscles

Answer 8

 Covered with superficial fascia ; NO deep fascia below the muscles; transversalis fascia is deep to muscles
 Anterior group of muscles (2 rectus abdominis) •Innervation - intercostal nerves T7-T11; subcostal nerve T12; Segmented by tendinous intersections
 Lateral group of muscles (external oblique, internal oblique, transversus abdominis)
• Innervations – intercostal nerves T7-T11; subcostal nerve T12; (internal oblique and transverses abdominis also iliohypogastric and ilioinguinal nerves L1)
 Arrangement of muscles similar to arrangement of intercostals muscles
 Nerves and blood vessels run in between the internal oblique and transverses abdominis

Question 9

Aponeurosis of Anterior Abdominal Wall

Answer 9

Attach to corresponding muscle group on opposite side via broad aponeurosis which encases the 2 rectus abdominis muscles in a rectus sheath
o Anterior rectus sheath made up of external and internal obliques
o Posterior rectus sheath made up of internal obliques and transverses abdominis; ends at the arcuate line midway between umbilicus and pubic crest; inferior epigastric artery enters the posterior rectus sheath here
 Linea alba – where the aponeuroses interlace in the midline; 2 rectus abdominis muscles lie on either side of the linea alba; extends from xiphoid process to pubic symphysis
-BELOW THE ARCUATE LINE - the posterior sheath ends and only the anterior rectus sheath exists

Question 10

Layers needed to be crossed to enter peritoneal cavity

Answer 10

Skin  superficial fascia of Camper’s and Scarpa’s  external oblique, internal oblique, transverses abdominis anterior rectus sheath  rectus abdominis muscles  posterior rectus sheath  fascia transversalis  extraperitoneal fat  peritoneum

Question 11

CC: Transverse Rectus Abdominis Myocutaneous (TRAM) Flap

Answer 11

o Replace a boob after a mastectomy with rectus abdominis muscle; bring vessels along with it

Question 12

Inguinal Canal

Answer 12

o Superior to medial portion of inguinal ligament
o Two openings (external oblique aponeurosis forms superficial ring and deep ring formed by transversalis fascia that is more lateral)
o genitofemoral nerve, Spermatic cord (males) and round ligament (females) run through inguinal canal; ilioinguinal nerve exits the superficial ring
o Boundaries: anterior – external oblique aponeurosis; lateral – internal oblique muscle; posterior – transversalis fascia and conjoint tendon
 Conjoint tendon – tendinous insertions of the medial most portions of the internal oblique and transversus abdominis
o Inguinal canal represents a weakness in the anterior abdominal wall that may lead to hernias
 Where the deep ring is week, the superficial wall is strong and where the superficial ring is weak the deep wall is strong

Question 13

Descend of Testis & Cremastic Reflex

Answer 13

o Testicular descent – process of testes developing within the main body cavity of the fetus and then exiting the body cavity; takes ~6 months; exits via iguinal canal
o Testes are attached to external oblique aponeurosis by connective tissue (gubernaculum)
o Anterior to gubernaculums is the processus vaginalis (part of peritoneum); process grows and the testes are able to slide down behind the processus vaginalis of the peritoneal cavity
o Once testes reach the scrotum, the process pinches off from the peritoneal cavity
o Carries a layer of tissue from each muscle layer that forms the anterior abdominal wall, from peritoneum to external oblique aponeurosis (except transversus abdominis muscle)
 Layer of internal oblique muscle gives rise to cremasteric muscle and fascia of spermatic cord
 Cremasteric reflex - Stimulation of inner thigh results in elevation of the corresponding testis into the inguinal canal brought about by contraction of the cremastic muscle

Question 14

Scrotum

Answer 14

sac outside the body cavity that contains both testes and helps to maintain the appropriate permissive temperature of 35o C that allows sperm maturation

Question 15

CC: Cryptochidism

Answer 15

undescended testis; infertile and most likely will become cancerous later in life; treatment – orchidopexy to surgically make the testis descend

Question 16

CC: Hydrocele vs hematocele

Answer 16

 Hydrocele – presence of fluid in the processus vaginalis; fluid originates from peritoneal fluid and is an indication that the processus vaginalis remains patent
 Hematocele – presence of blood in the tunica vaginalis

Question 17

CC: Varicocele

Answer 17

enlargement of the testicular veins

Question 18

Inguinal Hernias

Answer 18

– 30 times more often in males because the spermatic cord weakened this area
 Indirect inguinal hernias – neck of hernia lies lateral to the inferior epigastric vessels and passes through the deep inguinal ring; head of hernia often found in the scrotum or labia majora; common in infants and tend to be congenital
 Direct inguinal hernias – neck lies medial to inferior epigastric vessels; head of hernia moves into hesselbach’s triangle (between rectus abdominus, inguinal ligament, and inferior epigastric vessels); common in older men

Question 19

Femoral hernias

Answer 19

– occur when abdominal viscera protrude through femoral ring
 Femoral ring is weak area in lower anterior abdominal wall BELOW the inguinal ligament
 Often it is loop of small intestine
 More common in females
 Initially it is only a small protrusion but over time tend to enlarge and can cause interference with the blood to the viscera making it a medical emergency

Question 20

Other hernias

Answer 20

(less common) – result of weaknesses in anterior wall muscles or aponeurosis and an increase in abdominal pressure (pregnancy, constipation, etc)

Question 21

Peritoneum/Retroperitoneum/intraperitoneal

Answer 21

o Visceral peritoneum lines the organs of the GI tract
o Parietal peritoneum lines the body wall
o Alimentary tract – develops as a tube attached via a dorsal and ventral mesentery within a tube; tube undergoes various twists and some of ventral mesentery is resorbed into the posterior wall making some organs fixed to posterior abdominal wall (considered retroperitoneal)
o Intraperitoneal organs are mobile and within peritoneal cavity with mesentery that attaches them to the posterior wall but still allows for motion

Question 22

Peritoneal Reflections

Answer 22

 Lesser omentum – double layer of peritoneum extending from porta hepatis of liver to lesser curvature of stomach and beginning of duodenum
• Consists of hepatogastric and hepatoduodenal ligaments
• Contains the right and left gastric vessels
• Right free margin contains the proper hepatic artery, bile duct, and portal vein
 Greater omentum – hangs from greater curvature of stomach
• Covers transverse colon
• Right and left gastroepiploic (omental) vessels contained within
• Adheres to areas of inflammation
 Air will float to superior abdominal cavity; fluid will flow inferiorly

Question 23

falciform ligament

Answer 23

– connect liver to anterior abdominal wall; free lower border contains the ligamentum teres hepatic

Question 24

ligamentum venosum

Answer 24

– remnant of ductus venosus; lies in fissure of liver forming left boundary of caudate lobe of liver

Question 25

CC: peritoneal dialysis

Answer 25

– injection of fluid into peritoneal cavity that will be absorbed into the blood stream and dilute toxic material in the blood

Question 26

CC: blood transfusion in infants

Answer 26

– performed through peritoneal cavity because they are capable of absorbing whole RBC’s through their peritoneum

Question 27

CC: Peritonitis

Answer 27

– infection in peritoneal cavity; keep patient sitting up (Fowler’s position) so that diaphragm absorbs less of the infected fluid
 If lying down; fluid will collect in subphrenic recess and hepatorenal recess (Morrison’s pouch)

Question 28

CC: Peritoneal Cavity

Answer 28

closed in males but open in females because the tip of fallopian tube opens directly into peritoneal cavity and transmitted infections (gonorrhea) can progress through reproductive tract and cause peritonitis

Question 29

Inguinal Ligament and Associated Ligaments

Answer 29

– connects anterior superior iliac spine to pubic tubercle; lower portion of external oblique aponeurosis
 Lacunar ligament (Gibernat’s ligament) – medial triangular expansion of inguinal ligament; forms medial border of femoral ring and the floor of the inguinal canal
 Pectineal (cooper’s) ligament – strong fibrous band that extends from lacunar ligament along pectineal line of pubis (inner circle)

Question 30

transpyloric plane

Answer 30

level of L1 where spinal cord ends; celiac trunk and superior mesenteric arteries originate above and below this point

Question 31

subcostal plane

Answer 31

approximate location of inferior mesenteric plane; just above belly button

Question 32

supracristal plane

Answer 32

approximate location where abdominal aorta bifurcates; just below belly button

Question 33

intertubercular plane

Answer 33

approximate location where right and left common iliac veins join to form inferior vena cava; L5

Question 34

arcuate line

Answer 34

• approximately midway between umbilicus and pubic crest
• where the posterior rectus sheath ends
• where inferior epigastric artery enters the posterior rectus sheath

Question 35

conjoint tendon

Answer 35

tendinous insertions of medial most portion of internal oblique and transversus abdominis
-near midine of body

Question 36

Abdominal Muscle Layers and Corresponding Scrotum Layers

Answer 36

external oblique muscle = external spermatic fascia
internal oblique muscle = cremaster muscle/fascia
transversalis fascia = internal spermatic fascia

Question 37

ligamentum teres hepatic (round ligament of liver)

Answer 37

remnant of left umbilical vein