Anterior Abdominal Wall, Inguinal Region, & Peritoneum Flashcards
4 Regions
line drawn through midsternal plane and transumbilical plane at L4; varied location in obese people
9 Regions
– 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
Superficial Fascias
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
CC: Urethra Rupture Outcome
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
Nerves of Anterior Abdominal Wall
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
Blood Supply of Anterior Abdominal Wall (superior, lateral, inferior)
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
Lymphatics of Anterior Abdominal Wall
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
Muscles
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
Aponeurosis of Anterior Abdominal Wall
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
Layers needed to be crossed to enter peritoneal cavity
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
CC: Transverse Rectus Abdominis Myocutaneous (TRAM) Flap
o Replace a boob after a mastectomy with rectus abdominis muscle; bring vessels along with it
Inguinal Canal
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
Descend of Testis & Cremastic Reflex
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
Scrotum
sac outside the body cavity that contains both testes and helps to maintain the appropriate permissive temperature of 35o C that allows sperm maturation
CC: Cryptochidism
undescended testis; infertile and most likely will become cancerous later in life; treatment – orchidopexy to surgically make the testis descend
CC: Hydrocele vs hematocele
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
CC: Varicocele
enlargement of the testicular veins
Inguinal Hernias
– 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
Femoral hernias
– 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
Other hernias
(less common) – result of weaknesses in anterior wall muscles or aponeurosis and an increase in abdominal pressure (pregnancy, constipation, etc)
Peritoneum/Retroperitoneum/intraperitoneal
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
Peritoneal Reflections
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
falciform ligament
– connect liver to anterior abdominal wall; free lower border contains the ligamentum teres hepatic
ligamentum venosum
– remnant of ductus venosus; lies in fissure of liver forming left boundary of caudate lobe of liver
