Anterior abdominal wall & Inguinal Region Flashcards
How is the abdomen anatomically divided for clinical assessment?
Divided into 9 regions using horizontal (subcostal/transpyloric, transumbilical, intertubercular) and vertical (midclavicular lines) planes.
Alternatively, divided into 4 quadrants: RUQ, LUQ, RLQ, LLQ.
What are the layers of the superficial fascia below the umbilicus?
Camper’s fascia (fatty layer, specialized for fat storage).
Scarpa’s fascia (membranous layer, prevents fluid spread, continues as Colles’ fascia in perineum).
What are the key landmarks of the anterior abdominal wall?
Xiphoid process
Costal margin
Umbilicus (L3-L4 disc level, T10 dermatome)
Iliac crest
Anterior superior iliac spine (ASIS)
Pubic tubercle
Inguinal ligament
Name the 5 muscles of the anterolateral abdominal wall.
External oblique (largest, superficial).
Internal oblique (fibers perpendicular to external oblique).
Transversus abdominis (deepest flat muscle).
Rectus abdominis (vertical, enclosed in rectus sheath).
Pyramidalis (absent in 20%, tenses linea alba)
What is the rectus sheath, and how is it formed?
A fibrous sheath enclosing the rectus abdominis, formed by aponeuroses of external oblique, internal oblique, and transversus abdominis.
Above arcuate line: Anterior (EO + IO aponeuroses), posterior (IO + TA aponeuroses).
Below arcuate line: All aponeuroses pass anteriorly; posteriorly only transversalis fascia remains.
Differentiate between direct and indirect inguinal hernias.
Indirect:
More common in males/children.
Hernia sac enters via deep inguinal ring (lateral to inferior epigastric vessels).
Associated with processus vaginalis.
Direct:
More common in elderly men.
Hernia bulges through Hesselbach’s triangle (medial to inferior epigastric vessels).
What is processus vaginalis
A funnel-shaped peritoneal outpouching that forms during embryonic development.
Function: Guides the descent of the testes (in males) or round ligament (in females) through the inguinal canal into the scrotum/labia majora.
Fate: Normally obliterates after descent, leaving a small remnant (tunica vaginalis around the testes).
What are the boundaries of Hesselbachs triangle
Lateral (Superior): Inferior epigastric vessels
Medial (Inferomedial): Lateral border of the rectus abdominis muscle
Inferior (Base): Inguinal ligament
Floor: Formed by transversalis fascia.
Mnemonic: “RIE” (Rectus, Inguinal ligament, Epigastric vessels).
What structures form the boundaries of the inguinal canal?
Anterior wall: External oblique aponeurosis + internal oblique (lateral).
Posterior wall: Transversalis fascia + conjoint tendon (medial).
Roof: Arching fibers of internal oblique/transversus abdominis.
Floor: Inguinal ligament + lacunar ligament.
What is the conjoint tendon?
The conjoint tendon (or inguinal falx) is a fibrous band formed by the fusion of the aponeuroses of two muscles:
Internal oblique (lower fibers)
Transversus abdominis (lower fibers)
Mnemonic:
“CIT” = Conjoint = Internal oblique + Transversus abdominis.
What nerves are at risk during abdominal incisions?
Thoracoabdominal nerves (T7-T12): Run between transversus abdominis and internal oblique.
Iliohypogastric/ilioinguinal (L1): Sensory to hypogastric/inguinal regions.
Damage can cause weakness, hernia, or sensory loss.
What is the clinical significance of the umbilicus?
Level of L3-L4 IV disc (T10 dermatome).
Marks aortic bifurcation (~2 cm below).
Caput medusae: Engorged veins due to IVC/portal obstruction.
Position varies (low in children/obese individuals).
What are the actions of the abdominal muscles?
Compress abdominal contents (increase intra-abdominal pressure).
Flex/rotate trunk (rectus abdominis/external oblique).
Assist in forced expiration, micturition, defecation, parturition.
What is the arcuate line, and why is it important?
A horizontal line midway between umbilicus and pubis.
Marks the inferior limit of the posterior rectus sheath.
Below this line, the rectus abdominis contacts transversalis fascia only (no aponeurotic coverage).(Posterior)
What is the significance of the transpyloric plane?
Lies at L1 vertebral level.
Passes through:
Pylorus of the stomach.
Duodenal-jejunal junction.
Pancreas (neck).
Hilum of kidneys.
Origin of superior mesenteric artery.
Describe the nerve supply to the abdominal muscles.
External oblique: T7-T11 + subcostal nerve (T12).
Internal oblique/Transversus abdominis: T7-T12 + iliohypogastric/ilioinguinal nerves (L1).
Rectus abdominis: T7-T12 (segmental supply).
What is the linea alba?
A midline fibrous raphe formed by the fusion of aponeuroses of all flat abdominal muscles.
Extends from xiphoid process to pubic symphysis.
Clinical note: Site for midline surgical incisions (e.g., laparotomy).
What is a hydrocele?
Hydrocele: Fluid accumulation in the tunica vaginalis (persistent processus vaginalis).
What are the contents of the inguinal canal in males vs. females?
Males: Spermatic cord (vas deferens, testicular vessels, ilioinguinal nerve).
Females: Round ligament of the uterus + ilioinguinal nerve.
Both genders: Genital branch of genitofemoral nerve.
What is a cryptorchidism?
Cryptorchidism: Undescended testis (failure to migrate through inguinal canal).
Why is the femoral hernia more common in females?
Females have a wider femoral ring (due to broader pelvis).
Hernia protrudes through the femoral canal below the inguinal ligament.
Coverings: Peritoneum → femoral septum → femoral sheath → cribriform fascia.
What are the posterior abdominal wall muscles?
Psoas major: Flexes thigh/vertebral column (L2-L3).
Quadratus lumborum: Stabilizes 12th rib, lateral flexion (T12-L1).
What are the principles of abdominal incisions?
Follow Langer’s lines (for minimal scarring).
Avoid cutting nerves (e.g., ilioinguinal).
Split muscles rather than cut (e.g., gridiron incision for appendix).
Examples: Midline, paramedian, subcostal, McBurney’s.
What is caput medusae?
Dilated periumbilical veins due to portal hypertension or IVC obstruction.
Caused by porto-systemic anastomosis (superficial veins connect femoral → axillary veins).
