Anatomy Atlas

Inguinal canal

Canalis inguinalis
Space / regionHigh-yielddraftGIGU

Oblique passage through the lower anterior abdominal wall carrying the spermatic cord or round ligament. It's the site of indirect and direct inguinal hernias, the most common hernias overall.

Core anatomy

Location

Above and parallel to the medial half of the inguinal ligament, about 4 cm long, running inferomedially from the deep ring to the superficial ring.

Boundaries
deep ring
Opening in the transversalis fascia, just above the midpoint of the inguinal ligament and lateral to the inferior epigastric vessels
superficial ring
Opening in the external oblique aponeurosis, just superolateral to the pubic tubercle
anterior wall
External oblique aponeurosis (reinforced laterally by internal oblique)
posterior wall
Transversalis fascia (reinforced medially by the conjoint tendon)
roof
Arching fibers of internal oblique and transversus abdominis
floor
Inguinal ligament (with the lacunar ligament medially)
Contents
  • Males: Spermatic cord
  • Females: round ligament of the uterus
  • Both: ilioinguinal nerve (enters the canal partway along, not through the deep ring, and exits the superficial ring); genital branch of the genitofemoral nerve (within the cord in males)
Communications

From the extraperitoneal space (deep ring) to the scrotum or labium majus (superficial ring).

Notes

Mnemonic for the walls, MALT from superior clockwise: roof Muscles (internal oblique, transversus), anterior Aponeurosis (external oblique), floor Ligament (inguinal), posterior Transversalis fascia. The canal's obliquity and the muscle "shutter" mechanism normally resist herniation.

Found in

Mentioned in

Generated automatically from links in other entries.

Inguinal region from inside (Hesselbach triangle)The right inguinal region viewed from inside the abdomen, with the midline on the left. The inguinal ligament runs from the anterior superior iliac spine down to the pubic tubercle. The inferior epigastric vessels arise from the external iliac artery just above the ligament and ascend medially to the lateral border of rectus abdominis. The inguinal (Hesselbach) triangle is bounded by the inferior epigastric vessels laterally, the rectus abdominis medially and the inguinal ligament inferiorly; direct hernias pass through it. The deep inguinal ring lies lateral to the inferior epigastric vessels, above the middle of the ligament, where the ductus deferens and testicular vessels enter; indirect hernias enter here. Below the ligament, the femoral ring lies medial to the femoral vein; femoral hernias pass through it.Testicular vesselsIndirect hernia: through thedeep ring, lateral to the IEVAnterior superior iliac spineDeep inguinal ringInguinal ligamentInferior epigastric vessels (IEV)External iliac → femoral arteryExternal iliac → femoral veinRectus abdominisDirect hernia: through thetriangle, medial to the IEVInguinal (Hesselbach) triangle"RIP": Rectus, Inferior epigastrics,Poupart (inguinal) ligamentDuctus deferens (to the pelvis)Superficial ring(in front of this plane)Pubic tubercleFemoral hernia: through the femoralring, medial to the femoral veinRight side, seen from inside theabdomen · midline ← · not to scalemidline

Swipe sideways to see the whole diagram →

Inguinal region from inside (Hesselbach triangle). Right side seen from inside the abdomen, as at laparoscopy. The inferior epigastric vessels separate indirect hernias (lateral, through the deep ring) from direct hernias (medial, through the inguinal triangle). Femoral hernias pass below the inguinal ligament, medial to the femoral vein. The inguinal canal and superficial ring lie in front of this plane (dashed).
Original schematic, created for this atlas.
Dissection of the right groin showing the spermatic cord leaving the superficial ring near the femoral vessels
The spermatic cord in the inguinal canal and at the superficial ring.
Henry Vandyke Carter, Gray's Anatomy of the Human Body, 20th ed. (1918), Fig. 1146. Source · Public domain (Public domain in the US: published before January 1, 1931 (per Wikimedia Commons))

Clinical correlations

Indirect inguinal hernia PANCE

Mechanism / lesion

Viscera enter the deep ring lateral to the inferior epigastric vessels and follow the canal, often through a patent processus vaginalis (congenital). The most common hernia in both sexes and in children. Can descend into the scrotum.

Classic presentation

A groin bulge that may extend into the scrotum, enlarging with coughing or straining. In infants, an intermittent groin or scrotal swelling while crying.

Direct inguinal hernia PANCE

Mechanism / lesion

Protrusion through a weak posterior wall (transversalis fascia) in the inguinal triangle, medial to the inferior epigastric vessels. Acquired, usually in older men.

Classic presentation

A bulge in the medial groin that rarely enters the scrotum. Lower strangulation risk than indirect or femoral hernias.

Femoral hernia (for contrast) PANCE

Mechanism / lesion

Passes below the inguinal ligament through the femoral ring into the femoral canal, medial to the femoral vein. More common in women.

Classic presentation

A small bulge below and lateral to the pubic tubercle. Highest risk of incarceration and strangulation of groin hernias, so repair is recommended.

High-yield PANCE pearls

  • Indirect = through the deep ring, lateral to the inferior epigastrics, patent processus vaginalis, most common (including in women and children).
  • Direct = Hesselbach triangle, medial to the inferior epigastrics, older men.
  • Femoral = below the inguinal ligament, women, highest strangulation risk.
  • Canal walls: MALT (Muscles, Aponeurosis, Ligament, Transversalis fascia).
  • Incarcerated/strangulated hernia (tender, irreducible, erythema, obstruction) → emergency surgery.

Imaging anatomy

CT

Shows hernia contents and complications (bowel obstruction, strangulation). Helpful in obese patients or equivocal exams.

MRI

Occult hernias and athletic groin pain ("sports hernia" or athletic pubalgia) when ultrasound is inconclusive.

Ultrasound

Dynamic ultrasound with Valsalva is first-line imaging for an equivocal groin bulge: it locates the sac relative to the inferior epigastric vessels (indirect vs direct) and distinguishes a femoral hernia (below the ligament, medial to the femoral vein).

Key views & landmarks
  • Dynamic groin ultrasound at rest and with Valsalva

Physical exam

Surface landmarks

ASIS and pubic tubercle mark the ends of the inguinal ligament. The deep ring lies about 1.5 cm above the midpoint of the inguinal ligament. The superficial ring lies above and lateral to the pubic tubercle.

Palpation

Examine standing. Inspect both groins while the patient coughs. In males, invaginate the loose scrotal skin with a finger up toward the superficial ring and ask the patient to cough or bear down; feel for an impulse. Examine for femoral hernias below the inguinal ligament.

Strength / function testing

Attempt gentle reduction if not tender. The traditional teaching that an impulse at the fingertip means indirect and at the finger pad means direct is unreliable on exam; the distinction is made surgically or on imaging. verify

Self-quiz

Q1.

A 6-month-old boy has an intermittent swelling in the right groin extending into the scrotum that appears when he cries. What is the underlying defect?

Show answer

B

An indirect inguinal hernia in infants results from a patent processus vaginalis, which lets bowel follow the path of testicular descent through the deep ring.

Q2.

Which structure forms the posterior wall of the inguinal canal?

Show answer

C

The transversalis fascia (reinforced medially by the conjoint tendon) forms the posterior wall. Weakness of it in the inguinal triangle produces direct hernias.

Q3.

A 70-year-old woman has a small, tender, irreducible bulge just below the inguinal ligament, lateral to the pubic tubercle, with vomiting. What is the most likely diagnosis?

Show answer

C

A bulge below the inguinal ligament in a woman is a femoral hernia, which has the highest risk of incarceration and strangulation. This one needs emergency repair.

Q4.

Which nerve travels through the inguinal canal but does NOT pass through the deep inguinal ring?

Show answer

B

The ilioinguinal nerve enters the canal from its lateral wall (not through the deep ring) and exits the superficial ring. It can be injured in open hernia repair, causing groin and scrotal/labial numbness or pain.

Q5.

The superficial inguinal ring is an opening in which layer?

Show answer

A

The superficial ring is an opening in the external oblique aponeurosis, just superolateral to the pubic tubercle. The deep ring is an opening in the transversalis fascia, lateral to the inferior epigastric vessels.

Flashcards

See also