Anatomy and Structure
The superficial inguinal ring is an oval-shaped opening located superior to the medial part of the inguinal ligament and just above the pubic tubercle (tuberculum pubicum).
It is formed by the divergence of the fibers of the broad flat tendon (aponeurosis) of the external oblique abdominis muscle into two crura:
- Lateral crus (crus laterale) — attaches to the pubic tubercle.
- Medial crus (crus mediale) — attaches to the pubic symphysis.
- Intercrural fibers (fibrae intercrurales) — arcuate fibers that bridge across the upper part of the ring to prevent lateral expansion.
In males, the longitudinal dimension of the opening is 2–3 cm and the transverse dimension is 1–2 cm. In females, these dimensions are about half as large.
Contents of the Superficial Inguinal Ring
The ring serves as the terminal opening of the slit-like inguinal canal (canalis inguinalis). Its contents vary by sex:
- In males — the spermatic cord (funiculus spermaticus). This contains: the ductus deferens (ductus deferens), testicular artery (a. testicularis), pampiniform venous plexus (pampiniformis plexus vv.), cremasteric artery and vein (a./v. cremasterica), artery of the ductus deferens (a. ductus deferentis), lymphatic vessels, genital branch of the genitofemoral nerve (ramus genitalis n. genitofemoralis), sympathetic and parasympathetic fibers, and the cremaster muscle (m. cremaster).
- In females — the round ligament of the uterus (lig. teres uteri) along with its neurovascular bundle; the artery of the round ligament of the uterus (a. lig. teretis uteri) passes through the superficial inguinal ring to supply adjacent structures.
Note: The aponeurosis of the external oblique muscle gives rise to the external spermatic fascia around these structures.
Topography and Internal Projection
On the internal surface of the anterior abdominal wall, the superficial inguinal ring corresponds topographically to the medial inguinal fossa (fossa inguinalis medialis).
This paired peritoneal depression lies between the medial umbilical fold (plica umbilicalis medialis) and the lateral umbilical fold (plica umbilicalis lateralis). This fossa represents a potential weak spot in the abdominal wall where direct inguinal hernias may occur.
Clinical Significance
- Palpation: Clinicians evaluate the patency and integrity of the superficial inguinal ring during physical examination.
- Herniorrhaphy: In traditional hernia repair techniques (such as Postempski repair), the posterior wall of the inguinal canal is reinforced, the canal is obliterated, and the spermatic cord is relocated into the subcutaneous tissue. The aponeurosis is overlapped to create a double layer. Care must be taken during surgical closure not to excessively narrow the superficial inguinal ring.
- Cryptorchidism: When testicular descent is arrested, an undescended testis may become lodged near the superficial inguinal ring. This condition occurs in about 4% of newborn boys and 0.4–0.8% of adult males.