Contents of the inguinal canal
The anatomical contents of the canal exhibit pronounced gender differences. Despite variations in the main passing structures, there is a common element: the ilioinguilogastric nerve (n. ilioinguinalis) always runs along the anterior surface of the contents in both men and women.
- In men, the spermatic cord (funiculus spermaticus) is located inside the canal.
- In women, the round ligament of the uterus (lig. teres uteri) passes through this space.
Structure of the spermatic cord
In men, the structures of the spermatic cord are tightly packed and surrounded by a common fascial sheath. This sheath is derived from the transversalis fascia of the abdomen. The cord contains a complex of elements vital to the reproductive system:
- Ductus deferens (ductus deferens).
- Blood vessels: artery and veins of the ductus deferens (a. et vv. deferentiales), testicular artery (a. testicularis), cremasteric artery (a. cremasterica), and the pampiniform venous plexus (plexus venosus pampiniformis).
- Lymphatic vessels, ensuring lymph drainage from the testis and its epididymis.
- Nerves: genital branch of the genitofemoral nerve (r. genitalis n. genitofemoralis), sympathetic plexus of the ductus deferens (plexus sympathicus deferentialis), and testicular sympathetic plexus (plexus sympathicus testicularis).
- Remnant of the processus vaginalis peritonei — a rudimentary structure persisting after the descent of the testis into the scrotum.
Walls of the inguinal canal
The space of the canal is bounded by four walls formed by the musculo-aponeurotic and fascial structures of the anterior abdominal wall:
- Anterior wall: represented by the aponeurosis of the external oblique abdominal muscle.
- Posterior wall: formed by the transversalis fascia (fascia transversalis). Anatomically, it is firmly attached to the superior ramus of the pubis. In about one-third of cases, this wall is additionally reinforced by tendinous fibers of the transverse abdominal muscle.
- Superior wall: formed by the lower free edges of the internal oblique and transverse abdominal muscles, which are fused together in this area.
- Inferior wall: represented by the inguinal ligament.
Inguinal rings
The canal has two openings serving as the entrance and exit points for anatomical structures:
Deep inguinal ring (annulus inguinalis profundus) Serves as the internal entrance to the canal. It is located on the peritoneal side and clearly corresponds to the lateral inguinal fossa. The edges of the deep ring are thickened and reinforced by fibers of the transversalis fascia.
Superficial inguinal ring (annulus inguinalis superficialis) Represents the external exit. It is formed by two diverging crura of the aponeurosis of the external oblique abdominal muscle. In its outer part, this ring is additionally reinforced by arcuate intercrural fibers (fibrae intercrurales). Topographically, it projects onto the medial inguinal fossa. The opening has an irregular oval shape with a longitudinal dimension of about 2–3 cm and a transverse dimension of 1–2 cm. Notably, in women, the dimensions of the superficial ring are approximately half those in men.
Briefly: answers to topical questions
What are the topographic and anatomical boundaries of the inguinal triangle?
The topographic and anatomical boundaries of the inguinal (Hesselbach's) triangle include three anatomical structures.
- Lateral boundary — inferior epigastric vessels (a. et v. epigastricae inferiores), which form the lateral umbilical fold (plica umbilicalis lateralis).
- Medial boundary — lateral edge of the rectus abdominis muscle.
- Inferior boundary — inguinal ligament.
The floor of this triangle is formed by the transversalis fascia (fascia transversalis), which is thinned in this area and unsupported by muscles.
How does a direct inguinal hernia differ from an indirect inguinal hernia?
Direct and indirect inguinal hernias differ in their site of emergence, relationship to the inguinal canal, and the spermatic cord.
| Sign | Indirect inguinal hernia | Direct inguinal hernia |
|---|---|---|
| Hernial orifice | Lateral inguinal fossa (fossa inguinalis lateralis) | Medial inguinal fossa (fossa inguinalis medialis) |
| Relationship to vessels | Lateral to the inferior epigastric vessels | Medial to the inferior epigastric vessels |
| Path | Passes through the entire inguinal canal | Emerges directly through the superficial ring |
| Relation to the cord | Located inside the spermatic cord | Located outside the spermatic cord |
| Descent into the scrotum | May descend into the scrotum | Does not descend into the scrotum |
What layers does the surgeon dissect during inguinal hernia repair?
During surgical access to the inguinal canal for a hernia, the surgeon sequentially dissects the superficial layers of the anterior abdominal wall.
- Skin — the first layer dissected.
- Subcutaneous tissue — the fatty layer beneath the skin.
- Superficial fascia — its deep layer is dissected, while the superficial epigastric vessels (a. et v. epigastricae superficiales) are transected and ligated.
- Aponeurosis of the external oblique abdominal muscle — dissected along the fibers after introducing a grooved probe through the superficial inguinal ring.
Rule of walls: Anterior — aponeurosis (external oblique), Posterior — fascia (transversalis), Superior — muscles (internal oblique and transverse), Inferior — ligament (inguinal).
Class and exam questions
What structures pass through the inguinal canal in males and females?
In men, the main content is the spermatic cord, while in women it is the round ligament of the uterus. In both sexes, the ilioinguinal nerve runs anterior to these structures.
What are the anterior and posterior walls of the canal formed by?
The anterior wall is formed by the aponeurosis of the external oblique abdominal muscle. The posterior wall consists of the transversalis fascia, which is occasionally reinforced by tendinous fibers of the transverse abdominal muscle.
Which fossae on the abdominal wall correspond to the inguinal rings?
The deep ring corresponds to the lateral inguinal fossa, whereas the superficial ring projects onto the medial inguinal fossa.
What are the dimensions of the superficial ring?
Normally, it has an irregular oval shape with a longitudinal dimension of 2–3 cm and a transverse dimension of 1–2 cm. In women, these dimensions are 2 times smaller.
What else to study on this topic
- Anatomy of the inguinal fossae (medial and lateral) and their role in hernia formation
- Syntopy of intercrural fibers and crura of the external oblique aponeurosis
- Space between the inguinal ligament and the lower edges of the internal oblique muscle
- Topography of the muscular and vascular lacunae in relation to the canal
- Mechanism of formation of the vaginal process of the peritoneum and its anomalies
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