1300 HERNIA (1300 437 642)
Anatomy of the Inguinal Hernia
SURFACE MARKINGS IN THE GROIN:
The bony structures, which are readily palpable, are - laterally the anterior superior iliac spine and medially the pubic tubercle, pubic crest and the midline pubic symphysis.
The deep inguinal ring is at the mid-inguinal point - midway between the anterior superior iliac spine and the pubic symphysis.
The superficial inguinal ring through which inguinal hernias emerge is above and medial to the pubic tubercle.
Directly below the mid-inguinal point, as they emerge from the pelvis to the groin, are from lateral to medial, the femoral nerve, artery, vein and femoral canal. Femoral hernias descend through the femoral canal.
The femoral canal is below and lateral to the pubic tubercle.
Thus, inguinal hernias emerge above and medial to the pubic tubercle and femoral hernias, below and lateral to the pubic tubercle, allowing usually clinical differentiation.
Fascia lata or deep fascia of the thigh may direct a femoral hernia upwards to make the distinction between the two hernias more difficult particularly if the hernia is irreducible or very large.
Differentiation is important because femoral hernias have a greater tendency to strangulate and require emergency surgery.
The spermatic cord is formed at the deep inguinal ring by the emergence of the vas deferens, the testicular artery and pampiniform plexus. The coverings of the cord are added from the abdominal wall muscles and fascia as the cord passes obliquely downwards and forwards. The muscles and fascia form a canal, which transmits the cord. To better understand the anatomy it is worth considering the inguinal canal as a tunnel because it has one of the muscles covering it like a bridge - the external oblique anteriorly.
The lower abdominal wall is composed of three muscles - the most superficial - the external oblique abdominis, which is anterior to the cord and forms the anterior wall of the canal or tunnel. The other two deeper muscles start off superficial lateral to the cord, but arch obliquely over the cord like a roof and finish up medially behind the
cord as the cord passes forward. Thus, the inguinal canal is composed anteriorly of the external oblique muscle and posteriorly of the internal oblique and transverses
abdominis, which fuse medially to form the conjoined tendon. The thin
layer of fascia transversalis and peritoneum are deeper to the muscles.