This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
Hydrocele is an accumulation of fluid in the tunica vaginalis testis. It is usually an acquired affection of adult life, and then does not appear to be dependent on congenital anomalies.
This consists of a cystic collection in the course of the spermatic cord. It makes its appearance in infancy and childhood, and is due to some portion of the funicular or vaginal process failing to become obliterated. Serum accumulates in this unoccluded portion, forming a small serous cyst. Sometimes a small opening furnishes a communication with the abdominal cavity, forming a congenital hydrocele. In this case the contents of the cyst can be pressed back into the abdominal cavity only to reappear. Should the communicating opening become dilated by a descending coil of intestine, a hernia into the funicular process would be the result.
The inguinal canal in the female transmits the round ligament, and sometimes a finger-like extension of the peritoneum resembling the vaginal process in the male. Accumulation of fluid may occur in this in the same manner as hydrocele of the cord is formed in the male. It is then called hydrocele of the canal of Nuck.
Acquired inguinal herniae may be either of the indirect or direct kind. To understand them one must know the construction of the inguinal canal and spermatic cord.
As the testicle descends it leaves in its wake the vas deferens, the essential part of the spermatic cord. It carries with it the spermatic artery, from the aorta, the pampiniform plexus of veins, and the. artery of the vas from the superior vesical. The vas deferens with its artery lies posteriorly and the spermatic artery and pampiniform plexus are anterior. The cremasteric branch of the deep epigastric supplies the cremaster muscle. The cord also contains sympathetic nerves, lymphatics, some fibrous remains of the vaginal process, and a few muscular fibres. These structures are imbedded in fatty tissue continuous with the subperitoneal fat and are covered by a fibrous sheath formed by a continuation of the structures of the abdominal walls, viz., the intercolumnar fascia from the external oblique, the cremasteric fascia from the internal oblique, and the transversalis fascia. Inguinal Canal (Canalis Inguinalis). - This runs from the external to the internal abdominal ring and is about 4 cm. (1 3/4 in.) in length. The external ring inguinalis subcutaneus) (Fig. 395) barely admits the tip of the finger; it lies immediately to the outside and above the spine of the pubis. It is formed by a splitting of the fibres of the external oblique aponeurosis into two columns or pillars. The external column (crus inferius) blends with Poupart's ligament, passes beneath the cord, and inserts into the spine of the pubis. The internal column (crus superius) inserts into the crest and anterior surface of the body of the pubis. The fibres running across from one column to the other are the intercolumnar fibres (fibrae inter-cruralis) and are prolonged over the cord as the intercolumnar fascia (Fig. 395).
Fig. 396. - Parts concerned in inguinal hernia; the inguinal canal exposed.
The internal ring (annulus inguinalis abdominalis) is the opening in the transversalis fascia where the cord enters the canal. It is 1.25 to 2 cm. (1/2 to 3/4 in.) above the middle of Poupart's ligament. This brings it to the outer side of the external iliac artery.
The body being upright, the inguinal canal has an anterior and a posterior wall and a roof and floor. The anterior wall (nearest to the skin) is formed by the aponeurosis of the external oblique, and by the internal oblique muscle for its outer third and sometimes even its outer half. The posterior wall is nearest to the vertebral column. It is formed by the transversalis fascia and at its inner third the conjoined tendon. The roof, nearest to the head, is formed by the arching fibres of the internal oblique muscle and - still farther above - the transversalis. The floor is nearest to the feet. The cord rests on Poupart's ligament with some of the fibres of the cremaster muscle.
Fig. 397. - The coverings of an acquired oblique inguinal hernia; from an actual dissection. The external and internal oblique have been divided along Poupart's ligament and turned inward exposing the transversalis.
To the inner side of the internal ring and almost midway between it and the external ring runs the deep epigastric artery, it is between the transversalis fascia and peritoneum, in the subperitoneal fat.