UMBILICAL HERNIA 1141 



Some of these may be deficient by the hernia bursting through them, or they 

 may be matted together. Sir A. Cooper thought this especially likely to occur 

 with the layer of femoral sheath and septum crurale to which he gave the name 

 of fascia lyropria. 



PARTS CONCERNED IN UMBILICAL HERNIA 



A hernial protrusion at the umbilicus, or exomphalos, may occur at three dis- 

 tinct periods of life, according to the anatomy of the part. Any account of umbil- 

 ical hernia would be incomplete without an attempt to explain how this region, 

 originally a most distinct opening, is gradually closed and changed into a knotty 

 mass of scar, the strongest point in the abdominal wall. 



During the first weeks of foetal life, in addition to the uraclius, uml)ilical 

 arteries, and vein, some of the membranes and a portion of tlie intestine ])ass 

 through the opening to join that part of the digestive tract which is developed out- 

 side the abdomen up to a certain time, and then re-enters that cavity. Occasionally 

 this condition persists, owing to failure of development, and the child is born with 

 a large hernial swelling outside the abdomen, imperfectly covered with skin and 

 peritoneum. To this condition the term congenital umbilical hernia should be 

 applied. 



Later on in fcetal life it is the umbilical vessels alone which pass through this 

 opening. At l>irth there is a distinct ring, Avhich can be felt for some time after in 

 the flaccid Avails of an infant's belly. If this condition persist, a piece of intestine 

 may find its way through, forming the condition which should be known as 

 infantile umbilical hernia. 



This condition is not uncommon, ^^'hy it is not more fre(|uently met with is 

 explained by the way in which this ring of infancy is closed and gradually con- 

 verted into the dense mass of scar tissue so familiar in adult life. This is l)rought 

 about (1) by changes in the ring itself; (2) by changes in the vessels which pass 

 through it. 



(1) Changes in the ring itself. — The umbilical ring is surrounded by a 

 sphincter-like arrangement of elastic filn-es, best seen during the first few days of 

 fcetal life, on the posterior wall of the l)elly. In older infants these fibres lose their 

 elasticity, become more tendinous, and then shrink more and more. As they con- 

 tract they divide, as by a ligature, the vessels passing through the ring, thus account- 

 ing for the fact that the cord, wherever divided, drops off at the same spot and 

 without bleeding. 



(2) Changes in the vessels themselves. — When blood c<^ses to traverse 

 these, their lumen contains clots, their muscular tissue wastes, while the connective 

 tissue of their outer coat hypertrophies and thickens. Thus, the umbilical vessels 

 and the umbilical ring are, alike, converted into scar-tissue, which blends 

 together. This remains weak for some time, and may be distended by a hernia 

 (infantile). 



Finally, we have to consider the state of the umltilicus in adult life. The very 

 dense, unyielding, fibrous knot shows two sets of fibres: — (1) Those decussating 

 in the middle line; and (2) two sets of circular fibrous bundles Avhich interlace at 

 the lateral boundaries of the ring. The lower part of the ring is stronger than the 

 upper. In other words, umbilical hernia of adult life, when it comes through 

 the ring itself and not at the side, always conies tlirough the upper ])art. In the 

 lower three-fourths of the umbilicus the umbilical arteries and urachus are fimdy 

 closed by matting in a firm knot of scar-tissue; in the upper tliere is only the 

 uml)ilical vein and weaker scar. To the lower part run up the umbilical arteries 

 and the urachus. Owing to the rapid growth of the alKloniinal wall and pelvis 

 before puberty, and the fact that the urachus and the umbilical arteries, being of 

 scar-tissue, elongate with difficulty, the latter parts depress the umlnlicus l>y reason 

 of their intimate connection witii its lower half. 



Coverings of an umbilical hernia. — These, more or less matted together, are: 

 — (1) Skin; (2) superficial fascia, which loses its fat over the hernia; (3) prolonga- 

 tion of scar-tissue of the umbilicus gradually stretched out; (4) transversalis fascia; 



