THE ABDOMEN 1371 



ite site of incisions in opening the abdominal cavity. Since the resulting scar is weak and 

 jdelding, however, it is now more customary to make vertical incisions through the rectus 

 sheath, to one side of the middle line, where the abdominal wall can be sutured in layers, and 

 an incisional hernia prevented. 



The umbilicus lies in the linea alba rather below its centre. It is somewhat 

 prone to hernia formation (p. 1402) and is occasionally the site of congenital 

 fistulae, which may originate in a Meckel's diverticulum (p. 1376) or a patent 

 urachus. 



When the recti are thrown into contraction the linea semilunaris on each side 

 is made evident as a groove, extending with a slight lateral convexity from 

 the tip of the ninth costal cartilage, where the lateral vertical line meets the thoracic 

 margin, to the pubic tubercle. 



The contraction of the recti muscles also shows up the three linese transversse, fibrous 

 intersections adherent to the anterior layer of the sheath of the rectus, which cross the substance 

 of the muscle (1) at the umbilicus, (2) at the tip of the xiphoid, and (3) midway between the 

 former two. A tonic contraction of one or both recti localised to one of these segments occa- 

 sionally gives rise to the "phantom" tumors which occur in some hysterical cases. 



The linea semilunaris shares the disadvantages of the linea alba as a site for incisions, and 

 there is the further danger of injury to the nerve supply of the rectus, which may involve a 

 diffuse bulge of the atrophied muscle. 



In tapping the bladder above the pubes, the trocar should be introduced immediately above 

 the pubes and driven backward and a little downward. In this operation, and in suprapubic 

 cystotomy, the retro-pubic space or cavum Retzii is opened. This is bounded in front by the 

 pubes and superior fascia of the urogenital diaphragm, behind by the anterior surface of the 

 bladder. Below are the true ligaments of this viscus. The space contains fatty tissue and veins, 

 increasing in size with the advance of life. If about ten ounces of fluid are injected into the 

 bladder, the peritoneum will be raised sufficiently to allow of a three-inch incision being made 

 between the recti and pyramidales immediately above the pubes. The transversalis fascia is 

 thicker below, and is often separated from the linea alba by fat, which must not be mistaken 

 for the extra-peritoneal layer. The peritoneal reflexion is loosely connected to the bladder 

 and can always be peeled upward. 



A transverse line drawn from one anterior superior iliac spine to the other crosses at about the 

 level of the top of the promontory of the sacrum. Such a line will always show whether the 

 pelvis is horizontal or not. (Holden.) 



The inguinal (Poupart's) ligament corresponds to a line drawn with a slight 

 curve downward between the anterior superior iliac spine and the pubic tubercle. 

 The first of these bonj^ prominences corresponds to the starting-point of the 

 above ligament, the attachment of the fascia lata to the ilium, the meeting of the 

 fleshy and aponeurotic parts of the external oblique (denoted by a line drawn 

 upward from this spine to the ninth costal cartilage, or often a little anteriorly 

 to these points), the point of emergence of the lateral cutaneous nerve of the 

 thigh, and part of the origins of the internal oblique, transversus, and tensor 

 fascise latse. 



The pubic tubercle marks the lateral pillar (inferior crus) of the subcutaneous 

 inguinal (external abdominal) ring, the mouth of which corresponds to the crest 

 of the pubes lying between the tubercle and the symphysis. The neck of an 

 inguinal hernia is above the tubercle and Poupart's ligament; that of a femoral 

 hernia below and lateral to the tubercle, and below the same ligament. The ring, 

 and especially its lateral pillar, can easily be felt by invaginating the scrotal skin 

 with a finger, and pushing upward and laterally. In a female patient, if the thigh 

 be abducted, the tense tendon of the adductor longus will lead up to the site of the 

 ring. The abdominal inguinal (internal abdominal) ring is situated about 1.2 cm. 

 (I in.) above the centre of Poupart's ligament; oval in shape, and nearly vertical 

 in direction, it has the arching fibres of the transversus above it, and to its 

 medial side the inferior epigastric artery, lying behind the spermatic cord. The 

 pulsations of this vessel here guide the finger in the insertion of the uppermost 

 deep sutures in radical cure of hernia. The canal runs obliquely downward and 

 forward between the two rings. In the adult it is about 3.7 cm. (1| in.) long, but 

 in early life, and in adults with a large hernia dragging upon the parts, the two 

 rings are much nearer, and may be one behind the other. For the anatomy of 

 inguinal hernia see p. 1304. 



Vessels in the abdominal wall. — The three superficial branches of the com- 

 mon femoral, the external pudic, epigastric, and circumflex iliac, supply the lowest 

 part of the abdominal wall and the adjacent groin and genitals. The others 

 that have to be remembered are the inferior epigastrics and the epigastric branch 



