ABDOMEN. 



11 



joint (from which as well as from the ramus 

 of the pubis it is separated by a bursa) over 

 the head and along the inner side of the neck 

 of the femur, and is inserted into the posterior 

 part of the trochanter minor at its base, being 

 separated by a small bursa from the surface of 

 that process. As the tendon is passing over 

 the ramus of the pubis, it receives by its outer 

 margin a series of fibres from the iliacus in- 

 ternus muscle. At its superior portion the 

 psoas muscle is covered by a thin fibrous ex- 

 pansion, which is attached on the one hand to 

 the apices of the transverse processes, and on 

 the other to the bodies of the upper lumbar 

 vertebrae ; this expansion, the arcus interior of 

 Senac and Haller,* also called ligamentum 

 arcuatum, separates the psoas from the dia- 

 phragm. Below this the psoas muscle is 

 covered with a lax, and in some degree fatty 

 cellular tissue, which separates the muscle from 

 the kidney externally, and from the peritoneum 

 and ureter within, excepting where the psoas 

 parvus covers it, and on the right side where the 

 vena cava lies upon it. Along its internal margin 

 are the lumbar portion of the sympathetic, the 

 crura of the diaphragm, more especially on the 

 left side, and on this side too the aorta ap- 

 proaches a little its internal margin. The 

 common and external iliac arteries and veins 

 lie along the internal margin of the pelvic 

 portion of the muscle, which is covered by the 

 fascia iliaca. The several branches of the 

 lumbar plexus issue from this muscle at its 

 external margin, and the genito-crural nerve 

 descends in front of it inferiorly. We refer 

 to the article on the muscles of the thigh for a 

 further account of this muscle, its relations in 

 the upper part of the thigh, and its actions. 



Psoas parvus, (prelombo-pubien). This 

 muscle is similar to the psoas magnus in 

 course and position. It is very much elongated, 

 its fleshy portion being small and tapering. Su- 

 periorly it is attached to the body of the first 

 lumbar vertebra, and to the intervertebral sub- 

 stance between it and the last dorsal, and 

 sometimes to the body of the last dorsal ver- 

 tebra. The fleshy belly soon ends in a flattened 

 tendon, which descends obliquely downwards 

 and outwards over the anterior surface of the 

 psoas magnus, and at its inferior extremity ex- 

 pands considerably, and is inserted along the 

 linea ilio-pectinea near the junction of the 

 ilium and pubis. An expansion from the 

 margins of this tendon becomes united on the 

 outside to the fascia iliaca, and on the inside 

 to the internal portion of the same fascia which 

 covers the great psoas, and passes beneath the 

 iliac vessels to become united at the brim of 

 the pelvis to the pelvic fascia. 



We must not omit to state that the crura of 

 the diaphragm, as they descend over the bodies 

 of the lumbar vertebrae, (see DIAPHRAGM,) may 

 be regarded as entering into the formation of 

 the posterior wall of the abdomen. The inferior 

 wall of the abdomen is not devoid of muscle, 

 although those muscles can exercise very little, if 



* Vid. Haller Icon. Scpti Transversi. Op. Minora, 

 torn. 1. 



any influence upon the contents of the cavity. 

 The iliac fossa affords a large surface for the 

 attachment of one of the principal muscles 

 connecting the thigh with the trunk. This 

 muscle is named 



Iliacus internus, (iliaco-trochanterien.) This 

 muscle fills up the iliac fossa, to the whole of 

 whose concavity as well as to its margin, and 

 the two anterior spinous processes of the ilium 

 and the interval between them, its fibres are 

 attached. From these several points of origin 

 the fibres converge to form a thick and 

 broad belly, which passes over the upper part 

 of the acetabulum and horizontal ramus of the 

 pubis, filling up the external portion of the 

 space between that bone and Poupart's ligament ; 

 and it is inserted, as we have already observed, 

 into the outer margin of the tendon of the 

 psoas magnus, which is for that reason gene- 

 rally described as the common tendon of the 

 psoas and iliacus. The anterior surface of this 

 muscle is traversed by two of the external 

 branches of the lumbar plexus (inguino-cuta- 

 neous), and the anterior crural nerve passes 

 between its internal margin and the psoas 

 magnus. 



The superior wall of the abdomen is entirely 

 formed by the muscular vault of the diaphragm, 

 which by its contraction and relaxation exer- 

 cises a considerable influence on the abdominal 

 contents, and causes very obvious changes in the 

 form of the cavity. The concavity of this vault 

 is towards the abdomen, and is greater on the 

 right side than on the left, in consequence, as 

 it is said, of the presence of the liver on that 

 side. It is through the several openings in this 

 wall that a communication is established be- 

 tween the thorax and abdomen. The largest of 

 these openings are, that on the right side, 

 which is completely tendinous, for the passage 

 of the vena cava; the opening for the oeso- 

 phagus; and that for the aorta; in addition 

 to these there is a small one behind the 

 centre of the xiphoid appendix formed by a 

 divarication of the anterior fibres of the dia- 

 phragm, through which the cellular tissue of 

 the anterior mediastinum communicates with 

 the abdominal subserous tissue. There are, 

 moreover, openings for the transmission of the 

 splanchnic nerves, and the continued trunks of 

 the sym pathetics, as well as of branches of the 

 phrenic arteries and nerves, and the abdominal 

 branches of the internal mammary. The par- 

 ticular description of this muscle will be given 

 under the article DIAPHRAGM. 



4. The next element which enters into the 

 formation of the abdominal parietes is a fibro- 

 cellular expansion, which, varying in density 

 in different situations, lines the whole internal 

 surface of the muscular walls. It is strongest 

 and exhibits most of the real fibrous character 

 in the iliac region on the anterior wall, and 

 over the iliac fossa in the inferior. In the 

 former situation it has received the name of 

 fascia transversalis, which was applied to it by 

 Sir A. Cooper in consequence of its close con- 

 nexion with the transversalis muscle : in the 

 latter, it is called the fascia iliaca, from its 

 connexion with the iliac fossa and muscle. 



