374 



DISSECTION OF THE ABDOMEN. 



Obturator 

 in the 

 abdomen ; 



ends in the 

 thigh ; 



occasionally 

 an accessory 

 branch. 



Sympathe- 

 tic cord in 

 the abdo- 

 men 



joins that 

 in thorax ; 



has four or 

 five ganglia 



branches to 

 the spinal 

 nerves, 



and to the 

 viscera. 



Last dorsal 

 nerve : 



course to 

 wall of the 

 abdomen ; 



branch to 

 muscle. 



Lumbar 

 arteries five 

 in number 

 on each 

 side: 



of which varies much, is distributed around the upper part of that 

 vessel. 



6. The obturator nerve (ri) is distributed chiefly to the abductor 

 muscles of the thigh (p. 164). Arising in front of the anterior crural 

 from the second, third, and fourth nerves in the plexus (sometimes 

 not from the second), it makes its appearance at the inner border of 

 the psoas near the sacro-iliac articulation. Escaped from beneath the 

 muscle, the nerve crosses the side of the pelvis below the external 

 iliac, but above the obturator vessels, and enters the thigh through 

 the aperture at the top of the thyroid foramen. Occasionally the 

 the obturator gives origin to the following branch : 



The accessory obturator nerve (I) arises from the trunk of the 

 obturator, or from the third and fourth nerves of the plexus. Its 

 course is along the inner border of the psoas, beneath the investing 

 fascia, and over the hip-bone to the thigh, where it ends by joining 

 the obturator nerve, and supplying the hip-joint (p. 163). 



GANGLIATED CORD OF THE SYMPATHETIC (fig. 140, o). The 

 lumbar part of the gangliated cord of the sympathetic is continuous 

 with the thoracic part beneath the internal arched ligament of the 

 diaphragm. It lies on the front of the spinal column, along the 

 inner border of the psoas muscle, and is somewhat concealed on the 

 right side by the vena cava, on the left by the aorta. The cord has 

 four or five oval ganglia, which supply connecting and visceral 

 branches. 



Connecting branches. From each ganglion two small branches are 

 directed backwards along the centre of the body of the vertebra, 

 with the lumbar artery ; these unite with one or two spinal nerves 

 near the intervertebral foramen. The connecting branches are long 

 in the lumbar region, in consequence of the gangliated cord being 

 carried forward by the psoas muscle. 



Branches of Distribution. Most of the internal branches throw 

 themselves into the aortic and hypogastric plexuses, and so reach 

 the viscera indirectly. Some filaments enter the vertebrae and their 

 connecting ligaments. 



LAST DORSAL NERVE (fig. 138, p. 363, and fig. 140, e}. The 

 anterior primary branch of the last dorsal resembles the intercostal 

 nerves in its distribution, but differs from them in not being con- 

 tained in an intercostal space. Lying below the last rib, the nerve 

 is directed outwards across the upper part of the quadratus lumborum, 

 but beneath the external arched ligament and the fascia of the 

 quadratus. At the outer border of that muscle it perforates the 

 middle layer of the fascia lumborum, and enters the wall of the 

 abdomen, where it ends in an abdominal and a lateral cutaneous 

 branch (pp. 110 and 274). The first lumbar artery accompanies it. 



Near the spine it furnishes a small branch to the quadratus muscle ; 

 and it may communicate by means of this with the first lumbar 

 nerve. 



The LUMBAR ARTERIES of the aorta are furnished to the back, 

 the spinal canal, and the wall of the abdomen : they resemble 



