FASCIA LUMBORUM. 357 



tory muscle ; or they may assist the pectoralis major in drawing the 

 movable trunk towards the humerus, as in the act of climbing. 



* Dissection. The latissimus is to be divided about midway between 

 the spines of the vertebrae aud the angle of the scapula, and the pieces are 

 to be reflected inwards and outwards. In raising the inner part of the 

 muscle, care must be taken not to destroy either the thin lower serratus 

 with which it is united, or the aponeurosis continued upwards from the 

 serratus. In the interval between the last rib and the iliac crest the latis- 

 simus is adherent to the aponeurosis of the transversalis abdominis muscle, 

 and should not be detached from it. 



* Parts covered by the latissimus. The latissimus dorsi lies on the 

 erector spinre, the serratus posticus inferior, and the lower ribs with their 

 intercostal muscles. As it rests on the angle of the scapula, it conceals 

 the teres major, and part of the rhomboid muscle. Its position to the 

 teres is worthy of note : at the angle of the scapula it covers the posterior 

 surface of the teres, but nearer the humerus it turns round the lower bor- 

 der, and is inserted in front of that muscle. Between the angle of the 

 scapula and the humerus the latissimus forms part of the posterior boundary 

 of the axilla. 



Dissection of fascia lumborum. After the latissimus dorsi has been 

 reflected, the dissector of the abdomen can look to the disposition of the 

 posterior tendon of the transversalis abdominis (fascia lumborum) between 

 the last rib and the innominate bone. 



In the spot referred to are portions of the external and internal oblique 

 muscles, left in the dissection of the wall of the abdomen. After the 

 removal of those muscles the aponeurosis of the transversalis muscle (fas- 

 cia lumborum) appears, and perforating it are two nerves one, the last 

 dorsal with an artery near the last rib : and the other, the ilio-hypogastric 

 with its vessels, close to the iliac crest. 



Two offsets are prolonged backwards from this fascia to the transverse 

 processes. To see the more superficial layer which passes beneath the 

 erector spinae to the apices of the processes, the latissimus dorsi is to be 

 cut through (both its aponeurosis and fleshy part) by a horizontal incision 

 directed outwards from the spinous processes, on a level with the third 

 lumbar vertebra. On raising the outer border of the erector spina 1 

 muscle which comes into view, the strong process of the fascia will be 

 apparent. 



After dividing transversely this first prolongation, another muscle (quad- 

 ratus lumborum) will be seen; and on raising its outer border the second 

 thin offset of the fascia will be evident on the abdominal aspect of that 

 muscle. 



The fascia lumborum (fig. 136, c ) is the posterior aponeurosis or tendon 

 of the transversalis abdominis muscle, and occupies the interval between 

 the last two ribs and the crest of the hip-bone. By its cutaneous surface 

 it gives attachment to the internal oblique muscle, and sometimes to the 

 external oblique. The last dorsal (*) and ilio-hypogastric (-) nerves, ac- 

 companied by vessels, pierce it in their course from the abdomen. From 

 the inner part of the aponeurosis two offsets are prolonged to the trans- 

 verse processes of the lumbar vertebra, and inclose the quadratus lum- 

 borum in a sheath. 



The more superficial of the two is the strongest ; it lies beneath the 

 erector spina? in this position of the body, and is connected to the apices 

 of the transverse processes, but it also fills the intervals between them : at 



