DISSECTING MANUAL. 



teriorly) lumbar vertebra, by the crura, and arcuate ligaments. 

 Insertion; central tendon. The crura are two fibro-muscular 

 bundles arising from the front of the upper three lumbar ver- 

 tebrae on the right side, from the upper two on the left. After 

 ascending they descussate (right cms in front of the left) in 

 the midline in front of the aorta, encircle the oesophagus, de- 

 cussate again and join the central tendon. There are five 

 arcuate ligaments; the middle one is a fibrous arch connecting 

 the crura in front of the aorta and giving fibres to the lower 

 decussation; the internal one is a thickened edge of psoas 

 fascia connecting the body of the first lumbar vertebra with 

 its transverse process, across the Psoas; the external is the 

 thickened edge of the anterior layer of the lumbar fascia lying 

 over the Quadratus lumborum, and connecting the last rib 

 with the first lumbar transverse process. The central tendon 

 has three lobes: right (the largest), left (the smallest), and 

 anterior, or middle; it lies anteriorly. [423] 



Openings. The aortic, under the middle arcuate ligament, 

 transmits the aorta, vena azygos major, and thoracic duct. 

 The oesophageal transmits the oesophagus and both vagi. The 

 foramen guadratum, in the right lobe of the central tendon, 

 transmits the inferior vena cava and branches of the right 

 phrenic nerve. [424] 



Superficial Muscles of Back. 



Trapezius. Origin; inner third of superior curved line of 

 occipital; external occipital protuberance; ligamentum nu- 

 chae; spines of seventh cervical and all dorsal vertebrae and 

 corresponding supraspinous ligaments. Insertion ; (upper part) 

 outer third of posterior surface of clavicle ; (middle part) inner 

 side of acromion process and whole upper border of spine of 

 scapula; (lower part) tuberosity at the base of scapular spine, 

 by a flat tendon, with a bursa underneath. [318] 



Latissimus Dorsi. Origin ; vertebral aponeurosis (posterior 

 layer of lumbar fascia), through which it is attached to the 



[116] 



