144 Anatomy of the Rabbit. 



IX. THE POSTERIOR LIMB. 



Dissection on the side opposite to that of injection. The dissection 

 is largely a muscular one; to be conducted in the same way as in the 

 anterior limb. The corresponding muscle groups should be compared 

 with respect to the difference in orientation of the equivalent segments. 



1 . Muscles arising from the ventral surface of the posterior thoracic 

 and lumbar vertebrae and inserted on the pelvic girdle, or on the lesser 

 trochanter of the femur. These muscles are chiefly distinguished by 

 their vertebral position, on account of which and the fixed condition of 

 the pelvic girdle they combine the characters of vertebral and appen- 

 dicular muscles. 



(a) The psoas minor. Origin : Bodies of the four posterior 

 lumbar vertebrae. Insertion: Pecten of the pubis. The 

 flat, pointed tendon forms a square cross with a dorsal 

 (sacral) continuation of the inguinal ligament, which is 

 stretched transversely from the middle of. the inguinal liga- 

 ment to the centre of the body of the first sacral vertebra, 

 and on which it is also inserted. 



It is necessary to divide the inguinal ligament and reflect its sacral 

 continuation, together with the tendon of the psoas minor. 



(b) The psoas major. Origin: Internal surfaces of the bases of 

 the last three ribs and bodies of the corresponding thoracic 

 vertebrae ; also the lumbar vertebrae. Insertion : Lesser 

 trochanter. 



(c) The iliacus. Origin: Bodies of the last lumbar and first 

 sacral vertebrae, extending to the sacroiliac union. Inser- 

 tion: With the psoas major on the lesser trochanter. The 

 two muscles together form the iliopsoas. 



The lumbar portion of the lumbosacral plexus, beginning with the 

 fourth lumbar nerve, lies on the ventral surface of the psoas major 

 and between the latter and the iliacus. The fifth lumbar is the chief 

 root of the femoral nerve, (p. 149), the trunk of which may be traced 

 from a position between the two muscles distad over the dorsal 

 surface of the inguinal ligament to the medial surface of the thigh. 

 The remaining four nerves crossing the dorsal body^wall obliquely 

 are the twelfth thoracic and first three lumbar. 



The psoas major should be freed at its lateral margin and turned 

 toward the middle line, the fourth lumbar nerve being divided. 



(d) The quadratus lumborum. Origin: Bodies of the posterior 

 five thoracic vertebrae and the bases of the corresponding 

 five ribs; bodies and transverse processes of the lumbar 

 vertebrae. Insertion : Triangular processes of six Itimbar 

 vertebrae and the posterior ventral angle of the iliac wing, 

 together with the adjacent portion of its medial surface. 



2. Muscles arising from the pelvic girdle and sacrum and inserted 

 on the femur, for the most part at its proximal extremity. 



The muscles of this group enclose the proximal portion of the femur 



