THE RABBIT. 



339 



third sacral nerves, and giving oif branches to the leg 

 and hip. 



Three chief nerves arise from the lumbo-sacral plexus : (a) the crural 

 nerve, passing out ventral to the pelvis and supplying the extensor 

 (anterior) muscles of the thigh : (i) the obturator nerve, passing along 

 the inner edge of the pubis and through the obturator foramen : and (c) 

 the sciatic nerve, the largest of the three, passing out between the 

 ischium and the sacrum and going mainly to the flexor muscles.^ 



L. Remove the skin from the back and limbs, and make 

 out the following muscles : ^ 



390. The dorso-lumbar fascia, a strong sheet of 

 connective tissue which covers all but the most superficial 

 muscles of the back : it is continuous in front with the 

 cervical fascia. 



391. The trapezius (Fig. 65, A, fe), a thin superficial 

 sheet of muscle extending over a great part of the dorsal 

 aspect of the cervical and thoracic regions : it arises in the 

 middle dorsal line from the cervical and thoracic fasciae : the 

 fibres of its anterior part pass backwards and outwards, and 

 are inserted into the metacromion (§ 81), those of its 

 posterior portion pass forwards and somewhat outwards, and 

 are inserted into the dorsal half of the spine of the scapula. 



392. The latissimus dorsi (Id), an extensive sheet of 

 muscle arising partly from the dorso-lumbar fascia, partly 

 from the three posterior ribs by as many triangular slips or 

 digitations, which fit between or interdigitate with 

 similar slips of the external obUque (§ 139) : in its posterior 

 part it is united with and scarcely distinguishable from the 



1 If the muscles of the leg are to be dissected in the same specimen, 

 the tracing of these nerves must be deferred. 



2 It is advisable to have another specimen, well hardened in alcohol, 

 for the muscles, as many of those described will have been destroyed by 

 the previous dissection, 



Z 2 



