Charles R. Bardeen Bis i) 
b. Nerve Variation. 
1. Variation in the Origin of the Nerves to the Obturator Internus and 
Quadratus Femoris Muscles. 
In Table XXIII the frequency of variation in the origin of the nerves 
to these muscles is shown. The nerve to the quadratus femoris muscle 
arises usually from the lumbo-sacral cord and the 1st sacral nerve (24th, 
25th, and 26th spinal nerves.) Not infrequently the 25th spinal nerve 
is the most distal nerve to furnish fibres to this nerve. This condition 
occurs usually in the more proximal forms of plexus. In the more distal 
forms of plexus the 25th and 26th spinal nerves furnish the fibres for 
this muscle. 
TABLE XXIV. 
Number of Instances = i 
Association of the Branches Distributed to the Obturator iecenivon at | Ze 
Internus, Gemelli, and Quadratus Femoris Muscles. the Bie 
BoC (Deal seaieG 
Branch 1, to Mm. obturator int. and gemellus sup. | | 
Branch 2, to Mm. quadratus femoris and gemellus inf. !® per hee eos ak | | 13 
ss | 
| 
Branch 1, to M. obturator int. | | | 
Branch 2, to M. gemellus sup. 1 | | | 1 
Branch 3, to Mm. quadratus femoris and gemellus inf. |b oa | 
| | I> 
Branch 1, to M. obturator int. 
Branch 2, to Mm. quadratus femoris and both gemelli. | 3/ 3 
Branch 1, to Mm. obturator int. and gemellus sup. 
Branch 2, to M. quadratus fem., gemellus inf., and adductor 2 2 
magnus. 
| 
Total Number. ' 1} 8] 4] 2 | Wea. 18 
| { | 
“ Hor types of plexus see preceding table. 
47 Tn one instance a branch was traced to the M. obturator externus. 
The nerve to the obturator internus muscle arises usually from the 
(24th) 25th, 26th, and 27th spinal nerves. Rarely the 26th spinal nerve 
is the most distal nerve to furnish fibres to it and occasionally in distal 
forms of plexus the 28th spinal nerve may do so. 
It is difficult to trace these nerves back to their roots of origin. The 
charts on which these tables are based are those recording the most ac- 
curate dissections of these nerves. They are, however, of positive rather 
than negative value and it is possible that a more extensive origin than 
here indicated was present in some of the plexuses here recorded. 
