764 



SPINAL NERVES. 



that muscle and the cruraeus, and, in company 

 with the descending branches of the external 

 circumflex artery, enters its inner aspect by 

 two or three divisions, having previously given 

 off a superficial articular branch. This filament, 

 the analogue of the corresponding branch of 

 the vastus internus, creeps beneath the su- 

 perficial muscular fibres, and near the pa- 

 tella becomes cutaneous, some of the ter- 

 minal filaments passing behind the outer part 

 of the ligamentum patella, others over the 

 patella, where they are lost in the skin and 

 periosteum. 



The saphasnus nerve ("tro^s, manifest), the 

 most internal of the deep-seated branches, 

 and arising behind and external to the mid- 

 dle cutaneous, is the largest branch of the 

 crural. It passes downwards and outwards 

 towards the femoral artery, and, about two or 

 three inches below Poupart's ligament, en- 

 ters its sheath. The nerve first lies outside 

 and behind the artery ; but a little before the 

 vessel enters Hunter's canal it gets anterior 

 to it. During the course of the artery down- 

 wards and outwards, to enter the ham, the 

 nerve inclines forwards and inwards, and quits 

 the canal, in company with the anastomotic ar- 

 tery, a little above the level at which the fe- 

 moral vein and artery pass out. It now follows 

 the course of the sartorius lying behind it, to 

 the inner condyle, and one or two inches above 

 the head of the tibia is placed between that 

 muscle and the gracilis, and gives off, before 

 continuing its course, the cutaneous tibial or re- 

 flected branch. This nerve first runs parallel 

 for a short distance with the tendons of the 

 two muscles, then sweeps downwards, for- 

 wards, and slightly upwards over the fascia 

 covering them and their tendinous expansions, 

 and across the spine of the tibia to the skin 

 at the upper and outer part of the leg, about 

 two or three inches below the head of the 

 tibia, communicating above with the internal 

 cutaneous. 



The continuation of the nerve, or what 

 may be termed the posterior trunk, inclines 

 slightly backwards from between the tendon 

 of the sartorius and gracilis, and on a level 

 with the knee-joint is a little to the inner 

 and back part of the tendon of the latter. 

 Having received its connection with the cu- 

 taneous branch of the obturator, it passes in 

 company with the saphaena vein into the re- 

 gion of the leg, inclining slightly forwards to 

 the back part of the inner border of the tibia. 

 Having supplied the integuments at the upper, 

 inner, and anterior part of the leg, it inclines 

 slightly backwards about its middle, sends 

 filaments to communicate with the continu- 

 ation of the cutaneous branch of the obturator 

 at the posterior part of the leg. It then again 

 inclines forwards, and terminates about three 

 or four inches above the ankle in two 

 branches. The anterior terminal, the smaller 

 of the two, supplies the skin at the lower 

 sixth of the inner and front part of the 

 leg, and over the front of the ankle joint, 

 a few of the branches entering the articu- 

 lation. The posterior terminal, apparently the 



continuation of the trunk, supply the inte- 

 guments over the inner malleolus, upper, inner, 

 and back part of the foot. 



The saphsenus nerve not un frequently, in its 

 course in the thigh, in company with the fe- 

 moral artery, gives off, at a variable height, 

 usually however at the lower fourth of the 

 leg, a small branch corresponding more or less 

 with the distribution of the outer division of 

 the accessory saphaenus. The internal sa- 

 phaenus nerve first lies behind the correspond- 

 ing vein ; then in front of it to the middle third 

 of the leg, when it again is placed behind it : 

 an inch or two before it divides into its ter- 

 minal branches, it is again anterior to it, the 

 latter passing over in front, and the other 

 behind. 



The obturator nerve, derived from the third 

 and fourth, and sometimes also from their 

 internal intercommunicating branch, is much 

 smaller than the anterior crural, and rounded. 

 It perforates the inner border of the psoas, 

 along which it is conducted to the pelvis, 

 a little below the level of which it runs to 

 between the external and internal iliac ves- 

 sels. It then passes obliquely behind the ex- 

 ternal iliac vein, crossing it at a very acute 

 angle, and reaches the obturator foramen in 

 company with, and above, the obturator artery. 

 It passes through this foramen into the 

 thigh, and terminates by dividing into super- 

 ficial and deep divergent muscular branches, 

 situated behind the pectinaeus and adductor 

 longus. Soon after its origin a small nerve, 

 the accessory obturator, is occasionally ob- 

 served to proceed from the outer part of the 

 trunk. It passes in company with the femo- 

 ral vein, anterior and internal to it, beneath 

 the femoral arch, over the horizontal ramus 

 cf the pubis, and external to the pectinaeus. 

 It is then directed a little inwards, and divides 

 into several branches, some of which -enter 

 the joint through the anterior part of the cap- 

 sular ligament ; others supply the posterior 

 surface of the pectinaeus, and* the remainder, 

 as the continuation of the nerve, terminate by 

 communicating either with the upper part of 

 the trunk of the obdurator itself, or with the 

 branch of the nerve destined for the adductor 

 longus. 



The obturator nerve, in passing through the 

 subpubic canal, gives off two or three branches 

 to the obturator externus muscle : one pene- 

 trating its upper edge, the others its anterior 

 surface. Some articular filaments are also 

 sent off in this direction, and accompany 

 some of the branches of the inferior division 

 of the obturator artery, beneath the trans- 

 verse ligament to the hip-joint. The relation 

 of these filaments as to size and numbers, how- 

 ever, is not constant, being in the inverse pro- 

 portion to the size and number of branches 

 given off from the accessory obturator, which 

 is not unfrequently absent. 



From the superficial branch is given off a 

 long filament internally to the gracilis muscle, 

 which runs for about two inches along the 

 outer surface of the muscle before entering it, 

 another to the posterior surface of the pec- 



