1898.] ANATOMY or PEDETBS CAFFEE, 889 



only ; the lower supplies chiefly the teres major, but, as in man, 

 gives a small branch to the lower part of the subscapularis. 



Lumbo-Sacral Plexus. — The nerves which enter into this plexus 

 are the 4th, 5th, 6th, and 7th lumbar, and the 1st and 2nd sacral. 

 The genito-crural nerve rises from the 4th lumbar, appears on the 

 surface of the psoas, and passes down to the middle of Poupart's 

 ligament, where it is distributed to the skin of the groin. 



The external cutaneous rises from the fourth and fifth lumbar 

 nerves and pursues its usual course to the outer side of the thigh ; 

 this it supplies, as well as the platysma, which is here well 

 developed. The anterior crural comes from the fifth and sixth 

 lumbar and appears on the outer side of the psoas. At Poupart's 

 ligament it divides into a superficial and a deep division. The 

 superficial supplies the skin of the front and inner side of the thigh, 

 and, owing to the feeble development of the ilio-tibialis (sartorius), 

 the long saphenous is part of this division. The long saphenous 

 supplies the inner side of the leg as far as the foot, but it lies con- 

 siderably anterior to the long saphenous artery. The deep division 

 of the anterior crural supplies the deep muscles of the front of 

 the thigh. 



The obturator nerve also rises from the fifth and sixth lumbar, 

 and passes through the obturator foramen to supply the obturator 

 externus and adductors. 



The great sciatic nerve conies from the sixth and seventh lumbar 

 and the first sacral ; before it leaves the sciatic notch it gives off a 

 nerve to the hamstrings and about the middle of the thigh an 

 extra branch to the fiexor cruris lateralis (biceps). In the lower 

 half of the thigh it divides into external and internal popliteal, but 

 these nerves, as Paterson points out, are capable of being separated 

 quite up to their commencement. When this was done it was 

 found that both of them, as well as the nerve to the hamstrings, 

 obtained fibres from the sixth and seventh lumbar and first sacral 

 nerves ; the fibres of the nerve to the hamstrings were most 

 ventral, then those of the internal popliteal, while the external 

 popliteal fibres were most dorsal. 



The nerve to the hamstrings breaks up into five branches ; two 

 of these enter the semitendinosus, two the flexor cruris laterahs 

 (biceps), while the fifth supplies the semimembranosus and pre- 

 semimembranosus. It will thus be seen that the flexor cruris 

 lateralis has three separate nerves entering it. 



Before dividing into external and internal popliteal the great 

 sciatic nerve gives off two cutaneous branches : one of these 

 supplies the skin on the outer side of the leg ; the other one, 

 corresponding to the short saphenous of human anatomy, runs 

 dovni the back of the calf and supplies the outer side of the foot. 

 It has already been said that the great sciatic divides in the lower 

 half of the thigh, and of its two branches the internal popliteal 

 is considerably the larger; this branch supplies the superficial and 

 deep muscles of the calf, and is continued on as the posterior tibial 

 to the sole ; here it divides into internal and external plantar, the 



Puoc. ZooL. See— 1898, No. LIX, 59 



