PERONEAL NERVE. 



431 



Fig. 194.f 



the posterior tibial artery ; it then becomes placed superficially to that 

 vessel, and at the ankle is again situated to its outer side ; in the lower 

 third of the leg it lies parallel with the inner border of the tendo 

 Achillis. 



The Branches of the posterior tibial nerve are three or four muscular 

 twigs to the deep muscles of the posterior aspect of the leg, the branch to 

 the flexor longus pollicis accompanies the fibular artery ; one or two fila 

 merits which entwine around the artery and then terminate in the integu- 

 ment ;* and two or three plantar cutaneous branches which pass down- 

 wards upon the inner side of the os calcis, and are distributed to the 

 integument of the heel. 



The INTERNAL PLANTAR NERVE, larger than the external, crosses the 

 posterior tibial vessels to enter the sole of the foot, where it lies in the 

 interspace between the abductor pollicis and flexor 

 brevis digitorum ; it then enters the sheath of the 

 latter muscle, and divides opposite the bases of the 

 metatarsal bones into three digital branches ; one to 

 supply the adjoining sides of the great and second 

 toe ; the second the adjoining sides of the second 

 and third toe ; and the third the corresponding 

 sides of the third and fourth toes. This distribution 

 is precisely similar to that of the digital branches of 

 the median nerve. 



In its course the internal plantar nerve gives off 

 cutaneous branches to the integument of the inner 

 side and sole of the foot ; muscular branches to the 

 muscles forming the inner and middle group of the 

 sole ; a digital branch to the inner border of the 

 great toe ; and articular branches to the articula- 

 tions of the tarsal and metatarsal bones. 



The EXTERNAL PLANTAR NERVE, the smaller of 

 the two, follows the course of the external plantar 

 artery to the outer border of the musculus accesso- 

 rius, beneath which it sends several large muscular 

 branches to supply the adductor pollicis and the 

 articulations of the tarsal and metatarsal bones. It then gives branches to 

 the integument of the outer border and sole of the foot, and sends forward 

 two digital branches to supply the little toe and one half the next. 



Tl PERONEAL NERVE is one-half smaller than the popliteal ; it passes 

 downwards by the side of the tendon of the biceps, crossing the inner 

 head of the gastrocnemius and the origin of the soleus, to the neck of the 



* It is extremely interesting, in a physiological point of view, to observe the mode of 

 distribution of these filaments. I have traced them in relation with several, and I have 

 no doubt that they exist in connexion with all the superficial arteries. They seem to be 

 the direct monitors to the artery of the presence or approach of danger. 



f- A view of the termination of the posterior tibial nerve in the sole of the foot. 1 . In- 

 side of the foot. 2. Outer side. 3. Heel. 4. Internal plantar nerve. 5. External plantar 

 nerve. 6. Branch to flexor brevis. 7. Branch to outside of little toe. 8. Branch to space 

 between 4th and 5th toes. 9, 9, 9. Digital branches to remaining spaces. 10. Bran'-b 

 to m>-nal side of great oe. 



