540 SURGICAL APPLIED ANATOMY. [Chap. xxin. 



during delivery. The muscles implicated are the 

 adductors, gracilis, pectineus, and external obturator. 

 The patient is unable to press the knees together, or 

 to cross the legs. Rotation outwards is difficult, arid 

 sensation is affected in the skin supplied. 



Paralysis of the internal popliteal nerve. 

 There is inability to extend the ankle and to flex the 

 toes (flexor longus digitorum, flexor proprius pollicis, 

 tibialis posticus, gastrocuemius, and soleus). The 

 patient is unable to stand upon the toes owing to loss 

 of function in the two last-named muscles. The 

 power of adducting the foot and of raising its inner 

 border is impaired (tibialis posticus), and lateral move- 

 ments in the toes are lost owing to paralysis of all the 

 'small muscles of the sole. Sensation is impaired over 

 the plantar aspect of the toes, the sole, and in part of 

 the lower half of the back of the leg. 



In paralysis of the external popliteal nerve 

 the action of the muscles on the front of the leg is 

 lost. The foot hangs down and the toes catch the 

 ground in walking. The foot can be neither flexed 

 nor abducted (extensor communis digitorum, extensor 

 proprius pollicis, peroneal muscles). Adduction is im- 

 perfect, owing to paralysis of the tibialis anticus. 

 Extension of the toes is only possible to the slight 

 extent effected by the interossei. The arch of the foot 

 becomes flattened owing to loss of the support furnished 

 by the peroneus longus. Sensation is impaired over 

 the front and outer side of the leg and on the dorsum 

 of the foot, and also some part of the back of the leg, 

 owing to paralysis of the communicans peronei. 



When the great sciatic nerve is paralysed 

 there will be, in addition to the loss of function in the 

 two preceding nerves, an inability to flex the knee, 

 owing to paralysis of the hamstrings, while rotation 

 of the limb may be impaired by loss of power in the 

 quadratus femoris and obturator intei-nus. 



