Fig. 204. Innervation of the Skin and Muscles of the Lower Limb 

 according to their Segmental Origin from the Cord : Anterior Aspect. 



Outlines modified after FAV's Atlas; Nen>e-siipplv after WiCIIMAMJV ivitji modifications stiggestea 

 bv Ziehen. In the text Arabic figures indicate the Lumbar, Roman the Sacral Segments. 

 As each plexus has only 5 segtnents the fundamental colours of the Spectrum Red, Orange, 

 Yellow, Blue and Green are employed. Black lines represent the boundary betiveen trunk 

 and limb and the so-called A.xial Line luhich, iiivisible in the thigh, appears at the outer side 

 of the leg ru7!7iing obliijuelv doivnwajds to the Internal Malleolus and encircling the latter. 



The Segmental Distribution of the Nerves in the Lower Extremity is more com- 

 plicated than in the Upper Limb. Li man the distribtition of both Motor and Sensory 

 Nerves has not been properly determined. This figure is intended to contrast the Cutaneous 

 Suj^ply with the Muscular. 



Naturally the Nerves are to be divided intu Dorsal or Extensor Nerves, and 

 Ventral or Flexor Nerv^es, the former being the Anterior Crural and External Popliteal, 

 the latter the Obturator and Internal Popliteal. Apart from these, special branches for 

 the Muscles of the Pelvic Girdle will (as well as the Flexor Nerves) be considered in tlie 

 next figure. In this figure onlv the Extensor Nerves will be described. 



The Anterior Crural Nerve corresponds more to the Musculo-Cutaneous than to 

 the Radial; this divides into a branch to the Iliacus (cf. Fig. 105), the Anterior Di\'ision 

 (mixed) which supplies the Sartorius and Pectineus, and the Posterior Division (also mixed) 

 which supplies the Quadriceps Extensor Group of Muscles. 



These muscles correspond to the following spinal segments, Pectineus 2 and 3 ; 

 Sartorius 2 and 3 : Rectus Femoris 2, 3 and 4 ; Vastus Internus 2 and 3 (and 4), Crureiis 

 (2) 3 and 4; Subcrureus 3 and 4; Vastus Externus 3 and 4. 



The Sensory Portion of the Nerve is formed by the Middle and Internal Cutaneous 

 (Anterior Divisions) and its communication to the Obturator Nerve, by the Long Saphenous 

 Nerve (Posterior Division). Of these, the former supply the thigh chiefly from 2 and 3, 

 the latter supplies the Leg and is formed from 3 and particularly 4. 



The External Cutaneous Nerve (a modified lateral branch of the Lumbar Nerves) 

 contains i, 2 and 3; its Posterior Branch may be a trochanteric branch; occasionally its 

 Anterior Branch contains the Crural Branch of the Genito-Crural (the internal twigs of 

 which also contain ventral elements). This nerve is not constant, neither is there any 

 constant relation between the fibres which it receives from 2, 3 and 4. 



The following remarks are made m connection with the incompletely studied 

 External Popliteal Nerve : — Motor part : Short Head of Biceps 5. I. (II). Long Peroneal 

 Muscle (4) 5. I. Short Peroneal Muscle 5. I. Long Extensor of the Toes 4. 5. I. Long 

 Extensor of the Big Toe (4) 5. I. Anterior Tibial 4. 5. (I). Short Extensor of the Toes 

 4. 5. I; The slip from the muscle to the Big Toe 4. 5. I. 



Sensorv part : On the outer side of the leg from above and in front, downwards 

 and backward, 5. I and II. 



At the foot (iNIusculo-Cutaneous and Anterior Tibial Nerve) 5. I and II. The 

 whole of the Dorsum of the Foot contains: on the inner side, according to Paterson, 

 3 and 4 ; on the Dorsum proper 4. 5. I ; on the outer .side, I and II. 



