Fig. 205. Innervation of the Skin and Muscles of the Lower Limb 

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



TJie preliniinarY remarks made in connection will) J^io. 204 a[>plv to tin's fiiriire. Tlie boundary 

 line (difficult to define} between the Trunk and the Limb lias not been especially indicated but 

 the continuation of the A.xial Line is shewn in this figure. This line runs uptvards on the 

 back of the thigh to the Crest of the Ilium and heloiv, after encircling the Inner Malleolus, it 

 runs on the posterior aspect of the leg to reach the inner side of the thigh. On the back of the 

 limb the distribution is still more romplicatcd than on the anterior asfn-ct, because the dorsal 

 neroes of the Plexus enter in, and the neii'es of the muscles of the Gluteal Region haiie to be 

 divided into a Dorsal and a Ventral Group. 



Obturator Intermis Muscle, Gemelli and Quadratus Femoris Muscles belong to 

 the Flexor Group : to the Extensor Group belong, in front the Psoas Group, behind the 

 Gluteal Muscles, Tensor of the Fascia of the Thigh and the P3Tiformis. 



The following is the segmental relation ; 



Obturator Intemus 5. I. 11. (Ill), Gemellus Superior 5. I. II. (Ill), Quadratus 4. 

 5. I. Gemellus Inferior .4. 5. I. (so that the first two and the last two go together). 



Psoas and Psoas Minor i. 2. 3. (4), Iliacus 2. 3. 4. belong to the Extensor Group. 



Gluteus Maximus is supplied by 4. 5. I. II. Medius and Minimus b}- 4. 5. I. 

 Tensor of the Fascia of the Thigh 4. 5. I. Iliac Portion of the Quadratus Lumborum 

 I. 2. 3. (4). 



The Motor part of the Internal Popliteal supplies the Muscles of the Thigh, Leg 

 and Foot: Long Head of Biceps 4. 5. I (or according to Boi.k I and II); Semitendinosus 

 and Semimembranosus 4. 5. I; Adductor Magnus (hamstring portion) (3) 4. (and 5). To 

 the Superficial Muscles of the Calf and the Popliteus 4. 5. I (II) are generally accepted: 

 for the deep Flexors 5. I. (II). The terminal branches contain 5. I. II, the Internal Plantar 

 chiefl}' 5. I, the External mostly I and II. 



The motor fibres of the Obturator Nerve (2. 3. 4.) are divided as follows: — 

 Obturator Externus 3 and 4. Adductor Magnus (2) 3 and 4. Adductor Brevis 2. 3. 4. 

 Adductor Longus 2 and 3. Pectineus (exceptionally) 2. 3. Gracilis 2. 3. (and 4). 



Sensory part : — the Small Sciatic Nerve is composed of I. II and III ; Internal 

 Popliteal Nerve I and II and its continuation also I and II, on the sole of the foot the 

 Internal Plantar 5 and I, the External I and II. The Cutaneous Fibres of the Obturator 

 Nerve are like the motor fibres derived from 2. 3 and 4. 



Over the Sacrum the Dorsal Branches of the Sacral Nerves and the Coccygeal 

 Nerve must be mentioned. They are chiefly derived from II and III (yellow). As 

 other nerves take part in the supply of this area, the other colours Green, Blue and 

 Red for the Coccygeal Nerve should have been put in. 



The red colour (indicative of the ist segment of a new plexus) has been omitted 

 to avoid complexity in the figure. 



On the outer side of the Hip it is necessary to remember the Ilio-hypogastric 

 superficial to the Fascia covering the Gluteus Medius Muscle (Schwalbe). 



