MUSCULAR DISTRIBUTION. 353 



Posterior muscles of the arm and forearm. The triceps (7, 8 f), anconeus 

 (7, 8 f), supinator longus (6 c), and extensor carpi radialis longior ((>, 7 c) are 

 supplied by direct branches of the musculo-spiral nerve ; while the extensor carpi 

 radialis brevior (6, 7 c), the supinator brevis ((> c), and the other extensor muscles in 

 the forearm (7 c) receive their branches from the posterior interosseous division of 

 that nerve. 



Anterior muscles of the arm and forearm. The coraco-brachialis is supplied by 

 the seventh cervical nerve, and the biceps and brachialis anticus by the fifth and 

 sixth cervical nerves through the musculo-cutaneous trunk ; the brachialis anticus 

 likewise receives a twig frequently from the musculo-spiral nerve (6 c). The 

 muscles of the front of the forearm are supplied by the median nerve, with the 

 exception of the flexor carpi ulnaris and the inner half of the flexor profundus 

 digitorum, which are supplied by the ulnar nerve. The offsets to the pronator tere. 

 and flexor carpi radialis are derived from the sixth cervical nerve, those to the flexor 

 sublimis digitorum from the seventh and eighth cervical and first dorsal nerves, and 

 those to the flexor carpi ulnaris, flexor longus pollicis, flexor profundus digitorum and 

 pronator quadratus from the eighth cervical and first dorsal nerves. 



Muscles of the hand. The abductor, opponens, and outer head of the flexor 

 brevis pollicis are supplied by a branch of the median nerve (6, or 6 and 7 c). The 

 lumbricales (7, 8 c, 1 d) receive their branches, the outer two from the median, and 

 the inner two from the ulnar nerve. All the other muscles are innervated through 

 the ulnar from the eighth cervical nerve. 



5. To muscles of the lower limb. Muscles of the hip. The ilio-psoas is 

 supplied by the second and third lumbar nerves, the branches to the iliacus being 

 given off from the anterior crural. The gluteus medius and minimus and the tensor 

 vaginae femoris are innervated by the superior gluteal (4, 5 I, 1 s), and the gluteus 

 maximus by the inferior gluteal (5 I, 1, 2 s). The pyriformis (1, 2 s), quadratus 

 femoris and inferior gemellus (4, 5 /, 1 s), and obturator internus with the 

 superior gemellus (5 /, 1, 2 s), receive special branches from the sacral plexus. 

 The obturator externus is supplied by the obturator nerve (3, 4 I). 



Muscles of the thigh. The sartorius (2, 3 Z), pectineus (2, 3 /), and quadriceps 

 extensor cruris (3, 4 I) are supplied by the anterior crural nerve. The adductor 

 longus (2, 3 D, gracilis (2, 3, 4 /), adductor brevis (2, 3, 4 /), and adductor magnus 

 (3, 4 I) are supplied by the obturator nerve, but the adductor magnus likewise 

 receives a branch (4, 5 I) from the internal popliteal division of the great sciatic 

 nerve. The hamstring muscles are supplied by branches of the great sciatic nerve, 

 the semimembranosus (4, 5 /, 1 s), semitendinosus (5 I, 1, 2 s\ and long head of 

 the biceps (1, 2, 3 s), receiving their branches from its internal popliteal division, 

 and the short head of the biceps (5 /, 1, 2 s) from its external popliteal division. 



Anterior muscles of the leg and foot. The muscles in front of the leg, together 

 with the extensor brevis digitorum, are supplied by the anterior tibial nerve 

 (4, 5 ?, 1 s). 



The peroneus longus and Irevis are supplied by the musculo-cutaneous 

 nerve (4, 5 Z, 1 s). 



Posterior muscles of the leg. The gastrocnemius (1, 2 5), plantaris (4, 5 Z, 1 *), 

 popliteus (4, 5 /, 1 s), and soleus (5 /, 1, 2 s) are supplied by the internal popliteal 

 nerve, the last muscle receiving also a second branch (1, 2 s) from the posterior 

 tibial nerve. The flexor longus digitorum (5 /, 1 s), tibialis posticus (5 /, 1 s), and 

 flexor longus hallucis (5 /, 1, 2 s) derive their nerves from the posterior tibial. 



Plantar muscles. The flexor brevis digitorum, the abductor and flexor brevis 

 hallucis, and the innermost lumbricalis are supplied by the internal plantar 

 nerve (5 ?, 1 s) ; all the others, including the flexor accessorius and interosseous 

 muscles, are supplied by the external plantar nerve (1, 2s). 



