Muscles of the Arm. 



315 



AI. triceps 

 (cut through 



obliquely) 

 Epicondylus 



medialis ^^ 

 Bursa iiitra- 



tendiuea 



olecrani 



Bursa sub- 

 tendinea 

 olecrani 



Bursa sub- '- 

 cutanea 

 olecrani 



M. 



anconaeus 



M. flexor 



carpi 



ulnaris 



360. Muscles of 

 the right forearm 



(deep layer), 



viewed from behind. 



(The mm. extensores carpi, digitorum 



communis and digiti V ])roprius have 



been removed.) 



M. extensor poUieis lou^us 



(0. T. extensor secundi internodii 

 pollicis) (see also Figs. 357 359 

 and 361). Form: long-spindleshaped. 

 Position: ulnarward from and be- 

 hind the two preceding muscles, im- 

 mediately upon the ulna and radius, 

 covered by the same muscles as are 

 they. Origin: facies dorsalis ulnae 

 and membrana interossea. Inser- 

 tion: the fibers go over into a long 

 tendon, which passes obliquely behind 

 the tendons of the ram. extensores 

 carpi radiales through the third com- 

 partment of the lig. carpi dorsale and 

 then tothe base of the second phalanx 

 of the thumb, partly also fused with 

 the fendon of the m. extensor pollicis 

 brevis. A c t i o n : it extends the thuml) 

 and draws it backward. Innerva- 

 tion: ramus profundus n. radialis. 



M. extensor indieis proprius 

 (0. T. extensor indieis) (see also 

 Fig. 359). Form: oblong - spindle- 

 shaped. Position: ulnarward from 

 and behind the preceding nuiscle, im- 

 mediately upon the ulna, covered by 

 the mm. extensor digiti V pro]n'ius, 

 extensor digitorum communis and ex- 

 tensor carpi ulnaris. Origin: facies 

 dorsalis ulnae and membrana inter- 

 ossea. Insertion: the fibers con- 

 verge to form a flat tendon which 

 goes in common with the tendons of 

 the m. extensor digitorum communis 

 through the fourtli compartment of 

 the lig. carpi dorsale and then fuses 

 with the tendon of this muscle that 

 goes to the index finger. Action: 

 it extends the index finger. Inner- 

 vation: n. interosseus dorsalis of 

 the n. radialis. 



Bursa subcutauea olecrani, 

 very frecpient. ujiun the olecranon. 



Bursa intratendinea olecrani, 

 very ft-equent, in the tendon of the 

 ra. triceps. 



Bursa sul)tendinea olecrani, 

 jccasional, in front of the tendon 

 of the m. triceps. 



Bursae subcutaneae epicondyli | humeri] late- 

 ralis et epicondyli medialis (not shuwn in figure), 

 the former occasional, the latter more frequent in 

 the adult, upon the c*responding epicondylus humeri. 



- Humerus 



epicondylus lateralis 



Origin of the 

 m. extensor 

 carpi ulnaris 



__M. supinator 



liadius 



jM. abductor 



pollicis longus 



M. extensor 

 pollicis iongus 



rina 



M. extensor 

 indieis proprius - 



Compartment for the 

 mm. extensor digitorum 

 communis and extensor - 

 indieis ]>roprius 



Ligainentum carpi dorsale 



Compartment 



for the ra. extensor- 



digiti V proprius 



M. extensor 

 jiollicis brevis 



Compartment 

 for the m. extensor 

 carpi radialis longus 



Compartment 

 for the lu. extenso: 

 carpi radialis brevi: 



Bursa 



m. extensoris 



, carpi radialis 



brevis 



M. extensor 

 - carpi radiali: 

 brevis 



Ossa 

 metacarpalia 



